Replace front rotor and hubs or only rotors? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Wincks2 · 04-12-2010, 11:53 PM

Edit: looks like I had been misinformed and the hub and rotor is a single piece so no decision need be made.

James McClure · 04-13-2010, 10:07 AM

Wincks, I did mine (3\4 ton also) And I replaced rotors only because I have done it many times over the years. It isn't easy, but certainly even a novice mechanic can do it if they pay close attention to what they are doing. There are a few areas to be careful about, and you are going to need a special socket to R&R the spindle nuts. First area is the inner hub snap ring, (fits into a groove in the hub) There may be another one on the axel itself (some have it some don't, mine don't) After get the ring(s) out, pull the inner hub, (use 2 of the retaining screws from the cover to pull it) Now, with the special socket remove the first nut. Under that there is a ring with holes in it and 4 tabs on the outer edge and a keyway tab inside, a pick will pull it out.. Next is the inner nut and governs bearing pre loading. When you get this nut off you will see a pin sticking out of the nut. [U]IT IS CRITICAL THIS NUT BE REINSTALLED WITH THE PIN FACING OUT BECAUSE IT MUST FIT INTO ONE OF THE HOLES IN THE RING WITH 4 TABS ON IT!![U] If someone did this before they could have put it in upside down OR didn't get it aligned with a hole in the ring and crushed the pin. In that case get a new nut. Next is actual rotor replacement. Drive the studs out and tap the rotor off the hub. Clean the hub mounting surface until there is no rust evident and THIN coat it with anti seize and reassemble. You will have to beat the studs back in (I use a 2 pound sledge) Inspect wheel bearing, repack or replace as necessary. Replace seal and hang rotor. Same with outer bearing. Install the nut with the pin next (pin faceing you) and do your preload. Slip in ring and make sure it sits flat over the pin!! If not flat, loosen the inner nut a little bit at a time until it does. Install outer nut and tighten good and tight. Reassemble outer hub & caliper. This should about do it. Hope I helped you, Jim

Wincks2 · 04-13-2010, 01:56 PM

Thanks James McLure

So that is how it is done on the K20s with the front axles. My manual discusses the front axles on K20s but I hadn't fully understood it.

Someone at a parts store had told me the rotors and hubs were separate on mine also. Turns out the rotor and hub I took off is a single unit. Apparently Old Smokey doesn't have a front axle. She is a C2500. Lucky for me!

Thanks again.

James McClure · 04-13-2010, 07:21 PM

Wincks, the rotor\hub will come off as a unit. You have to seperate them after removal. While your in there you might want to check the front axel "U" joints. Depending on how heavily used the 4WD is or was and what it was exposed to, these are a common failure. NAPA has the joints and they are greasable. 6 more bolts to remove the caliper support\mounting bracket and just pull the axel out and change the joint and stuff it back in and your good to go. Might take you an extra hour a side, but it's well worth the effort in the long run. Jim

04-12-2010, 11:53 PM	#1
Wincks2 Registered User Join Date: Feb 2010 Location: Canada - Manitoba - Winnipeg Posts: 425	Replace front rotor and hubs or only rotors? Edit: looks like I had been misinformed and the hub and rotor is a single piece so no decision need be made. __________________ Old Smokey: 85 GMC 3/4 ton long bed crew cab originally a 5.7 gas engine now with an 84 6.2 with a 92 serpentine belt system, a banks sidewinder, torque converter, and a shift kit. I bought her this way from someone handy - and now am trying to figure out how all this truck works. The Old Smokey project: http://67-72chevytrucks.com/vboard/s...d.php?t=390518 Last edited by Wincks2; 04-13-2010 at 10:08 AM.

04-13-2010, 10:07 AM	#2
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: Replace front rotor and hubs or only rotors? Wincks, I did mine (3\4 ton also) And I replaced rotors only because I have done it many times over the years. It isn't easy, but certainly even a novice mechanic can do it if they pay close attention to what they are doing. There are a few areas to be careful about, and you are going to need a special socket to R&R the spindle nuts. First area is the inner hub snap ring, (fits into a groove in the hub) There may be another one on the axel itself (some have it some don't, mine don't) After get the ring(s) out, pull the inner hub, (use 2 of the retaining screws from the cover to pull it) Now, with the special socket remove the first nut. Under that there is a ring with holes in it and 4 tabs on the outer edge and a keyway tab inside, a pick will pull it out.. Next is the inner nut and governs bearing pre loading. When you get this nut off you will see a pin sticking out of the nut. [U]IT IS CRITICAL THIS NUT BE REINSTALLED WITH THE PIN FACING OUT BECAUSE IT MUST FIT INTO ONE OF THE HOLES IN THE RING WITH 4 TABS ON IT!![U] If someone did this before they could have put it in upside down OR didn't get it aligned with a hole in the ring and crushed the pin. In that case get a new nut. Next is actual rotor replacement. Drive the studs out and tap the rotor off the hub. Clean the hub mounting surface until there is no rust evident and THIN coat it with anti seize and reassemble. You will have to beat the studs back in (I use a 2 pound sledge) Inspect wheel bearing, repack or replace as necessary. Replace seal and hang rotor. Same with outer bearing. Install the nut with the pin next (pin faceing you) and do your preload. Slip in ring and make sure it sits flat over the pin!! If not flat, loosen the inner nut a little bit at a time until it does. Install outer nut and tighten good and tight. Reassemble outer hub & caliper. This should about do it. Hope I helped you, Jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

04-13-2010, 01:56 PM	#3
Wincks2 Registered User Join Date: Feb 2010 Location: Canada - Manitoba - Winnipeg Posts: 425	Re: Replace front rotor and hubs or only rotors? Thanks James McLure So that is how it is done on the K20s with the front axles. My manual discusses the front axles on K20s but I hadn't fully understood it. Someone at a parts store had told me the rotors and hubs were separate on mine also. Turns out the rotor and hub I took off is a single unit. Apparently Old Smokey doesn't have a front axle. She is a C2500. Lucky for me! Thanks again. __________________ Old Smokey: 85 GMC 3/4 ton long bed crew cab originally a 5.7 gas engine now with an 84 6.2 with a 92 serpentine belt system, a banks sidewinder, torque converter, and a shift kit. I bought her this way from someone handy - and now am trying to figure out how all this truck works. The Old Smokey project: http://67-72chevytrucks.com/vboard/s...d.php?t=390518 Last edited by Wincks2; 04-13-2010 at 01:57 PM.

04-13-2010, 07:21 PM	#4
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: Replace front rotor and hubs or only rotors? Wincks, the rotor\hub will come off as a unit. You have to seperate them after removal. While your in there you might want to check the front axel "U" joints. Depending on how heavily used the 4WD is or was and what it was exposed to, these are a common failure. NAPA has the joints and they are greasable. 6 more bolts to remove the caliper support\mounting bracket and just pull the axel out and change the joint and stuff it back in and your good to go. Might take you an extra hour a side, but it's well worth the effort in the long run. Jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.



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