bry593

I'm in the process of converting '68 Cutlass drums to '69 discs. I was going to reuse my iron distribution block, but the brass inserts in the block look very deformed and I'm worried about leaks.

Are aftermarket distribution blocks okay? Any problems with the brake light switch or seats? Do all brands use the same mfr, or is there is a preference?

Here is one from RSD: https://www.getdiscbrakes.com/pv06

boese1978

You will need a proportioning valve in addition to the distribution block which you will want to replace from the sounds of it.

bry593

Good point, and I do have a pressure reducing valve as it is called on the '69. Also have a disc cylinder and '69 front brake line kit. I did not anticipate needing the rear brake line kit, but I boogered up the F-R line tube nut pretty bad getting it out of the distribution valve. Probably also need to replace rear axle hose while I'm thinking about it.

Now, back to the topic at hand. Distribution block. I see RSD and IT both offer one. Are these reliable, made well? I typically avoid aftermarket since most of it is less reliable than a beat up GM component.

joe_padavano

Actually, the 1967-1970 disc brake A-body cars did NOT use a proportioning valve. The front/rear brake bias was set by carefully selecting relative wheel cylinder area and brake lining sizing. These cars DID use a metering valve (also called a hold-off valve) that delayed the application of the front brakes briefly to allow the linkage in the rear drums to take up any slack. This is the cylindrical valve that mounts below the M/C on these cars. Other than that, there is no proportioning valve to adjust line pressure to the rear brakes. The full size cars with disc brakes did use a proportioning valve in addition to this metering valve, but the A-bodies did not. Starting with the 1971 cars, GM incorporated the metering valve, the proportioning valve, and the differential pressure switch into a single combination valve, which is what most people call a "proportioning valve".

It doesn't hurt to use the combo valve, as it makes the braking system a little more forgiving across all vehicle loading conditions, but if you duplicate the factory setup with the metering valve and the correct wheel cylinder sizes, it isn't necessary.

cruiser 88

I’ve had good luck with Performance World aftermarket braking products. They replace stock and I’m actually in the process of converting the whole braking system in my 74 Delta 88. The booster, master cylinder and proportioning valve for my front disc / rear drum set up.

http://www.performance-world.com/Und...sis-s/1833.htm

most of the parts are the same price if not cheaper than stock if you can even find stock replacement.

Good luck

bry593

Thanks Joe for the correct description of "hold-off valve". That's what I have. I'm basically copying the '69 Cutlass design so when I sell it, I can say that the brakes are converted to '69 442 and this will make it easy for the new owner to service plus it will have an original appearance. The combo valves mounted under the master just don't look right.

Cruiser, thanks for the input. I'll check PW out.

bry593

PW looks like they have a selection of generic brake parts. The distribution block is a specific piece. I'll probably just buy the aftermarket repop from right stuff detailing when I get the rear hose, hard lines and cylinders. That will make this brake system as new.

joe_padavano

I agree with you. The other advantage of keeping it to the OEM configuration is that the pre-bent tube kits will fit.

Yellowstatue

You will also have to replace the frame brackets for the flex hoses. The '69 hoses don't fit properly into the '68 brackets.

bry593

Yes sir, and I already have the brackets. Also, rebuilding control arms, new springs and steering linkage. Well, most of steering linkage had been replaced before me. Just needed a center link, 10:1 steering gear, rag joint, steering shaft rebuild and as you know already, I went thru the steering column as well. It takes me forever to repair anything because I have a bad habit of finding new stuff to fix.