Brakes, Wheels and Tyres

As promised, I thought I would cover wheels, brakes and tyres this time round. These are all restricted by Historic regulations, but the great thing is that we can use these rules to get a small advantage over the opposition.

Wheels

These can be any width, so long as they are housed within the original bodywork and the diameter must be the original showroom size, plus or minus 1 inch, to a maximum of 15 inches. The only other stipulation is that the wheels are of a period (pre 1966) design. 14 inch wheels would be lighter and help lower the centre of gravity slightly, but we have chosen to stick to 15 inch rims as it enables us to run larger brakes and it gives us a wider choice of wheels and tyre sizes.

We've fitted 5x15 inch Raders to replicate the 1965 'Inch Pincher' that the car is based on. We are currently limited to 5 inch wide rims as the car is a 1970 which has quite a wide track (distance between the two wheels on the same axle) and this has been widened further by fitting disc brakes all round, having said that we are fitting 10mm wheel spacers on the rear to get the rear track as wide as the bodywork will allow.

The reason for running as wide a track as possible is that it reduces the lateral load transfer...put simply, when you corner hard, the weight of the car is thrown laterally (sideways) to the outside of the corner which upsets the handling, widening the track reduces this effect, as does lowering the centre of gravity.

Brakes

In this Championship the brakes are unlimited, so anything goes! To suit the bolt pattern of the Rader wheels we have fitted CSP 'wide 5' disc brakes all round, which are pretty much the largest that you can fit inside the wheels. The brakes will be worked hard and as a result will reach high temperatures which can reduce their efficiency, so the rear discs are drilled and the fronts are vented, drilled and grooved to provide some extra cooling. We are also using racing brake pads which are made of a harder material and operate at a higher temperature than regular pads.

To keep the costs down we will use the standard cast CSP 2 piston (2 pot) brake calipers and we will see how they perform over the season. In the future we may replace these with 4 or 6 pot aluminium calipers which will not only provide stronger braking but are half the weight of the CSP items.

To allow us to tune the brakes to the conditions, we have included bias adjustment which gives us the ability to adjust the amount of braking force applied to the front and rear brakes. In the dry, most of the braking force will go to the front and in the wet the braking force will be sent towards the rear. This can be adjusted from the drivers seat during the race.

Tyres

As with all Historic Touring Car Racing we are only allowed to use Dunlop crossply racing tyres which are nothing like a modern tyre. Firstly they are treaded but not road legal and despite being of a much softer, stickier compound than a modern road tyre, they are very tall, skinny and provide very little grip.

They come in 2 styles with various widths and heights. Style wise we have a choice of 'L' or 'M' section tyres. 'L' section tyres are an older style of tyre which are skinny and very tall and the 'M' section tyres are more modern in appearance as they are wider and have a lower profile. Despite this they have very tall sidewalls by todays standards. All the tyres have the same '204' compound of rubber and share the same tread pattern.

We've chosen L550x15 for the front and L600x15 for the rear, which are the widest tyre that we can fit on 5 inch rims. Even so, the tread width is only 128mm on the front and 135mm on the rear (told you they were skinny!) and how much do they cost?...How about £900 for a set of 4 and they only last for 6 races!! This motor racing isn't cheap.

If you want to see how great they are in the wet!!...take a look at this 150bhp Ford Anglia at Silverstone on youtube (http://www.youtube.com/watch?v=Ks7WP1xJI7o&feature=channel)

Now how do our wheels, brakes and tyres compare to our main rivals the Mini Coopers? Well the Minis are limited to 4.5x10 inch wheels which means that the largest brakes that they can use are only 7.5 inches in diameter, whereas ours are nearly 12 inches, so baring in mind that we are the same weight, we should have an advantage under braking. The largest tyre that the Minis can run are only 120mm wide and we have 128/135mm tyres plus a larger diameter which both add up to a much larger tyre footprint, so that looks pretty good.

All this is theory of course...Only time will tell whether we have a true advantage here as there are so many other factors which can affect each cars performance.

The Beetle is currently having the custom made dampers and suspension linkages, fire bottle plumbed in and the brake lines fitted. Once thats done its off for final wiring while the engine is being finished. Currently we are looking at testing in early June with our first race planned for the 14th June at Castle Combe near Bristol.

Keep your eyes peeled for the next blog...we're nearly there!

ian