Rear axle wear pattern

[Casey Balvert]

I have been complaining to the dealer about a slight whine around 50 mph on slight acceleration. This started around 8,000 miles. I changed out the rear axle fluid at 4,000 miles using the DC stuff specifically made for the AAM axles. Yesterday with just under 12,000 miles on the truck I changed the oil again before we head south. In my opinion the fluid had the consistency of water, grey water. Very thin. Anyway, it was my intention to go with Redline 75W140 this time. There were no chips in the old oil or on the bottom of the housing and the oil smelled fine. There was some grey paste on the plug magnet. I inspected the teeth of the ring gear and noted that the pattern on the acceleration side goes all the way from the heel to the toe and appears to have scoring marks running from heal to toe. It has been a LONG while since I have done any ring and pinion work but it seems to me that the wear pattern should be smooth and long egg shaped positioned about the center of the teeth. I will go back to the dealer after my trip south but I would appreciate the opinions of anyone out there with rear axle experience. Have a great weekend.



Casey

 

[mr plow]

wear patterns...

if my memory serves me, the correct wear pattern is outlined in the service manual. pm me, i'll make u a copy and mail it to you.

 

[KevinWatts]

New gearsets will have the oval shape to them but used gears cover the whole tooth. That is what makes used gearsets a little harder to set up than new.



The scoring doesn't sound good. Once gears are broken in they get a mirror polish to them. Did you do proper break in on them?



I don't mean this about you but, I've read so many people on this board saying to take a new truck and "drive it like you stole it". I wonder how many of those ended up with whining gears?



Kevin

 

[NSperduto]

I don't know about the wear pattern, but both my 04 and my buddies 03 have the same whine at a really light throttle between 65-70 mph. He swears it's the rear. I don't know what it is and I never noticed it (i'm usually listening to the radio) until he said his truck was making noise. Both truck's have 10k on them. He's taking his to the dealer. I'll just leave mine until I see what happens with his. I plan on getting a 100k warranty, so I assume if it's the rear making noise, it will get worse with age.



I keep hearing on here that guys are saying it's the exhaust.



Nick

 

[bighammer]

I just changed my oil and wish I had looked in there before refilling.

 

[Casey Balvert]

Originally posted by KevinWatts

New gearsets will have the oval shape to them but used gears cover the whole tooth. That is what makes used gearsets a little harder to set up than new.



The scoring doesn't sound good. Once gears are broken in they get a mirror polish to them. Did you do proper break in on them?



I don't mean this about you but, I've read so many people on this board saying to take a new truck and "drive it like you stole it". I wonder how many of those ended up with whining gears?



Kevin

Kevin, I broke it in very carefully, putting about 3000 miles on it before I towed anything. Primarily because I could not find a hitch at the time. I kept speeds low both for the first 500 miles and the first 500 miles of towing. I will say that I tow pretty heavy but well within the rating of the truck. I rarely exceed 65 towing and I changed the rear axle lubricant twice now in 12,000 miles. I really don't think there was any more I could have done. I still maintain that the factory recommended oil is too light however I went to heavier oil on the recommendation of the dealer on this last change. He says the scoring of the teeth is normal wear. While I doubt that, if it is not normal the noise will get worse with time and I have 100,000 mile warrantee on it. And he says he will stand behind the use of the heavier oil, and I agree with him on the oil viscosity issue.



Casey

 

[PLaFrombois]

I thought that the correct contact pattern should be centered on the gear teeth. This might be the cause of the whine you're hearing. Sounds like the need of a depth shim is required to change the wear pattern. Bring it in after the trip.



Paul

 

[DE Jeeper]

There are atcually several different acceptable wear patterns. Is there any chance you can get some grease paint and paint some teeth? Then rotate the gears with the wheels off the grond. This will show the pattern. Take a pic of both sides of the teeth (drive and coast) and I'll be able to tell if the pattern is good.

 

[Casey Balvert]

I will do that next time I chance the oil. Actually the scoring concerns me more than the actual wear pattern. Scoring is due to the breakdown of the lubrication.



Casey

 

[GDouglas]

I would say the scoring is definitely an abnormal issue. As far as checking the pattern, I have always had good results with some white lithium grease brushed on a few teeth with an acid brush. I like the contrast I get between the white grease and the dark grey gears.



By the way, mine has the 65-70 mph whine on slight accel too. I checked my pattern a couple of weeks ago during a fluid change and the pull side where I hear my noise is textbook perfect for contact. My coast side was acceptable but I don't hear any noise at all when coasting, so I am leaving well enough alone and drive it like I stole it. If it makes it all the way to the end of the 7/70 warranty, I guess a little whine won't hurt anything, as long as it isn't obnoxious.

 

[CAKUZ]

Originally posted by Casey Balvert



I still maintain that the factory recommended oil is too light however I went to heavier oil on the recommendation of the dealer on this last change. He says the scoring of the teeth is normal wear.







Casey





Sorry to hear you are having this problem after all the trouble you go to in careing for your CTD. I changed mine at 14,200 miles. There was some grey 'gum' on the magnet but oil looked fairly clean. I examined the gears closely and noted there seemed to be a full tooth wear pattern on both ring and pinion gear teeth and teeth surfaces were smooth/highly polished. There were no sign of any scoring, pits or unusual wear. No whine yet but I also thought the oil was much too thin. I filled my axle with 75W-140 Royal Purple. Could not find Redline locally.



I am going back out to Arizona in a couple weeks to bring my heavy 5th wheel back to Tennessee. That should give everything a good workout.



Good luck and keep us posted as problems like this concerns us all.



Charles

 

[Hayman]

I HAD A NEW REAR END INSTALLED AT 5000 MILES . BAD WHINE AT 65 . metal in gear case is the reason for complete new rear. I tmay effect outer bearing and limited slip.

 

[RobbieH]

Me too, same as Hayman. Mine had about 12,000 when they replaced it. New one works perfectly.

 

[Scrappy]

rear end whine

Is the whine in you all's trucks only at 65 ish? mine is doing it around 20-30 mph in 3rd and 4th gears whether I am accelerating or decelerating. ( it has even done it coasting to a stop in neutral).

 

[RobbieH]

Yes mine was at about 65-70 at the loud point.

 

[RTWhitfield]

Mine was replaced at 16,000 miles, no problems since.

Sounds like a common problem with assembly line rear axles.

Tom Whitfield

 

[patrickreyn]

chysler is aware of a problem with the rear ends and has referred the problem to american. they have notified dealers that they are not paying for one more rear end period. Houston we have a problem that deserves a class action law suit . there problem is system wide on the rear ends.