Brakes Looking to upgrade or get the most out of what you have stock? All brake discussions go here!

Proportioning valve

Thread Tools
 
Search this Thread
 
Old Mar 14, 2017 | 11:38 AM
  #1  
RS Chris's Avatar
Thread Starter
Supreme Member
 
Joined: Aug 2004
Posts: 1,046
Likes: 6
From: Pasadena, TX
Car: 1991 RS
Engine: 5.0
Transmission: 700r4
Proportioning valve

Getting ready to install a 4th gen 10 bolt and I'm converting to disc rear from drums. I have everything I need except the prop valve. Found these on ebay. Anybody use them? Any reason why I shouldn't? Price is nice compared to others, but I don't want to be too cheap on brake system parts.

http://www.ebay.com/itm/GM-Universal...3D322419344315
Reply
Old Mar 14, 2017 | 02:59 PM
  #2  
RBob's Avatar
Moderator
iTrader: (1)
 
Joined: Mar 2002
Posts: 18,432
Likes: 233
From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: Proportioning valve

Because it has the wrong thread/fittings to go into your '91 without running adapters.

RBob.
Reply
Old Mar 14, 2017 | 07:14 PM
  #3  
QwkTrip's Avatar
COTM Editor
25 Year Member
iTrader: (22)
 
Joined: Mar 2001
Posts: 10,405
Likes: 2,081
Car: '89 Firebird
Engine: 7.0L
Transmission: T56
Re: Proportioning valve

Prop valves are vehicle specific to create the brake bias needed for your car. Don't just ***** nilly toss any prop valve in there without knowing how it will behave in your car.
Reply
Old Mar 15, 2017 | 10:12 AM
  #4  
RS Chris's Avatar
Thread Starter
Supreme Member
 
Joined: Aug 2004
Posts: 1,046
Likes: 6
From: Pasadena, TX
Car: 1991 RS
Engine: 5.0
Transmission: 700r4
Re: Proportioning valve

After some research I came to the same conclusion as both of you.
Reply
Old Mar 15, 2017 | 05:28 PM
  #5  
Base91's Avatar
Supreme Member
iTrader: (1)
 
Joined: Sep 2010
Posts: 1,928
Likes: 1
From: Georgetown TX
Car: Base 91 'bird
Engine: 3.1 v6
Transmission: 4L60
Axle/Gears: 9-bolt 3.27 & PBR
Re: Proportioning valve

You may want to look at adjustable valves (Summit etc). I did with drum to disc conversion and it made a huge difference being able to dial up the rear braking beyond what a fixed valve would do.
Reply
Old Mar 15, 2017 | 09:33 PM
  #6  
86White_T/A305's Avatar
Supreme Member
20 Year Member
Liked
Loved
 
Joined: Nov 2001
Posts: 2,266
Likes: 37
From: Canada,Ont
Car: 1987 TransAm Ttop
Engine: 2005 LQ4
Transmission: Ls1 T56
Axle/Gears: 3:54
Re: Proportioning valve

You not have to change the prop at all..just try different spring in the stock prop.Your cheapest route for sure and reading the thread it seems extremely effective.I also choose this to increase rear brake pressure. I think the 19lbs spring in the stock prop might suit you..I opted for the 22lbs spring but im also converting to ls1 front brakes.
Reply
Old Mar 16, 2017 | 08:01 AM
  #7  
QwkTrip's Avatar
COTM Editor
25 Year Member
iTrader: (22)
 
Joined: Mar 2001
Posts: 10,405
Likes: 2,081
Car: '89 Firebird
Engine: 7.0L
Transmission: T56
Re: Proportioning valve

Just something to think about....

I have drag radials on the back of the car so rear traction is much greater than normal in dry weather, and much less than normal in rain. That causes a wild shift in brake bias depending on road conditions since my front tires are different. On dry roads I run the brakes almost to the max to create a decent bias so the car stops well. If I get caught in rain my rear traction goes to poo and that adjustable prop valve allows me to dial down the rear brakes so I can get home in one piece. It doesn't matter when braking easy, but it would matter if I had to do a hard stop in the rain.
Reply
Old Mar 18, 2017 | 11:54 AM
  #8  
Base91's Avatar
Supreme Member
iTrader: (1)
 
Joined: Sep 2010
Posts: 1,928
Likes: 1
From: Georgetown TX
Car: Base 91 'bird
Engine: 3.1 v6
Transmission: 4L60
Axle/Gears: 9-bolt 3.27 & PBR
Re: Proportioning valve

I did mine the easy quick way and mounted the valve right on the distribution block but if I did it again I'd go the extra mile and mount it somewhere on the tunnel. But my car is stripped out so doesn't have to work with the console or any trim.
Reply




All times are GMT -5. The time now is 02:22 AM.