Anyone experienced this?

Had (front AND) rear pinion seal and fluid replaced a couple of days ago due to seal leaks. Discovered after about a 700 mile trip. Got some diesel today, put the truck in drive and eased off the brake and the truck came to a stop within 2 feet or so. Felt like I ran he frame up on a manhole cover or something. It was like there was some sort of driveshaft or transfer case binding. I backed up a few feet and had my son put truck in drive and ease forward (no throttle), stopped for him too. Pretty worried so I had him put it in park. I then put the transfer in 4WD, backed up then forward about 10 feet and seemed OK. I have heard a slight whine from rear end over the past few days or so. I am wondering if the diffs ran low on oil due to their seal leaks or if I have another problem. Has anyone ever heard of anything like this? Any 3500 SRW 4WD AAM diffs problems out there? Just hit 10K miles. Thanks for any help.

 

Check your driveshaft yoke and see if they left the pinion nut loose. If that isn't the problem maybe they sent it out without any oil in it.

 

Two very possible causes. I thought of the loose yoke myself but said, naah, couldn't have!

 

loctite is seen as "expensive"to some techs... . or even the correct loctite... .

 

Actually it appears they used an impact gun on the pinion nut in lieu of a torque wrench. Trashed the pinion bearings, sent fine metal throughout the rear end. Dealer order all of the bearings and seals. NOW it is in the hands of the guy who should have done the pinion seal in the first place. . We will see what it sounds like Thursday morning. .

 

The pinion overtight (preload) is what first came to my mind as well.

I would be VERY concerned about the race seats now. If the vehicle were driven with the pinion set so tight that it would stop the truck, then a HUGE amount of heat was built up in the pinion supports and very well may have weakened the differential housing in that area.

I would be there to look for blueing (really is a term, the machined area where the bearing races are seated will look blu-ish or like it got VERY hot) and demand a new rear axle if that is the case. The weakening of the pinion support area can wreak all sorts of havoc from bearings and seals not seating properly to eating bearings and leaking forever to catastrophic failure of the housing that could cause a serious or even fatal crash at highway speeds.

Trust me on this, we do about 50 differentials a month at the shop and have seen things that would scare you inside diffs (like the recent customer who kept driving after he exploded an ARB air locker and put a hole through a Dynatrac 60 housing... in the thickest area of the housing near the tube supports!)



Personally, I would NOT settle for simply replacing the bearings and seals. If you have an LSD, then the clutches in there are now impregnated with fine metal grit and will die much sooner than normal service life, the gears will have pits from crushing the filings in between the teeth, causing stress spots, the bearings (all of them) are filled and have been run with filings in them, possibly pitting the rollers.

I would be severely torqued off and demanding a new axle and internals. You are highly unlikey to have escaped this without future issues on their way.



EDIT: I was so mad at the shoddy work that my spelling suffered considerably. Just fixed my spelling.

 

Please tell us the dealer whose service department screwed up your truck!!

 

Yes, please do!



Ryan

 

Got it back tonight. Looks and sounds good. Understand and somewhat agree with the concern over the rear end. I now worry about the front end as well although I drove 700 miles after the front seal change and observed no noise/problems. I only drove the truck about 45 miles after noticing the rear binding problem. I also looked at the entire rear end during and after the disassembly. The bearings only showed slight to moderate race wear although the rear end fluid was obviously carrying metal. I have an extended 100K mile warranty so we will see how it wears. The guy did a great job putting it back together, thoroughly cleaned every conceivable part of the rear carrier and differential housing. The most confusing part of the entire ordeal was the type of rear end lube to use, whether or not I have an limited slip diff. Sticker says I do, there are no clutches that I could see in the rear end. I had them use the Mopar synthetic 75/140 with NO limited slip additive. Sure miss the Dana days. .

 

Right, it's a torsen-type limited slip. There are brake shoes on the pinion gears, no clutches.



You will likely get some other opinions, but I think 75W-90 is a better choice. Look in your owners manual.



