Loud Rear End after Redline???

[wolfman00hd]

After having my rig up on the lift last week to put my MEP and new tip (thanks Rip) on, I was reminded of the piddle that has been coming from my rear diff seal and decided that since I was approaching 33k, it was time for a fluid change anyway. So..... took her to the dealer yesterday for the seal change under warranty and asked them to change the fluid while they had her and put in the Redline that I had bought. $77 for one hour of labor to drain/refill fluid??? Sounded a little high but what the heck, it was the cleanest fluid change I had ever done <grin>.



Picked her up from the dealer yesterday afternoon and watched the porter? go hop in, fire it up instantly and run it up to me like he was doing a quarter mile pass . I fought the urge to hang my foot in his *** and politely asked him if he drover all customers' trucks like that and he just looked at me like I had just asked him to explain the theory of relativity to me



Anywho, looks like they only put just shy of 4 qts. in for the fluid change. I thought it held almost five??? Also, it now seems that I can hear a whine or growl from the rear end on deceleration w/no pedal? I don't know if I am imagining this or not. Would the "slipperyness" of the new Redline be causing this? I DO NOT want to trash a rear end anytime soon. Especially since I'm approaching 36k.



Thoughts / suggestions / ideas???



Wolfman

 

[TowPro]

When they replaced the pinion seal they have to remove the front yoke which has a real large nut holding it on. Not 100% sure about the AAM rear, but most rears this nut is also used to crush a collar that is used to adjust the pinion depth



We used to "count turns" back in the old days when we took the nut off so we got it back into the same spot. If you run the nut on with an impact gun you can compress this collar some which moves the pinion gear away from the ring gear changing the gear depth.



Somebody with more knowledge of this new AAM axle should chimb in here.

 

[Nate]

The crush collar adjust the pinion bearing preload, not pinion depth. That's adjusted with shims. I'm not sure if the AAM axles use them. I'm more familar with Dana axles.



If you tightened it too much, you'd burn up the bearings.

 

[KevinWatts]

Nate's right, it would not be the pinion depth that was changed, but the pinion bearing preload.





http://www.ring-pinion.com/content/technicalhelp/default.asp?pid=109



"Several situations can create ring-and-pinion noise. If the gears have been quiet and begin to howl, they are probably worn or wearing. If the gears howl during deceleration only, it's possible that the pinion-bearing preload has loosened. Howling under acceleration at all speeds indicates that something in the differential -- gears, pinion or carrier bearings -- has worn or no longer keeps the gear alignment correct. If the gears howl ... "



Sounds like they're going to have to dump your new gear lube and check the pinion preload.

 

[wolfman00hd]

Is the rear end and its components covered under the 100k powertrain warranty or just the 36k bumper to bumper? I only have whatever warranty came from DC, nothing extended. I thought the seal replacement would have just been to pull the old one out and drive the new one in???



Wolfman

 

[KevinWatts]

To replace the seal you have to pull the yoke. Once the new seal is in you can usually just put the yoke back on, and tighten it back down with an impact (but not too tight). The problem is that there is a crushable metal collar between the two pinion bearings. This keeps the correct distance between the bearings so they don't get destroyed (crush the sleeve too much and the bearings are too tight, don't get it crushed enough and there will be slop between the bearings. ) So if it's too loose they can just tighten it up some more. If it's too tight they'll have to pull the whole rearend apart and start with a new crush sleeve.



I'm not sure about the warranty, but they'd have a hard time arguing that the pinion gear isn't a part of the powertrain...

 

[TowPro]

Thanks guys, I stand corrected (its been a long time since I had a rear apart).



so its possable they did not tighten the yoke nut all the way causing the bearing preload to be loose, causing a noise while slowing down.

 

[KevinWatts]

Yes, and it wouldn't be all that hard to do. If you've never set up a crush sleeve you may worry about overtorquing it, when actually it takes over 400 ft/lbs to crush them (sometimes alot more). At the same time you're tightening a lock nut, that's pushing a semi press fit yoke and a press fit bearing. The best way after changing a seal is to just torque the pinion nut to around 150 ft/lbs.

 

[Got HO?]

Get ready for a replacement differential assembly if you are hearing pinion bearing noise or gear whine caused by a floating pinion. My local dealer replaced my pinion seal twice, got the preload wrong & the pinion bearings collapsed. They "rebuilt" the diff very unsatisfactorily (noisy afterwards & left a bunch of stuff loose & not connected, minor things like parking brake cable mounts, brake lines kinked & not secured & LOTS of ugly orange shmoo around the diff cover)

After my blood pressure came down to about 160/250, I took photos & e-mailed them to the service writer, the owner of the dealership & to DC.



I got a completely new diff & brake lines etc the following week... ... ... ... .....

 

[DPKetchum]

The correct way by the book is to disassemble the pinion,new crush sleeve with preload etc. on this type axel. Many mark the thread or count them and just put the nut back to the original spot. Your is NOT back where it moved from. I've been in this pickle before and managed to snug it up a bit more and noise went away and all was well. Usually EXPERIENCED techs DON"T have this happen tho it could. They need to tightened it a hair more and test drive it.

 

[RPolidora]

This is going to make more me more paranoid than I already am. I just had the front one done yesterday and my biggest fear is that the bearing preload wouldn't be right. I almost just did it myself but I decided to let them fix it under warranty. The tech that always works on my truck really is good and he knows diesels so I trust that he did it right. He told me he was going to mark the nut and tighten back to that same spot and then just like a 1/16 of a turn more. I keep thinking I am hearing a little growling but I have a tendancy to make myself hear things I am worried about. I am pretty sure it is good to go but some of these guys really don't have a clue. the leak is gone for now so I am hoping it stays that way.

 

[TowPro]

Wonder why DC can't get the pinion seals to quit leaking? My 98 had 2 done, I have heard many other 2nd gen guys getting them replaced. I have not looked at my 02, but there is no drips on the garage floor. Now the 3rd gen's are doing it. Do Chevy and ford have this problem?

 

[DPKetchum]

The way I did them customer pay was TWO options. The BIG price(puilling the rear apart etc. OR the cheaper no warranty option. Customers ALWAYS went for the cheaper way. Once YEARS ago had a Nissan RWD wagon come back sounding like a COP siren when slowing. Made a ADJUSTMENT and all was well. Saw that same vehicle for a few years after and no problems.

 

[wolfman00hd]

2nd Dealer visit follow-up

Well, got a call back from the NEW svc. manager at the dealer early this week and explained my complaints from my original post. He was very accomodating and got me back in there today. Here's the results:



1 - Bearing -Drive Pinion

1 - Bearing - Drive Pinion??

1 - Spacer - Drive Pinion Bearing

1 - Seal - Drive Pinion

4 - Mopar Synth. Lubricant :{

1 - Gasket - Axle Shaft



Replaced inner and outer rear axle pinion bearings and pinion seal. I was told the visit last week resulted in the pinion nut not being torqued down tight enough so they "allegedly" replaced the whole shooting match.



Much to my dismay, away went my 4 qts. of Redline that was one week old. <grrrrrr> Did get a voucher for a free diff fluid change next time it's due. They satisfied me I suppose. I'll be listening extra close for noise now though.



Anyone need one full quart of Redline rear diff fluid???