1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Rear brake proportioning valve options on 1985 GSL

Old Jul 17, 2018 | 01:37 PM
  #1  
racerx01's Avatar
Thread Starter
Full Member
 
Joined: Nov 2016
Posts: 225
Likes: 19
From: Louisville, KY
Rear brake proportioning valve options on 1985 GSL

Went thru tech section and it appears that many FB owner don't run this valve. And from talking to other Rotor-heads; many replace with aftermarket. Questions: 1) What is the reduction of brake efficiency (or reduced stopping distance) if not running this valve. 2) What is most common aftermarket valve and how do you have balance set-up. I am having trouble finding OEM replacement (any recommended sources). Thanks.
Reply
Old Jul 17, 2018 | 03:13 PM
  #2  
t_g_farrell's Avatar
Waffles - hmmm good
Tenured Member: 20 Years
Community Favorite
iTrader: (1)
 
Joined: Jul 2004
Posts: 9,250
Likes: 464
From: Lake Wylie, N.C.
Replacements are from used sources. I don't think a new one will be found. Not running one will cause brake imbalance on hard stops and possible uneven wear. You should use one. For drum rears this is especially true but for disc I don't know how critical it is.
Reply
Old Jul 17, 2018 | 05:48 PM
  #3  
KansasCityREPU's Avatar
Out In the Barn
Tenured Member: 20 Years
Liked
Loved
Community Favorite
iTrader: (9)
 
Joined: Mar 2005
Posts: 6,705
Likes: 1,250
From: KC
On my 1979 (drum brakes), there isn't a valve. The line comes from the master to one side of the brake cylinder and out to the other side. Not sure about other drum brake years.
Reply
Old Jul 18, 2018 | 07:36 AM
  #4  
Freeskier7791's Avatar
Senior Member
Tenured Member 05 Years
 
Joined: Oct 2013
Posts: 749
Likes: 34
From: Clemmons, NC
You could probably run a wilwood valve, I have been thinking about running one since I can lock the fronts super easy with my Turbo II brake conversion
Reply
Old Jul 18, 2018 | 08:16 AM
  #5  
t_g_farrell's Avatar
Waffles - hmmm good
Tenured Member: 20 Years
Community Favorite
iTrader: (1)
 
Joined: Jul 2004
Posts: 9,250
Likes: 464
From: Lake Wylie, N.C.
Originally Posted by KansasCityREPU
On my 1979 (drum brakes), there isn't a valve. The line comes from the master to one side of the brake cylinder and out to the other side. Not sure about other drum brake years.
My 80 has a proportioning valve hanging off the side of the master which the rear drum lines go through. You need the valve for drums so they maintain a minimum pressure to make them stay slightly out against the drum, otherwise they would rattle around in the drum and not work right. I would think your 79 is missing this but would have had it when new.
Reply
Old Jul 18, 2018 | 08:19 AM
  #6  
KansasCityREPU's Avatar
Out In the Barn
Tenured Member: 20 Years
Liked
Loved
Community Favorite
iTrader: (9)
 
Joined: Mar 2005
Posts: 6,705
Likes: 1,250
From: KC
Originally Posted by t_g_farrell
My 80 has a proportioning valve hanging off the side of the master which the rear drum lines go through. You need the valve for drums so they maintain a minimum pressure to make them stay slightly out against the drum, otherwise they would rattle around in the drum and not work right. I would think your 79 is missing this but would have had it when new.
I was thinking of the block normally on the rear axle. Yes, I have the one at the firewall.
Reply
Old Jul 20, 2018 | 05:48 PM
  #7  
Carl's Avatar
Rotary Enthusiast
Tenured Member: 20 Years
Liked
Loved
Community Favorite
iTrader: (2)
 
Joined: Oct 2002
Posts: 845
Likes: 135
From: Cardiff, CA
Freeskier7791,

When you did you T2 brake install, did you do the rear brakes also? If not, that would explain your front lock-up. We did that with our endurance racer and the car lost braking ability (because of the lock-up) and ruined a lot of tires. Installing the T2 (or at least 2nd gen) brakes on the rear solved the problem.

Carl
Reply
Old Jul 27, 2018 | 10:51 AM
  #8  
Freeskier7791's Avatar
Senior Member
Tenured Member 05 Years
 
Joined: Oct 2013
Posts: 749
Likes: 34
From: Clemmons, NC
Originally Posted by Carl
Freeskier7791,

When you did you T2 brake install, did you do the rear brakes also? If not, that would explain your front lock-up. We did that with our endurance racer and the car lost braking ability (because of the lock-up) and ruined a lot of tires. Installing the T2 (or at least 2nd gen) brakes on the rear solved the problem.

Carl
Yes I have not done the rear brakes yet, I am going to be doing that and dual rear calipers soon!
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
1badFB
1st Generation Specific (1979-1985)
6
Mar 31, 2007 10:39 AM
XLNDRVR
1st Generation Specific (1979-1985)
6
Feb 28, 2006 09:53 AM


Thread Tools
Search this Thread

All times are GMT -5. The time now is 09:35 AM.