Front brake drums

[Huck]

Honestly I've been searching.
What's the service limit for the front drums? Going junkin would like to find an extra.
Regards!

[58flh]

Huck!---I pushed mine to .110/ At one point & made the year-(8 months!).But I wouldn't recommend it!--I always felt uneasy & Used the mixer & rear brake ALOT!.---I do not know the running limit -but I was under a 1/8-inch!-& It always bugged me in the back of my mind!---I actually used it for 2-more months the following year until I found a OEM one in NICE COND.----Respectfully----RICHIE

[Cotten]

Huck!

A "service limit" would just be the largest spec that an OEM lining would match.

So its really about the linings, not the drum.
If you can have oversized linings properly arc'd, I would trust the drum even over OEM limits.

....Cotten

[58flh]

Thanks COTTEN!--Sounds good!--Im glad I saved my old drum!---I had no problem fitting shoes to it.--Ok another part I don't have to get for my bobber-build.---Richie

[RUBONE]

Cast iron drums over the service limit max are subject to cracking and even fracturing. I suggest you have the person suggesting you go beyond limits supply you with a valid insurance policy before following his poorly thought out response. Cast iron is very forgiving, but only to a certain point. Stamped drums will only stretch more once beyond safe limits. Iron drums will not.
Robbie

[Hop Up]

Palmer's book says that the cast iron drums are safe at 8,10 inch. Standard diameter is 8,00.

[Cotten]

Folks,

It takes heat to make a drum fail.
Steel drums will warp long before a cast drum will crack.

Chrome should be avoided with either!

....Cotten

[Huck]

Thanks Guy's, I like to hear the different opinions, they allow a good base to form my own. I didn’t strike on anything there, thought they were too crusty for the asking price.

Good time, great weather, not as many sellers as last year. Forgot my camera. wth?

Ps: the Pan ran great.

[Hop Up]

I just checked the book and the extra info is:
"if you are going to go past 8.040", you must use special 0.030" oversize brake shoes or linings. The drum must be turned at least 8.060" for the oversize linings to work properly."
And 8.100" max for the drum.

[Cotten]

I just checked the book and the extra info is:
"if you are going to go past 8.040", you must use special 0.030" oversize brake shoes or linings. The drum must be turned at least 8.060" for the oversize linings to work properly."
And 8.100" max for the drum.

Which brings us back, Folks...

...to my previous post.

Its about the linings and having them accurately arc'd.

You wouldn't be forced to take out the full 8.060" with proper equipment.
But Dealerships rarely had the equipment.
So the Factory "limit" was set by their off-the-shelf replacement linings.

There is plenty of "meat" left beyond that, unless you really have tight panties.

The secret to avoiding drum damage is to not get them hot.
If you live in the mountains, with a heavy machine like a sidehack,...you might.

.....Cotten

[Huck]

Terribly stubborn regarding others working on my pile. Do you make a pattern? Is the drum itself the pattern? Surly you’ve made a tool to accomplish the mission? My front brakes shouldn’t be called such a word.

[Cotten]

Huck!

It takes either equipment designed to arc oversized linings, or fixtureing upon a lathe to do it safely.

I would farm it out, myself.

.....Cotten

[Mr.Big]

I took my shoes to a local brake shop and had them install new linings. They wouldn't arc them (EPA stuff I think) so I took some 100 grit sticky back sandpaper and stuck a couple side by side inside the drum and arc'ed them myself by working the shoe back and forth.

Go easy as it doesn't take much and my brakes work very well considering what they are......

brakes1.jpg

Here is a pic from 1937 of the shop here in Houston where I had them done.........

brakes2.jpg

[Panacea]

Hi Mark! Just curious, did you have the shoes mounted on the backing plate while doing the sanding? I'm thinking the arc would be quite a bit different off the plate. If your process could be done with all the parts installed on the fork it would be ideal!...Mike

[hplhd]

mike, i did what mark did on my front drum. cut a pice of adhesive backed sand paper the length and width of the drum and slide it over the assembled shoes. i bought the paper in a roll somewhere, can't remember.