C1 Drum Brakes

[Donald W.]

Does anyone know if there is information available regarding possible identifying casting/part numbers on the brake drums of C1 Corvettes, especially that of a 1958 or 1959. My 1959 Corvette was once an old drag car that someone swapped out the rearend housing to a larger Oldsmobile type, of which I am now replacing with a 1959 Corvette rear housing, but it lacks drums and backing plates. I am considering buying some drums/backing plates that were supposed to have come off a 1958 Corvette and have been given the following information about them:



Rear Drums are stamped GM 3694775-20 and GM 3694775-18. Front Drums are stamped W46 and W47

Any idea as to if these numbers mean anything with regard to a Corvette, and if so what? Would they be appropriate for a 1959 Corvette. I have looked in the Nolan Adams Restoration Guide but can't seem to find any reference to any brake drum identification or casting/part numbers for the 1958/59 Corvette.

Thanks so much for your help. Don

[Gary C.]

Re: C1 Drum Brakes

Donald,

Moved your post from the Help Forum (help for using the forum) to the Technical Forum (forum for posting technical questions).

Gary
....

[Erich C.]

Re: C1 Drum Brakes

Check out this post from the 11/ 24. I think it might help in answering your questions. https://www.forums.ncrs.org/showthread.php?t=90681
Erich

[Tom P.]

Re: C1 Drum Brakes

Does anyone know if there is information available regarding possible identifying casting/part numbers on the brake drums of C1 Corvettes, especially that of a 1958 or 1959. My 1959 Corvette was once an old drag car that someone swapped out the rearend housing to a larger Oldsmobile type, of which I am now replacing with a 1959 Corvette rear housing, but it lacks drums and backing plates. I am considering buying some drums/backing plates that were supposed to have come off a 1958 Corvette and have been given the following information about them:



Rear Drums are stamped GM 3694775-20 and GM 3694775-18. Front Drums are stamped W46 and W47

Any idea as to if these numbers mean anything with regard to a Corvette, and if so what? Would they be appropriate for a 1959 Corvette. I have looked in the Nolan Adams Restoration Guide but can't seem to find any reference to any brake drum identification or casting/part numbers for the 1958/59 Corvette.

Thanks so much for your help. Don

Don,
The REAR backing plates from a 55-58 Chevy pass car will be the same (they will be easier-------------------and a heck of a lot cheaper to acquire).
The std drums for 53-62 Vettes are 100% interchangeable with ALL FOUR drums on a 51-58 pass car and rear drums ONLY on 59-64 pass cars. Originally, they would have had the anti-vibration springs around the perimeter of the drums, but replacement drums do not have the springs (you have to transfer the old springs).

[Donald W.]

Re: C1 Drum Brakes

All-
Thanks so much for the valuable information that each of you have posted. I guess I am still wondering about the part numbers I listed in my original thread (GM 3694775-18, GM 3694775-20, W46 & W47). They are cast into the back side of the brake drums. Do they mean anything with reference to a Corvette? Thanks again.
Don

[William C.]

Re: C1 Drum Brakes

Generally those would have been internal GM Casting part numbers for the drums. The machined drum would have had a different part number not necessarily visible on the part. The other letter-number codes would have been internal manufacturing codes, core number, shift, that type of thing would have been usual GM practice.

[Bill M.]

Re: C1 Drum Brakes

My original '59 drums have GM 3752623 XX cast into the bevel at the outboard outer diameter edge. XX = 11, 11, 12, and W3 for the 4 drums. I believe the drums were a new design for 1959.

They look like this picture. (I borrowed this picture from another post on brake drums.)

[Gary C.]

Re: C1 Drum Brakes

Donald,

Might send Joe Lucia an email and ask him what the cast #'s in your original post are for. He and Duke are the only two that might know.

Gary
....

[Joe L.]

Re: C1 Drum Brakes

Does anyone know if there is information available regarding possible identifying casting/part numbers on the brake drums of C1 Corvettes, especially that of a 1958 or 1959. My 1959 Corvette was once an old drag car that someone swapped out the rearend housing to a larger Oldsmobile type, of which I am now replacing with a 1959 Corvette rear housing, but it lacks drums and backing plates. I am considering buying some drums/backing plates that were supposed to have come off a 1958 Corvette and have been given the following information about them:



Rear Drums are stamped GM 3694775-20 and GM 3694775-18. Front Drums are stamped W46 and W47

Any idea as to if these numbers mean anything with regard to a Corvette, and if so what? Would they be appropriate for a 1959 Corvette. I have looked in the Nolan Adams Restoration Guide but can't seem to find any reference to any brake drum identification or casting/part numbers for the 1958/59 Corvette.

Thanks so much for your help. Don

Don------

The 3694775 drums would be correct for Corvettes through 1958. Is it possible that they were used for early 1959? Yes, it's possible but I doubt it. It would take observations of 1959's still possessing their original drums to determine this one way or the other. I would expect 1959 Corvettes to have drums GM casting #3752623 as Bill M. has pictured. The 3694775 should be FUNCTIONAL for a 1959 but not as originally equipped.

I don't know what the drums with casting "W46" and "W47" are. They might be aftermarket or later Delco SERVICE. I would expect all original drums for a 1959 Corvette to carry 7 digit GM casting numbers. This is not an absolute, hard-and-fast rule because I have seen some exceptions.

Brake drum casting numbers should not be an issue for judging since the numbers cannot be seen when installed on the car and as presented on the judging field. Of course, it might be possible to discern certain nuances of brake drum configuration associated with certain casting numbers with the drums installed on the car.

Consider this: if you were building a car that was to be, essentially, a "trailer queen" seeking out the actual original drums might well be the thing to do. However, if actually driving the car is important to you. I'd go with brand new brake drums. Brakes are an important safety item on a car. The judging field discernable differences between original drums and current SERVICE drums are too insignificant to compromise safety.

Now, if you could find some NOS brake drums in old yellow-and-black GM boxes with the part number 3752622 on the box, that would be the best of all worlds. Finding them might be difficult and expensive, though.

[Bill M.]

Re: C1 Drum Brakes

I don't know what the drums with casting "W46" and "W47" are. They might be aftermarket or later Delco SERVICE. I would expect all original drums for a 1959 Corvette to carry 7 digit GM casting numbers. This is not an absolute, hard-and-fast rule because I have seen some exceptions.

The service replacement drums I bought for the '59 in 1970 (part no. 3868801) have the number 3869538 cast into the outboard face almost like the picture above (but there isn't a bevel like the picture). There is no GM logo. Opposite the casting number (180 degrees away) is a W-1 on the one drum I looked at. Too cold today to look at the other 3...

[Joe L.]

Re: C1 Drum Brakes

The service replacement drums I bought for the '59 in 1970 (part no. 3868801) have the number 3869538 cast into the outboard face almost like the picture above (but there isn't a bevel like the picture). There is no GM logo. Opposite the casting number (180 degrees away) is a W-1 on the one drum I looked at. Too cold today to look at the other 3...

Bill------


The 3868801 is about a 1965-released part number.

[Bill M.]

Re: C1 Drum Brakes

The 3868801 is about a 1965-released part number.

Thanks, Joe.

[Donald W.]

Re: C1 Drum Brakes

All-

Again, a most gracious thank you to Joe and all who responded to my question. Although my car is going to be a driver and not a trailer queen, when obtaining parts I have normally tried to find the most original parts that I could come up with.

Joe - just a note, my car was a very early 59 (#109), so maybe it is conceivable that it could have had drums the same as a 58.

Thanks again to all. This is a great service of NCRS.

Don Wagner