I see nicely high end restored cars with satin black master cylinders and some with the natural cast finish. So, which came from the Flint factory? I presume that the hold-off valve color will match the master cylinder. Thanks in advance for setting me straight. Art B.
"I see nicely high end restored cars with satin black master cylinders and some with the natural cast finish. So, which came from the Flint factory?" To keep the answer short I believe the correct answer is both, at least that is the way we have always Judged them. Kleiner got to really inspect (on a lift) a very low mileage Original Owner car and sent me some pics. It came with a Black MC. It would appear that at least some of the Disc Brake Masters that were destined for Corvettes made it to the Buick lines. "I presume that the hold-off valve color will match the master cylinder." The answer to this is No. The MC/Power Boosters were a sub-assembly when they were sent to the Assembly Plant in 70. The brake lines and hold-off valve were installed at final assembly, therefore they should all be natural. Again that is historically how they have always been judged. Now the above info is for the 1970 Disc Brake Master Cylinders ONLY. All others would have been natural color. If you look at the 70 assembly manual it shows how they were assembled. That same page also shows how the front brakes were put together at Final Assembly...........which is completely different then how the 72 Model year brakes were installed. The Assembly Manuals were a guide used by the line workers to build the car. If it shows a pic of a part, like the front suspension center link, and it doesn't show the workers putting the idler arm or pitman arm on it, then those 3 pieces were part of a sub-assembly. (And the cotter pins were installed differently on the center link then they were at other locations. Also due to the fact that it was a sub-assembly when it hit final assembly.) If you look at the assembly manuals with this in mind you can figure out exactly how the parts came in to Final assembly, and get an idea as to how the pieces were painted/plated. Duane
Duane: Thanks for your response. Does the black and natural finishes occur randomly through the GSX build cycle or more focused during one or more batches? I am restoring an original '70 GSX, but it is not numbers matching. I am trying to get as close to Dave's work as I can with what I have. The MC I have is not the original, but has the correct casting number, but the wrong stamped code, EA rather than the correct TH. I will go with the natural finish on both the MC and hold-off valve. Is the application code something you look at during judging? Copperheadgs1: Thanks for your comment. I will go with the "Most" observation. Thanks to you both for taking the time to set me straight. These posts are so interesting and informative. Art B
Art b. You are getting the codes confused. "TH" is the code on the tag that goes between the valve on the power booster and the hose that comes off of it. If memory serves me correctly the TH is the code for the MC/PB sub-assembly. I put together a long response to your post last night and then lost it by accident. Instead of writing another one if you PM me your number and when to call I can discuss this with you. It will only take a few minutes. Duane
Art, I think your EA is correct. Another good thing about cast is it is easy to care for. A little brake fluid on the black and good by. I think I used the same Calyx manifold dressing I used on exhaust manifolds.
Good Evening 1970 Stage 1: Thanks for the picture. That's what mine looks like with the EA stamp. As Duane said, the TH is for the tag on the assembly. Art B
The 70 assembly manual says the 70 Power Disc brake set-ups are supposed to be "TH" and they are the only ones I have even seen on these cars. I have never seen an "NM" on any tag. Maybe you could post some pics and we can see what you have. Even the 69 cars used the same "TH" code. Looking forward to seeing what you have. Duane
I was wondering if it was a Leeds car, I don't see very many of them. That is definitely not the codes Flint used, or what the assembly manual calls out for the GMAD Plants. Do you know if they built other Brand GM cars there? That might explain this. Duane
I believe I have this all figured out now. Just need to fine tune a few things and I should post it later today. Duane
Olds was not using this type Master in 1970. I owned a few and they all had rectangular type used on 71 Buick. I think last year for double bail style on Olds was 68.
Jackpot guys. Here is all your 70 MC stamp info. Found it real easy in the service manual. No one else saw this?
