I pulled the front drums off my 63, and was wondering if there was any chance they were original. Did the drums have a date code? They both have the following sets of numbers 3828671 & W7.

Thanks in advance.

 

Yes, those are probably original, and your car was probably equipped with J-65 Metallic Brakes. No date code as far as I know, but the "W7" is probably the tooling set (mold) number.

There is some ongoing research in this area. The AMA specs list a thicker web for J-65 versus base front drums, which would imply a different casting number.

I would appreciate if you would take and post an average web thickness measurement with a caliper and the current drum diameter.
A local brake shop should have a drum diameter measurement tool. Metallic brakes were very long lived, but once the linings were worn out, so were the drums. The maximum allowable drum diameter is 11.090" for both base and J-65. This was molded into the casting on later replacement drums.

I'm assuming that the linings are conventional replacements. The metallic linings are easily recognizable as they consist of several separate bonded segments on each shoe. The base linings were also bonded, but are continuous. Riveted continuous lining material is a sure sign of aftermarket replacement linings.

I would also like to know the rear drum casting numbers, and any other markings - diameter too, if you can get them measured.

Do know the original mileage? Also, what engine/drivetrain options? J-65 was probably more commonly found on SHP/FI engines, but J-65 could be ordered with any engine or drivetrain combination except Z-06, which included the HD brake system.

Duke

 

Duke,
Here is more to the story. The car has approx 79K miles, and is original (unrestored) as far as I can tell. I’ve already had the drums to NAPA and they said they are .010 from max (I didn’t get the numbers, must be 11.080 from what your saying); I’ll get the web thickness to you later tonight.
The current shoes are riveted 1 piece (with a good amount of meat).
I’d be really surprised if this is a J-65 car, it specs out as follows:

Build date, 5’th week of March
300 horse, 4 spd
PS
AM radio

Pretty plane jane, still has the original alt & carb; only real option is PS (no PW or anything else). I’ll check the numbers on the rears and get them to you.

Thanks!

 

Based on what I know now, if the front drums are 671s it would be a J-65 car. Get the actual measurement of the drums. "Ten under" means nothing, especially if the guy doesn't know the maximum.

The fact that they may be well worn is also evidence of J-65, however, if new shoes were installed the drums were probably turned. Organic shoes tend to wear the drums in a fairly smooth manner. J-65 drums usually look pretty knarly.

Eventually when enough evidence is available to warrant a definitive conclusion it will be documented in The Corvette Restorer.

Unfortunately little data is available because evidence of J-65 is not visually discernable in NCRS judging, so I have to rely on whatever data I can get from drum brake C2 owners.

J-65 only cost about $37.70, but was only on about one out of five cars. It was a cheap option for those who envisioned driving their Corvettes in a sporting manner.

Duke

 

My '64 also has J-65 and the 3828671 brake drums. The other cast in number located on the periphery of the drum is, 'W6'. I used a digital caliper to take a few measurements off one of the drums (front).

Overall width - 4.00

Inside drum measurement, brake lining contact patch width - 3.164

Web vertical depth - .860 nominal

Web horizontal depth - 1.04

In addition, there is also an 'X', presumably stamped at the factory, on both drums that measures about 3/8 inch in height. The segmented metallic brake shoes are the originals. I don't believe these brake drums have ever been turned. This car came equiped with the 300hp engine and 4-speed.

John