Tiger Avon Build Diary

Assembling Front Hubs and Brakes

2007-08-06T20:06:00.000Z

New Bits from Rally Design

As i've dicussed in another post, I really didn't want to be fitting completely standard front brakes to my Avon, the car is going to be used for a lot of track days, and i'd already seen how it ran out of brakes at Curborough spint circuit, courtesy of Bill Sollis in the Ultimate Kit car DVD. I am also quite concerned with the unsprung weight of the car, so I ordered a Wilwood brake pack(BK1P) and two aluminium hubs (RD752) from Rally Design. Both the aluminium lightweight calipers and the lightness of the aluminium hub design greatly reduce the corner weight of the car. The wilwood powerlite caliper weighs in at just under 1 kilo. Its a simple 4 piston caliper intended for formula cars or other cars of a low weight. Opening the box I was quite alarmed to find a 'for racing use only' sticker. Doing a bit of research it seems as though the caliper does not come equipped with piston dust seals. Although I spoke to several people who said they have run them for thousands of miles on road cars with no trouble. Occasional removal of the pads and a good clean out is all that is required.

I opted for Poly-matrix E pads. Looking at the graphs provided by Wilwood, they looked to give a good balance from cold to hot, staying fairly consistent with a longer wear rate than the Poly-matrix A race pads.

Fitting the Bearings to the Hubs

Quick trip to the local motor factors to get a QH bearing kit (P/N ####), these were quite reasonable at £24.00 for the pair. The kit contains an inner and out bearing and race, grease and split pin. I would have to reuse the wheel hub nut, castelated nut and washer, so I gave them a good cleaning up.

Fitting the bearing races to the hubs is a tricky business, requiring a special bearing tool to ensure the race goes in squarely, so I went to my local garage where I watched my friend Lea hit my lovely new shiny hubs with an unbelievable amount of force using a very large lump hammer! The bearing tool is simply a connical shaped press that fits inside the race and ensures even pressure is applied to push it squarely into the cavity in hub. Its important to go in square as if it doesn't it will distort the aluminium and excessive bearing wear will occur.
With the races in, fitting the bearings is a doddle. The next job is to pack the bearings full of grease, you can do this yourself by working the grease into the bearing with your fingers, however by far the better approach is to use a special gun. The bearing is fitted inside and then grease is crammed into it. Again this is important as excessive bearing wear will occur is it isn't properly lubricated.
Copious amounts of grease was crammed into the bearing cages. The inner seal is then gently tapped into place to prevent grease escaping past the hub and onto the upright.

Fitting the Wheel Studs

Well now this was hard work. Everything I had read said I should be able to pop the stud into the hole and use a wheel nut to lock it into position. Well its a nice theory but mine were too tight to budge. So I spent and hour with a big hammer, balancing the hub on two blocks of wood battering them into position. The wheel studs were longer than the standard Cortina studs, this is because I was planning to fit alloy wheels, the Cortina studs are too short so not enough of the nut is on the stud, the SVA man understandably gets a bit upset at this. Again rally design to the rescue with some 47mm studs (SS36).

Fit the Caliper Bracket

The caliper bracket needs to be attached to the back of the upright, using the M12 30mm bolts provided. I found that the bolts were too long for this job, doing them up to the fullest extent caused the end of the bolt to touch the brake disc. So I switched the bolts for stainless steel M12 25mm bolts and also fitted a washer. I used the original manufacter torque setting of 45-50 ft/lbs to secure these bolts.

Fitting the Disc to the Hub

The brake disc is secured to the inner face of the hub by means of x4 M10 25mm bolts. I switched the orignal mild steel bolts for stainless steel and after ensuring the two faces were free of debris and giving them a good clean with brake cleaner, bolted them together. Again I used the original manufacters torque settings of 30-34 ft/lbs of torque, tightening in stages diagonally. I also put a couple of lines of blue thread lock on these bolts to ensure they stayed put.

Fitting the Hub and Disc to the Upright

Firstly I just double checked the bearing cages were fully packed with grease, then gently fitted the hub assembly onto the spline, you have to give in a good push down to make sure its properly in place, and that the outer bearing is seated correctly. It should be free to turn at this point, I put another good dollop of grease onto the bearing at this point. Place the washer, which should have a peg matching the groove in the spline, ontop of the outer bearing. Tighten up the hub nut until its finger tight. Torque this nut up to 27 ft/lbs of torque and check for full and free rotation of the hub, it should be quite difficult to turn at this point. Now slacken the nut off by 90 degrees. This gives the hub endfloat the required 0.001-0.005 inches of movement. Place the castleated nut ontop of the hub nut and push the split pin through (if the pin wont' fit, move the castelated cover round). Bend the pin out to stop the nut moving. Gently tap the bearing cover into place.

Attach the Caliper to the bracket

The caliper is attached to the bracket by means of two long hex bolts passing through two tubular spacers (to give the required distance). Not sure about a final torque figure for these bolts, will have to do a bit of research with Wilwood, however I suspect 30 ft/lbs or greater will suffice
Check the run out on the disc with a feeler gauge between the disc and caliper bracket. Hopefully there shouldn't be any!

Job Done!

Test fitting the caliper and bracket to the upright

Disc bolted to the hub

Brute force to get the wheel nuts in

Nearly there

Completed hub assembly

Accidentally Dismantling a Differential....Ooops

2007-05-21T21:22:00.000Z

Why?

Ok, I didn't start out meaning to dismantle it, I only wanted to clean it. After the diff came back from shot blasting I couldn't turn the drive plate. On closer inspection it seemed as though the bearings had seized because they were full of grit. This was not in the plan. I couldn't leave it like that as corrision would set in. After a quick call to Road and Race transmissions and a few local companies the cheapest rebuild quote I got was £250. Ouch. This was not in the plan either. I was always planning to run the open diff until funds allowed me to change it to a Quaife ATB differential. In one of my early posts I had become diinclined to run a limited slip differential, having done a lot more research and experienced a Quaife ATB first hand my mind was made up. The articles I researched previously related to the viscous coupling differential used in the XR4x4. This uses a different principle and didn't yield the results expected, anyway I digress. More on LSD's later in the build.

