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| | | | Joined: Jan 2010 Posts: 36 'Bolter | | 'Bolter Joined: Jan 2010 Posts: 36 | Hello all
I have a pair of front drums of a 1942 Chev 3/4 ton truck. I would like to have them machined but I need to find out what the service limit for these drums are.I know all newer drums have this cast into the drum. If a limit was never specified what is the general consensus on the limit for these drums?
I know I can buy new ones but being in Australia the freight will most likely cost more than the drums.
Thanks
Steve | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | How do you know they need turning, might be best to try them out first since they are so hard to find. Many shops here just turn everything as a matter of course, not considering they might be hard to get.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy reidy, .060" is the usual maximum oversize for standard car/light truck brake drums, hope that helps. | | | | | Joined: Feb 2004 Posts: 29,740 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,740 | .060" for passenger car drums, and .090" for most light trucks was the rule of thumb back when I was making a living doing brakes. You can get by with slightly larger dimensions if you grind the linings to match the radius of the drums, but don't make it a habit of hauling heavy loads if you do that. Since most brake shops refuse to grind linings any more, a shade tree method that works well is to glue a piece of coarse sandpaper inside a drum and scuff the linings to a good fit. Using water-soluble glue on the sandpaper makes it easier to remove with boiling water when you're done with the fitting job.
Jerry
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| | | | | Joined: Mar 2010 Posts: 10,270 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,270 | With the scarcity of these drums, I would only have them turned if they where horribly scored (probably not salvageable if that were the case) or not round. A little bit of scoring will not affect braking, as the shoes will form fit to the grooves fairly soon.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Jan 2010 Posts: 36 'Bolter | | 'Bolter Joined: Jan 2010 Posts: 36 | Thanks for the replies. The ones I have are currently .070 oversized and are mildly scored and well weathered. There is a shoulder at the top. I will give them a cleanup and de-rust.If they can have the worst bits knocked of and come in at under .090 I will be happy to use them.
Steve | | |
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