Brake proportion rear disks.

[twinturbo]

How do people set the rear disk balance to prevent them locking?

Do you just use a Drum brake valve? or a bias bar?

Do you use the small drum brake master cylinder and put up with the pedal travel, or use the 25mm ( RARE!! ) XR4x4 non abs cylinder?


Has anyone used the Pumped master cylinder from an ABS car without using the rest of the ABS system?

TT

[flyerncle]

Spuds car went through SVA no probs with standard rear drum/front disc setup,on the other hand others have had problems with front to rear balance and had to swap cylinders etc.
The abs pump is to large as has been discussed before on here so its probably sensible to go for a standard setup and modify after IVA to avoid headaches.
If you want a bias bar setup do it later as they have to be locked,make two brake plates.

[twinturbo]

So disk rears could be a problem?

Main reason for asking is the cost of rear uprights and having to swap if there's an issue.

TT

[flyerncle]

Possibly,you could fit reducers inline to loose a little rear pressure, and adapters are available for the uprights for disc's/from drums(3GE do them cheap) I have the uprights and will fit drums for test and then replace them after.

[alga]

Worth mentioning, the only Roadster that passed IVA needed drum brake cyliders downsized.

[twinturbo]

So what's everyones plans?

How many have failed the IVA

How many have passed the SVA?

TT

[les g]

Adrian
it would appear the wallet is the limit with brakes
i think upgrades are more about heat dissipation and survivability of brakes in racing conditions
also things like lightness of pedal/pedal effort/driver fatigue.
speed of brake application and release.
and also lightening of brake assemblies to reduce unsprung weight etc
you cant get better braking than if you can lock all the wheels which is obviously achievable with a sierra set up
its the other bits that people are looking at
cheers les g

[Talonmotorsport]

Has any body thought about using the load sensing valve from an escort van? It can be made to be adjustable with a 2 lock nuts and a bolt,mounted in the engine bay near the master cylinder would make it more accessable than a bias bar which needs to be welded come IVA time.

[Bonzo]

Has any body thought about using the load sensing valve from an escort van? It can be made to be adjustable with a 2 lock nuts and a bolt,mounted in the engine bay near the master cylinder would make it more accessable than a bias bar which needs to be welded come IVA time.

Must admit. The thought has crossed my mind ;)

I'll be able to have the chance to ballance my brakes on the rolling road prior to my IVA ............ Or whatever the test is called in a few years time :o :o :D

[les g]

Adrian
the only benefit of rear discs i can remember from my college days
(dont laugh )
were unsprung weight and lack of brake fade and less parts of course
i cant remember any thing else
cheers les g

[twinturbo]

I guess the "Looks" is the only other advantage of disks.

And that all the LSD's are designed for the disk brake bolt on shafts.


I think Drums will be the way to go for me.

It had the big advantage that the crappy handbrake system on the seirra calipers will not be an issue.

TT

[Matthew]

I've got the rear disks as they came fitted to the donor, and after reading around a bit have also bought a Mini brake pressure regulating valve. I'm planning to just plumb it in initially, then modify it after IVA if necessary.

Matt

[carlknight1982]

ive done some maths and gone for a 380mm cosworth single piston disc/caliper set up up front and standard rear discs on the back the increased front braking should counteract the increase in rear braking enough to get a good balance.

[Enoch]

I have fitted the rear brake limiting valve from a pre abs Sierra on to mine. It does not affect the braking under normal conditions but will limit the rear braking effort under heavy braking. You can change the point at which it cuts in by changing the angle that it sits at in the car - it works on inertia. I fitted one to my Robin Hood which passed SVA, the tester ran through the automatic tests and it failed on over braked rear. He knew it had the valve in so took it out in the car park and slammed on the brakes to make sure the rears did not lock. He then passed the car even though the auto test still showed a fail.
If you are fitting a limit valve remember to fit the pressure activated brake light switch between the master cylinder and the valve - if it is installed after the valve your brake lights will turn off when the valve activates. Initially install the valve at the same angle as it was installed in the Sierra - it was about right on my Robin hood so should be about right in the Haynes.
Enoch.