Method

Undo the drain plug and drain out the oil

Remove the back plate to inspect the crown wheel and planet gears. You can do a normal clean of the diff internals without going any further, unfortunately I couldn't as the grit was well and truly in the bearings.

Unscrew the two crowned bearing races caps from each side of the drive shaft. These hold the gears in place and are used to set the 'backlash'. The pressure and position of the crownwheel against the pinion.

The crown wheel and planet gears should just fall out in one big lump.

Remove the nut holding the drive plate onto the front of the diff.

Remove the drive plate

STOP!

The reason I say stop is, the nut underneath the drive plate holds the pinion and bearings in place. Changing the setting of this nut means you need special equipment to reset it again afterwards, firstly to centre the pinion and secondly to get the right amount of torque on the bearings (to collapse the washer). Too loose and it will shake itself apart, two tight and it will wear prematurely, get hot and you will lose power though the diff.

So my next job was cleaning. I took it down to a friend at the local garage we used a combination of a long soak in the parts washer combined with using a compressed air line to blast through whilst the parts washer was dripping fluid through the bearings. After an hour or so everything seemed clean to me. I dried it off and tested the bearings with a little lubricant. Phew.... they were all clear.

Reassembly would be a little more tricky and required some research. I needed some new oil seals for the two drive shaft bearings and a seal for the pinion. I got these from http://www.bearingkits.co.uk/ for about £12. The tricky part is getting the crown wheel gears to mesh correctly with the pinion. For this its required to smear the teeth with engineers blue (available from Frosts for £3). This helps you see how well the teeth are meshing with each other, the wider the smear mark the better the contact. Fortunately as you may remember I have the second diff, which I can't use as it has the bolt on shafts, I can however, use it as a guide to getting the backlash correctly set. I found this technique on the mycaterham site.

Shot Blasting Donor Parts

2007-04-23T19:54:00.001Z

Been a bit tardy on the posting so here goes:

12/04.2007

As you can see from the pictures of the completed rear axles in an earlier post, my donor parts were in pretty shoddy shape, agricultural doesn't cover it. This isn't really surprising, given that they have spent the best part of 15 years under a Sierra and then the last couple outside in Tigers Sierra graveyard.

Some serious reconditioning was required. I vaguely thought about attempting it myself with a wire brush and a degreasant. However sense prevailed and I contacted a local restoring company who do shot blasting at very reasonable prices.

The basic process is, you take along your rusty components and they are placed in a cabinet. An air blaster is then used to fire an abrasive particle substance such as glass beads or iron grit to scour the surface clean. It is very effective. The company I used is called MRP on 01462 814244. The contact is Martin and the blasting premises is based near Baldock.

I had the differential, front and rear hubs and carriers, brake drum back plates and the drive shafts blasted and primed for £40. The primer used is a zinc phosphate primer, the parts he painted for free, as Martin explained it was important to have a base coat that protects the exposed steel. Zinc is commonly used as it forms a barrier between the metal to be protected. It reacts with the air forming a variety of zinc compounds that further protect the zinc (and metal underneath it) from further oxidation, similar to the protection afforded by the oxidation layers of aluminium and stainless steel.

New 2 Litre Zetec Engine

2007-04-01T00:20:00.000Z

31/03/2007

Picked up my new (or not so new) Zetec engine today. After a frantic last minute bidding war on eBay that saw it go from £81 to £151 in the space of a minute!

Its an October 1994 Silvertop unit, this is critical to my car passing its SVA, for emissions reasons as discussed in another post. The engine has covered 86,000 miles and was running shortly before it was removed from the car. No obvious damage or problems. The mileage is quite good for the age and type of car. The oil seemed clear and there were no obvious leaks which is all encouraging. I have been told it was a good running engine prior to its dismantling, I will just have to take their word for it.

Borrowed the trusty transit again to nip up to Birmingham to get the engine.

Work will be starting on refurbishing this later in the build. Only job for now is to get the engine validated by Ford and a letter sent out prooving the age for the SVA inspector to see.

New Bike Carbs

2007-03-30T00:22:00.000Z

29/03/2007

Picked up a lovely set of Keihin 40mm carburettors from a Kawasaki ZX9 R B1 (means nowt to me), from eBay. They set me back £56 including delivery.

These carbs are from a 1995 bike which is slightly older than the usual carbs used in Zetec conversions (usually 1998 and up). They are in great condition and come with the idle adjuster cable. The only dissapointment being they are too old to have a throttle position sensor. No matter though. If I use them on a Zetec I can use a MAP sensor to detect engine load. I may even use this set on my Vauxhall C20XE engine which doesn't require an ECU to control it (as it has a mechnical distributor for ignition).

Most people now seem to be obsessed with having the carbs from a Yamaha R1, I learned from Bogg Brothers, who manufacture the manifold for carb conversions, that it simply doesn't matter where the carbs come from.

I know nothing about motorbikes, however my research has shown there to be only two main manufacturers. Keihin and Mikuni and there appears to be nothing between them.

These carbs will be sent away to Bogg Brothers to be cleaned, rejetted and a manifold made up to suit the car. I found this company as it just happened to sponsor the Tiger owners club site for a while. They come highly recommended by all.

I have spoken quite extensively to Bogg Brothers about how they tune the carbs, they have done a lot of work on the rolling road to derive the various jetting setups for the carbs. They can balance them and jet them to near as spot on without having to actually see the vehicle.

More on this when I get the manifold and carbs back!

Hubs Dismantled

2007-03-30T00:14:00.000Z

28/03/2007

Phew all the donor parts are now completely dismantled. I finally managed to get those rear hubs dismantled but it was a struggle!

Front Hubs (Cortina Mk4/5)

The front cortina hubs and uprights come from Tiger as a completely assembled unit, so you have to separate out the various components. At first glance it looks just like a heap of rust. Diassembly is done as follows:

Remove x2 19mm caliper retaining bolts
Remove x2 split pins and use a drift to knock out the pad retaining pins
Remove outer facing pad by bashing it with a hammer and screw driver, the caliper should be easy to remove now.
Remove the centre hub nut cover, by prying it with a screwdriver
Remove the split pin and castlated nut cover
Use a 27mm socket to undo the hub nut, it shouldn't be tight.
Remove the washer and extract the bearing. Pull the hub off. If it is tight use a hub puller
Undo the x3 13mm bolts securing the back plate to the upright
Use a 15mm socket to remove the 4 bolts from the back of the disc
Bash the disc with a hammer to separate it from the hub.

