Diff. Oil
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Diff. Oil
Well as most of you have heard my 
about installing my 3rd D44. I put the sealer on it yesterday, let it dry and im ready to add oil. On my first one I used 1 bottle of additive and mobil 1 75-90 oil. The second one I used 2 bottles of additive and mobil oil.
This may be grasping at straws, but is any chance the 75-90 is causing any problems? The factory fill is 80-90.
I just want to know if there is any better lubricant then the mobil oil.
about installing my 3rd D44. I put the sealer on it yesterday, let it dry and im ready to add oil. On my first one I used 1 bottle of additive and mobil 1 75-90 oil. The second one I used 2 bottles of additive and mobil oil. This may be grasping at straws, but is any chance the 75-90 is causing any problems? The factory fill is 80-90.
I just want to know if there is any better lubricant then the mobil oil.
Safety Car
Joined: Jun 2006
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From: FL
Looking at the earlier posts I'd say changing lubricant has little chance of helping. If you were experiencing bearing failure or the gears were getting noisy lubricant might be a factor. Actual gear failure is probably caused by type of operation. Just my take of course, if you find the majic formula let the rest of us know! 
Team Owner
Joined: Oct 2000
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From: Fort Knox, KY
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I think the Mobil 1 75/90 weight synthetic gear oil has superior properties than the dino-based lube, but I think the root of your problem occurred before the diff service.
Gordon Killebrew (C4 guru) said add the GM rear axle additive so I did.
Gordon Killebrew (C4 guru) said add the GM rear axle additive so I did.
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,713
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From: Manassas VA
Originally Posted by toptechx6
Looking at the earlier posts I'd say changing lubricant has little chance of helping. If you were experiencing bearing failure or the gears were getting noisy lubricant might be a factor. Actual gear failure is probably caused by type of operation. Just my take of course, if you find the majic formula let the rest of us know!
Actually both of the previous rears were noisey. I blamed that on the richmond gears. Both diffs. came from forum members, but neither did the actual rebuild, someone else did it for them. I hold out a little slim hope that maybe something was not done exactly right in those two.
My car is a automatic, slack on the launch dosnt happen. One thing I am going to watch for is to make sure both tires are wet when burning out.
I wish I had the majic formula, thats probably going to be a solid diff.
But thanks for your input!!
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by vetteblack
I changed my fluid with the penzoil 80-90. The back of the bottle reads, limited slip additive is not needed, nor is it recommended.
If the bottle says don't add, I don't add.
If the bottle says don't add, I don't add.
Thats a good point. I went to mobils web site and here is a quote from the oil brochure.
Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid.
I will look at the penzoil exspecially since it is 80-90 and not 75-90.
I feel sure it will not make a difference, but at this point im trying anything.
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by onedef92
I think the Mobil 1 75/90 weight synthetic gear oil has superior properties than the dino-based lube, but I think the root of your problem occurred before the diff service.
Gordon Killebrew (C4 guru) said add the GM rear axle additive so I did.
Gordon Killebrew (C4 guru) said add the GM rear axle additive so I did.
Yes, consistant drag runs do damage. That I am pretty sure of. And I dont think it has to be 1.30-1.50 runs either. I have never got below a 1.65 60ft. Mostly low 1.70's. But I do have around 200 of those on this last diff. set.
Well I feel very confident that this one is setup correctly and all parts are in good shape so we will see what happens.
Again thanks to everyone for your input.
Le Mans Master
Joined: Feb 1999
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From: South Carolina
St. Jude Donor '03 & '05
When I did my 3 D36's and my now D44 I used Mobil 1 and I had to add one bottle after the fact. I dont know why but I got the little chatter noise. My Diff's were done by the same person, IKERDS.
Now, if you keep breaking parts, in a auto D44 I would look into other things that could be putting undo stress on the diff, ie half shafts, driveshaft. Is it possible they are misaligned and causing added stress. I am no alignement rearend etc expert, but my D44 has been through some abuse with my auto 396lt1 and I havent had any problem other than a leak.
Now, if you keep breaking parts, in a auto D44 I would look into other things that could be putting undo stress on the diff, ie half shafts, driveshaft. Is it possible they are misaligned and causing added stress. I am no alignement rearend etc expert, but my D44 has been through some abuse with my auto 396lt1 and I havent had any problem other than a leak.
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Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Originally Posted by 93 ragtop
Actually both of the previous rears were noisey. I blamed that on the richmond gears. Both diffs. came from forum members, but neither did the actual rebuild, someone else did it for them. I hold out a little slim hope that maybe something was not done exactly right in those two.
My car is a automatic, slack on the launch dosnt happen. One thing I am going to watch for is to make sure both tires are wet when burning out.
I wish I had the majic formula, thats probably going to be a solid diff.
But thanks for your input!!
My car is a automatic, slack on the launch dosnt happen. One thing I am going to watch for is to make sure both tires are wet when burning out.
I wish I had the majic formula, thats probably going to be a solid diff.
But thanks for your input!!
I find it interesting that GM specified no specific maintenance interval for the rear end while Chrysler suggests changing the lubricant between 18 and 22 thousand miles on Viper with the same Dana 44 axle.
Difficult to relate to mileage but 200 drag runs is a lot of abuse, sure wouldn't hurt to change the lubricant once in awhile either, just a suggestion, best of luck with the latest set.
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by steve40th
When I did my 3 D36's and my now D44 I used Mobil 1 and I had to add one bottle after the fact. I dont know why but I got the little chatter noise. My Diff's were done by the same person, IKERDS.
Now, if you keep breaking parts, in a auto D44 I would look into other things that could be putting undo stress on the diff, ie half shafts, driveshaft. Is it possible they are misaligned and causing added stress. I am no alignement rearend etc expert, but my D44 has been through some abuse with my auto 396lt1 and I havent had any problem other than a leak.
Now, if you keep breaking parts, in a auto D44 I would look into other things that could be putting undo stress on the diff, ie half shafts, driveshaft. Is it possible they are misaligned and causing added stress. I am no alignement rearend etc expert, but my D44 has been through some abuse with my auto 396lt1 and I havent had any problem other than a leak.
Steve, It seems that other then the pinion tooth breaking this time, it has been wear out. IE. first one, the pin seized and broke. The second one, the axle gears had worn into the case and clutches. I was told to make absolutely sure both tires were wet before doing a burnout. That will take out the clutch packs and side gears. As far as I can tell, the driveshaft and axles are fine. Heck Im still using the greasable brute force u-joints I put in when I purchased the car.
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by toptechx6
If your previous gear sets were noisy from the get go that would be caused by the gears themselves or the set up. I've heard the same story regarding Richmond gears but have no first hand knowledge. If the noise developed over time that could be caused by poor or deteriorated lubricant.
I find it interesting that GM specified no specific maintenance interval for the rear end while Chrysler suggests changing the lubricant between 18 and 22 thousand miles on Viper with the same Dana 44 axle.
Difficult to relate to mileage but 200 drag runs is a lot of abuse, sure wouldn't hurt to change the lubricant once in awhile either, just a suggestion, best of luck with the latest set.
I find it interesting that GM specified no specific maintenance interval for the rear end while Chrysler suggests changing the lubricant between 18 and 22 thousand miles on Viper with the same Dana 44 axle.
Difficult to relate to mileage but 200 drag runs is a lot of abuse, sure wouldn't hurt to change the lubricant once in awhile either, just a suggestion, best of luck with the latest set.
On this carrier, we drilled a small hole into the lower bolt hole. That way I can remove the bottom bolt and drain it. I plan on doing that often.