Rear Brakes Lock Up

[Guest Megster]

I've spun my car at the last four sprints/hillclimbs I've done and each time it was a case of the front suspension loading up, the rear going light, the rear disk brakes lock up and around 180 degrees she comes! Lucky I've not actually hit anything more solid than tyres so far, but how can I try and prevent this from happening again?

 

Two very experienced front wheel drive racers (one a 205 driver himself) have told me to decrease the amount of rear braking by machining half the material off the rear pads. What do you think?

 

My car has standard 1.9 brakes front and rear and runs on Yoko AO32R softs.

 

Thanks - AJ

[hengti 2]

i spun a couple of times on my last sprint too, but i reckon that's more to do with immediate over-exuberance on cold (medium) tyres

try renewing the compensators - mine always used to lock at the back first, but after renewing compensators, the fronts invariably lock up first

[Jonmurgie 2]

I had that problem a LOT on the track... I've not got a brake bias valve to fit but when I fitted 23mm TB's and 25 ARB on the beam the back end totally stopped stepping out under breaking, it still locks up though, it's just a LOT more stable with the uprated beam...

 

What's your suspension setup?

[feb 47]

As hengti said replace the brake compensators. Had the same problem until i replaced the compensators.

[Butler 0]

I'd fit an adjust adjustable valve. T the rear lines into 1 line and through a valve and T out to both wheels. Ditch the compensators.

 

Machining the pads would work, but a bit of a bodge.

[Guest Megster]

Thanks guys,

 

I have Gaz adjustables front and rear. Front shocks have spax progressive springs that a tarnac rallying friend gave me - unsure of their spec if honest. Rear beam has Baker group A solid bushes. Standard ARB and torsion bars.

 

Shock settings pretty much depend on the tarmac we're running over and how dry it is. I always start the day halfway and stiffen up/slack off depending on weather and surface.

 

 

 

AJ

Edited August 17, 2006 by Megster

[Garry 1]

I'd fit an adjust adjustable valve. T the rear lines into 1 line and through a valve and T out to both wheels. Ditch the compensators.

 

I too had the same problem and fitted internal lines with a lever type proportioning valve, the car is fine now.

[jonah 1]

I'd fit an adjust adjustable valve. T the rear lines into 1 line and through a valve and T out to both wheels.

 

I say again, DON'T connect the rear lines together on a diagonal split system, you will lose the safety feature of the dual hydraulic circuit. Do it properly and re-plumb the system with a front/rear split.

[Butler 0]

Oh yes I did set mine to a front / rear split as well. Easy enough to do.

[engine killer 6]

I too had the same problem and fitted internal lines with a lever type proportioning valve, the car is fine now.

 

 

I say again, DON'T connect the rear lines together on a diagonal split system, you will lose the safety feature of the dual hydraulic circuit. Do it properly and re-plumb the system with a front/rear split.

 

 

Spliting the system and putting a lever type proportioning valve seems the easiest and cost effective way. if budget allows, pedal-box it would be most ideal.

 

pedal box like this

http://community.webshots.com/photo/541476...084130750UrDODk

 

at first i found it too stiff and difficult to stop the car - extremely dangerous on street. but after a month of practice, i can make the whole system under full control much better than with brake-servo, very detail pedal-feel as well.