Its all pretty straightforward, the only real pain is getting those caliper bolts undone as I found them pretty tight. Breaker bar to the rescue!!

Rear Hubs (Sierra)

There are two main types of Sierra rear drum axle, the main difference is the drum size. One uses an 8 inch drum, the other a 9 inch drum. The most common seems to be the 9 inch and this is what I seem to have.

Dismantling the wishbones and hubs is made more difficult because of the hub nuts. Do any google search and you'll find people who have had big problems with getting them off. I was quite daunted as compounding the problem is the fact they aren't on the car, so I couldn't use the weight of the vehicle to lever against!

The rear sockets use a 41mm socket, which I seemed to have tremendous difficulty locating at any of my local motor factors. Still if you need one and are having problems you need a socket with a Sealey part code of SX007. It can be found quite reasonably on this site.

Removing the driveshafts and separating the hubs is as follows:

Remove the centre hub nut using the 41mm socket. Be aware of the contra-rotating nut. The right hand side hub nuts undo as normal (anti-clockwise), the left hand side nuts undo in the opposite way so trying to loosen them as normal is actually tightening them!
Prise the drum off, the shoes may be stuck on, so use liberal doses of the hammer and crow bar to pry them off.
Twist the spring loaded retaining catches to loosen the shoes from the back plates.
Release the other springs from the shoes and extract the mechanism from the drum.
dettach the handbrake cable from the shoes, this should just be a retaining lug.
Remove the handbrake cable from the back plate, either unclip it or bash it through the hole if it is stubborn.
Use a 10mm socket to remove the two bolts holding the brake cylinder in place, and extract the cylinder.
Use a 13mm socket to remove the four bolts holding the hub to the carrier.
Pull the drive shaft completely through the carrier and discard the wishbone
Use a hub puller to extract the drive shaft from the hub

I can say with absolute certainty the rear hubs are a complete nightmare!! I managed to get the two right hand side (normal rotating nut) loose by using my trusty breaker bar, it did take me lying at full stretch and a liberal soaking in WD40 before they finally cracked. However the other sides I had no luck with.

I finally threw in the towel when I gave up using the vice and jammed them into a reasonably sturdy black and decker work bench, with my full weight on the breaker bar, and me at full stretch all I succeeded in doing was snapping the work mate clean in two!
So I gave up and took it to a friend of mine at the local garage. I can only say that I was amazed at what happened next. He took my socket, went to his tool box, and came back with a 19v 2 amp cordless impact gun. 30 seconds of chuntering and straining and the first nut came free. a minute later and the second was free.

As you can imagine, we then proceeded to the office to discuss prices for said item in the catalog...

Phew... its all done!

Cortina front hub and disc assembly

Cortina front upright

Front hub extracted

Discarded calipers. These can be reconditioned if you wish to use them

The separated Cortina uprights.

The rear back plates separated out

separated rear hub assembly

Driveshafts (diff side)

Driveshafts (hub side)

All ready for shot blasting, priming and painting.

Stripping Down the Back Axles

2007-03-30T00:12:00.001Z

(14/03/2007)

After picking up the donor pack from Tiger on the Saturday morning, I decided to take my final days leave of the year later in the week and set about getting the axles stripped down. Fortunately the Avon does not require the entire mass of the sierra layout, it favours a more elegant fully independent arrangement, this saves quite a lot of weight, so the only parts I would be reusing we the differential, driveshafts, hubs and the drum back plates.

First task was to give everything a really good soaking in WD40. These axles have been stored outside exposed to the elements for quite some time, as the pictures show they have become quite corroded and very agricultural looking! The hub nuts would be especially difficult to crack, even more so as there isn't the weight of the car to use as leverage and stop the hubs moving round.

Next task was to remove the prop shaft drive plate, when it was removed from the car it was simply cut through, its held on with 4 small bolts, you have to brace the universal joint to stop the differential from spinning.

Four bolts hold the differential to the axle beams. Two are long bolts that pass through the centre of the diff and bear the main load. The other two are smaller bolts that hold the front of the diff. These were all in pretty tight, so I needed to use a breaker bar to get them off, the long bolts required the use of a percusive maintenance device (hitting it with a hammer), and a drift to push the bolt out the other side of the diff. Once free of the axle, the diff can be removed, the drive shafts simply push in to the diff on this model. Remember to remove the rubber mounting bush from the back of the diff, this is not required.

To make things easier, I decided to move the upper portion of the axles, this would help me later on getting each hub into a vice to undo the hub nut. This is done by removing the 4 mounting bolts, again the use of a breaker bar was required as they are torqued quite highly and a lot of thread lock has been used. The upper portion simply lifts away, splitting the remaining wishbones into two sections. These are now big enough to man-handle into a vice.

To remove the drive shaft, hub and back plate from the wishbones the main hub nut has to be undone. This is made much more difficult because, firstly the hubs aren't mounted to the car, and these nuts are notoriously difficult to get undone. Secondly it is a problem because Ford in their infinte wisdom, decided to use a whacking great socket that I don't have. A 41mm socket is needed for the nut, and i've had tremendous difficulty in locating one. Suffice it to say its going to be a few days before I can get one sent, so poor old Raf has to put up with more rusting metal in his garden for a bit longer. More on getting these monsters apart in another post.

The completed axles ready for dismantling

The wishbones and hubs after the diff and top section have been removed

My Scrap yard!

The axles top section removed and both differentials.

The difficult rear hub nut!

