more rear brake bias
08-31-09 | 08:56 PM
#1
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From: Chino and Lake Arrowhead Calif
more rear brake bias
On my autocross car I would like to add more rear braking ability... Now I know that you must have the majority of your braking on the front, but sometimes I need more to the rear. Sometimes it seems that I am locking up the front too much while the rear NEVER locks.
Has anyone added a rear brake bias adjuster?? Is there anything you can do with the stock proportioning valve to add more rear bias???
Please advise if you have done something like this!
Has anyone added a rear brake bias adjuster?? Is there anything you can do with the stock proportioning valve to add more rear bias???
Please advise if you have done something like this!
08-31-09 | 11:37 PM
#2
Without knowing your whole situation and setup, I would suggest playing with pad compounds. This is relatively cheap and won't screw anything else up. If you go with Hawk pads, for example, you can get a higher mu pad for the rear and see if that does it. If you don't like it, you can easily switch back.
As for prop valves, they're generally plumbed in line with the OEM prop valve to reduce pressure to the rear -- which is the opposite of what you want.
As for prop valves, they're generally plumbed in line with the OEM prop valve to reduce pressure to the rear -- which is the opposite of what you want.
09-01-09 | 08:44 AM
#3
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Joined: Jul 2008
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From: Chino and Lake Arrowhead Calif
Without knowing your whole situation and setup, I would suggest playing with pad compounds. This is relatively cheap and won't screw anything else up. If you go with Hawk pads, for example, you can get a higher mu pad for the rear and see if that does it. If you don't like it, you can easily switch back.
As for prop valves, they're generally plumbed in line with the OEM prop valve to reduce pressure to the rear -- which is the opposite of what you want.
As for prop valves, they're generally plumbed in line with the OEM prop valve to reduce pressure to the rear -- which is the opposite of what you want.
09-01-09 | 11:19 AM
#4
09-01-09 | 11:46 AM
#5
No way to adjust the bias that I know of unless you replace the proportioning valve with an adjustable one which might bump you into another class. Anyway, make sure your back brakes are adjusted every time you go out.
Other than that the reason the fronts start locking up more than the rears is that the rear drum brakes (I'm assuming stock drums) will heat up faster than the fronts and start fading faster. As stated you can try playing with various shoe compounds to see what you can get. Of course if its an 84 and you have discs in back then I'm out of ideas for now.
Other than that the reason the fronts start locking up more than the rears is that the rear drum brakes (I'm assuming stock drums) will heat up faster than the fronts and start fading faster. As stated you can try playing with various shoe compounds to see what you can get. Of course if its an 84 and you have discs in back then I'm out of ideas for now.
09-01-09 | 01:08 PM
#6
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i think the prop valve chart is in the FSM, might be worth looking at. it does bleed off pressure to the rear, but maybe you can slow it down.
ive seen the stock valve made adjustable before...
ive seen the stock valve made adjustable before...
09-01-09 | 01:40 PM
#7
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Joined: Jul 2008
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From: Chino and Lake Arrowhead Calif
No way to adjust the bias that I know of unless you replace the proportioning valve with an adjustable one which might bump you into another class. Anyway, make sure your back brakes are adjusted every time you go out.
Other than that the reason the fronts start locking up more than the rears is that the rear drum brakes (I'm assuming stock drums) will heat up faster than the fronts and start fading faster. As stated you can try playing with various shoe compounds to see what you can get. Of course if its an 84 and you have discs in back then I'm out of ideas for now.
Other than that the reason the fronts start locking up more than the rears is that the rear drum brakes (I'm assuming stock drums) will heat up faster than the fronts and start fading faster. As stated you can try playing with various shoe compounds to see what you can get. Of course if its an 84 and you have discs in back then I'm out of ideas for now.
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09-01-09 | 01:40 PM
#8
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From: Chino and Lake Arrowhead Calif
09-01-09 | 07:03 PM
#10
The PPV has a needle and a spring. Not sure what you could change other than a stiffer/softer spring. You might try going with a softer/grippier tire compound in the front, maybe lowering the air pressure.
09-01-09 | 07:48 PM
#11
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From: Chino and Lake Arrowhead Calif
Probably the same problem, but with grippy tires...
09-01-09 | 09:59 PM
#12
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Most of us who AutoX FB's run a more aggressive pad inthe front because of too much rear bias. You might have a sticky real caliper... Try rebuilding your calipers. It's dirty and nasty, but worth the work. I run Hawk HP+ front and regular hawks in the rear. Usually under steer from a FB menas you're going in too fast, and then not applying the throttle soon enough. I tend to go in too fast and throttle too early, so I tend to drift through a lot of turns. It's fun, but its so fugging slow....
09-02-09 | 08:31 AM
#13
Thread Starter
Joined: Jul 2008
Posts: 1,669
Likes: 9
From: Chino and Lake Arrowhead Calif
Most of us who AutoX FB's run a more aggressive pad inthe front because of too much rear bias. You might have a sticky real caliper... Try rebuilding your calipers. It's dirty and nasty, but worth the work. I run Hawk HP+ front and regular hawks in the rear. Usually under steer from a FB menas you're going in too fast, and then not applying the throttle soon enough. I tend to go in too fast and throttle too early, so I tend to drift through a lot of turns. It's fun, but its so fugging slow....
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