BUSY BOLTERS Are you one?  The Shop Area
continues to pull in the most views on the Stovebolt. In August alone there were over 22,000 views in those 13 forums.
| | Click on image for the lowdown. 
====
| | |
0 members (),
433
guests, and
1
robot. | | Key: Admin,
Global Mod,
Mod | | | Forums66 Topics126,777 Posts1,039,270 Members48,100 | | Most Online2,175
Jul 21st, 2025 | | | | Joined: Mar 2008 Posts: 105 'Bolter | | 'Bolter Joined: Mar 2008 Posts: 105 | Hello,
After nine years in storage, we are now working on our 48 GMC 1 ton. Break drums, 12" & 14" how much can one machine on them to get the wear edge off?
Thank for your help, Joerg | | | | | Joined: Feb 2004 Posts: 28,674 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 28,674 | Back when just about every vehicle ran drum brakes, the rule of thumb for machining passenger car drums was .060" max, and most light and medium-duty trucks had a .090" max oversize. Those 14" drums are virtually impossible to find new, and good used ones are almost as scarce. Don't machine them any more than absolutely necessary. If there's a deep groove, leave it and just clean up the main drum surface area.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Apr 2005 Posts: 7,442 Bolter | | Bolter Joined: Apr 2005 Posts: 7,442 | Joerg, are you going to do the machining yourself? Any good brake shop will have a list of thickness tolerances to go by. They will mic the drum to see if it is within tolerance or not. They usually remove just enough material to get rid of the lip and be smooth all the way around. They won't do an unsafe drum.
Martin
'62 Chevy C-10 Stepside Shortbed (Restomod in progress)
'47 Chevy 3100 5 Window (long term project)
‘65 Chevy Biscayne (Emily)
‘39 Dodge Business Coupe (Clarence)
“I fought the law and the law won" now I are a retired one!
Support those brave men/women who stand the "Thin Blue Line"! Hug a cop!
USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
| | | | | Joined: Mar 2008 Posts: 105 'Bolter | | 'Bolter Joined: Mar 2008 Posts: 105 | Hello and thanks,
The rear 14" are not off yet, they are hooked on the shoes. Need to see this pm how they come.
I have a break shop do them and you are correct, they should know.
Joerg | | | | | Joined: Mar 2008 Posts: 105 'Bolter | | 'Bolter Joined: Mar 2008 Posts: 105 | Hi,
the 8 bolt, 14" drums on my 49 GMC 1 ton rear axle have four holes, are they for push bolts and if, what size are they?
Can't see any thread at the start.
Thanks, Joerg | | | | | Joined: Apr 2005 Posts: 7,442 Bolter | | Bolter Joined: Apr 2005 Posts: 7,442 | Make sure you back off the adjusters as far as they will go. If it still won't come off, disconnect the brake line and remove the mounting bolts for the wheel cylinders. This should allow the brake shoes, Springs and brake cylinders to move enough to get the drums off. I don't believe the holes are threaded.
Martin
'62 Chevy C-10 Stepside Shortbed (Restomod in progress)
'47 Chevy 3100 5 Window (long term project)
‘65 Chevy Biscayne (Emily)
‘39 Dodge Business Coupe (Clarence)
“I fought the law and the law won" now I are a retired one!
Support those brave men/women who stand the "Thin Blue Line"! Hug a cop!
USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
| | | | | Joined: Sep 2010 Posts: 1,955 'Bolter | | 'Bolter Joined: Sep 2010 Posts: 1,955 | I thought the drums shoul have a min thickness stamped in them | | | | | Joined: Dec 2001 Posts: 14,522 Moderator: Welcome Centre, Southern Bolters, Legion Hall | | Moderator: Welcome Centre, Southern Bolters, Legion Hall Joined: Dec 2001 Posts: 14,522 | What HRL said....and be sure its a reputable shop doing the resurface. The local flaps will not do it if there is any "thinking" involved. I've had several along the way where we just resurface the face, as HRL suggested, and left the groove. Use Caution! | | | | | Joined: Jan 2008 Posts: 4,903 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,903 | If you are getting close to the max, just leave them alone because if a shop that doesn't know what they are doing ruins them, you will have a tough time replacing them. The new linings will wear a pattern pretty quickly. We ran grooved brake drums 50 or 60 years ago and it worked then and it will work now.
I am especially cautious about cutting drums that have been used with non asbestos linings. Non asbestos linings cause hot spots that will cause the cutter to jump over them. I have a lathe that will cut 16 ½ x 7 drums, but I quit cutting them when all we could get was non asbestos. I rigged up a grinder attachment to grind the hot spots, but it is just not worth all the effort. | | |
|
|