A very sorry looking differential, removed from the axle

Floor Mounted Pedals

2007-03-30T00:12:00.000Z

(09/03/2007)

I have been checking out the options for pedals. The Sierra standard pedal options is out for me (and most definately for my co-builder Raf). I am very keen on the racing style floor mounted pedals, several option are available for easy fitting to the Tiger

Tigers own floor mounted pedals

Locost originals from the Ron Champion design

Optimum Balance Products - All in one design

Tiger Floor Mounted Pedal

A highly recommended set of Tigers own engineered pedals. I first tested these in the blue Avon demonstrator car at Tiger and I must confess to thinking they had a great feel to them. Each pedal is seperately floor mounted, so you can space them as you choose. The main downsides to this arrangement is the throttle pedal is a top swing mounted design, so really only the clutch and brake are floor mounted. The brake pedal sadly doesn't have the option for a bias bar. The standard option also backs onto a standard Sierra master cylinder. This again isn't ideal as I wanted to have better control over the braking system, with two master cylinders and (after SVA of course) some form of bias adjustment. The price was a little bit of a turn off as well at £170

Locost Design

The locost design was originally penned by Ron Champion, i've seen a few pictures of his pedal designs in car, but couldn't find anyone doing a version of it. I couldn't find the plans either, not that I was up for making my own.

Optimum Balance Products

Who are they? (I hear you cry), well I hadn't the faintest idea either, until we came across their website. http://www.obp.uk.net/ The company specialises in kit car components and has a huge selection of pedal box designs to suit any application. A quick phone call to Grant, the owner, gave me the low down on the company, he informed me the company had just finished redesigning the pedal range. I told him the type of setup I was going to be running and he was extremely helpful with setup advice and in particular the master cylinder configurations to run.

The model range was extremely comprehensive, the website provides some good hi-resolution photos of the product which instantly shows off their quality. After a bit of rooting about I found the configuration I was looking for, all three pedals floor mounted to a steel frame, encompassing two master cylinders and a balance bar. I immediately liked the strong black powder coated finish, the general quality of the welding and construction looked first class. I particularly liked the elongated slimline throttle pedal, which I thought would most likely make for good heel and toe technique on the track. I also noticed the do a remote bias bar adjuster, which takes the form of a cable and knob mounted in the cockpit, this would be a great track addition post SVA.

As for price, well these pedals come out slightly more expensive than Tigers, but only by about 10 quid, weighing in at £181 for the complete setup (pedals, master cylinders, reservoirs and balance bar).

So I decided to take a gamble, and here they are sitting in my workshop. Complete with Girling master cylinders (0.675 for the front and 0.7 for the rear) and reservoirs.

I took a quick trip up to Peterborough to meet Grant and pick up the pedals, the workshops were very impressive, located on a farm, the workshops were out in what look like chicken shed! How very British! Still top chap, and top products, throughly recommended!

The pedals I got can be found here

The pedals on the bench

The pedals test fitting in the car

The pedals, complete with master cylinders loosely fitted.

Picking up the Donor Pack

2007-03-30T00:10:00.000Z

(10/03/2007)

Set out on a sunny Saturday morning after borrowing a friends van, which was suitably decorated!

We arrived at Tiger in good time, this trip was all about picking up the donor packs. Stopped in at the parts department to pay and to have a nose round the stock room.... Aladdins cave and Santa's grotto all rolled into one!! Sadly they wouldn't leave us in there, so we only came out with Handbrake assemblies and a rubber bung set (paid for of course)!

On to the workshop where Paul kindly fished out with a fork lift, the last two Sierra drum rear axles that Tiger have in stock. Rusty doesn't really do justice to how badly these things look, but hopefully they will all clean up and be as good as new. Cortina uprights, compensators, steering columns, master cylinders and two very oily type 9 gearboxes followed. I must say given the price of second hand sierra and factoring in the cost of stripping it down and disposing of it, not to mention the added cost of Cortina uprights and hubs (£75 a side), I do find Tigers donor pack exceptional value for money.

Visiting the factory is always a good opportunity to have a nose around the cars. A lime green Avon was on the ramps mid way through constuction. I always like to have a jolly good nose round underneath so I can see how Tiger have solved certain problems, how they routerd cables, pipes and wires etc.

A new R6 with a race duratec engine, also made for great viewing!

Its also a good chance to sit in the car and remember why it is you are building one in the first place... Fantastic feeling!

Choosing a Braking Setup

2007-03-30T00:09:00.000Z

Time to choose a braking setup. I've been toying with the various options of what braking setup to use on the Avon, the only reasons I have for not going completely standard are 1) Cost. To recondition the standard cortina components can cost nearly as much as some aftermarket conversions. 2) After seeing the Avon on the Ultimate kit car DVD, the only complaint the racing driver had with the car was that it ran out of brakes! As I will be using this car a lot on track, I didn't want the same thing happening.

Standard Setup

The standard setup for the Avon is to use the original cortina front discs and calipers. These are 245mm solid discs. The rear stopping is provided by Sierra 8 or 9 inch drums. The cost of reconditioning the fronts is about £75 per caliper + £25 for new discs and £10 for pads. Totalling £185 The rears are much cheaper coming in at about £100 for new back plates, cylinders, drums and shoes.
Although more than enough to stop the car on a day to day basis I wanted something that was going to be more durable on track. Also lets not forget that the Cortina caliper is getting on a bit now, parts may become increasingly hard to find so it makes sense to minimize the dependence on older kit, from a consumables point of view.

New Front Calipers

I came across the rally design site after a post on the Cam7 forum, although the name suggests rally parts they have a large kit car selection at some great prices. They offer numerous kits for all makes of kit car. They are also a stockist for the leading US brake manufacturer Wilwood.

I opted for the following brake kit [BK1P] as listed on Rally Design.
The kit consists of :

x2 Wilwood Powerlite Calipers
x2 Solid (plain or grooved - I am going for grooved) disc
x2 mounting brackets
x4 pads
Mounting bolts

All for the princely sum of £200. When I get nearer to the time of fitting the brakes I will order them and post up some pictures.

Rear Setup

Discs or Drums? Well its clear cut. Discs! Except that I can't afford them, so drums! My donor pack comes with 9 inch Sierra drums. I have to say that I really would prefer a disc brake setup as it is far more modern, easy to work on etc. However the drum setup is cheaper and easy to fit. The Avon can accept a rear disc setup but it requires modifying of the rear hubs. The drums just bolt straight on.

Whilst I was deliberating this, I spoke to a couple of people who race Seven cars, one of them had switched back to drums from discs as they preferred the feel of it.

As with all cars, most of braking force is dispensed by the front but given the weight of these cars, the rear brakes do little more than keep the car in a straight line under braking. So ultimately I don't think it really matters what you use. Switching over to discs at a later date might make a nice mini project once the car has been completed and passed its SVA.

