11.5 Inch rear end seal replacment went bad. Need Advice

Fllamb · February 27, 2017

I had a friend do a rear end pinion seal replacement on my 2001 2500 HD with 11.5 inch rear end. After a trip I noticed a pretty good gear oil leak coming out of the pinon seal. No noise from the rear end at all tho, all sounded good so I am assuming everything was good inside. I don't have the place or the tools to do this my self anymore so I had a friend do it. After the work was done there was a VERY noticeable whine from it when decelerating. Upon closer inspection I see noticeable play in the pinion, at least 1/8 inch when I push and pull on the yoke. There are no marks on the nut or pinon where one would expect to see them if you were marking them for reassembly. I took into the Chevy place and they are telling me it needs to be rebuilt to the tune of $1200 and and are recommending replacing the ring and pinion while I'm at it since it will all be apart. So now I need to know what my options are. Any suggestions are very much welcome. Can I just wrench down on the yoke nut until I get no play and noise when driving and hope for the best or is that a bad idea?Thanks!!

Edited February 27, 2017 by Fllamb

Formulabruce · February 28, 2017

Work probably wasnt done as you need the nut back on at same location, ran low on fluid, it Might be ok with bearings and seals, but could be cheaper to grab a rear axle . many yards have them, but who knows where you are.. I use JUSTCHEVYTRUCKS.COM

Yours is a DRUM brake rear axle? or the Disc?

Fllamb · February 28, 2017

Disk brakes.

sdeeter19555 · February 28, 2017

Always install a new pinion nut, once installed, they lose their crimp and will NOT hold. Been there, done that...ironically it was a dealer that did it.

If the nut came loose, you may get a few more miles out of it with a new nut, but the bearings will have damage and it'll fail sooner than later. Again, been there done that...that was a 9.25" Dodge Corporate.

As far as running it out of oil, a little gear oil looks like the Valdez ran aground. The 11.5AAM in my Dodge had a leaking pinion seal (for no reason) and it looked like gallons of oil had leaked under the truck (I was 2000 miles away from home adding to the stress), pull the plug and it was down a 1/4". If it had any oil in it, it's probably fine...it would have to spin the races in the casting to be beyond rebuilding.

I would have it rebuilt if it was me...but it will take new bearings, seals, and gears.

As I eluded to, my 11.5AAM had a leaking pinion seal, and new seals would just leak. I replaced the yoke, and it still leaked. I ran it like that for probably 50k miles and one day it just quit...no rhyme or reason.

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Formulabruce · March 1, 2017

I always use thread locker on the final nut torque, but a new nut is Great if you can get one readily

sdeeter19555 · March 3, 2017

I did the lock-tite route once, the key is to leave it sit long enough for the thread locker to cure...

Funny part about the nut that I encountered is that it isn't something typically stocked on hand...you can get seals all day long from a dealer, but no nut.

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Fllamb · March 19, 2017

Thanks all. I had the local Chevy place (Paul Thigpen) "rebuild" the rear end per their recommendation. They said the ring and pinion were ok. They said they replaced bearing and seals. $1400.00..... Sounded really high to me but what do you if you don't have the equipment or place. The rear end is quiet again but it still appears to have a minor leak........ Does anyone know how to do a job right???? Just aggravated.

Edited March 19, 2017 by Fllamb

AaronM · November 12, 2019

I had the issue of replacing 3 pinion seals from three different manufactures all in a week on these AAM 11.5 rear axles. All three Leaked as soon as they were installed…….. after further research I found that the oem seal from the parts stores does not fit the oem yoke correctly and it leaves a 16th to 8th inch gap between the stock oem yoke shaft and the supposed oem replacement seal. you have to either replace the yoke when doing the seal or get a shaft sleeve to solve the leak.

vucelick · November 15, 2019

Gear lube will leak past the splines. Most people put a 1/2" bead of silicone on the tip in the pinion splines. When you slide the yoke on it will distribute the RTV down the splines. Or you can RTV the back of the pinion washer/nut. I do both. Be careful to seal the splines, but not smear RTV down into the gear lube portion of the case.