[bob prichard]

I am on my second set of US Gear gears that have started making noise after a few hundred miles. They were installed by two different companies that I thought were competent, but don’t know now. I had the current set of noisy gears looked at by another installer who says he thinks last guy put them in too tight, but after driving the car said he did not think he could get a new set of aftermarket gears to be much quieter, but also said mine were turning blue and to avoid long trips.

I have read in these forums that the early 8.2 gray cast pumpkins can have internal problems, so I am wondering if that is my issue? I hate to give up on my original diff, but think maybe it's time for a 12 bolt, since I’m running a 461 anyway. I did have Moser make me some axles for the 8.2, so it is strong there, just tired of noisy gears. I do have a 65 Chevelle 12 bolt housing with very nice used OEM 3.31 gears on hand, or could buy complete assembly from Moser, but they also use aftermarket gears and told me over the phone they can be noisy. I know this has been discussed before, but would appreciate any insights from those who have been down this road before. Thank you in advance.

[5th TA]

The twelve bolt is certainly a stronger differential, it it sounds like your main complaint is about noise, not strength or durability. I would have gone back to the installers and asked them to make it right. At least figure out why the gear sets start out quiet and then get noisy.

No doubt the 461 is putting out a lot more torque than the original 389. If the car is raced on the strip with slicks, the twelve bolt is the way to go. If this is a cruiser driven on the street and it’s important to you to have the original housing then you might want to get the ten bolt shorted out.

Just a little FYI, back in 1972 a friend had a 1970 Judge with RA III, four speed and factory 433 axel ratio. He went through three ring and pinion sets tying to race at the strip with slicks. The first gear set was setup was as came from the factory, the two replacements were done by the local Pontiac dealer. In 1971 I owned a 65 GTO convertible with only a two speed turbo 300 transmission. On the street it blew one of the spider gears right through the side of the differential housing. I replaced the failed differential with a twelve bolt junk yard unit out of a Chevelle. Because the twelve bolt had larger universal joints and yoke, I had to get my driveshaft modified to accept the larger unjoint.

[bob prichard]

Originally Posted by 5th TA

The twelve bolt is certainly a stronger differential, it it sounds like your main complaint is about noise, not strength or durability. I would have gone back to the installers and asked them to make it right. At least figure out why the gear sets start out quiet and then get noisy.

No doubt the 461 is putting out a lot more torque than the original 389. If the car is raced on the strip with slicks, the twelve bolt is the way to go. If this is a cruiser driven on the street and it’s important to you to have the original housing then you might want to get the ten bolt shorted out.

Just a little FYI, back in 1972 a friend had a 1970 Judge with RA III, four speed and factory 433 axel ratio. He went through three ring and pinion sets tying to race at the strip with slicks. The first gear set was setup was as came from the factory, the two replacements were done by the local Pontiac dealer. In 1971 I owned a 65 GTO convertible with only a two speed turbo 300 transmission. On the street it blew one of the spider gears right through the side of the differential housing. I replaced the failed differential with a twelve bolt junk yard unit out of a Chevelle. Because the twelve bolt had larger universal joints and yoke, I had to get my driveshaft modified to accept the larger unjoint.

I took it back to the first installer, a once well respected rearend specialist who said he couldn’t get good help anymore, whose solution was to tighten up the pinion nut and tack weld it so it wouldn’t come loose. I moved out of the area shortly after that. The second installer pulled the cover, said he didn’t see anything wrong blaming aftermarket gears, and charged me for an oil change. Yes, I fully expect to have to modify my driveshaft which is an aftermarket aluminum unit, so my original will be untouched. I have saved all my old parts, including the 389 and Muncie. I don’t plan on doing much if any racing, but do like standing on it often. Thanks for your response.

[Tom Vaught]

"Standing On It Often" is basically saying you "Have pulled the Pin" on your 8.2 10 bolt rear axle. I just a matter of time. At that point you may destroy the gear set, or break the left cap off the cast iron housing or break an axle. Fortunately, the axles are "retained" by bolted plates on your rear axles if you do break an axle so the tire and wheel will not exit the vehicle.

