What to look for when buying a used differential? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lyrikz · 09-22-2016, 05:40 PM

Im picking up a set of 3/4 ton axles here in the next few days. I have access to pop off the covers. What am i looking for inside there? Is there anything that if i see would make this a no deal?

I believe they are a 74 up 3/4 ton 4wd axle. 4.10 gears i believe.

CG · 09-22-2016, 09:58 PM

Are you going to put these under your Blazer? If so ... Cool!

**special-K** · 09-23-2016, 08:33 AM

Mostly look for water contamination, either present or previous (rust). Look for pitting and any general damage such as chips in teeth or burred edges. Also look for bluing on parts (weakened from heat)

lyrikz · 09-23-2016, 10:39 AM

Quote:

Originally Posted by CG

Are you going to put these under your Blazer? If so ... Cool!

Yes. I blame you. ahaha. We talked briefly about bigger axles on a rig you had and it didnt even cross my mind until then.

lyrikz · 09-23-2016, 10:40 AM

Quote:

Originally Posted by special-K

Mostly look for water contamination, either present or previous (rust). Look for pitting and any general damage such as chips in teeth or burred edges. Also look for bluing on parts (weakened from heat)

Awesome... Thats what i needed.

Now say the diffs are messed up... Would 250 bucks for front and rear with the rims a decent deal even if i have to replace the diffs???

BILT4ME · 09-23-2016, 02:51 PM

That's still a bit high for "junk" diff's.. it will cost you about $800-$1000 to have it rebuilt with new bearings and R&P (assuming the carrier is good) or more if you want to install a limited slip or locker. That's $125 for each, assuming it's junked. A junk one should be about $50 in my opinion.

lyrikz · 09-23-2016, 03:00 PM

Quote:

Originally Posted by BILT4ME

That's still a bit high for "junk" diff's.. it will cost you about $800-$1000 to have it rebuilt with new bearings and R&P (assuming the carrier is good) or more if you want to install a limited slip or locker. That's $125 for each, assuming it's junked. A junk one should be about $50 in my opinion.

Ok.
I couldnt find any 3/4 tons... At all...

**special-K** · 09-23-2016, 10:27 PM

when you find some, don't buy any with issues I described. The cost of repir far outweighs the value of the axles. If the seller is willing to give them to you once you discover issues, then maybe go for it. But you can find well sealed axles with no issues for fairly cheap. Possibly as cheap as $250-300. And all you do is put them in

John H. · 09-24-2016, 10:16 AM

I have a 72 3/4 ton front end with 4:10's for $150. Just have the front end.

Located in sammamish.

lyrikz · 09-26-2016, 10:42 AM

Quote:

Originally Posted by special-K

when you find some, don't buy any with issues I described. The cost of repir far outweighs the value of the axles. If the seller is willing to give them to you once you discover issues, then maybe go for it. But you can find well sealed axles with no issues for fairly cheap. Possibly as cheap as $250-300. And all you do is put them in

I picked them up. The gears looked really good. I plan on replacing ball joints and all that stuff, they are super rusty.. Is there any value in the 8 lug rims?

I will post up pics.
Here is the numbers.. THe guy said they are 4.10 gears. Can you tell by these numbers?? I have yet to check the front differential. The axles are out of a 1979.

lyrikz · 09-26-2016, 10:50 AM

Quote:

Originally Posted by lyrikz

I picked them up. The gears looked really good. I plan on replacing ball joints and all that stuff, they are super rusty.. Is there any value in the 8 lug rims?

I will post up pics.
Here is the numbers.. THe guy said they are 4.10 gears. Can you tell by these numbers?? I have yet to check the front differential. The axles are out of a 1979.

If im correct by what the internet says, that is a 4:10 rear end...

cleszkie · 09-26-2016, 02:37 PM

My bit of advise was to make sure both axles have the same gear ratio. I once bought a set of axles that the seller swore were off the same truck. Ended up being 3.73 rear and 4.10 front - clearly not a matched set. If you have the covers off its as easy as counting the teeth on the ring gears and pinions. This will tell you that the axles are matched, as well as the ratio.

lyrikz · 09-26-2016, 03:26 PM

Quote:

Originally Posted by cleszkie

My bit of advise was to make sure both axles have the same gear ratio. I once bought a set of axles that the seller swore were off the same truck. Ended up being 3.73 rear and 4.10 front - clearly not a matched set. If you have the covers off its as easy as counting the teeth on the ring gears and pinions. This will tell you that the axles are matched, as well as the ratio.

Sounds good.. Definitely pulling covers... I want to replace all the wheel bearings and ball joints and what not.

**Boog** · 09-26-2016, 05:38 PM

Look for clumps in the gear oil. Some guys years ago would put saw dust in a rear axle to keep the rear end from singin a tune.

09-22-2016, 05:40 PM	#1
lyrikz PITbut Join Date: Sep 2007 Location: monroe washington Posts: 3,052	What to look for when buying a used differential? Im picking up a set of 3/4 ton axles here in the next few days. I have access to pop off the covers. What am i looking for inside there? Is there anything that if i see would make this a no deal? I believe they are a 74 up 3/4 ton 4wd axle. 4.10 gears i believe. __________________ New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel *DONE! SOLD!* My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold.

09-22-2016, 09:58 PM	#2
CG BlahBlahBlah Join Date: Feb 2002 Location: Wa. Posts: 19,826	Re: What to look for when buying a used differential? Are you going to put these under your Blazer? If so ... Cool! __________________ … … … … … … … … ... … … … … … … … … … … …

09-23-2016, 08:33 AM	#3
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,862	Re: What to look for when buying a used differential? Mostly look for water contamination, either present or previous (rust). Look for pitting and any general damage such as chips in teeth or burred edges. Also look for bluing on parts (weakened from heat) __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

09-23-2016, 02:51 PM	#6
BILT4ME Registered User Join Date: Jul 2016 Location: Olathe, KS Posts: 267	Re: What to look for when buying a used differential? That's still a bit high for "junk" diff's.. it will cost you about $800-$1000 to have it rebuilt with new bearings and R&P (assuming the carrier is good) or more if you want to install a limited slip or locker. That's $125 for each, assuming it's junked. A junk one should be about $50 in my opinion. __________________ 1970 GMC K2500 Dis-use is harder on a car than mis-use.

09-23-2016, 10:27 PM	#8
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,862	Re: What to look for when buying a used differential? when you find some, don't buy any with issues I described. The cost of repir far outweighs the value of the axles. If the seller is willing to give them to you once you discover issues, then maybe go for it. But you can find well sealed axles with no issues for fairly cheap. Possibly as cheap as $250-300. And all you do is put them in __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

09-24-2016, 10:16 AM	#9
John H. Registered User Join Date: Oct 2007 Location: Sammamish, WA Posts: 2,115	Re: What to look for when buying a used differential? I have a 72 3/4 ton front end with 4:10's for $150. Just have the front end. Located in sammamish.

09-26-2016, 02:37 PM	#12
cleszkie Registered User Join Date: Feb 2003 Location: Santa Ana, CA Posts: 2,191	Re: What to look for when buying a used differential? My bit of advise was to make sure both axles have the same gear ratio. I once bought a set of axles that the seller swore were off the same truck. Ended up being 3.73 rear and 4.10 front - clearly not a matched set. If you have the covers off its as easy as counting the teeth on the ring gears and pinions. This will tell you that the axles are matched, as well as the ratio.

09-26-2016, 05:38 PM	#14
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,103	Re: What to look for when buying a used differential? Look for clumps in the gear oil. Some guys years ago would put saw dust in a rear axle to keep the rear end from singin a tune. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross



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