what GM A body cars came with Manual disc brakes?

I figure you muscle car guys could help me out.. trying to find out what GM A body cars came from factory with optional manual disc brakes..I need to buy a master cylinder for my project which will have manual disc brakes in front only and i need to get the right one the first time since there is no return on special orders. i hear 70 corvette might fit but not sure..thanks in advance Bob

 

brakes

my 68 gto has manual 4 piston disc brakes on the front .drums on the rear. I have a pic but dont know how to resize. the master cylinder has two wire type straps on the lid.

 

When my master cylinder failed that came with my manual disc brake conversion kit from Stainless Steel Brakes I gave them a call to find out what it was from. They told me it was a '70 Corvette master cylinder for manual disc brakes. I ordered one from the local brake shop and it was identical, except it actually still works.

Ken

 

how would you guys rate your brakes as far as pedal effort and stopping power? I have a single piston setup from a 71 GS and it's going in a lightweight 65 special post coupe with a 455 of course. Bob

 

Manual disc brakes

Bob,

One source is parts for a 1970 (and up?) 442 "W" cars. (Maybe a 442 pro can chime in). From what I remember the W30 cars had a 455 with a 328 degree camshaft and did not have enough vacuum for power brakes, but they were all disc brake only cars. Master cylinder was for manual disc brakes.

 

I believe that it was '68-70 maybe '71 with the W-30 manual transmission that had the manual disc brakes. I know that '69 and up used the single cylinder disc brake caliper. In '68, I believe you were saddled with the 4- piston caliber (Dave H help me out on that one!). But I know if you look for a 69-70 W-30 Manual transmission master cylinder, you would have it!

 

Took some pics last night to post on ROP.com so this is convenient:

70 Olds W31s came with manual discs also--the 1" bore master cylinder on the far left of the pic is the one that was on the car when I got it. Don't know if it's the original MCylinder but it has the bleeders. The other two are 69/70+ style for power disc cars. The Corvette new cylinder they sell now looks like the one in the middle but doesn't have bleeder screws (the one that Master Power Brakes sells--I think other places now sell them with the bleeder screws).

The other two are 1-1/8" bore. The cap shown in the pic is for the master cylinder in the middle of the pic.

 

Kevin---I'm not 100% sure on all the little variations in shape between similar looking MCylinders...possibly they made running changes in the physical design. What's interesting is yours is a 1" bore.

I just spoke with a friend that has a 70 W30 4 speed manual disc car--his car uses the one in my pic on the far right. However--it's installed on his car so I can't say what the bore size on the cylinder is.

 

Can really only speak for Lansing built Oldsmobiles..

...but that includes all W31, W30, W32, and W34, W45, and W46 cars as all of them were built only in Lansing. Who knows what the BOP plants put on on a particular day, at a particular time, by a particular person......you get the picture. That's why Olds management only permitted the real W cars to be built in the home plant.

The MC I recall on the manual disc W cars that was originally put on was like the one on the left in Patton's pics (thanks, BTW). I can't say anything about the cars from 73 and newer, but I don't recall that "square" shape on the right on any manual disc application through 1972 and never saw the center one (like the Corvette) until recently with the restos and aftermarket kits.

I bought a manual disc MC from NAPA a few years back and it looks like the one on the right. It's discontinued now.

Single piston Disc brakes didn't come out until 1969, so all 1968 W30 and W31 cars came with manual drums with no options. The 68 Hursts all came with the dual piston discs with a power assist (W46 A/C or W45 no A/C). That system required a power booster to operate and the W31 and W30's didn't have enough vacuum to run the systems either with the 308 or the 328 adv duration cams. The larger pistons were more for the pressure than the volumetric flow.

They opened up the option book a little more in 1969 and the W32 (toned down W30) allowed power brakes. Not sure about the W30 automatics, but the W30 sticks still used the 328 cam and had manual discs. I want to say that manual discs were an option on 1969 W31, but I could be wrong there.