A good swap is installing a later 8.5 rear axle from a later year A-Body. A 9" is the best.
The 12 Bolts, even in bad shape draw Cubic Money these days with OEM or aftermarket
housings and gears. I blew up three 8.2 10 bolt GM rears in the first 3 years I owned my 64 GTO.

Tom V.

[Scott Roberts]

You know, I was always told the 8.2 was a weak rear.. I ran one on the street and track with slicks.. it was a pro auburn unit with Moser axles.. car ran 10.40's @ 3300lbs over a 3 year period..
Not as heavy as a 65 but never had the first problem... maybe I was just lucky..

[Tom Vaught]

Originally Posted by Scott Roberts

You know, I was always told the 8.2 was a weak rear.. I ran one on the street and track with slicks.. it was a pro auburn unit with Moser axles.. car ran 10.40's @ 3300lbs over a 3 year period..
Not as heavy as a 65 but never had the first problem... maybe I was just lucky..

Have to smile at your post Scott.

A Pro Auburn 8.2 rear with Moser axles is not a factory rear, It is better than
the factory offered Service Package GM 12 Bolt Rear Parts.

So apples to oranges in your example, Scott, BUT if a Guy put "a pro auburn unit with Moser axles", under his car I would expect the same results you had.

Tom V.

[Scott Roberts]

Originally Posted by Tom Vaught

Have to smile at your post Scott.

A Pro Auburn 8.2 rear with Moser axles is not a factory rear, It is better than
the factory offered Service Package GM 12 Bolt Rear Parts.

So apples to oranges in your example, Scott, BUT if a Guy put "a pro auburn unit with Moser axles", under his car I would expect the same results you had.

Tom V.

My point was people always said don't bother with the little 8.2.. it was more cost effective to change the carrier and axles that find another rear and swap that out then have to replace parts in that..
He was asking about upgrading axles, why not toss in a Eaton or Auburn unit, axles and he's good.

[NeighborsComplaint]

I had an 8.2 behind my 455 for over 30 years. It had 4.56 gears and I ran it until the posi gave up around 2015. I swapped in an earlier model 8.2 I bought from a forumite who claimed it was rebuilt, but it wasn't. I had it rebuilt with all new bearings and glass beaded the OEM 3.55 gears. My personal experience is if you exercise some common sense (like not doing burnouts on a street full of pot holes) as long as you are running street tires, you won't overstress the 8.2 diff.

[bob prichard]

Originally Posted by Scott Roberts

My point was people always said don't bother with the little 8.2.. it was more cost effective to change the carrier and axles that find another rear and swap that out then have to replace parts in that..
He was asking about upgrading axles, why not toss in a Eaton or Auburn unit, axles and he's good.

I do have Moser axles and a TA girdle, running on 8” rims with 2.55x15 radial TAs. I had them made five years ago as Moser didn’t make the 8.2 axles until I sent them my OEM axles for them to copy. My concern is the ring and pinion keep getting noisy and I am wondering if my pumpkin is allowing the gears to go out of adjustment after new gears are put in, Thanks.

[25stevem]

I have heard stories long ago that the ductile iron pumpkin in these factory items can bend / shift / twist ever so slightly at times and then no one can ever get the set up right.
It’s toast!

[blueghoast]

Sounds to me like there just not doing the job right, As far as getting
things tight as it should be?

GT

[Jay S]

Did you ever run it with the OEM gears, if so did those have issues? Where they quiet? Or are the noise issues just after the new gears were installed?

[b-man]

Quit while you’re ahead and swap in the 12-bolt with the GM 3.31 gears. Upgrade it with the aftermarket differential of your choice along with some good axles and be done with it.

Better yet you could probably sell that Chevelle 12-bolt housing for enough to purchase a new stronger aftermarket housing in the width of your choice and have money left over.