I decided to keep my drum arrangement, just fit new shoes, drums and cylinders. The back plates will be shot blasted and refurbished to as good as new.

Tiger Rear Handbrake

Tiger have a pretty simpe but effective handbrake system. I will show some pics when I put mine in place. Essentially it comprises of two cut down sierra cables feeding into the drums, attaching to a balance bar, behind the brake lever. The standard sierra handbrake then mounts above the drive tunnel and connects via a single cable to the centre of the bar. This is used on all Tiger models.

Master Cylinder Setup

Deciding on the master cylinder setup took me to quite a few experts, as I have to confess I know nothing about braking systems, i've never really trusted myself to do my own brake work, after all they do keep you from getting front row seats at the scene of the accident!

The general consensus from the forums and experts I spoke to was, if I was going to use a twin master cylinder system, the front master cylinder should have a bore of 0.625. Opinion was divided on the rears between a 0.7 and 0.75 bore cylinder. I finally decided on a 0.7 cylinder as this would apparently give me a firmer pedal, something I have longed for, ever since fitting large brakes to my road car and feeling the sponginess in the pedals after, I really wanted to get that racing feel back!

Pedals

I'm going to cover the selection of pedals and arrangements in another post. Suffice it to say, floor mounted is the way to go, the Sierra standard pedals are not comfortable for me, I tested them in a Tiger Cat and a Robin Hood and I think they feel horrible.

Bias Bar

I am very keen on having an adjustable bias bar, especially for track day use or if I decide to go racing, as this allows rapid change of the brakes setup. Even better would be a remote adjustable bias bar, allowing the bias to be changed whilst the car is in motion.

SVA

Whilst all this sounds lovely Mr SVA will have a few things to say before he passes my car. The first rule is that the rear brakes must NOT lock before the fronts in the braking test. Secondly, the bias cannot be adjustable. This requires a bit of a hack. The bias bar must be locked off so that it cannot move. This means drilling a hole through the retaining nut, the bar itself and then securing with a roll pin.

Fortunately I have a good friend who is an MOT tester, hopefully I will be able to set the brakes up properly on the brake tester machine before the SVA and locking off the bias bar.

More Build Resources - An Extra Helping Hand?

2007-03-18T22:12:00.000Z

As i've gotten a bit further down the line now, I thought I would share some of the resources i've found to help me build my Tiger Avon. As i'm sure you are aware if you've started building one of these cars, there is no factory supplied build manual. There is a book written by Jim Dudley (The owner of Tiger Racing) detailing construction of the car from scratch. While this is an excellent read, and would be invaluable if I were welding my own chassis and forming the GRP, i'm not quite at that level, the book can only help so far.

The Book

If you aren't familiar with it "How to Build Your Own Tiger Avon Sports Car For Road & Track" is available in the Speed Pro series from Veloce publishing. You can pick it up on Amazon or Tiger will give you a copy of the book free when ordering your kit. Amazon Link

Forums

Forums are an excellent method of discovering information about problems with your kit. Easily searchable either using the sites own search facility or by search engines such as Google, a wealth of kit car experience can be found from expert builders to first time builders, such as me, many of whom have had to deal with the same issues. Everyone is usually very friendly and helpful, often providing pictures of their own vehicles to illustrate a point.

The three main forums I have found useful are:

The Tiger owners club also provides information and ways to join a regional Tiger owner club near you.

Email Lists

Email lists are another great way of interacting with other Tiger or Lotus 7 owners. The format is slightly different to that of a forum. You subscribe to an email list server and you then start to receive emails from everyone subscribed. You can ask questions or simply interact on a social level via asynchronous email. There is again a wealth of experience out there.

I use this list server, and am a member of the Cam7 list for the Cambridge area.

Pictures

I've found the best source of research when solving a problem or trying to understand how I should attempt to do something on the car, is to see what someone else has done. Fortunately several like minded individuals have created websites with gallery sections. The best two are:

Builders notes

Builders notes are a bit few and far between, however I did find one Avon builder who jotted down a quite careful build plan in a word document. Unfortunately the site this belonged to doesn't seem to exist anymore (www.thetigeravon.co.uk). Fortunately I was able to save the word document, which is now available here. Hopefully the author won't mind me hosting it on his behalf.

Which Kit Car

Back in January 2004 'Doc' Watson was charged with building an Avon, and documenting his experience in a build guide. You can send away to Which Kit Car for this guide on CD. Its comes in a series of 5 articles in PDF format. Again I found this guide quite useful. Ian Stent (the Editor of Which Kit Car magazine) took the car for a spin after it was finished with nothing but praise.

Give Which Kit Car a call, the CD costs £9.99 and is entitled "Tiger Avon Build"

Ultimate Kit Car DVD

Ian Stent put togther an Ultimate Kit Car DVD, featuring the cream of the crop of Lotus Seven replicas. Among the cars tested by Brans Hatch racing instructor Bill Sollis were: MK Indy, Westfield Sport 2000S, Raw Striker, Quantum Extreme, Dax Rush and of course the Tiger Avon. Curiously most manufacturers opted to take their flagship model, Tiger on the other hand took a base run of the mill Avon with a standard 1800 engine on original injection. For comparision he also brought along an Original Lotus S3 with Jim Clark spec Lotus twin cam, and a Caterham Classic 1600.

The Avon was completely outclassed, having the least amount of horsepower, but Bill had nothing but praise for its on track performance (ahem... aside from the standard brakes), its time wasn't too shabby either, only 4 seconds slower around Curborough sprint circuit than the Westfield (with twice the horsepower).

Tiger, not to be outdone took along the Z100 twin engined bike car, just to show whose boss. This is a throughly entertaining DVD, great for seeing the Avon in action.

Duke Video Link

Mark Evans - A Racecar is Born

Somehow it always seems to end up with Mark Evans... "Its All His Fault" can be heard up and down the land. I think by now he must be single handedly responsible for the entire British kit car industry. His video A Racing Car is born follows his exploits in building a Westfield SEi 1800. The first part of the DVD concentrates on the build, the second half of the DVD shows his attempts at trackdays, auto tests, hill climbs, modyfying the car for racing use and culminates in a round of the Westfield Champsionship.

