Author Topic: Rear Brake proportion valve  (Read 2467 times)

Logix66

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Rear Brake proportion valve
« on: March 30, 2021, 18:05:43 »
   So I am in the process of completely redoing the rear brakes and front , lines and all. The proportion valve rear center for the rear brakes looks old and crusty, can i rebuild this myself or send it out some where ? is there a way to test this ? maybe its just fine... Cant seem to find anything on this or maybe not searching correctly. Thanks for any assistance in this.
John Peters
1968 280SL

pagodapete

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Re: Rear Brake proportion valve
« Reply #1 on: March 30, 2021, 18:27:46 »
PMB Performance rebuilds them for around $200 I believe.
Brian Peters
Motoring Investments

Logix66

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Re: Rear Brake proportion valve
« Reply #2 on: March 30, 2021, 18:37:14 »
Thank you !! Will be calling them shortly. hate to spend so much time and energy on everything else and leave that as is only to find out it doesn't work correctly and have to disassemble it again,lol.
John Peters
1968 280SL

Benz Dr.

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Re: Rear Brake proportion valve
« Reply #3 on: March 30, 2021, 20:51:05 »
Simple test: drive your car where someone can watch as it brakes to a panic stop.  Front wheels should pretty much lock up but never the back ones. If they do, we'll be looking for you in the pumpkin patch because the BFR is faulty. Every car with rear disc brakes should be tested this way at the start of every season.  20 MPH is fast enough to do this test.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

Kevkeller

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Re: Rear Brake proportion valve
« Reply #4 on: March 30, 2021, 22:00:41 »
Here is a post I started several years ago.

https://www.sl113.org/forums/index.php?topic=13099.msg90236#msg90236

Let us know what the rebuild company has to say.

Kevin
1970 280 SL

roymil

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Re: Rear Brake proportion valve
« Reply #5 on: February 01, 2023, 20:31:53 »
Hello, I was wondering how that rebuilt rear brake proportioning valve is working for you?   Did you end up having PMB do it?   I've use them for calipers with good results and now I think I need to have my proportion valve rebuilt too.    I did it my self a couple years ago and it seemed in good shape but at least twice recently I've tested my brakes with a hard stop from about 40MPH and had the rears lockup both times, way earlier than felt right.    I understand they should never lock before the fronts and I'm taking this warning to fix them correctly, either with PMB rebuild or with an aftermarket Tilton valve that I read about on an old post. 

Has anyone done any real life testing with a PMB rebuilt prop. valve or the Tilton valve under very hard braking? 

thanks!
Mark Miller
1968 280SL
Rode in his pagoda's first mile.