Brake balance
 

I increased the front brakes to the 4x4 cosworth 60mm single piston calipers with 290mm?? i think discs front a cosworth 2WD, this increase in front brake efficency is enough to offset the rear.

Ive no reducers or proportioning valves in my system at all.[/quote]

Taken from another post, simple when someone has used a bit of lateral thinking. Nothing complicated just up the fronts to compensate.

Bob

my brakes were all standard it went through fine. its only the bigger 9-10inch drums that cause a problem

I thought from reading posts about locking rears mainly at iva that there was a problem, I thought that there were all sorts of things going on like bias pedal boxes ,proportioning valves ect to sort out the balance issues. I am having discs all round so in theory should not have a problem?????????

Bob

I've read about problems with the rears looking before but I don't understand why this is happening as the braking system should be complete from the donor Sierra minus just the servo and that shouldn't cause brake bias upset. Granted the weight distribution is different but that reduces weight over the front wheels so they should look sooner.
Can only think that people arn't using the inertia valve or mounting it incorrectly which could allow more line pressure to the rear. (This was a problem with Tiger cat E's)
I wouldn't have thought just increasing the fronts would help as the lining material temp will affect its mu value so they may be worse than standard.
Also you would need to change the master cylinder to ensure the correct line pressure to the fronts with bigger section cylinders and that may adversely affect the rears performance.
I wonder how many others have had this problem and what they did about it.

Have just re-read your thread and see you're using discs all round. If I remember correctly didn't disc all round Sierra's come with ABS as standard? If so then the ABS computer would have controlled line pressure individually to each wheel and adjusted it to prevent wheel lock. Not sure how it would perform without the ABS system.

BV.

I thought you had to use the brake valve doodah to stop the arse end locking up, it needs bolting on at an angle if I remember right and usually mounted in the start of the trans tunnel.

It makes no difference fitting the inertia valve, because when they test the rear brakes on the rollers at IVA the car is stationary, therefore the inertia valve doesn't do anything.

Gus got around the bigger 9" drum problem by fitting smaller Escort wheel cylinders.

iva man at exeter said he can test the inertia valve operation by driving brake test when i asked about brake bits
so that can be used but have to ne set correctly at time of test