His quirky, comedic style, with the ever faithful "Pete mate" in tow makes for an entertaining couple of hours. This DVD was a big inspriation in my desire to build a lotus 7. Although Westfield is a little too costly for my means, the DVD is very pertinent to the Tiger build as well, with many shared components.

Amazon Link

Panelling Back Panel and Side Panels

2007-03-18T21:05:00.000Z

(14/01/2007)

Stage 1 of my panelling is complete, I now have the cockpit back panel and side panels in place. All of the main panels are now in place, allowing me to progress with the rest of the build.

Carboard Templates

Due to the promity and close fit nature of these panels, I decided to make a mock up of the whole thing in cardboard first, this helps to test how the panels will interlock

Back Panel Mistake

I rather messed up the first attempt at the back panel, accidentally cutting way to much material from the side facing the transmission tunnel! Whoops! Fortunately for me, Raf's panel set was still lying around in my shed.... he'll never miss it!

Forming Metal

For the back panel it is necessary to form the top and bottom sections to sit flush with the box section of the chassis. I was a little nervous at doing this at first, however I found an effective method was to clamp the panel (quite a lot) between two fairly thick pieces of wood and apply pressure uniformly across the panel. Tiger do say you can use the chassis rail as a former, I wasn't keen on this as I didn't want to damage the powder coating. The result using the wood was still a pretty good crease.

The gap between the top side panels and the back panel presents a particular challenge as it requires curving to meet the chassis side rail. The passenger side is not so bad, however in an effort to extend the room afforded to the driver, the drivers side has a 1 inch or so gap to stretch the metal over. Here I did choose to follow the tiger method and slowly roll the side panel over the tube on the chassis. This had the desired effect, and if done carefully leaves quite a nice finish. The rear section of the upper panel also needs formingto sit flush with the back of the chassis. The picture below illustrates a little better what I mean.

Panel Overlap

I chose to overlap the uppemost panels over the lowermost, simply because this gave a nicer finish. I chose to use quite a lot of sealant around these areas, to ensure the panels stick solid and don't rattle or move. I chose to use plenty of sealant in all cases around the back and side panels to try to reduce the exposure to water.

Panelling Phase 2

I still have number of panels left to fit to the car, however these have been left off until the gearbox, brake and fuel lines are in place, essentially so as not to impede access to the transmission tunnel, and to avoid any damage that might result in installing the transmission.

Panels remaining are:

Transmission side panels x4

Top tunnel panel

Battery tray panel.

Back panel

Drivers side panels

Passenger side panels

Chassis

Reconditioned Differential Purchased

2006-12-07T23:13:00.000Z

(04/12/2006)

I couldn't resist it. A shiny freshly reconditioned 3.92 7 inch open differential on eBay for next to no money. I bought it! However I then realised I had caused myself a bit of a problem. The Avon is designed to use a 7 inch differential from the back of a standard Sierra, as opposed to its bigger 7.5 inch cousin from the Cosworths and XR4's. I double checked this and it was indeed a 7 inch differential, what I forgot to check was that there were two type of 7 inch diff's. The older type had had push in inner drive shaft half shafts, the later version had a more modern bolt on sealed CV joint, that was secured to the diff with small hex bolts.

Speaking with Paul at Tiger enlightened me as to why this would be a problem. The bolt on driveshafts were thicker at the wheel end than the older units, this would cause a problem when the drive shaft tried to pass through the Tiger fashioned hub carrier. Drat!

He said it would be possible to machine the ends of the drive shaft to pass through the carrier, but this was all turning out to be extra hassle I hadn't originally envisaged. I still planned to get a donor pack from Tiger at a later stage which included the complete rear differential assembly, I was always going to use this as a spare and recondition it, but it looks like I would have to promote it to being the main component in the build.

I guess at some later stage I will have to purchase matching driveshafts and hubs to go with this differential.

The freshly reconidtioned internals

New crown wheel

Genuine 3.92 stamped on teh crown wheel

Side view, the bolt on CV cup is clearly visible

Shame I don't get to use it right away!

Panelling Footwells

2006-12-07T23:11:00.000Z

(28/11/2006)

I have completed both driver and passenger side footwells. These were fairly straightforward to cut, I didn't feel the need to make a cardboard cut out. Simple measurements sufficed, followed by a few trial fits. The main challenging aspect to this was to try to get a nice smooth and accurate fit around the steering wheel bracket. Most of this work was done with an assortment of small files, starting by cutting jagged triangular sections out with some shears.

Not much more to say other than it was tricky getting the air rivetter so close to the floor panels, so had to resort to the hand rivettor.... shock horror!

Hole cut for the steering colum shaft to go through

Drivers side footwell panel (from inside)

Drivers side footwell panel (from the engine bay)

Passenger side footwell (from the engine bay)

Passenger side footwell (from inside)

Finally Got Started

2006-11-21T22:38:00.000Z

Finally Got Started (21/11/2006)

First order of business for the Avon (according to all the build diaries) is to do the majority of the panelling, starting with the bottom floor pan panels. These are the largest panels on the car, and require the car to rotated on its tressel, most tend to lay it flat, but I have found it easier to work on the car whilst it is sitting on its side.

The panels supplied by Tiger are as promised (by them) very generous. They have been professionally cut however with acres of material to spare. I have never done any serious metal work before, so I decided to trim the panels in the old fashioned way, with aircraft shears. I bought a set of three, left hand cut, right hand cut and straight cut shears.

My test cuts on some spare material, were encouraging, I found I could be quite accurate with them, but also trim closer and closer to my mark without any wild jagged edges.

The basic plan calls for attaching the panel to the chassis by means of clamps to line it up. I recommend using quick release clamps or sprung loaded clamps. G clamps are ok, but a pain when you are winding them in and out whilst trying to balance a panel, they are ok once the panel is actually in place.

Once the panel is in place, I simply drew around it with a felt marker, took the panel off, clamped it to a work bench and started to cut with the shears. I initially cut quite wide of the line, bit as confidence grew got closer to the line. O always left an extra millimeter or so to allow for filing and tidying of the edge.

Rippling

I soon found the problem with using aircraft shears is the slight rippling effect that shows on the metal each time the blades close. The shears also left a slight serated mark in the metal. I also found it difficult over long panels to get a truly straight finish.

