One more differental topic!

[jakemeister]

I have the AAM 11. 5 rear diff in my 2003, 3500 dually beloved 4x4 cummins. (did I mention how much I love this truck?)



I heard this rear end has a re-usable gasket. . and does NOT require silicon sealant



Can anyone confirm or deny this great rumor if its true?



P. S. If anyone cares I finally got EGT and Boost guages:Oo.

 

[Bertram65]

True, the gasket is reusable I have had mine off twice, no leaks. You do not need any type of sealant when you put the cover back on.

 

[jakemeister]

Thanks for the speedy reply. . do you know the torque specs on the diff cover bolts?

 

[bcpalmer]

Cover bolt torque

30 ft. lbs.

 

[Bertram65]

Be carefull using that much torque, a couple guys have snapped off the bolts. I would just use a 3/8" socket wrench and use your best judgement when tightening them.

 

[rbattelle]

Originally posted by Bertram65

Be carefull using that much torque, a couple guys have snapped off the bolts. I would just use a 3/8" socket wrench and use your best judgement when tightening them.

Just changed my fluid this past weekend, and torqued them until I felt they were "snug". No leaks. I also recommend lubricating the o-ring with some oil before reinstalling the cover.

 

[Hawkeye 04]

P. S. If anyone cares I finally got EGT and Boost guages:Oo. [/B][/QUOTE]





I care!!!! I'm jealous!! I'm almost at the breaking point... just need to pay off one more thing then it will be bombs away!

 

[jakemeister]

Lube the o'ring? Is the o'ring the diff gasket?



Also when you guys changed your diff fluid did you siphon it out or pull the cover?



If you pull the cover is there any recommendations for cleaning out the diff with blake cleaner, carb cleaner, no cleaner just a wipe will do?



Is the front gasket (o'ring?)re-usable like the rear?



Hawkeye: I must warn you, having guages is dangerous for other drivers... you will find youself staring in awe :--) and drooling at them while driving causing some slight changes in driving characteristics and endangering oncoming import trucks that wish they were as cool as ours... me thinks

 

[rbattelle]

I guess by "o-ring" I mean "gasket". It really is a gasket, but since it's rubber I have a tendency to refer to it as an o-ring.



Anyway, in my opinion you should apply some gear lube to the gasket before re-assembly. Just like you do to an oil filter before installing it to prevent it from getting mangled. This is just my opinion.



I "clean" my diff out by just wiping it with a couple paper towels. Some people go so far as to jack up each axle tube individually to drain out the oil still in the tubes. I don't bother: I figure with a 15000 mile interval it's getting changed so often that it doesn't matter the 10% old stuff that might remain.



The front gasket is also reusable.

 

[llotton]

Diff cover torque

According to the instructions that came with my diff cover the bolts should be torqued to 12-16 ft. lbs. Larry

 

[Prairie Dog]

The bolts bottom out when their tight enough - you'll feel it.

 

[Bertram65]

The bolts do not bottom out, I had thought that as well as I read it on one of the forums. I removed the cover and tested screwing in one of the bolts, it will go all the way in without the cover. I would also use blue Loctite, there is thread lock on factory bolts.

 

[jakemeister]

Well, I finally did it... It wasnt to bad... I went and got one of those guns that sucks the fluid out of the oil bottles for $10 at auto zone to squirt it in the diffs. ,,,the rear AAM 11. 5 used 4 quarts of mobile1 75w-140 synthetic and the front AAM 9. 25 used 3 quarts of mobile1 75w-140 synthetic. And the gaskets front and rear were reusable.



thanks to all for the info... it was definatly useful



For those that havent done it heres what it cost



7 quarts Mobil175w-150 synthetic $115 give or take with tax

1 oil suction gun $10 bucks

total $125



the stealership was going to charge me $145 each diff for synthetic



Im sure someone is going to say that 75w-140 for the front is overkill or to thick but i Tow extremely heavy and synthetic oil is not thick.

 

[Bertram65]

I have never seen it mentioned in any of the AA documentation to use 75/140. I would stick with what is reconmended myself, 75/90. There may be a reason not to use 75/140 in the AA diffs.

 

[jakemeister]

thats odd... the tech at the stealership told me when they were going to change my fluids they were going to use 75w-140 synthetic since i tow alot.



who knows... . I guess i will find out sooner or later if its bad for my diffs on my 3000 mile trip here in 2 weeks.

 

[rbattelle]

thats odd... the tech at the stealership told me when they were going to change my fluids they were going to use 75w-140 synthetic since i tow alot.



who knows... . I guess i will find out sooner or later if its bad for my diffs on my 3000 mile trip here in 2 weeks.

Most dealers don't have a clue about these sort of things. (note: I said most, not all).

 

[RGardner]

Can anyone tell me what the problem using synthetic 75-140 is?

 

[WNowlan]

The 75W140 gives you better high tempetature protection. It is perfectly acceptable to use. I would highly recommend if you are towing.



I have over 20 years in the lubes industry. I have worked closely with the Class 6-8 trucks for the last 16 years.

 

[Bertram65]

It's a different weight oil, a number of people have had problems with the AA rear ends, Dodge says to use 75/90, if they reconmend 75/140 for heavy towing than use it but I do not think have reconmended that. Seeing as they hold the warrantee I would stick with thier guildlines.

 

[rbattelle]

The 75W140 gives you better high tempetature protection. It is perfectly acceptable to use. I would highly recommend if you are towing.



I have over 20 years in the lubes industry. I have worked closely with the Class 6-8 trucks for the last 16 years.

Why would AAM specify an inappropriate oil for use in their differentials? Is it normal for lubrication engineers to dictate to mechanical engineers which lubricant they need to use for an assembly (from your statement I assume you are a mechanical engineer with a background in lubricating oils)? I am asking out of genuine ignorance, not to be a smarta$$.