The m/c and rear calipers are both from the donor E34, the only different parts are the sierra front calipers. I still have the donor front calipers, perhaps I could look into fitting them instead of changing the m/c? Would need bigger discs though.

im not sure greenstuff are that great either.... mintex 1144 and 1155 always seem to come much more highly rated on my vx220turbo.

I have used EBC black, green and reds. Reds were good with a bit of warmth in them. Green not impressed with, black were good for a road pad.

It seems that the brake system get over engineered thinking that it will be better than the original and we tend to lose the plot with large calipers and discs only to find exactly what this thread is about.

The donor whatever it is weighs possibly three times the Roadster and the brakes are made accordingly.

The clamping force is paramount and size is secondary,but larger is better with regard to heat dissipation.

Pad material again is a consideration as you need vehicle mass and pedal pressure to generate heat and the Roadster is light.

I go back to my post and still think its the mixture of parts that is mismatched with regard to m/cyl bore and caliper piston sizes.

Larger discs will require bigger carriers.

Yeah i understood, and that's why i suggested I might look into the possibility of fitting the donor E34 BMW front calipers so it would then be the entire system as taken from the donor, with the omission of the hydraulic servo.

At the moment, the only mismatch is the sierra front discs/calipers.

Sam
dont under estimate the amount of assist the servo gives
just think how crap the brakes are on your road car without the engine running .
as soon as you pump the brakes and use up any stored vacuum in the servo the brakes are non-existant.
ie. the servo was doing all the work
i think you need to increase the line pressure as the brakes are probably more than adequate .
as said by someone before a reduction in m/cyl bore size would increase line pressure
cheers les g

Good call Les,I used to think the opposite that larger gave more force untill proven wrong.

Good call Les,I used to think the opposite that larger gave more force untill proven wrong.

The race car I have built in conjunction with Saturn has used a G20 Ginetta as a donor and the pedal box has two cylinders and the front is .70 and the rear .75.

May be the answer to the problem Sam fitting the Bee Em parts,hope you get it sorted.

Does anyone know the dimensions of a sierra master cylinder and servo assembly?

I'll have a look at it tonight and see if I can fit it in. The problem with running a big V8 is it takes up most of the room in the engine bay.

Sam
why why not fit a remote servo it dont even need to be close to your master cylinder
Check out Car Builder Solutions i,m sure they do them
cheers les g

Hi Les,

yeah I've spotted the remote servo's, unfortunately I would need to run 2 as I have dual circuit brakes. As they are nearly £200 each it's not exactly something i can stretch my budget to.

Good idea though.