1974 proportioning valve
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,472
Likes: 2,180
From: Loveland
1974 proportioning valve
1968 to 73 there wasn't a true "proportioning" valve section on the brake block, they just used smaller calipers on the rear. In 1974 they went to a true proportioning valve, that reduced the pressure to the rear brakes. The rest of the system remained the same as far as I can tell. The vets up to 1982 still used smaller calipers on the rear than the front, to differentiate the pressure. Does anybody know why the added the proportioning section in 73 to the brake valve?
Last edited by kodpkd; May 4, 2022 at 07:27 PM.
Race Director
Joined: Mar 2017
Posts: 11,944
Likes: 4,506
From: Virginia
1968 to 73 there wasn't a true "proportioning" valve section on the brake block, they just used smaller calipers on the rear. In 1974 they went to a true proportioning valve, that reduced the pressure to the rear brakes. The rest of the system remained the same as far as I can tell. The vets up to 1982 still used smaller calipers on the rear than the front to differentiate the pressure. Does anybody know why the added the proportioning section in 73 to the brake valve?
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,472
Likes: 2,180
From: Loveland
Thanks,,,, That's interesting. Apparently GM figured they needed a bit of extra safety so the vet wouldn't swap ends. So, if someone wanted to use the older style block it would make the 74 just like the 68-73, and visa versa.
