Brake proportioning valve from Paragon
04-01-2003, 09:55 AM
#16
Burning Brakes
It is my understanding that on a Porsche, the bias valve is actually a pressure limiter. It also has NO effect until you have exceeded 50% of full braking power. Before you hit that threshold the valve is doing nothing. It is not really something you need to bother with for the street. On the track it will help reduce fade some because you are spreading out the work more.
I ran a 33bar on my '86 951. This is without anti-locks and it seemed to help on the track. I have installed one on my 928 too along with big reds. I haven't had a chance to track it yet though. It is an upgrade that is difficult to feel and really only helpful under racetrack conditions.
I ran a 33bar on my '86 951. This is without anti-locks and it seemed to help on the track. I have installed one on my 928 too along with big reds. I haven't had a chance to track it yet though. It is an upgrade that is difficult to feel and really only helpful under racetrack conditions.
04-02-2003, 07:21 AM
#19
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</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Brent 89-GT:
<strong>It is my understanding that on a Porsche, the bias valve is actually a pressure limiter. It also has NO effect until you have exceeded 50% of full braking power. Before you hit that threshold the valve is doing nothing. It is not really something you need to bother with for the street. On the track it will help reduce fade some because you are spreading out the work more.
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Do you never apply more than 50% braking force during street driving?
Brent is right about the valve function.
A well set-up brake system reduces brake distances when applying the brakes fully, simply because the rears are doing as much stopping they can without the rear end wandering off.
When you have ABS brakes that is really not a problem, but you do prevent the ABS from kicking in needlessly with a well balanced system.
Eirik Kvello-Aune
<a href="http://www.diateam.no/porsche" target="_blank">www.diateam.no/porsche</a>
<strong>It is my understanding that on a Porsche, the bias valve is actually a pressure limiter. It also has NO effect until you have exceeded 50% of full braking power. Before you hit that threshold the valve is doing nothing. It is not really something you need to bother with for the street. On the track it will help reduce fade some because you are spreading out the work more.
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Do you never apply more than 50% braking force during street driving?
Brent is right about the valve function.
A well set-up brake system reduces brake distances when applying the brakes fully, simply because the rears are doing as much stopping they can without the rear end wandering off.
When you have ABS brakes that is really not a problem, but you do prevent the ABS from kicking in needlessly with a well balanced system.
Eirik Kvello-Aune
<a href="http://www.diateam.no/porsche" target="_blank">www.diateam.no/porsche</a>
04-02-2003, 09:48 AM
#20
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Kevin.
The Bias Valve screws onto the master cylinder. It is a cylinderical piece about two inches in length. The metal brake line connects to the other end of the Bias valve.
Those with ABS, the bias valve screws onto the ABS unit( inside the passenger side fender towards the door) Inner fender lining has to be removed to get access.
Bleed the brakes after replacing the Bias valve.
Eugene.
The Bias Valve screws onto the master cylinder. It is a cylinderical piece about two inches in length. The metal brake line connects to the other end of the Bias valve.
Those with ABS, the bias valve screws onto the ABS unit( inside the passenger side fender towards the door) Inner fender lining has to be removed to get access.
Bleed the brakes after replacing the Bias valve.
Eugene.
04-02-2003, 01:23 PM
#22
Burning Brakes
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Is it worth changing to the 5/33 bar unit over stock setup on 87 951 with ABS. Spirited street driving, some auto-x and DE. I would like better braking, but will this make a worthwhile difference.
04-02-2003, 01:52 PM
#23
Burning Brakes
Well, I've suckered myself into doing it on two different cars now 
So I do think it helps. I think the most cost effective way to improve braking is with a set of good brake pads. The cost of the bias valve is pretty low and I figured every little bit helps. I was constantly fighting brakes in my 86 951. Much of that could be attributed to the extra 100hp I bolted on though 
For DE, the set-up I used, that worked the best for me, was slotted cryo rotors, Performance Friction "90" pads, ATE fluid, 33bar bias valve and 968 brake coolers. It worked pretty well.
For the 928 I immediately went to the biggest dang brakes I could find (GTS / Big Red). I bet an S4 or Big Red set-up would be just awesome in a 951.
Good Luck
So I do think it helps. I think the most cost effective way to improve braking is with a set of good brake pads. The cost of the bias valve is pretty low and I figured every little bit helps. I was constantly fighting brakes in my 86 951. Much of that could be attributed to the extra 100hp I bolted on though For DE, the set-up I used, that worked the best for me, was slotted cryo rotors, Performance Friction "90" pads, ATE fluid, 33bar bias valve and 968 brake coolers. It worked pretty well.
For the 928 I immediately went to the biggest dang brakes I could find (GTS / Big Red). I bet an S4 or Big Red set-up would be just awesome in a 951.
Good Luck
