Rear Axle update. Comments?

[Casey Balvert]

The DC rep took the truck for a ride a week ago and agreed that the rear axle was making noise. A very loud noise. Anyway, they pulled the cover and did a wear pattern check and I got a picture of the drive side of the ring teeth.



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The tech said once the gears make noise the only way to cure that is to replace the ring and pinion. So while I would have preferred a replacement axle assembly, I will let them try this route first. Any comments on the pattern? Looks narrow and too deep into the ring to me but then I am no expert on rear axles.



Casey

 

[Udaloy]

Casey,



You are right on. The pattern is too deep, and too narrow. It should be in the middle vertically, and extend across the tooth, with the "tallest" wear area in the middle. Picture an elipse spread across the length of the tooth.



I don't know how companies manufacture their assemblies, but I would think that QA should catch a setup like yours. MTC.

 

[Old Man]

Rear-end

Casey... ... ... . as stated in my last post, mech. on mine, changed ring gear and pinon, bearings and races. Mine had the whine between 60 & 70. Real bad at 68 mph. Mine was the 2nd one he had done in 6 days. He filled diff back up with Mopar synthetic 75-140. I put a Mag-Hytec cover on it about 100 miles after the rear-end was worked on. Glad I did. Diff fluid was very dirty in color and (to me) more than normal "fuzz" on the magnet. Went with Valvoline synthetic 75-140. I check the dip stick-magnetic approx. every 50-75 miles and the "fuzz" and color is clearing up. Mech. stated if this wasn't the fix, going to put a whole new rear end underneath it. Got almost 800 miles with speeds up to 85, so far so good. No whine.

 

[roperteacher]

I've been posting about the same issue... . As per the repair manual and American Axles. 140 is NOT to be used on these axles... I too have a small whine between 68-70 MPH. My dealer already replaced the ring, pinion, bearings, crush sleve, etc. . That was about 2200 miles ago. .

 

[rscurtis]

Definitely something wrong with that picture. My '03 has a

perfect contact pattern, but since it was run since new (9000mi)

with no pinion bearing preload, I still have a slight coast whine

despite re-adjustment. Never had any noise issues under load.

A friend's '03 has the typical 68 mph whine under load, which

we were able to reduce by decreasing pinion depth by . 002.

We did this by sanding this amount off the face of the pinion

bearing, as AAM shims are virtually impossible to find, and no,

the Dana 80 shims dont work.

It would seem to me that some of the more knowledgeable

members who have successfully cured the gear whine could

tell us which way and how much the pinion depth was changed

to get the desired result, and whether new gears were required.

 

[DGFoster]

Man if it isnt the transmission crapping out it is the rearend,another money saving plan from DC=AAM.

 

[jack-green]

found on alpar site;

Common problems and repairsA number of pickups appear to be having axle failures - we believe around one in ten sold. The basic axle design seems to be sound, but there are problems around components redesigned at the orders of a Chrysler executive who is no longer there. A redesign is expected with the next generation of Ram trucks in 2006 or so; in the meantime, failures appear to be dealt with on a case by case basis. Since this is a known problem, owners who encounter axle failure should press Chrysler for no-cost or subsidized replacement even if they are a reasonable time out of the warranty period. The redesigned axle will apparently not be completely interchangeable with the current version

 

[Dean Upson]

Originally posted by roperteacher

I've been posting about the same issue... . As per the repair manual and American Axles. 140 is NOT to be used on these axles... I too have a small whine between 68-70 MPH. My dealer already replaced the ring, pinion, bearings, crush sleve, etc. . That was about 2200 miles ago. .

My understanding is that MOPAR 75w140 is NOT a full synthetic and should not be used in the AA. I got this from AA tech support.

There are other brands out that have the 75w140 in full synthetic.

I just got back from a long haul to TN, and used an infra-red thermometer on the rear axle at various times during the trip and the highest reading I observed was around 153*. I use the 75w90 MOPAR full synthetic and just changed it at 12K. I will probably use the same weight, different brand at the next change.



Dean

 

[Yo Hoot]

A Chrysler executive orders AAM to redesign their axle? If true, I would think more like Chrysler didn't actually tell them what to redesign but what the cost target would be for them to drop Dana.



Ring and pinion gears are typically manufactured in matched sets. Problems in manufacturing can occur in the geometries of the gear set, the geometries of the mounting holes in the housing or simply in initial factory setup.



If the gears are geometrically correct, they can be sucessfully set up. If not, they may be trash from the get go.



If the housing is machined improperly, you can never get a good gearset setup properly.



Other factors include poor gearset materials and/or hardening or poor mating finish.



If the gearset is good as well as everything else but pattern, an adjustment is required. There are only two adjustments. Pinion depth and backlash. The idea is to get the gears into the optimum pinion tooth to ring tooth contact pattern while maintaining a specified backlash. This is accomplished by adding or removing shims under the head of the pinion and/or moving the ring gear sideways to adjust backlash. At least this axle has threaded adjusting sleeves. That makes setting backlash easy. Too bad they didn't keep the shimmed pinion carrier like the older GM/AAM 14 bolt. Much easier to adjust pinion depth with that axle.



Because of the design of the gears, the pinion teeth actually slide along the ring gear teeth. This design gives you more contact area and a larger pinion. It's accomplished by offseting the pinion off center (lower, inthe case of the rear). Because of this sliding motion under load, proper setup, gear finish, hardness and lubrication are essential.



The gearset in the picture looks in bad shape. Could be just a bad set of gears. I would be satisfied with just a new gearset but concerned about the proper installation. So many techs just throw the gears in and just set backlash. There is a number painted on the head of the pinion that should be pinion hieght. I saw numbers on mine but it was too hard to see behind the ring. That height is the distance from the top of the pinion to the center of the carrier bearing bores.



Pinion shims should be available from AAM but the problem is you need a box of various sizes. No time to order after finding out what you need.



This is mine at 2000 miles. Looking at the upper teeth on the ring you can see a relatively good wear pattern.



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[klenger]

Yo Hoot: Good description.

 

[Yo Hoot]

Thanks!

 

[JKnutson]

for u rear end guru's,please explain this... my whine appears @ 55-to about 73. why in general is the whine at a realitively high speed compared to low speed, and also why does it only do it in this (zone). anything under or greater then speed mentioned there is nothing. finally, i changed my lube out for the 2nd time w/ 7300 and it appears that the teeth on the ring look pretty good. .

 

[NSperduto]

My guess (and I'm no expert) but maybe it has to do with oscilations at a certain speed.

 

[KD7GYJ]

This could also be related to a specific machine being out of spec and producing material that is marginal. Rather than toss it, they pass it on to us and we get to deal with it. They have adopted the Ford priciple with the Pinto's. "If it starts, someone will buy it. "



Blair