Doing a bit of research I found 4 other ways of cutting aluminium.

Jigsaw with fine metal blades

Band or scroll saw with fine blade

Nibbler or Air shears

Scoring and breaking the metal

Didn't much fancy the idea of scoring down the aluminium and then trying to snap it, and air shears would have a similar effect to the normal shears, except the added risk that I might slip and chop the panel in half! I didn't fancy spending £80 on a scroll saw unless I really had to, so opted for the jig saw option. The blades are wider anyway, so this might help me keep a straighter line.

From what i've read you need to have an many teeth (teeth per inch or TPI) to cut metal as possible. 22 TPI minimum. However others have had experience of overheating of the blade and the metal with too many teeth. So I settled for a blade with 25 TPI. It not an exact science this, as nowhere on the packet does it say how many TPI. So I had to divide the length of the blade by the width of the teeth.

Disaster

I did not get on well at all with the jigsaw. I found that whilst it gave a neat unrippled cut the tendency was for the teeth to snag and lift the aluminium causing very undesirable bending. Fortunately I was able to bash these back into shape with a hammer without leaving any lasting mark. I decided to switch back to the aircraft shears. I found a better technique was to go as close to the line as I dare in one cut, rather than doing what I had done before, snipping bits off here and there. I left a little extra room again so that any rippling could be filed out with a large metal file. I also found it important to keep oiling the blades with WD40 to ensure a smooth cut and an easy blade action.

Filing

I managed to clean up the first panel with a coarse file. I used a technique of clamping the panel to the car, releasing the area I wanted to file, then covering the chassis with masking tape to prevent damage, filing the panel and then constantly checking against the chassis rail.

One the panel was finished I used a small fine craft file to carefully tidy up the edges.

De-Burring

I found a great tool on ScrewFix, for removing the sharp edges from the panels. The deburring tool, looks like a pen, it has a curved blade, the idea is you run the blade along the sharp edge and it trims away the metal and leaves a curved surface. It works quite well and quite quickly.

Drilling the Panels

With my completed panel clamped to the chassis, I used a steel rule to mark out the rivet spaces. Tiger recommends spacing the rivets approximately 75mm or 3 inches apart. However one thing it does not tell you, is how close to the edge of the to drill the hole for the rivet. Eventually after doing some estimation based on other build diaries I decided on 10mm from the edge of the panel. I felt this was far enough out to prevent the panel slipping out from under the rivet, but close enough to the edge to prevent the panel from lifting from the chassis.

I was advised to use 3.5mm metal drill bits for the rivets. This indeed made life much easier as it gave me a little leeway with the position of the panels and reduced the chances of getting a hole that did not fit.

The Avon floor pans require drilling all the way around the outside of the panel. Across the middle former, down the two longitudinal formers and although not required I also rivetting across the foot well strip at the front. Please note due to the thickness of teh steel on the other side 8mm rivets were required here.

With all the hole drilled, I removed the panel and cleaned the chassis surface and the panel surfaces with a deagreasant (I used brake cleaner).

Sealing the Panels

The sealant I used was black automotive silicon. This has a polyurethane base and is mildly adhesive. It comes in white, black or clear. I picked black as my chassis is powder coated in black, so any overrun would not be noticeable.
All the books or instructions I have read comment on using a 'thin' bead of sealant applied to to chassis rail. No-one could exactly quantify how much that meant. I cut the nozzle of the sealant gun to give an approximate 3mm wide bead of sealant. On a 25mm wide chassis rail I thought this was ample. If you are getting lots of sealant squeezing out of the panels then you are using too much.

Sealing the panels before rivetting helps in three ways.

Sticks the panel to the chassis

Acts as a shock absorber so the panel doesn't rattle when the car is in motion

Helps to seal the aluminium panel from the steel helping prevent corrosion. Aluminium has quite a high corrision factor.

Although not mentioned in the books or other instructions, I felt it would add additional protection to the panel if after rivetting I sealed the seam, inside an out, where the panel meets the chassis. This was achieved by using a thinner nozzle and running the sealant between the cracks, then running my finger (gloved or dipped in washing up liquid) along the crack to create a tidy seam. This would prevent water getting between the panel and the steel.

Rivetting

Its estimated that over 1000 rivets are required to correctly panel a Tiger Avon. There was no way I was using a hand rivetter to do this, so I purchased an air rivetter to take the pain out of rivetting the panels.

My basic method consisted of putting most of the rivets into position before rivetting them. This would help me ensure the panel did not shift, and all rivets correctly filled their holes.

I then rivetting each of the 4 corners to lock the panel in place, before rivetting the rest.

(26/11/2006)

I have completed the floor pans and the driver footwell plate so far.

First panel held in place ready for rivetting

Rivets close up

Panel 1 completed

Hole cut for the steering colum shaft to go through

Completed drivers footwell panel

Construction of the Tressel

2006-09-04T21:29:00.000Z

Tressel

At last I have gotten round to building a tressel to put the chassis on. I have gone for a fairly straight forward box design. This is similar to the type used by Tiger and other manufacturers alike, only in wood not metal. Constructed from bog standard pine from homebase I hope it will be strong enough to hold the car whilst it is panelled etc, until the engine is fitted. I have fitted extra bracing in, and with the chassis on top it it fairly rigid, although there is a bit too much lateral motion, hopefully this won't be an issue. I may be able to correct this with some wire brace. The whole thing probably cost about £25 to make, this is a bit pricey for wood, but then again I didn't go to a wholesaler.

New Tools

2006-09-04T21:23:00.000Z

I have purchased the following new tools for construction to begin:

Hand Rivetter (£9.99)
3 set of Aircraft Shears (left, right and straight cut) (£12.99)
Coarse metal file(£2.99)
Big vice (£14.99)
De-burrer (£3.99)
Wolf Air Compressor (24Litre 2Hp) (£99.00)
Air Ratchet (0.5 Inch) (£12.99)
Air Rivetter (£19.99)
Set square (£4.99)
Spirit level (£9.99)
Additional G clamps and spring clamps

Where to Build?

