C1 62 brake drum part number?

[Chris H.]

Re: C1 62 brake drum part number?

Duke I put two photos in. One of the full drawing and one of the revision column.

chenige chenige

http://www.photodex.com/sharing/viewalbum.html?alb=103858

[Duke W.]

Re: C1 62 brake drum part number?

Thanks for posting the photos. Unfortunately I cannot make out any detail on the drawing even after I increased the size.

This appears to be a finished brake drum drawing. I do not see this part number listed in the Corvette Parts catalog, but as I said before, the service part number may actually be an "assembly" consisting of the drum and anti-squeak spring.

These old drawings can be difficult to sort through, and it can take some time analyzing the information to put together the story.

Duke

[Michael H.]

Re: C1 62 brake drum part number?

Chris,

That really is confusing. I don't understand those dates at all. I know the drawing for the original design would have been released some time in 1957 for use on the soon to come 58 pass car. I believe there was at least one more change to the part (and number) before the revised drawing would have been released for SOP of the 63 cars that have no adj holes in the backing plates. I don't know what the 1-29-63 revision could have been but I know the part number did not change during the 63-64 run. The 6-2-64 date probably would have been about the right time for the next design and new part number that showed up in 1965. I know for certain that a part with anything near 3868xxx would not have been in existance until at least early 65 production. I'll do a little research and see what I can come up with.

[Frank H.]

Re: C1 62 brake drum part number?-photos

Hi
I bought a set of used virgin drums last year,when I also picked up Chris a
anti-vibration spring for his 62.
Two were the 623s(unknown source) and two were the 688s which came off the rear of a 63 full size chevy.
My 62 vette(46K mi)also had the two 623s in front and had been turned where as the 688s in the rear had never been turned or the brake shoes replaced.
I mixed up the drums after painting the drums and It brake-steered from the mixed diameter shoe/drums so I decided to make a set of four the same diameter.
I figured the larger dia.(623) drums where off the front(over 11")and the rears
were under 11" may have been replaced and the rears moved to the front may also be possible and the miles higher

I believe it came with the two part numbered drums!.....I can't prove it ,since I was only 6 years old when I bought the 62...

[Chris H.]

Re: C1 62 brake drum part number?

Duke, I posted closer pictures of the drawing. chenige chenige

Also figured out where I got the drawing number 3868801. It is the service part number for 53-65 corvettes in my 53-72 Corvette parts book.

Also I now see a note "Similar to 3828686" on the drawing.

Chris




drum drawing

[Chris H.]

Re: C1 62 brake drum part number?

I should have said in the previous message that 3828686 is probably the drawing number for the 3828688 Drum casting.

[Duke W.]

Re: C1 62 brake drum part number?

Is it the service number for base brakes or metallic brakes

The oldest Corvette parts manual I have is '77, and it shows as follows for 2" drums.

3985944 53-62 front and rear, 63-65 rear ex. metallic lining and HD brakes

3869537 53-62 front and rear, 63-65 read w/ metallic linings

Duke

[Chris H.]

Re: C1 62 brake drum part number?

My 53-72 (copyright 1989 from Motorbooks international) book says the same except replace your 3985944 with 3868801

Chris

[Duke W.]

First drawing revision date

The first revision date must be 1-28-65; 1-28-63 doesn't make any sense as you pointed out. In looking at these old drawings you have to do some "handwriting analysis" by comparing an obscured character to anothers that are more legible.
On first observation the last digit in the date looks like a "3", but it could also be an obscured "5".

Duke

[Chris H.]

Re: First drawing revision date

You are right. It is a 5.

This is a card (what did we use to call them?)copy. They photoed them somehow and put the tiny films on cards. Not microfiche, bigger than that. 25 year old technology.

But I wonder why it was redrawn after only 6 months?

Chris

[Duke W.]

Re: C1 62 brake drum part number?

There was a later casting number 3985945, and this has the "max diameter 9.090" in the casting mold. This change in the casting would have been implemented as a result of the FMVSS that went into effect, I think, on Jan. 1 1968. The 2" drum part number for base brakes was 3985944, which is sequential.

I ordered two 3869537 2" drums for metallic brakes in the mid-seventies. I got one 3869538 casting, which is sequential and has no max diameter marking and one 3985945 casting that had "max dia. 9.090" molded into the casting. Now I wonder if I got one drum for metallic brakes and one for base brakes. They worked okay after I completed the brake overhaul, so who knows.

Another relevant question is the applicability of the FMVSS requiring the maximum diameter. Was it required for all parts manufactured after the start date or all parts SOLD after the start date.

If the latter, then they would have had to take existing stock out for rework and stamp the max diamter, and change the drawing to require stamping until the new castings with the intergral max diameter were available.

Someday I'd like to sort all this out.

Duke

[Michael H.]

Re: C1 62 brake drum part number?

Duke,

You're right, this entire brake drum number thing should be sorted out. Hopefully, I'll have time tonight to look up and post all the original numbers and their "change to" records. I know for sure that the 63 model year introduced a complete new set of part numbers in the 382xxxx range and that these changed again for 65. The 3869537 would have been the release for 65 and serviced all past applications.

I don't have any records at all for pre 63 so if someone out there has a 62 or earlier printing of the parts book, we would appreciate the numbers and would then be able to make a complete history chart of these drums.

[John H.]

Re: First drawing revision date

Chris -

I remember them well - we called them "aperture cards" in those days

[Chris H.]

Re: First drawing revision date

Thats right, I believe Chevrolet Engineering's was on the 2nd floor of the Chevrolet building (or was it 3rd?) When I got my car around 1990 and started to work on it I pulled a bunch of drawings. Just wish I would have went thru the AIM and pulled every number and any referenced numbers.

Chris

[Michael H.]

Sort This Out, Step One.....

Duke, Chris,

The first thing I found is that the 59-62 drum, part number 3752622, is completely unrelated to any 63 or later drum, in production. They may look similar and actually be interchangeable but in production, the SOP 63 cars had their own unique drums. The reason, as Bob Jorjorian mentioned in an earlier post, was the fact that 63 was the first year for the absence of a brake adjusting hole in the backing plates. The drum, then, had to have a knockout for this adjustment. The part numbers for these 63 rear drums were listed in the 63 printing of the parts book as follows;

63 Pass, Corvette (exc.metallic lining) rear.........3828686

63 Pass, Corvette W/ metalic lining rear.........3828687

These part numbers/drums, continued through 63-64 production. Some time during, or possibly at SOP, of 65 production, the part numbers and drums changed. (can't remember why) They also changed numbers in service several months later. The changes in service are as follows;

3828686 use 3868801 effective March 1966

3828687 use 3869537 effective July 1965

Not sure when the 3869537 changed again to the 3985945 as it's not listed in my 1965-1970 change book so it had to occur, most likely, in late 1970. Either way, the 945 is of no interest as it would be a different design and would include, as Duke mentioned, the Min Dia specs.

The 59-62 drum, part number 3752622, was still listed in the 1963 printing of the parts book and continued to be available until Nov of 1963 when it was replaced by the 63 design, part number 3828686. This also means that no 59-62 would have originally had the knockout for the adjuster.

I have no info on casting numbers yet but that should clear up at least some of this. I'll try to dig out my casting# to part# conversion book later this weekend. May have to summons info from owners of orig cars for casting numbers. More later....

Michael