1937 Pontiac wheel cylinder question

[Guest bofusmosby]

I was going to re-build the wheel cylinders of my car, but the kit I ordered (from NAPA) was the wrong one, so I decided to order all 4 wheel cylinders from Kanter and be done with it. I spoke to the salesman, and he assured me that the wheel cylinders would be marked as to which ones went on the front, and which ones went on the back. Well, they are not marked, so I looked at the new cylinders, and noticed that they look the same, except the pistonn size and bore on 2 of them are larger than the other 2. Since I have already found several mistakes that had been done by the previous owner, I don't want to automatically install the smaller bore ones on the back (the previous owner had replaced all 4 of them about 10 years ago), without knowing if this is correct, just in case another mistake had be made years ago.

So my question is, does anyone know which cylinders go on the front, and which ones go on the back? This may be a simple question, but I do not know the answer. do the cylinders with the larger bore and pistons go on the front, or the back?

Thank you for any insight you can provide.

[JD in KC]

According to my Motors manual 1940-1954, Pontiac had the small bore in front from 1940 - 1948 then switched to large bore in front from 1949 - 1954. Same with my Packards. Don't have a general manual that goes back to '37. I'm sure somebody will have a definitive answer.

[poci1957]

Well, you really should buy a service manual immediately to help with this sort of thing. You are wise to not automatically trust the work of the previous owner.

A quick look at Pontiac Parts and Pontiac Auto Parts - California Pontiac Restoration says rears should be 15/16" and fronts should be 1". They indicate that each comes in a different left and right side configuration.

This is a great place that only deals in Pontiacs, I should have recommended them initially but forgot they covered 1930s models. They will send you a free catalog and also have a reprint of the factory service manual for about $30.

Remember my previous suggestion to take apart ONE SIDE at a time so the other is still there for reference. Good luck, Todd C

[Guest bofusmosby]

Thank you Todd. I have the actual service manual for the car (dated 1937), but it doesn't say anything about the size of the pistons. I guess that it is assumed that this knowledge is already known. You also mentioned that there is a definate left and right side. Now this really confuses me. I see no difference in the wheel cylinders when placed side-by-side, except the diameter of the pistons. I was told by the salesman from Kanter, that they would be marked. So far, I see no markings on them. Is it possible that these could be of a generic type, that will work for either side? Unfortunately, they are Chinese made, but I was told that most of them are made there now. As far as doing only one side at a time....definately! I also use my digital camera and take photos of everything, so if there is any doubt as to how something goes, I look at the photos. The difference in the piston size seems to be a lot more than just 1/16". Two of them are quite a bit larger than the other two.

I appreciate you checking JD. I had thought that the size difference would be a standard issue, but I see now that this is not always the case.

The wheel cylinders were replaced by some from Kanter about 10 years ago, so maybe they use some type of generics. You know, maybe the left and right sides are the same.

[JD in KC]

The left-right difference may be the direction of the brake line fitting... forward or back.

[Guest bofusmosby]

Thank you JD. I'll be sure and check that out. That would explain the difference, depending on the angle that the brake line comes from.

[poci1957]

The angle of the line going in is almost certainly the difference. It is likely the Chinese cylinders are a generic replacement but as long as they fit and the line in is correct then you are probably OK (although we would always prefer a higher quality original). If the line in is in the wrong place or angle that is certainly grounds for returning them.

The California Pontiac parts store I linked shows they are available there and are probably more correct than Kanter, but they are also likely more expensive. Keep us posted and keep them in returnable shape until you determine they are OK to keep. Todd

[Guest bofusmosby]

Thank you Todd. I have a feeling that the angle that the brake line enters is the same on all of them. I am at work right now, so I don't have them in front of me. Since the previous owner installed "Kanter" wheel cylinders before, I am hoping that maybe the brake lines will be at the correct angle. I was also told that they also replaced the brake hoses before, so if the lines came in at the wrong angle, then maybe they re-did them so they would work. I guess I'll find out this weekend when get the wheels off. I'll be sure and post my findings.

[Guest bofusmosby]

Well, when I got home, I checked, and the wheel cylinders have different angles where the brake lines connect. At least now I will know which is for the right, and which one is for the left side. If weather permits, I'll replace the wheel cylinders tomorrow. I was hooking up the turn signals this afternoon.

[Guest bofusmosby]

Well, the wheel cylinders were a proper match, so yesterday I replaced the 2 back ones. I would have (and still plan to) replaced the front ones as well, but I ran out of time because of the amount of time it took to remove one of the drums. Geez, what a pain! Replacing the wheel cylinders were a piece of cake. The master cylinder never ran out of brake fluid, so I bled the rear brakes, but I am not happy with the amount of pedal, or should I say the lack of pedal. I will be replacing the 2 front wheel cylinders this next weekend, so afterwards, will be bleeding the system again. Also, the previous owner told me that he believes that I need to either add or replace a spring for the brake pedal. The pedal does not return fully after pressing the brakes.

[FJD]

Good Morning

I don't know if it helps or not but the 1946 Wagner catalog list 4 different part numbers for a 1937 Pontac P6 & P7. The left front is FD2941, the right front is FD2940,group 60, the left rear is FD4284, & the right rear is FD4285, group 68 For future ref the master cylinder is listed as FD4363. It aslo appears as if the FD4940 & FD4941 were used on certain Buicks for 36 & 37, & certain 1937 Cadillac, also Certain 1937, & 1940 Hudson, and the 1939-40 Ford Zephyr, also certain 1939 , 1940, & 1941 Packards.. Just for laughs the prices were $2.20 & $2.75.

Good Luck

Fred D

[drwatson]

After disturbing brake hydraulics I often find getting a solid high brake pedal a challenge. Tips that helped me: Bleeding - If it appears there are no air bubbles yet still a low-spongy pedal, give it several hours rest, residual air might settle near bleeder valve for a later quick bleed. Start with longest line (you at bleeder, a good helper on the pedal). (I've not done well with 1-person bleeders).

Other places causing loss of pedal ht. are shoe to drum clearance. (no drag an indicator).

Brake pedal rod to master cyl play! should be 1/4"-1/2".

I have the major and minor Adj for your brakes. I'll post it here if you need it.

[Guest bofusmosby]

Thanks guys. Well, when I replaced the wheel cylinders, I removed both shoes together, and didn't touch the brake alignments. All that stayed together. When bleeding the brake system, my wife was in the car pumping the pedal, and I wouldn't even attempt to do it all myself. Because the brake pedal is not fully returning when pressed, I think that I either need to add or replace the pedal spring. One thing I noticed though, I don't believe the emergency brake is working. When I go to pull on the emergency brake handle, it really doesn't move. It almost feels like the cable is froze up somewhere. Also, on the right/rear brakes, the emergency brake wasn't even connected to the shoes. Does the emergency brake cable have a tendancy to lock (rust) up?

Yes, all 4 of the wheel cylinders are different. I believe that I got all the correct ones.

[Guest tcang]

Your front brakes take on more stopping load then the rears, so the larger bores should be in the front.