10 Bolt Rear Diff Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kelsfine69 · 04-19-2010, 01:11 PM

I have a 10 bolt rear diff in my 1987 Silverado. I took the cover off and found out its a posi(ya me) but the spyder gears are in really bad shape. Are the spyder gears the same as for a non-posi? or will I have to find a 10 bolt posi at the wreckers and rob the gears. non-posi would be alot easier to find if the gears are the same?

RandyP · 04-19-2010, 02:25 PM

I think most 1/2 ton 87's have posi in them (option G80), and are 3.42 ratio. Should be able to have good luck finding a complete assembly, which would be cheaper in the long run. We have mine apart right now putting in a pinion seal, but everything looks very good inside mine (thank you Jesus!). Was really scared, as always, of finding a lot of metal shavings.

LONGHAIR · 04-19-2010, 08:18 PM

That's a "Gov-lock", commonly known as "Gov-bomb", "Gov-pop" or simply "TimeX-posi" or a boat anchor for a small boat. I wouldn't spend the time or money to repair it...or to replace it with another one.

A "real" posi from Eaton will cost a few bucks, but it doesn't have all of the governor (clock works) junk....and they are rebuildable, if you happen to wear-out the clutches.

James McClure · 04-20-2010, 09:28 AM

Longhair, I do believe (could be mistaken for sure) that the Detroit locker type posi wasen't built in the 10 bolt diff. I think it was only in the 12 & 14 bolt flavors with ring gears over 9.0" Kelsfine's rear should be straight clutch type. The lockers also have clutches, so in answer to his question, the side gears are different from an open rear, the spiders are the same as is the pin. Jim

LONGHAIR · 04-20-2010, 07:56 PM

I just wish they had never used the "lock" work with those junk Gov-locks. They do NOT lock, it is just an RPM "regulated" clutch-type posi unit. Those "governor" pieces are the weak link...and not worth fixing. The cost would be way above any benefit....and you are right back where you started.
Gov-bombs are available in 10-12-and 14 bolt flavors, the only ones worth using are the 14s.

Detriot locker is a totally different animal....and they do not have clutches at all. They have square toothed side gears which are solidly engaged or "popped out" to allow differential action.
I'm fairly sure that GM quit using Detroit lockers after the 67-72 generation?....and those were only in the HO-52 and HO-72 anyway.

Everything else got the regular "clutch-type" posi-traction....until the dreaded gov-lock was introduced. At that point it was all you could get.

James McClure · 04-21-2010, 09:55 AM

Longhair, I stand corrected. I never saw an HO option diff. I drove a few gov-lock rearended trucks and never had a problem with them. I think that how this type of diff was operated had a lot to do with durability. Any thing mechanical is going to break if it gets run hard and put away wet. I do however agree that the straight clutch type is more durable under tough conditions and being driven by someone who dosen't understand whats going on back there. The gov-lock worked real well if you didn't have your foot in it to heavy or you took off hard around a corner and the driver understood how to work it within it's design limitations. I personally wish someone made a manual diff-lock like in tandum axel tractors. There again though, you didn't engage it with wheels spinning and you didn't try to get it to go around a corner, a tight one anyway. I have rebuilt any number of the diff-lock rears and they are aa bear even with the right tools, but all in all, I think there are OK IMO. Jim

kelsfine69 · 04-21-2010, 10:15 AM

So even if I do find find some gears its going to be a bear replacing them?

James McClure · 04-21-2010, 06:43 PM

Kels, Replacing the gears in ANY GM diff is a bear without reguard to what design the guts of the diff are. You have to deal with pinion depth (how far in the pinion is) backlash (how much clearance between pinion and ring gears) and side bearing preload. ALL effect general durability and noise. Get one thing off and it will sing and may fail. If you are going to get into one, have a tech there that IS FAMILIAR with GM rears. Once you see what goes into setting one up right you'll understand what you have to do the next time. There are tool you may not have that you need also. jim

kelsfine69 · 04-21-2010, 09:39 PM

If I pull the cover, then the pin, axles slide out. Remove the 4 carrier bearing bolts the whole ring gear assembley will come out. Now with it on my bench...how hard are the 4 internal spyders gears to remove with this type of posi? If it was a non-posi I could do it in the truck. Removing the carrier and leaving the pinion wont change anything.

