[No regrets]

Can someone inform on what this is exactly? Some type of proportion valve ? It has a regular style proportion valve along the frame below the master but I have never seen one of these before any insight would be great thanks in advance.

 

[69velle]

It’s a hold off valve to delay the discs until the drums have a chance to build pressure so you have synchronized brakes.

 

[No regrets]

I figured it had something to do w that in some way,just never seen one before. Is there some kind of aftermarket proportion valve that can be installed to do away w this for a cleaner look?

 

[DZAUTO]

From what I've observed, that was used on 69-70 cars with discs, and then in 71 it went away, and I presume a totally different valve was used down on the frame.
Anyone have more specific knowledge?

 

[Johnny Bravo]

The 60-70 "valve" on the frame is just a distribution block, it doesn't hold off pressure to anything. That is a hold off valve mounted by the master cylinder. I believe 69-70 had that valve, but the rear brakes would lock up under hard braking. 70 added an additional valve (more like a restrictor), on the rear crossmember, to allow the rear to come in just a split second later. They figured it all out and put it into one combination valve/proportioning valve on the frame starting in 71.

 

[sz0k30]

Like a post above said, just about any 69-71 GM with front disc brakes.

 

[No regrets]

I'm going to redo all of the braking system adding disk on back as well im assuming a newer kit will have the correct proportioning valve not needing this part.? any direction on an aftermarket kit would be great, the front is basically just getting replaced cuz everything is old however the rear is obviously factory drum so i figured its prob a tad cheaper to buy 1 kit that is all deigned to work together.

 

[Johnny Bravo]

I'm not sure what you mean by "correct" proportioning valve. The one on your car is correct for your car. Also, disk front-drum rear brakes have quite a bit of stopping power, especially for most of us. What exactly is it you plan to do with the car that would require disk in the rear? For the cost of adding disk to the rear, you could replace/rebuild what's there and it will stop your car just fine. It'll even be "correct ".😉

 

[AK71SS]

Here is the location of my cast iron proportioning valve on the frame of my '71 Chevelle SS.

 

[AK71SS]

Here is the location of my cast iron proportioning valve on the frame of my '71 Chevelle SS.

Appears the 71 Cutlass used the same. Disc Brake conversion - ClassicOldsmobile.com

 

[No regrets]

Since the factory brake system have some age on them and I’m doing a 12 bolt swap out back in place of the 10 bolt I just figured it’s all gonna be out and if I was going To redo the brakes might as well just upgrade to 4 wheel disc. The car is gonna be a street car /cruise nighter but will be putting down about 500hp to the tires, I know there is much more powerful cars on the street with drum on back , was trying to be proactive is all.. So if anyone has a kit they have used and are happy with please share,thanks in advance.