Anyone have a good 69 or 70 B body disc brake hold off valve? I have 2 69 types, but I think they are both seized in the open position.
Built my 65's 70 single piston caliper disc brake conversion without it, fronts work great, almost too good. Somewhat grabby. Going to need more rear braking at lower pedal pressures.
Thanks, Mark
seventy2plus2 said
Nov 12, 2020
There's a guy who sells the kits to rebuild them, something like $12 US per kit. I can post a link later.
cdnpont said
Nov 12, 2020
Thanks Clint, but I can't see for the life of me how the 69 valve opens up. The 70 I understand, as it has a large nut that comes out.
oshawacliff said
Nov 12, 2020
Did I include the brake pressure set of 2 gauges
From my tool box.
Would that help to diagnose?
cdnpont said
Nov 12, 2020
Thanks Cliff. True, I'd thought of the gauges, but it's not to that point that I'd need to measure it.
Just feels like it's all front at the lower pedal pressures. She'll stop fine, nice and straight, but you do feel the front start to dive somewhat.
4SPEED427 said
Nov 12, 2020
I'm wondering if 68SD396RAG (John) has seen this. He's done likely hundreds of disc brake setups for guys and last I knew he still had lots of parts around. If he doesn't reply by tomorrow I'll give him a call.
seventy2plus2 said
Nov 12, 2020
cdnpont wrote:
Thanks Clint, but I can't see for the life of me how the 69 valve opens up. The 70 I understand, as it has a large nut that comes out.
The 69 has the large nut, the 70 has a retainer ring.
Pop off the rubber bumper, that will expose the center pin of the valve. Then use a nut to straddle the center pin, and use a c-clamp to compress the part that the center pin comes out of, and you'll see the retainer ring.
email sent to you with the instruction sheets.
-- Edited by seventy2plus2 on Thursday 12th of November 2020 09:14:53 PM
Anyone have a good 69 or 70 B body disc brake hold off valve? I have 2 69 types, but I think they are both seized in the open position.
Built my 65's 70 single piston caliper disc brake conversion without it, fronts work great, almost too good. Somewhat grabby. Going to need more rear braking at lower pedal pressures.
Thanks, Mark
Thanks Clint, but I can't see for the life of me how the 69 valve opens up. The 70 I understand, as it has a large nut that comes out.
Thanks Cliff. True, I'd thought of the gauges, but it's not to that point that I'd need to measure it.
Just feels like it's all front at the lower pedal pressures. She'll stop fine, nice and straight, but you do feel the front start to dive somewhat.
The 69 has the large nut, the 70 has a retainer ring.
Pop off the rubber bumper, that will expose the center pin of the valve. Then use a nut to straddle the center pin, and use a c-clamp to compress the part that the center pin comes out of, and you'll see the retainer ring.
email sent to you with the instruction sheets.
-- Edited by seventy2plus2 on Thursday 12th of November 2020 09:14:53 PM
Thanks Clint.
Clint put me onto these excellent how to articles for the hold off valve. Great site! https://www.musclecarresearch.com/
Turns out I have a 1970 Valve,
Hopefully if the bore isn't too bad, I can rebuild it.
https://www.musclecarresearch.com/gm-1233464-autopsy
https://www.musclecarresearch.com/gm-1233464-rebuild
Got mine apart. The bore does not look good at all. Will likely need a new one at this point.
An example of how brake fluid absorbs water. Turns into sludge and rust.
Thanks John.
No particular date code required. Its for a 1970 single piston caliper disc conversion on the 65.