Can a faulty proportioning /combination valve screw up and only deliver part pressure to one front brake and not the other?
Everything else is new and adjusted properly even the suspension has all new bushings ,ball joints everything.
New flex lines,new wheel cylinders, both wheel cylinders seem to bleed properly
the proportionping valve is one of the only things NOT replaced
while bleeding each front brake the light on the dash comes on and promptly goes out when bleeding each wheel
is that normal?
far as I can tell the proportioning valve is original
seems odd that the it bleeds the left front fine but wont give it any pressure?
if I slam on the brakes in gravel
i get 3 skid marks both rears and the right front
nothing from the left front
the wired thing is this problem has came and went for the last few years now
I swear its gotta be in that proportioning valve but when I do a search on the net NOTHING comes up pointing to this problem being related to the proportioning valve
4SPEED427 said
Jul 12, 2018
I don't have time at the moment for a detailed reply but experience over the years, and from talking to others with similar issues, two things come to mind. Assuming your brake shoes are adjusted properly, it's either the valve, or, crazy as it sounds, the front brake hose.
SGS Welding said
Jul 12, 2018
Just out of curiosity?
Is that a part General Motors still sells?
Or is it aftermarket?
Thanks Carl
seventy2plus2 said
Jul 12, 2018
I doubt GM would still sell the proportioning valve, but if you can get the part # you should be able to find an NOS one online. I know the proportioning valves are different from 1969 to 1970, so maybe GM changed them from year to year.
SGS Welding said
Jul 12, 2018
Ok
I will try switching the flex lines side to side
If that donāt work
Does anyone know where to get a proportioning /combination valve in
Ontario or Canada?
Hubbardās has them but thatās a last resort.
Napa and the local chev dealership have a confused look on there face.
If someone has a part # pen or aftermarket that would be very helpful
Thanks Greg
pontiax said
Jul 12, 2018
When bleeding a system with a proportioning valve, you must remove the pressure switch and insert a bleeder tool into the port. It prevents the valve from shutting off flow.
Ok I didnāt use that
I think itās a great idea
BUT the light went off and on
As if the piece inside centred when I was all done
Iām so confused at this point...
seventy2plus2 said
Jul 12, 2018
My parts book shows the same switch for 1967 & 1968 B body cars.
Group 4.874 Part # 3906933 Distributor & Switch Assembly, Brake Pipe. A quick ebay search came up empty.
4SPEED427 said
Jul 12, 2018
Greg, if you do want a valve, try contacting 68sd396rag on this forum. He does pretty much all disc brakes and boosters and valves, but he may have stuff for drums too.
seventy2plus2 said
Jul 12, 2018
I seem to remember our dearly departed Rick (67rag396) having a problem with the junction block on his 67 2+2 rag at one time. I don't remember what the problem was, or what he did to rectify the problem.
SGS Welding said
Jul 12, 2018
Well I think I have it figured out
FINALLY!
My buddy came over to have a look at my issue tonight
He said letās put a set of brand new drums on
So we did
Perfection!
The other drums had a clean up cut
And must have got hot at some point
Because the one especially was HARD!
Iāve learned
No more clean up cuts on old drums
Just by new!
SGS Welding said
Jul 12, 2018
Thanks for everyoneās input
I truly appreciate it
Itās nice knowing someone has your back when your in the middle of a problem
I hang on every word you guys type when Iām stuck!
Thanks again Greg
4SPEED427 said
Jul 12, 2018
Excellent, and thanks for posting the solution because chances are good it will help someone in the future.
Can a faulty proportioning /combination valve screw up and only deliver part pressure to one front brake and not the other?
Everything else is new and adjusted properly even the suspension has all new bushings ,ball joints everything.
New flex lines,new wheel cylinders, both wheel cylinders seem to bleed properly
the proportionping valve is one of the only things NOT replaced
while bleeding each front brake the light on the dash comes on and promptly goes out when bleeding each wheel
is that normal?
far as I can tell the proportioning valve is original
seems odd that the it bleeds the left front fine but wont give it any pressure?
if I slam on the brakes in gravel
i get 3 skid marks both rears and the right front
nothing from the left front
the wired thing is this problem has came and went for the last few years now
I swear its gotta be in that proportioning valve but when I do a search on the net NOTHING comes up pointing to this problem being related to the proportioning valve
When bleeding a system with a proportioning valve, you must remove the pressure switch and insert a bleeder tool into the port. It prevents the valve from shutting off flow.
Group 4.874 Part # 3906933 Distributor & Switch Assembly, Brake Pipe. A quick ebay search came up empty.