Ryan

 

Not gonna take the opportunity to bash the local dealer. They are a good group of guys and have treated me right for years, especially the parts guys. They had a "new guy" in service and I guess he decided to do the seal change by himself rather than ask the lead mechanic or anyone else for advice. I will say that I will only play the nice guy until I have another problem with the rear, then I will get a shiny new unit. . Only 10K miles on the new beast.

 

Was that 45 miles in stop and go, with shut downs (to cool) between jaunts? If it was 45 miles, one start or highway speeds, I'd be VERY involved in looking at it.

On these, is the t-case a full time unit? I didn't think so. So the front won't turn unless engaged. It's worth another trip in to let them check the torque on the pinion nut before you get into something somewhere that tow trucks charge a boatload to come get you from.



Pinion gears? There's only one pinion gear. Are you talking about the side or spider gears... or in the case of a TORque SENsing diff, the helical gears? Torsens dont' use any sort of friction material, but instead rely on pressure against metal gears to operate. Unless DC has really gone wacky and devised their own type of this very old technology... reinventing the wheel, per se.

Reading about the Torsen diff:

http://en.wikipedia.org/wiki/Torsen

 

It's funny, in my opinion the correct terminology is "side gears", but the service manual and most people I've spoken to call them "pinion gears".



In my opinion, there are friction surfaces in a Torsen unit. Something has to enable the friction to react to the transverse loading from the side gears. How do you transfer a force from one component to another without friction? In the case of the AAM11. 5, the surfaces are called brake shoes.



Ryan

 

I agree, that is odd... they actually use the terms Pinion gears and brake shoes. I'd never seen that, but you learn something new every day.

Now I've gotta go crack open my diff (LSD) and investigate!



Typically that friction is actually caused by the binding of the differential when one axle stops or slows down, causing the "gears" to shift into the position that will allow the transfer of force to the other side.

I'm going to have to seriously investigate this differential, as it just looks ODD to me. The images above don't illustrate how this differential applies the force from one side to the other. And it does look like DC reinvented the wheel, so to speak.

Anyone know who's manufacturing the LSD for these trucks?

 

DesertFab. The diffs are made by American Axle & Manufacturing, aka AAM. http://www.aam.com. I drove 15 miles 3 times to get the 45 miles discussed above.



Update. The next morning I heard some serious gear whine after the rear end rebuild. It was 30 degrees colder that morning. Went by the dealer and drove with the lead mechanic, he said leave it there. I opted to keep the truck through the weekend and put about 225 miles on it. They checked it out this past Monday am, called me and said the FRONT was a mess. They opened the pan and metal chunks came out. Looks like I either lost enough oil to ruin the pinion gear carrier bearings from the original oil leak or the dealer who did the front seal replacement over tightened that pinion nut. Either way, entire guts of the front now being replaced including ring and pinion assy. They said that they could easily move the pinion input shaft prior to dissasembly. Kinda scary.



To clarify, I sprang an oil leak first on the front end, had it replaced in Virginia during a road trip. Drove back to Georgia and discovered the REAR leak on the way home. Took to the Georgia (local) dealer for the rear seal fix, then noted the binding problem the next day after REAR seal as replaced. Looks like the rear might have not been a problem although we heard a slight whine on the rack from the rear after I complained about a slight noise and the binding issue stated above. GA dealer rebuilt the rear end and the next day I heard the much louder noises in the cold weather. I assumed the noise was from the newly rebuilt rear. Wrong. It was the front (now or the entire time). I put almost 1000 miles on the front end seal change before local dealer opened it up and discovered it to be the source of the original binding and increasing whurr and grinding noises. Word of caution. Do not take any differential leaks lightly on the new trucks (AAM axles) and make SURE the mechanic doing the work gets the entire picture, especially on the pinion shaft nut torque specs, back spacing, etc. I would strongly recommend they remove the cover and fully inspect the innards vs changing the seal and topping off the lube which was the case for both my front and rear leak. .

 

Hi, raf2000,



Hello from one formerly from Waycross. I moved up north a couple of hundred miles a couple of months ago, but the local dealer there in Waycross always did right by me.