brake bias valve
04-24-2002, 12:17 PM
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brake bias valve
How can you tell if you need one?
In my 86 951 track car set up with big reds I have noticed that during high speed threshold braking (non ABS)the rear end feels like it is getting a bit loose. Is it possible that the rears are approaching lockup when the weight transfers to the front? Would a brake bias valve help?
TIA <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
In my 86 951 track car set up with big reds I have noticed that during high speed threshold braking (non ABS)the rear end feels like it is getting a bit loose. Is it possible that the rears are approaching lockup when the weight transfers to the front? Would a brake bias valve help?
TIA <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
04-24-2002, 01:09 PM
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If under heavy braking the rear begins to step out, the brakes are too biased to the rear, ie too much brake at the rear as compared to the front.
A bias valve would allow you to "dial" out braking to the rear. You would do this incrementally until the problem is solved.
A bias valve would allow you to "dial" out braking to the rear. You would do this incrementally until the problem is solved.
04-24-2002, 01:33 PM
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Sloth,
If you race the car in a PCA stock class a brake bias adjuster is prohibited. If it is a GT car you can do what you want of course. A cheaper solution is to try a different compound of brake pads in your car. This helped my 993.
Greg
If you race the car in a PCA stock class a brake bias adjuster is prohibited. If it is a GT car you can do what you want of course. A cheaper solution is to try a different compound of brake pads in your car. This helped my 993.
Greg
04-24-2002, 02:25 PM
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[quote]Originally posted by Sloth:
<strong>I may as well go all out as the car would run as a GT3.</strong><hr></blockquote>
Yeah it is only money, we burn it like fuel when racing.
<strong>I may as well go all out as the car would run as a GT3.</strong><hr></blockquote>
Yeah it is only money, we burn it like fuel when racing.
04-24-2002, 03:01 PM
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You could go with a Tilton proportioning valve as I did, it a joystick type valve which is easy to adjust on the fly. I mounted it on top of the tunnel within reach.
The other solution would be to try a different "T" intersection in the brake line running to the rear. As smaller fixed orifice may be allowed in your class, but it will take some experimentation.
Good luck !
The other solution would be to try a different "T" intersection in the brake line running to the rear. As smaller fixed orifice may be allowed in your class, but it will take some experimentation.
Good luck !
04-24-2002, 09:51 PM
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[quote]Originally posted by Sloth:
<strong>How can you tell if you need one?
In my 86 951 track car set up with big reds I have noticed that during high speed threshold braking (non ABS)the rear end feels like it is getting a bit loose. Is it possible that the rears are approaching lockup when the weight transfers to the front? Would a brake bias valve help?
TIA <img src="graemlins/burnout.gif" border="0" alt="[burnout]" /> </strong><hr></blockquote>
Hey Sloth,
Do you have a limited slip in your transaxle? If so are the plates worn significantly? If you have a LSD already you may find that going to a 60 or 80% lockup will help settle your car under braking. I am running an 87' 951 w/big reds in front (pagid orange pads ) and stock rear calipers and pads. This car is gutted and pretty much track only, eight pt. cage etc. When I ran this car with the oem open diff. it liked to wag in the rear end under heavy braking. I recently installed a GT LSD and the problem seems to have gone away.
Kevin
<strong>How can you tell if you need one?
In my 86 951 track car set up with big reds I have noticed that during high speed threshold braking (non ABS)the rear end feels like it is getting a bit loose. Is it possible that the rears are approaching lockup when the weight transfers to the front? Would a brake bias valve help?
TIA <img src="graemlins/burnout.gif" border="0" alt="[burnout]" /> </strong><hr></blockquote>
Hey Sloth,
Do you have a limited slip in your transaxle? If so are the plates worn significantly? If you have a LSD already you may find that going to a 60 or 80% lockup will help settle your car under braking. I am running an 87' 951 w/big reds in front (pagid orange pads ) and stock rear calipers and pads. This car is gutted and pretty much track only, eight pt. cage etc. When I ran this car with the oem open diff. it liked to wag in the rear end under heavy braking. I recently installed a GT LSD and the problem seems to have gone away.
Kevin
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04-25-2002, 09:12 AM
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The car has a brand new GT LSD, I am not sure the lockup percent though. I would have hated to have seen the braking effect with an open rear end.
With the big reds all around I hope that a valve would be the way to go.
Thanks. <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
With the big reds all around I hope that a valve would be the way to go.
Thanks. <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
04-25-2002, 01:22 PM
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I agree with the percent diff affecting the rear braking. I have been running a totally locked rear ( welded spiders) for over two years which has vastly improved the overall braking of the car. For me it is the only way to go...cheaper and lighter than quaiffe or OEM LSD.
Try it ..you will like it. Just a thought.
Pete
Try it ..you will like it. Just a thought.
Pete