:bglasses: :bglasses:

 

You guys make great big brothers!

This is straight from www.442.com and can add some info also:

HTH

 

Thanks guys.. excellent information.. now can anybody tell me what the braking is like on a Manual db equipped car? pedal effort..

 

Manual Brakes work fine

I use a Bendix R11479 manual disc brake master cylinder (be sure to change the pedal to master cylinder rod) with a stock GM brake setup except for the rotors which are drilled and I my brakes stop my GS from almost 140mph with plenty of pedal.

Mike

 

Whoa factor.

I have had two 71 w-30 with manual disc brakes and they use the oval type master cyl displayed in Patton's photo(center cyl). It is known as a dual bale cylinder. I have original photos of the hardtop car and it had that cyl. My Convert had its orig cyl on it when I bought the car. My 72 Hurst Also had the dual bale Cyl as well. My 71 Convert with auto and power brakes has the square cyl.

Peddle effort for the manual brakes is moderate,although I have not had to do any panic stops.

 

you just push down harder. :laugh:

 

My experience is the manual discs (with the proper balanced master cylinder) and the drum brakes have almost the same amount of effort. Think they both can stop you in a panic stop with same pedal pessure.......the first time. Think the discs can stop you quicker, though. The drums don't cool down so are much less effective when they get hot. No way I can go three rounds with my manual drum brakes with minimal cooling off in between (like in test and tune). With discs that's not a problem.

Lots of people that are converting from drums to discs are converting from worn drums to new discs. Definitely a big improvement there.

 

Patton,
First, thanks for the pic. Does the W-31 master cylinder (one on the left in your pic) have any casting numbers on it? From what I understand, it should be coded "EB" on the flat spot on the front of the MC. And for some reason I thought they were 1 1/8" bore. looks like I may have thought wrong. I need to dig for the pics a guy sent me of his low mile unrestored nugget gold 70 W-31. The master cylinder on that car looks like the one on the right in your pic, IIRC.

 

Chris--Sorry about the delay--was away from the computer all weekend. I will check it out tonight and post tomorrow. Thanks, Patton

 

Chris, for what it's worth, the original master cylinder on my '70 W-30 is stamped "EB" and looks like the one on the right side of Patton's picture. Mind you, this is a power disc brake car, being an automatic W-30. I think manual and power used the same master cylinder, just connected the pedal to the pushrod in a different hole? I'm calling my master cylinder original, because it has the right application code stamped on it (EB), the date code makes sense with my car's build date, and it sprung an internal leak a couple years ago (something I'd expect if original to the car, but not if it was already replaced).

My notes, which were probably based on what's printed in the Chassis Service Manual, say it's a "Moraine power brake unit, because it has the bleed screws." Take that for what it's worth. The casting number is "5470409-1 D2". (Like many cast parts, I expect there are parts with different D1, D2, D3, etc suffixes on them. Probably only the first 7 digits are significant.) I would expect that the exact same casting was used for many application codes, but maybe not. Conversely, I bet you can have master cylinders with the same application code that look completely different -- if made by two different manufacturers. Also, I vaguely recall, the 1970 Assembly Manual has some interesting notes about the braking system depending on which plant built the car.

I probably just made things more cloudy for you. Let me know if you need any more research.

 

Not meaning to permanently change the subject but since Brian is on here and we are talking about firewalls (well--the master does attach to the firewall so let's stretch our imaginations a little)...does anyone know, exactly what the double letter firewall stampings denote on the Oldsmobiles? Thanks and after you guys answer this we can return to the regular programming. :grin: Patton

 

Dave H will be able to say for certain, but those are probably inspection stamps and they were used to identify who inspected the car so there was accountablility for things done right/wrong! I was looking at my truck yesterday and saw an interior paint sag in the passenger door (oops) and a stamp on the opposite side firewall saying 'Pierre'. Did I mention the truck is an '84 Ford built in Canada!