Brakes

[Graham]

Ok so not stictly in the remit of the engines forum but i thought i'd start here...

im looking to upgrade the brakes and psssibly the pedal box on the racer,
i've gone for the biggest disk size that i can get away with weight penalty size 299-300mm but how do i work out what caliper is it just the most pistons and piggest pad area i can get in the wheel? and with the widest disk?


ALso if i change the pedal box and go to twin master cylinder how do i work out the master cylinder piston size and if i need to source twin remote master cylinders or if i can do without?


cheers
G

[shpub]

Graham.... How much is your budget?
Looked into this last year on the 520 and was shocked at some of the costs.

1. To get twin remote masters while retaining a servo will cost around 2-300 pounds for an adapter before the cost of the twin masters...

2. To get twin remote masters on that pedal box without the servo is a real no no as the pedal leverage is not that great and there is not much room for extending the pedal length. Looked into this and it was about £600 to get this sorted. Decided against it!

3. Your calliper choice will be determined by what will fit in the wheel gap. Wilwoods will or APs and they are much a muchness in terms of pad size and pistons.

4. The biggest challenge is that you will need a much bigger master cylinder to reduce pedal travel. The twin is fine BTW. I use an external brake balance valve (Wilwood lever type) that I can adjust the balance with. I have lost rear brakes and still maintained full braking on the front so it should be reliable.

5. I ended up with a custom master cylinder that has a much bigger bore than the standard but meant I had to modify quite a few things. Basically went around a scrappy looking at the servo fittings and measuring bore dimensions. Got a Girling part number and then got different reservoirs and bits to make it fit.

I don't know which one of the many servos that TVR fitted you have so it is best to look and get a match. I reckon you need close to a 1 inch bore.

[AndyS2]

Why not try getting parts from a breaker? Porsche have a good reputation for brakes and I've heard of quite a few people retro-fitting the big red calipers from the 911 Turbo ( or big blacks from the 928GTS ) to different cars. Once youve bought the calipers and master cylinder from a breaker the discs arn't too expensive new, then all youve got to do is get an adapter plate made up for the calipers which is not too difficult. As long as you've got 18" wheel they should fit no problem.

[heliox]

What about a Tuscan AP pedal set from a scrappy,fab.

h

[shpub]

heliox said:

What about a Tuscan AP pedal set from a scrappy,fab. h

Don't fit. Looked at this style and there is not enough depth to take the cylinders. Looked at AP, Wilwood, Brembo and only the overhead style fit but then there is the pedal length and depth problem. The question is it really worth spending several hundreds for a brake pedal setup that doesn't offer any more than what is there originally.

[Graham]

I was really hoping to be able to go floor mounted but as you say there is no space to do it. the real problem i have is that the pedal box is so poorly mounted it moves around to much loosing feel. i also wanted to run the twin cylinders for better adjustment control.

Ap do do a very nice looking 3 pedal box with pull rather than push cylinders but i hate to ask how much as a fully specced up Tilton 3 pedal unit id about 650..

SO it looks like finding some way to stiffen the pedal mount on the bulk head for now... and adding a better proportioning valve

As for brakes themselves im currently looking at hispec racing 132-6 ( 6pot) calipers and 299X32 performance friction disks and pads, i just need to work on the offset to clear the top wichbones.

g