I’m guessing the new housing would have bolt in axles, bonus not having to deal with leakage from C-clip eliminators used on stock axle housings. Have it built up locally at a shop you can hopefully trust using the GM 3.31 gears if they turn out to be in nice shape.

The biggest issue with the 8.2 is lack of pinion support and the grey iron axle housing that 99.999% of them have that flexes and allows the pinion to climb the ring gear.

The corporate 8.5 10-bolts that superseded the 8.2 all had nodular iron housings and used the same pinion bearings as the 12-bolt for excellent pinion support.

Honestly I wouldn’t spend another penny on that 8.2 rear. Stow it away if it’s the original and include it with the car if you ever decide to sell it.

[Skip Fix]

When I was racing NMCA years ago with my TA John McWhirter one of Comp Cams oriignal owners had a '66 442 TriPower stick car in the same class. It had been a race car for decades. He had most of us covered in the class BUT you never knew when his rear would break. I think he finally started having the gear re heat treated and having better luck with his 8.2.

I think B-man has the right idea!

[carcrazy]

Quite frankly I've never had much luck with 8.2 rears. Racing always managed to scatter them for me...even on street tires. I'll never put money in one again...switch to the 8.5, 9" or 12 bolt.

[bob prichard]

Originally Posted by Jay S

Did you ever run it with the OEM gears, if so did those have issues? Where they quiet? Or are the noise issues just after the new gears were installed?

Yes, the OEM gears were quiet. Good point.

[bob prichard]

Originally Posted by b-man

Quit while you’re ahead and swap in the 12-bolt with the GM 3.31 gears. Upgrade it with the aftermarket differential of your choice along with some good axles and be done with it.

Better yet you could probably sell that Chevelle 12-bolt housing for enough to purchase a new stronger aftermarket housing in the width of your choice and have money left over.

I’m guessing the new housing would have bolt in axles, bonus not having to deal with leakage from C-clip eliminators used on stock axle housings. Have it built up locally at a shop you can hopefully trust using the GM 3.31 gears if they turn out to be in nice shape.

The biggest issue with the 8.2 is lack of pinion support and the grey iron axle housing that 99.999% of them have that flexes and allows the pinion to climb the ring gear.

The corporate 8.5 10-bolts that superseded the 8.2 all had nodular iron housings and used the same pinion bearings as the 12-bolt for excellent pinion support.

Honestly I wouldn’t spend another penny on that 8.2 rear. Stow it away if it’s the original and include it with the car if you ever decide to sell it.

I will have to look into the 12 bolt with bolt in axles. I thought the c clip eliminators leaked, from what I read. I think the ready built Moser axle would be more expensive than my building the 65 Chevelle axle when I do the math.

[b-man]

Pretty sure you can put different housing ends on your current 12-bolt housing to eliminate the leak prone C-clip eliminators. Talk with some rear end builders and they should be able to tell you what your options are if you’re determined to use it.

I have a 71-72 Olds/Buick 8.5 corporate 10-bolt rear that has tapered axle bearings and bolt in axles, most versions of the 8.5 have C-clip axles. I had it built with an Eaton 30-spline posi and Moser axles. It’s a strong enough rear end for my purposes (430 hp 6.2 LS3) but thinking back I should have just spent the extra money for a brand new 12-bolt instead.

In the long run buying a complete new aftermarket rear with a stronger housing and all the modern upgrades is the best way to go. Trying to build up your current Chevelle rear might end up costing almost as much. Right now you don’t even know if that old housing needs to be straightened which isn’t uncommon, a possible added expense to consider.

Spend the extra money to do it right and know that you’re able to drive it hard without worrying.

[lust4speed]

Have told my friend for over a dozen years he's going to scatter the original 10-bolt 2-pinion original posi rear with no work done to it. Sooner or later we have to be right, but so far it's proven us wrong. Running low 11:20's.

[25stevem]

The life span of a 8.2” posi rear has to be judged in two categories and both of them assuming a 3400 lb car running slicks and producing better then 1.6 short times.

1) beat on by a auto trans.

2) beat on by a manual trans.