The Stovebolt Site Forums The Parking Lot Tons 'o Fun Drum specs

Im getting my drums turned for a '51 1 ton and need to know what specs they should me turned to, does anybody know?

I do not believe there are any specs involved. What you want to accomplish is to get all the grooves out and still end up with enough "Drum wall" to dissipate the heat . More brake pureists may chime in and discredit what I believe.

I think he's right. Just make sure there is enough thickness to the drum. You can adjust the brake shoes to fit a slighter larger diameter, so there is no specification in that respect.
Minimum thickness of the drum is what you'll have to check for. Maybe someone in the know can post it.

Ok thanks, i do believe somebody posted it being .090"

It's actually maximum diameter when dealing with drums, and there is a specification for it. As Josh has mentioned from the other post on this subject, .090 over nominal is the maximum you would want to go and still mainatan a safety margin. Most drums have a machine to spec of .060 over nominal, with the .090 being the discard spec, as you would not want to go any firther than that.

ok, so correct me if I'm wrong.

When having the drums turned or machined, that increases the diameter, and you only want to go a maximum of 0.090 over stock. but when having the drums turned you want them turned until all the grooves are out, so if i get my drums turned and they are "smooth" within that 0.090 maximum then my drums are fine to use?

Even if there are a few minor grooves left at the .090" oversize point, as long as most of the drum surface is smooth and straight, go ahead and re-use the drums. The major reason to turn a drum is to get a smooth, straight surface, with minimum out-of-round. A few small grooves don't really cause a problem, as the lining will wear in to a perfect contact within a few miles.

The owner of a small trucking company where I managed the shop insisted that a grooved drum added area to the brake, and he wouldn't let me get drums machined. The "golden rule" applies here- - - -the guy with the gold makes the rules! I coudn't convince him he was wrong, so I just did it his way!
Jerry

I would say be extremely careful here. Replacement drums for a 51 1 Ton are extremely rare and very hard to find. You don't want to have your drums ruined by too much machining. In the past, I have found two references in the shop manual for the maximum diameter that they can be turned to. For the smaller drums it seems to be .060" and for the 16" and up I believe it was .125".

Ill take a look in manual once I find it haha, but I do believe I have 15" drums

Usually the drums are refered to by the inside diameter which in your case is probably 14".

alright, well i guess ill just have to giver a shot and hope the drums will still be think enough.....

Anybody know any tricks as to how to get a seized drum off? im taking the fronts off, coated the drums in loctite oil and was able to maybe get it 1/4" off the hub (with a lot of choice language and prying)... and now its stuck

I just removed (2) 1 ton drums this week. Back off the adjusters till they dont back any more. Use about 2 or 3 long pry bars/ Screwdrivers. Bang on drum with the biggest BFH you have all around edge. I AM not talking a 16 ounce claw hammer but a BFH. Drive one pry bar between drum and backing plate at the 12 o clock area and force the drum outward. BFH the oposite side of drum. You will see movement. Use the other pry bars at the 8 and 4 o clock positions and force drum out ward. Use BFH again all around the drum. It is moving , isn't it. Dont give up, just keep working the pry bars and the BFH. When the drum falls to the ground, grab a cold bud , then start the other side. The key to it is to get the adjusters backed off and to break the rust around the lug bolts and the drum.

Are you trying to remove the front drums from the hubs? I think the machining is done with it still on the hub.

Im trying to just get the drum off so I can get at the wheel cylinder and brake parts

and hopefully find out if the small crack on the front drivers drum is gonna cause me trouble or not....

Where is the crack located? If it;s just on the outer lip area, it shouldn't be a concern, but if it's in the actual braking surface, you'll need a replacement drum.

its ont he top of the outside of the drum... where the grooves are?

If it's scored deep enough to cause a crack, then it's not going to be reusable. Is there any way you could post pictures of the crack location, and perhaps the scoring? Might be able to get a better idea of what you have going on if we can see it.

Crack top
Crack side

They dont go all the way through so my guess is they should be fine, the insides of the drum are in amazing shape

I hate to be the bearer of bad news, but that drum is not going to be usable. That crack is in a vital part of the drum, and would be a safety issue. I wouldn't risk trying to reuse it.

Probably a stupid question but would i be able to TIG weld it together. the pics look a lot worse than the crack actually seems

I wouldn't advise it.

hmm alright well i guess ill just take it to the shop and see, maybe ill be lucky?

I totally agree with you but out here in Cali..."the land of fruits and nuts" it's illegal for a shop to turn an out of spec drum. So unless you can do it yourself your screwed!!!

Not just California, all 50 states. I suppose that some of the shadier "mechanics" might turn a drum (or rotor for that matter) beyond the specs just to make a buck, but those of us that actually take pride in our work know better.

hmmm, hopefully not in Canada?

I think that is preyy well the same here in Canada. Although the specs may be hard to find, I think there is mention of .060" over for the lighter duty trucks and I think starting at the 16" drums it is .125". I would have to do some searching to find the references. Back then I would imagine new drums were plentiful and cheap. Of course, that isn't the case for these old trucks now. Half ton owners have it easy in this department because the market demand is large enough to produce new drums.

In the manual i have, it has a bunch of "sepcidications" but i have no idea what they mean. if anybody would like i can post them?