Brake rotor minimum thickness - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hgs_notes · 09-25-2009, 12:54 AM

Been looking over the brakes on my 72 Jimmy 4x4 and need some info. I can't find the minimum thickness for the front rotors. It's supposed to be stamped on them, but I just don't see it.

If someone wants to share their tips for removing rusted on rear drums, I'd love to here them. I've got PB blaster on them now. I tried heating the drum and then cooling the hub, no luck. I'll keep spraying the PB on em and bang on 'em. Unless someone else has a sure fire way of knocking them loose.

Another thing, are the 4x4 rear drums any different than rear drums on a 67-70 2wd C-10?

texanidiot25 · 09-25-2009, 01:31 AM

Rust on the outside or inside braking surface? The only decent way I know is to turn them a bit on a lave, or just drive and let the brake shoes do the work

unclewatts · 09-25-2009, 04:23 AM

To answer your question about drums. From 67 to 69 half ton 2WD and 4WD rear drums are the same. After 69 they are different. As far as that frozen drum goes, Are you sure that it's not the brake shoes hung up inside the lip worn into the drum? If it is, you gotta back off the shoes through the adjusting hole (If you got one) on the bottom of the backplate. If the drum is actually frozen on the axle, then keep bangin'.

Longhorn Man · 09-25-2009, 06:14 AM

if the drup doesn't move at all, then you need to beat on it with a hammer. If it does move, but gets pulled right back, then adjust the shoes down

hgs_notes · 09-25-2009, 08:25 AM

I backed off the shoes before I started, I've done this work before. Guess I'll keep spraying and banging.

Anyone have the spec book for rotor minimum thickness?

unclewatts · 09-25-2009, 11:26 PM

Quote:

Originally Posted by hgs_notes

I backed off the shoes before I started, I've done this work before. Guess I'll keep spraying and banging.

Anyone have the spec book for rotor minimum thickness?

I would think that any machine shop that turns rotors would have that information. Here in California there is a law that prohibits any shop to turn down a disk or drum past a specified thickness.

hgs_notes · 09-25-2009, 11:53 PM

I found it stamped on the back side of a spare rotor I had in the garage.

JimKshortstep4x4 · 09-26-2009, 05:04 AM

The rotor minimum thickness spec is 1.230 inches.

Jim

09-25-2009, 12:54 AM	#1
hgs_notes GEARHEAD Join Date: Aug 2003 Location: MN Posts: 6,126	Brake rotor minimum thickness Been looking over the brakes on my 72 Jimmy 4x4 and need some info. I can't find the minimum thickness for the front rotors. It's supposed to be stamped on them, but I just don't see it. If someone wants to share their tips for removing rusted on rear drums, I'd love to here them. I've got PB blaster on them now. I tried heating the drum and then cooling the hub, no luck. I'll keep spraying the PB on em and bang on 'em. Unless someone else has a sure fire way of knocking them loose. Another thing, are the 4x4 rear drums any different than rear drums on a 67-70 2wd C-10? __________________ If no one knows what you're doing, they can't tell you you're doing it wrong HG's Dream Car Build - Shelby Cobra Kit Build your own adjustable track bar 71 Long Fleet C/10 72 Jimmy 4x4 (Junkyard Jimmy) HG's Plow Truck '78 K35 Dually Bigass Farm Truck HG's thread of miscellaneous stuff Last edited by hgs_notes; 09-25-2009 at 12:55 AM.

09-25-2009, 01:31 AM	#2
texanidiot25 Eat My Rust Join Date: Jan 2007 Location: Cypress, Texas Posts: 3,362	Re: Brake rotor minimum thickness Rust on the outside or inside braking surface? The only decent way I know is to turn them a bit on a lave, or just drive and let the brake shoes do the work Last edited by texanidiot25; 09-25-2009 at 01:31 AM.

09-25-2009, 04:23 AM	#3
unclewatts 70 Chevrolet=Obsession Join Date: Jun 2009 Location: nice ca Posts: 1,067	Re: Brake rotor minimum thickness To answer your question about drums. From 67 to 69 half ton 2WD and 4WD rear drums are the same. After 69 they are different. As far as that frozen drum goes, Are you sure that it's not the brake shoes hung up inside the lip worn into the drum? If it is, you gotta back off the shoes through the adjusting hole (If you got one) on the bottom of the backplate. If the drum is actually frozen on the axle, then keep bangin'. __________________ I'm Just like my truck. Old, Ugly and Grouchy. Except my truck starts easily in the morning and doesn't smoke! IT'S NOT EASY BEING GREEN! -Kermit the frog 1970 Chevrolet C-10 Longbed Stepside : 350, Muncie M20, 3.08 GM corp. positraction Forest green exterior/light green interior(Where all my money goes) 1996 Toyota Corolla (Parts runner)

09-25-2009, 06:14 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Brake rotor minimum thickness if the drup doesn't move at all, then you need to beat on it with a hammer. If it does move, but gets pulled right back, then adjust the shoes down

09-25-2009, 08:25 AM	#5
hgs_notes GEARHEAD Join Date: Aug 2003 Location: MN Posts: 6,126	Re: Brake rotor minimum thickness I backed off the shoes before I started, I've done this work before. Guess I'll keep spraying and banging. Anyone have the spec book for rotor minimum thickness? __________________ If no one knows what you're doing, they can't tell you you're doing it wrong HG's Dream Car Build - Shelby Cobra Kit Build your own adjustable track bar 71 Long Fleet C/10 72 Jimmy 4x4 (Junkyard Jimmy) HG's Plow Truck '78 K35 Dually Bigass Farm Truck HG's thread of miscellaneous stuff

09-25-2009, 11:53 PM	#7
hgs_notes GEARHEAD Join Date: Aug 2003 Location: MN Posts: 6,126	Re: Brake rotor minimum thickness I found it stamped on the back side of a spare rotor I had in the garage. __________________ If no one knows what you're doing, they can't tell you you're doing it wrong HG's Dream Car Build - Shelby Cobra Kit Build your own adjustable track bar 71 Long Fleet C/10 72 Jimmy 4x4 (Junkyard Jimmy) HG's Plow Truck '78 K35 Dually Bigass Farm Truck HG's thread of miscellaneous stuff

09-26-2009, 05:04 AM	#8
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Brake rotor minimum thickness The rotor minimum thickness spec is 1.230 inches. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

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