Brake Drum Research

[Joe L.]

Re: Brake Drum Research

All----


By the way, one can still obtain brake drums for 1963-64 Corvettes with standard brakes from AC Delco. These are not OEM quality parts but I expect they will SERVICE the application quite well as part of AC Delco"s "Professional" product line (one notch below OEM). Of course, they are made in China as are many automotive castings these days. Here are the part numbers:


Front ACDelco #19183549

Rear ACDelco #19171697

[Harry S.]

Re: Brake Drum Research

What I'm seeing does not match the parts manual. I have two boxes with PN 3830166. The drums inside are cast with 3828671. According to what I've read on the TDB and other places these are for regular brakes not metallic. But both drums are stamped with an X indicating metallic.

Could be that someone swapped drums in these yellow and black boxes long ago.

I've got no more to add at this time until I find more real examples.

Thanks all!

[Dorsey F.]

Re: Brake Drum Research

Thank you Duke. Great information. Still wonder why that item was omitted from the 67 parts book. 2 or 3 years out you’d think service parts would still be there. Maybe a misprint.

Bad eyesight on my part. There is a listing in the 67 printed P&A book.

[Duke W.]

Re: Brake Drum Research

What I'm seeing does not match the parts manual. I have two boxes with PN 3830166. The drums inside are cast with 3828671. According to what I've read on the TDB and other places these are for regular brakes not metallic. But both drums are stamped with an X indicating metallic.

Could be that someone swapped drums in these yellow and black boxes long ago.

I've got no more to add at this time until I find more real examples.

Thanks all!

As I previously stated the ...671 drum casting was finished to both the ...166 base brake drum AND the ...167 metallic brake drum. I previously asked if you could measure the web thickness with a micrometer or caliper. Since the web for the metallic drum is slightly thicker, even though the casting number is the same for both metallic and base, this measurement is proof of whether the drum is a ...167 or ...166.

Duke

[Harry S.]

Re: Brake Drum Research

As I previously stated the ...671 drum casting was finished to both the ...166 base brake drum AND the ...167 metallic brake drum. I previously asked if you could measure the web thickness with a micrometer or caliper. Since the web for the metallic drum is slightly thicker, even though the casting number is the same for both metallic and base, this measurement is proof of whether the drum is a ...167 or ...166.

Duke

Web thickness = .320

Sorry for the delay

[Duke W.]

Re: Brake Drum Research

It couldn't be that thick. I listed the web thickness for both base and metallic drums in post #4. The web is the center portion of the drum stamped from steel that was inserted into the mold before the iron was poured, and then the molten iron wrapped around the OD of the steel web and bonded to it as it solidified.

Use a caliper or mic to measure thickness at the hole the center of the web.

Duke

[Harry S.]

Re: Brake Drum Research

U B correct. New Gauge.

IMG_5245.jpg

[Duke W.]

Re: Brake Drum Research

I can't make out the reading. Can you just use the tip of the caliper jaw to measure at the edge of the hub hole and then state the reading. Measure at about three points and look for consistency. A photo isn't necessary.
Duke

[Harry S.]

Re: Brake Drum Research

I can't make out the reading. Can you just use the tip of the caliper jaw to measure at the edge of the hub hole and then state the reading. Measure at about three points and look for consistency. A photo isn't necessary.
Duke

The reading is .139

[Duke W.]

Re: Brake Drum Research

That's .020" above the spec for a metallic front drum, but most of that is probably because using the full width of the jaw will pick up surface corrosion of many a little warpage. Using just the tip of the caliper would likely yield a measurement closer to the actual thickness of the original steel material.

In any event it's ...067 metallic brake front drum. I have no idea why it is in a ...166 box, which is how the ..166 base brake front drum was packaged.

Duke

[Dorsey F.]

Re: Brake Drum Research

Was waiting for this to be clear, but it seems it may never be.
To add to the mud: I have two front drums, packed on the blue/ white boxes, printed 2/69, marked part #3830166. Casting # X3828672 and also cast into the drums W-10. No other markings, no max dia., so prior to ‘71 FMVSS. Web is 0.13++”, mostly around 0.140+” (lots of burrs and roughness to clean up), stamped with “X”.

Got to wonder if GM made too many metallic lining drums and just supply the X drum for both applications.

[Alan D.]

[Chuck G.]

Re: Brake Drum Research

Not sure how this might add to the discussion.

I'm the guy that Harry S helped out. The front brakes on my 63 started pulling, and the pulling was getting worse. Time to redo them, as I hadn't looked at them for 20 years or more. Long story short, one piston in the wheel cylinder on the LT side was frozen. Thus, I was getting 2 shoes working on the RT and only 1 on the LT...

I discovered that one of my original drums was cracked. Could have been cracked for 20-30 or more years. But, knowing that, it bothered me.

Harry helped me out with an original drum stamped F on the face.

Just the other day, at a yard sale in my neighborhood, I came across an "old Chevy" brake drum. It was a 2.5" one. No history. I bought it for $5.00.

I measured the face/spider/mounting surface of my original cracked F drum. It measured 0.131 using my digital caliper.

The passenger drum measured 0.112, so the flange/spider is roughly 0.020 thinner than the F Corvette drum.

There are no casting numbers on the passenger drum, and there is nothing stamped on the face of the flange/spider.

[Dorsey F.]

Re: Brake Drum Research

Glad you got fixed up Chuck.
Apparently documentation and availability on drums is as good as documentation and availability on distributor internal parts