2006-09-04T21:20:00.001Z

Buying a House

Although superficially it may look as though I have bought a workshop that comes with a free house, its honestly not the case. Starting the kit car build and buying my first house came a complete coincidence. In fact delivery of the chassis came exactly 1 week after I completed. Although not strictly necessary the temptation of having a workshop was the clincher for the house I purchased. I've always wanted my own space where I can tinker to my hearts content!

The minor flaw in the plan.... the passagway. It not wide enought to get a completed car out. So I can only part build my car at my house. All panelling, wiring etc, will be completed at home. For the final assembly of engine, bodywork, suspension and so on, the car will be transported to my long suffering girlfriends house. She by way of fortune has a garage going spare. I have structured the build accordingly. Hopefully by the time the chassis is complete and all the other parts are ordered it should only take about 2 weeks to assemble to car.

Picking up the Kit

2006-09-04T21:20:00.000Z

Picked up the car, one week after moving into my new house.

More on this later.

Limited Slip Differential (LSD)?

2006-06-14T17:42:00.002Z

I'm quite keen on fitting a limited slip differential to the back of the Tiger Avon. For obvious reasons, I want to reduce wheel spin, and tank slapping moments in the corners. However it doesn't seem quite as straightforward as it sounds.

Avon Mountings?

The Tiger Avon chassis is designed around the 7 inch open differential with push on drive shafts, typically found on most sierra's. I happen to have lying around a Sierra XR4x4, with a very good 3.62 Limited slip differential, naturally I wanted to use it as it would save me money in the long run.
However after a conversation with Tiger technical support, it seems as though quite a bit of work may be required to fit one to an Avon. Firstly the chassis mounting would have to be modified to take a 7.5 inch differential which is fairly prohibitive. They did tell me that a certain number of 7 inch LSD's were manufactured but these seemed quite rare. My best bet would be fitting a Quaife custom LSD. This would cost around £600.

Also another issue would be the size of the hub carrier. This would have to be machined out to accept the wider bolt on style shafts. This could be done relatively easily, probably by Tiger themselves.

Living with an LSD

LSD's may be great on track, but what are they like to live with. Well I hadn't really thought about it until I started researching more. An article from the Tiger Owners Club forums seems to suggest that handling in everyday trim might be impaired. The major complaints were a general lack of feel from the car, less warning when the back was about to step out and an inability to get the power down with out the back end of the car squirming.

The article related to LSD's fitted to Tiger CAT's which feature the full sierra rear axle. It would be interesting to see if the characteristics of the Avon with its full independent rear suspension, would cope any better.

Build Process

2006-06-14T17:41:00.000Z

Whats what? - No Build Manual

Well, the Avon maybe the baby of the bunch, and it may be the cheapest, but there are reasons for this... No step by step instructions and MFI style glue bracket A to Shelf B with Glue C diagrams. Fortunately, Jim at Tiger wrote a book on how to build one. When you place your chassis order they even mail you a copy free so you can read up.

The book is very well layed out with lots of practical advice for the techniques on how to construct a car. It is really focused on the hard core builder, someone who wants to construct their chassis and uprights etc themselves. It goes into great detail on welding tips, jigs and how to contruct GRP body panels.

If there is only one downfall of the book, its that it doesn't show enough Avon only pictures and diagram. It does rather get hijacked to showcase Tigers other models.
I think to get the Avon completed, the book, a healthy dose of common sense and a large amount of Internet and Tiger club research is going to be in order. Seeing what other more experianced builders have done will be key.

Build Ethos

My build ethos is to build the car as standard as possible, no frills or extra parts. Just do what everyone else has done to get the car built. Once I understand how it all goes together and what makes the car work well I can then start modifying, improving and altering the car to my liking.

The advantages of this are, as i'm not doing anything fancy then plenty of people should be able to help me if I get stuck. So this will be a straightforward Zetec 2 lite, Type 9 box, open diff, with cortina brakes.

The only exceptions to this rule are:

Floor mounted peddles - None of that sierra rubbish for me
Induction system is yet to be decided. Depending on cost.
Quick steering rack.

All of the above are pretty well documented by Tiger, so i'm not overly worried.

The General Build Process

From the research I have done and the reading of Jim's book I have decided to build my Tiger in the following steps. Others may have done things differently but this works for me with my time and space constraints.

Cut and Fit the panels
Fit the brake and fuel lines
Fit the wiring loom
Fit the steering column and rack
Fit the floor mounted peddles and master cylinders
Fit differential
Fit the fuel tank and ancillaries
Fit the suspension and wishbones
Fit the brakes
Fit the Engine, gearbox, propshaft and cooling
Wire and plumb the engine
Fit the bodywork and exhaust
Fit the interior
External wiring and lights
Finishing touches

Stoneleigh 2006

2006-06-14T17:37:00.000Z

First Visit

As this was my first visit Stoneleigh I was hoping for a warm sunny affair with cucumber sandwiches and tea and biscuits on the lawn, imagining myself whiling away the hours in deep conversation about engine mountings and the intricacies of rivitting panels. As it happens I was greeted with a monsoon, cursing my decision to camp, a cold night ensued. However bright and early with my enthusiasm undampend (even though I seemed to have developed a limp) I set off to explore the show, with my fellow Avon builder Raf.

Ordering

The time had finally come to stop mincing about and place an order for a car. Having spent the morning wandering the show, and revaluating all our past decisions about which car to go for, we decided to bite the bullet and place the order for the Avon. The benefits of doing it at the show, means you take advantage of the show prices, which for a chassis only worked out about £100 cheaper than the list price. If I could have afforded the whole kit, it would have been nearer £500 off. I chose a Tiger Avon chassis with black powder coating. I think it is important to have the chassis powder coated, it seemed to give an excellent finish and helps protect the chassis against corrosion.

I've seen a couple if Avon's up close now, and the most overiding memory of them is how low and sleek they look. There is no excess fat on the car, which I find very appealing. In the end it won out over the likes of the MK Indy, of which we were having some last minute umming and arring.

We left Stoneleigh with an extremely positive view on the whole kit car world. The number of trade stands and parts companies was mind boggles. I think Stoneleigh is definately a place you need to go with a wallet full of cash right before you start building, as i'm sure you could save a fortune on odds and ends like switches, rivets, tools and bolts etc.

Right. Can't wait to start now. Just need to find a place to build it and i'm sorted!