Adjustable Brake Bias
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,254
Likes: 1
From: Edinburgh
Adjustable Brake Bias
Hi guys, I am finding it very easy to lock up the front brakes especially in the wet. How hard is it to make the brake bias adjustable?
Thanks
Graeme
Thanks
Graeme
Last edited by Graemeinvette; May 27, 2009 at 07:10 AM. Reason: Add notification
Tech Contributor
Joined: Jun 2004
Posts: 20,850
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Well, generally adjustable bias is to reduce the tendency of the rear to lock up, not the front. I think you should put your energy towards getting the rear to bite better, rather than trying to reduce the front. I would check to see if your rear soft lines are swelled shut, or perhaps investigate a higher c/f rear pad.
JMO
JMO
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,254
Likes: 1
From: Edinburgh
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
The small in comparison 245 with 25.7 diameter makes your front brake rotor more effective. Then your rears are 26.7 inches in diameter with lots more tread on the ground.
I run 275 kumho ecsta mx front tires on 10 inch rims with 4 inch BS. If your front rims are at least 9 inch I think they could be fitted. My fronts touch the sway and frame on extreme lock to lock. So I just never over steer to far.
Another option is to use a higher friction rear pad and lower in the front.
I have single front tire lock if I am coming into a turn and turn a little bit. It's not a big deal, I just let of a little on the brake petal. I just see a puff of blue smoke coming out of the offending fender
I run 275 kumho ecsta mx front tires on 10 inch rims with 4 inch BS. If your front rims are at least 9 inch I think they could be fitted. My fronts touch the sway and frame on extreme lock to lock. So I just never over steer to far.
Another option is to use a higher friction rear pad and lower in the front.
I have single front tire lock if I am coming into a turn and turn a little bit. It's not a big deal, I just let of a little on the brake petal. I just see a puff of blue smoke coming out of the offending fender
Last edited by gkull; May 27, 2009 at 02:07 PM.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
Brake bias can be adjusted with a proportioning valve like the J-56 brake package of the 67-68 (but NOT 69) L-88 Vette had, brake pad material or Caliper piston diameter. You may want to try some agressive rear pads like an EBC "yellow" at the back with the EBC "red" on front and then adjust bias with proportioning valve to get even braking. BE CAREFUL when playing with bias as spin-outs can easilly happen in testing, make sure you are expiriementing in the proper "open space" (away from all your UK photo speed cameras 
)
)
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,254
Likes: 1
From: Edinburgh
Thanks Solid, thats useful, the problem I have at the moment is the likelyhood of 'spinning out' with the fronts locking up since they come on so hard, hence the reason for the original question about bias adjustment. I could take the braided lines off the front to give it a more gentle take up but that would seem to be going backwards.
I should also mention that I have hydroboost and Sports rotors from VB&P.
I should also mention that I have hydroboost and Sports rotors from VB&P.
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Le Mans Master
Joined: Dec 2003
Posts: 5,727
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From: Fremont CA
Are you sure the rear brakes are properly bled because I only have expirienced front lock-up in racing situtations with EXTREEM application of brake and even though the fronts are weighted, they will lock-up. If you are getting front lock-up in normal driving, I would re-bleed your rear brakes, you need the Master Cylinder cover off, and start gravity bleeding at right rear outside bleeder, inside the left rear outside/inside. The brake fluid should come out of the bleeder in a steady streem with no air (I use clear Ploy tubing to observe the fluid streem, and sometimes you need to lightly push brake pedal about 4-6mm to unseat MC piston.) Brake fluid type can effect bleeding, I won't use DOT 5 Silicone based fluids in my Vettes, Castrol LMA is a good "street" fluid while in the USA Ford factory brake fluid is some of the best for tracked Vettes (something to do with some obscure Lola based Ford race car that went down the Mulsanne straightaway at 230MPH in the 60's made Ford engineer good OEM brake fluid.) Make SURE you rear brakes are properly functioning. I also take the Vette for a drive and quickly bleed the brakes while the fluid is hot after working on hydraulic system of any C2/3 Vette.
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,254
Likes: 1
From: Edinburgh
Thats a good point Solid. I will give them a bleed over the weekend and see. I am using DOT4, no silicone. I have heard about the Ford US fluid, but I dont think its available here, there are other DOT4 high performance fluids available though, Castrol do one thats highly recommended. And I will give it a drive first to warm it up.
I appreciate your input, thanks.
Graeme
PS I think you mean the Lola Ford Mk 6 GT
This car led Ford directly to develop the GT 40.
I appreciate your input, thanks.
Graeme
PS I think you mean the Lola Ford Mk 6 GT
This car led Ford directly to develop the GT 40.
Last edited by Graemeinvette; May 28, 2009 at 03:14 PM. Reason: adding info
Le Mans Master
Joined: Apr 2007
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From: Graceland in a Not Correctly Restored Stingray
Thanks Solid, thats useful, the problem I have at the moment is the likelyhood of 'spinning out' with the fronts locking up since they come on so hard, hence the reason for the original question about bias adjustment. I could take the braided lines off the front to give it a more gentle take up but that would seem to be going backwards.
I should also mention that I have hydroboost and Sports rotors from VB&P.
I should also mention that I have hydroboost and Sports rotors from VB&P.
Last edited by TheSkunkWorks; May 28, 2009 at 05:01 PM.
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
The fronts locking up first is very suspect.
I don't think you are getting good rear brakes.
The vette is rear biased from the factory, how did yours change? Are you running stock brakes?
I do not like your brakes doing that. It is unnatural.
Keith
I don't think you are getting good rear brakes.
The vette is rear biased from the factory, how did yours change? Are you running stock brakes?
I do not like your brakes doing that. It is unnatural.
Keith
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,254
Likes: 1
From: Edinburgh
Thanks guys especially Solid, I bled the rear brakes today and found some air, the road test after showed a big improvement! One thing though, I notice I have a bleed nipple on the inner and outer caliper, should I bleed both?
Graeme
Graeme
