The Stovebolt Site Forums The Shop Area Driveline Measuring brake drums

Hi, I've got some brake drums I need to measure. What is used for this. I've got an inside mike(sp) but it's way too small.

Hy Savannah54, there are special brake drum micrometers, are we talking about drums for a light truck or for a big bolt? I think if you took your drums to a shop which does brake jobs, they would measure them for you and tell you if they are turnable or if it is time for them to be replaced. Sometimes a drum will measure as turnable, but when put on the lathe it is too much out of round to cut it back to circular without going oversize, hope that helps.

Thanks 3B, I'm also Googling it. Just trying to figure out if they are good enough to give away.

To see what they look like, search Ebay for "brake drum micrometer". There are about a dozen of them on there today, and some are priced right. I have two of them left over from back when I did a lot of brake drum machining.
Jerry

Thanks HotRod, That's what I purchased.

You bought mic's to measure drums to give away? Can't "Brakes are us" places measure them? or a turn buckle? or a threaded rod with a threaded post on one end? anything that spreads and holds so as to take out and measure. Magnets and a string?

Maybe we need a Tech Tip to demonstrate all those techniques?

I will never need to measure a drum. Put on your shoes and drive. No offence meant to Julian's kindness. I don't have the character to buy a mic to measure a drum to give to someone.

The "techniques" are brainstorming thoughts to illustrate that any home device that will expand, like a turnbuckle or modified turnbuckle, can be used to get a "set" of the inside diameter. Pull it out and measure the tip to tip of the DIY unit. If it's within a 1/16 of "not sure" then recycle the drum to scrap. I don't intend the suggestions to measure to .001 accuracy. This is all predicated on if you can find the spec for your drums.

Don't forget, one "technique" is take them to a "brakes are us" and ask the person to measure.

Tim, thanks for your suggestion on tips. It's nice you think they are worthy of that. If you were joking, I get that also because of the funkyness of the ideas. There is always something to pick out and message from a brainstorming exercise that ends up a good idea.

My Dad told me and we are both Machinist, if it is grooved a little, but the main dia. is within specs.
The new linings will break in to the drums.
Some shops that do brakes drums, would rather sell you new ones, than machine the old ones for less profit.
Anyway, that's what he taught me, good or bad.
He was born in 1927.

Don

Don, That's what I have said for 50 years. Never had a problem with groovy shoes/drums.
You are supposed to "arc" the new shoes to a turned drum. Good luck finding that service. It's kind of always been a scam that has some reasoning behind it.

Gracious!! Now I've got 4 Cars that have brake drums. That put the measuring device to work. In the end I'll have 4 ea. 3/4 ton drums to provide someone. Sense I'm going to disk brakes. Everyone has a valued opinion Thanks.

Bueno

Since we've got all these experts on board, I won't try to share 50-something years' worth of experience doing precision work on brakes. I do have two drum micrometers for a reason, I own a disc/drum lathe, and I've generated several hundred pounds of cast iron shavings with a drum lathe, though!
Jerry

"It's kind of always been a scam that has some reasoning behind it."

Hello bartamos.

What is it you're saying about arc grinding? That subject causes some people to get their feathers up (I'm not one of them).

I am saying that after you turn your drums you are supposed to arc the shoes. What are you asking me? I said good luck finding a place that still does that. There are dust/EPA issues also.
I had "luck" spelled wrong in that post.

Ask the Google Guru!
Jerry

"It's kind of always been a scam that has some reasoning behind it."

Thanks for clarifying bartamos. I was asking only because I find the differences of opinions on these topics interesting. I don't know what the actual regulations are. So far I've been able to have my own personal brake shoes arc ground professionally. I simply pay the fee for that and don't ask any questions. It's becoming moot anyway as many cars/trucks now have 4-wheel disc brakes and our antiques don't get driven enough to require new brake friction once they are set up and running. My '36 pickup restored in the early 1970s has only about 13,000 miles on it and my 'roadster street rod finished in 2003 has only about 22,000 miles. That amount of use won't wear out any brakes in my lifetime.

To some of us it's a scam because for 50 years and many vehicles, we have done our own brakes all those years. Have never turned drums or arced shoes. Even with grooved drums, no stopping problems. No noticeable extra wear. So it seems like no difference between us and those who had it all done. The theory of doing it makes since. The actual outcome of not doing it makes since also.

If by "regulations" you mean a requirement to turn and arc by some government entity, there are none. A requirement to have brakes done at a certified shop, there are none. Inspection of old truck's brakes, no. A prohibition on doing your own brakes, none. There are no "regulations".
But that does not include the very unusual state you live in. No one knows what they will do next. They have regulated everything.

There are regulations in all 50 States about asbestos control/abatement. It’s known to be bad stuff. Proceed with caution.🛠

If it matters: I was not joking about a Tech Tip.

As posted in another thread regarding asbestos in brake linings:

Warning to readers: once asbestos gets into your lungs, it does not disappear.
Asbestos in your lungs can be carcinogenic (has the potential to cause cancers).

If you use/service/sand/grind asbestos-containing brake linings, heed and follow these precautions (you and your family, if they enter your garage/work-area). I have always worn a mask (mount and nose cover), and wash clothes and spray down after servicing old brake shoes.

"But that does not include the very unusual state you live in. No one knows what they will do next. They have regulated everything."

bartamos,

That's so true. I'm embarrassed to admit that I'm from here. But they don't regulate "everything". To identify the one thing they don't regulate may violate political correctness.but I think you probably know what it is.

One of the ironies about the "dust up" (pun intended) this conversation has caused is that except in rare instances where a guy like me has gone looking for asbestos brake shoes, arc grinding can't generate any asbestos "dust" because the linings made since about 1980 don't contain any asbestos. The new substance in brake friction to be paranoid about is copper. Yes, copper. It never ends with the things with potential adverse health effects..Never mind that the water we drink flows through copper pipes in our houses and copper is soluble in even the most slightly acidic water. So much so that in areas of acid rain domestic water makes pin hole leaks in copper pipes causing huge re-piping expenses.