brake bias

[Tim.duncan]

Hey guys

quick background car ae86, im running a zenki jdm disc rear end. up front there is some magna rotors and holden single pot calipers. running a nissan r32 master. I have also gutted the preportion valve as the rears were not doing enough work. im pretty happy with the brakes she stops well BUT under really hard braking the front locks up.

now i have been scoping flea bay and there is some wilwood brake bias valves. to me these just look like a restrictor and normally fitted to the rear brake lines.

my problem is the fronts are doing to much work can i fit one of these valves on the front brakes? to try and let the rears do some more work?

any light on the subject would be great
cheers

[LittleRedSpirit]

I believe that you want the fronts to lock before the rears ever would. Rear brakes really dont do a tonne of work in a hard stop really. Couldnt be more than 25 or 30%, Id say you should do some further testing to see whether you can get the rears to lock up at all. You dont want them to ever, even if you lock the fronts. Its a fine line.

[Tim.duncan]

just wanted to be able to fine tune the brakes i feels like there is a little bit left in it.

when i first got the car the brakes had been upgraded and it was really bad i would just look at the brake pedal and the fronts locked but no slowing down was happening just sliding and tyre smoke. My enginear who was testing the car was explaning that the rears are very important beacuse with out them the nose dips down loading up the front wheels with heaps of wait and your braking performance is worse than if the front brakes were left stock. the rears help pull the back of the car down and allow the fronts to work harder as the car is sitting flat. i hope that made some sort of sense.

any way i would love to be able to adjust the brakes so the rears lock up first then slowley tune it back till the braking feels more balenced.

[fantapants]

i thought weight transfer was regarded as a benefit... the more weight on the front the harder you can brake befor the tyres lock up?

[Tim.duncan]

to a point this is true, but if the front brakes are doing all the work then really you are only using 2 wheels to stop instead of 4. if you transfer to much weight this would be the case

when testing we were able to stop to car with about 0.85 g force. then we would re run the test but this time using the hand brake to assist the back brakes we could pull a bit over 0.9 so the backs have a little more left in them to help pull the car up

so back to my original question. can i use a restrictor valve in the front bracks?

[ROLL3R]

With my Ae71 i use Ta63 front disks and St141 rear disks running through a R32 non turbo Master cylinder. In place of the stock proportioning valve i used the Wilwood proportioning valve insted to control my rear brake line thus giving me fine tuning to balance the braking. I looked into other products Wilwood make and they do a Proportioning valve to suit front brakes which is in car adjustable (though illegal) which provides even flow to both left and right front lines which would be an issue if you tried using 2 single Prop valves to control each left and right line. Contact Wilwood or if in Melbourne look up VPW (Victorian Performance Warehouse) as they stock all Wilwood products.

[LittleRedSpirit]

If you just want a brake bias valve to play with, I have one you can get off me. Send a pm if you like.