3r!c84 · 04-21-2010, 11:49 PM

Quote:

Originally Posted by kelsfine69

If I pull the cover, then the pin, axles slide out. Remove the 4 carrier bearing bolts the whole ring gear assembley will come out. Now with it on my bench...how hard are the 4 internal spyders gears to remoce with this type of posi? If it was a non-posi I could do it in the truck. Removing the carrier and leaving the pinion wont change anything.

that dont sound like a posi

04-19-2010, 01:11 PM	#1
kelsfine69 18 Till I Die Join Date: Mar 2005 Location: Alberta, Canada Posts: 1,522	10 Bolt Rear Diff Question I have a 10 bolt rear diff in my 1987 Silverado. I took the cover off and found out its a posi(ya me) but the spyder gears are in really bad shape. Are the spyder gears the same as for a non-posi? or will I have to find a 10 bolt posi at the wreckers and rob the gears. non-posi would be alot easier to find if the gears are the same? __________________ 2011 GMC Acadia 1969 GMC BBC LS7 2007 GMC Crew Duramax 1987 Camaro Iroc 350 Tuned Port Injection 42000Km 1987 Chevrolet Silverado 350 TBI 1987 Chevrolet Silverado 350 TBI(yes 2) Take me drunk, I'm too home... Last edited by kelsfine69; 04-19-2010 at 05:13 PM.

04-19-2010, 02:25 PM	#2
RandyP Getting Old; Going Broke Join Date: Apr 2010 Location: Owasso OK Posts: 2,764	Re: 10 Bolt Rear Diff Question I think most 1/2 ton 87's have posi in them (option G80), and are 3.42 ratio. Should be able to have good luck finding a complete assembly, which would be cheaper in the long run. We have mine apart right now putting in a pinion seal, but everything looks very good inside mine (thank you Jesus!). Was really scared, as always, of finding a lot of metal shavings. Attached Images __________________ *Why is every used 350 sbc out of a corvette?* There's only two things that excite a man, expensive toys and real expensive toys. *VEGETARIAN: That's an old Indian word meaning "I don't hunt so good."* When the going gets tough, switch to power tools.

04-20-2010, 09:28 AM	#4
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: 10 Bolt Rear Diff Question Longhair, I do believe (could be mistaken for sure) that the Detroit locker type posi wasen't built in the 10 bolt diff. I think it was only in the 12 & 14 bolt flavors with ring gears over 9.0" Kelsfine's rear should be straight clutch type. The lockers also have clutches, so in answer to his question, the side gears are different from an open rear, the spiders are the same as is the pin. 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.

04-21-2010, 09:55 AM	#6
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: 10 Bolt Rear Diff Question Longhair, I stand corrected. I never saw an HO option diff. I drove a few gov-lock rearended trucks and never had a problem with them. I think that how this type of diff was operated had a lot to do with durability. Any thing mechanical is going to break if it gets run hard and put away wet. I do however agree that the straight clutch type is more durable under tough conditions and being driven by someone who dosen't understand whats going on back there. The gov-lock worked real well if you didn't have your foot in it to heavy or you took off hard around a corner and the driver understood how to work it within it's design limitations. I personally wish someone made a manual diff-lock like in tandum axel tractors. There again though, you didn't engage it with wheels spinning and you didn't try to get it to go around a corner, a tight one anyway. I have rebuilt any number of the diff-lock rears and they are aa bear even with the right tools, but all in all, I think there are OK IMO. 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.

04-21-2010, 10:15 AM	#7
kelsfine69 18 Till I Die Join Date: Mar 2005 Location: Alberta, Canada Posts: 1,522	Re: 10 Bolt Rear Diff Question So even if I do find find some gears its going to be a bear replacing them? __________________ 2011 GMC Acadia 1969 GMC BBC LS7 2007 GMC Crew Duramax 1987 Camaro Iroc 350 Tuned Port Injection 42000Km 1987 Chevrolet Silverado 350 TBI 1987 Chevrolet Silverado 350 TBI(yes 2) Take me drunk, I'm too home...

04-21-2010, 06:43 PM	#8
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: 10 Bolt Rear Diff Question Kels, Replacing the gears in ANY GM diff is a bear without reguard to what design the guts of the diff are. You have to deal with pinion depth (how far in the pinion is) backlash (how much clearance between pinion and ring gears) and side bearing preload. ALL effect general durability and noise. Get one thing off and it will sing and may fail. If you are going to get into one, have a tech there that IS FAMILIAR with GM rears. Once you see what goes into setting one up right you'll understand what you have to do the next time. There are tool you may not have that you need also. 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.

04-21-2010, 09:39 PM	#9
kelsfine69 18 Till I Die Join Date: Mar 2005 Location: Alberta, Canada Posts: 1,522	Re: 10 Bolt Rear Diff Question If I pull the cover, then the pin, axles slide out. Remove the 4 carrier bearing bolts the whole ring gear assembley will come out. Now with it on my bench...how hard are the 4 internal spyders gears to remove with this type of posi? If it was a non-posi I could do it in the truck. Removing the carrier and leaving the pinion wont change anything. __________________ 2011 GMC Acadia 1969 GMC BBC LS7 2007 GMC Crew Duramax 1987 Camaro Iroc 350 Tuned Port Injection 42000Km 1987 Chevrolet Silverado 350 TBI 1987 Chevrolet Silverado 350 TBI(yes 2) Take me drunk, I'm too home... Last edited by kelsfine69; 04-22-2010 at 11:45 AM.



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