1995 P30 Differential Problems; Large Shavings

[1969SSCamaro]

After draining diff fluid, I found some large shavings on the magnet. I feel compelled to remove the entire differential for closer inspection. So far I can see nothing obvious like a disintegrated bearing cage, but it is all but impossible to see the differential gears. I measured backlash at .009 and looked at gear mesh using ring/pinion paint; see photos. Based on gear mesh patterns the coast side looks to be a little too high on the ring gear. I'm certainly no expert reading these patterns, so input welcome. I do have some reference material. The drive side looks okay to me.

Link to Photos of Diff Pattern and Shavings

Second link to photos - slideshow

[1969SSCamaro]

jolooote wrote:
Check wheel bearings also. I had a P30 & the wife complained of a low tone howl. I could never hear it. I had it checked by a truck manchanic who said all ok. She kept complaining until the driver side rear axle sawed itself off at the wheel. The only thing that kept the duel wheels on the rig was the brake assembly. Completely destroyed the entire axle housing. $6000. P30 chassis are notorious for overloading the rear axles.

Regarding your last statement about overloading rear axle; I have found two axle-specific reference sources that state my axle GAWR is 8600lbs (10.5" GM Corporate/AAM). The sticker on the MH states 10,000 lbs. I am wondering if GM made unique changes for MH chassis to increase the GAWR?

[1969SSCamaro]

I will definitely check the passenger side wheel bearings and axle. The driver side looks good.

No howling/whining noises; I was just doing a routine fluid service (recent purchase)when I discovered the mystery shavings. I hate to disassemble the pinion mainly because 1) don't have the tools (no air tools/press) and 2) the setup appears to be working well. I guess the minor risk in disturbing the setup (seal/pinion-depth, crush sleeve) is probably worth it? At a minimum I will definitely do a better check on the pinion end play and side-to-side by reinstalling the pinion in the housing (to firmly hold it in place).

Thanks for all the responses!

[jolooote]

Check wheel bearings also. I had a P30 & the wife complained of a low tone howl. I could never hear it. I had it checked by a truck manchanic who said all ok. She kept complaining until the driver side rear axle sawed itself off at the wheel. The only thing that kept the duel wheels on the rig was the brake assembly. Completely destroyed the entire axle housing. $6000. P30 chassis are notorious for overloading the rear axles.

[jolooote]

Check wheel bearings also. I had a P30 & the wife complained of a low tone howl. I had it checked by a truck manchanic who said all ok. She kept complaining until the driver side rear axle sawed itself off at the wheel. The only thing that kept the duel wheels on the rig was the brake assembly. Completely destroyed the entire axle housing. $6000.

[spcorvette]

While you have it apart, I would disassemble the pinion and inspect the bearings for sure. It would be a shame to put it all back together and still have an issue.
Did the rear end make any howling noises?

[1969SSCamaro]

Completed disassy, cleanup and initial inspection; see link to photos Post Disassy Photos
Surprisingly everything appears to be okay; at least for MH with 37K miles. I strongly suspect that the shavings were actually burrs left over from the casting and/or machining process. When I performed initial inspection after removing Diff cover, I found two shavings that appeared to be stuck to the passenger side differential carrier (made a note on photo - example of smaller burr); about a 1" rectangular cutout where you can see spider gear. I figured it was stuck on the edge of the cutout due to pressure from spider gear, but I now think it was leftover burr. Anyway, I think I will just reassemble, that is, after carefully deburring the diff castings. This seems crazy to me that the Mfg wold leave so many burrs. Exercise in futility, but I guess I can have piece of mind? Please let me know if there is anything I can check. The only area of the assy that seemed unusual was the slop on the spider gears, but then again, this is the first and only one I have ever seen.

Forgot to mention that I still need to cleanup and inspect the axle/diff housing and passenger side axle bearings. The pinion bearing in the housing appears to be fine (supports the pinion nose).

[spcorvette]

Had that on my P30. It was the pinion bearing. Not hard to change. 5 bolts on the front of the housing. Take it to your local machine shop and have them press the old bearings of and new ones on.

Once you get the bearings out, you will see the chunks out of the bearings. You will also notice the rear end is a lot quieter.

Hope this helps.
Terry

[APRSRVer]

That debris is way too big to be from a failing roller bearing. And, assuming it is not a limited slip differential, the only place thin, malleable stuff can come from are the thrust bearings behind the spider and side gears. When it does it's differential work of letting one axle over speed the other, those gears rotate and there is a cup shaped bearing, bushing material between them and the carrier. Shims for positioning the pinion and carrier for proper meshing of the hypoid gears don't rub or slide on anything.

[John_Joey]

Born To Travel wrote:
...snip... Check your pinion for looseness by gripping the driveshaft where it meets the pinion yoke and try shaking it around.. If there is any movement of the pinion where it comes out of the case then it could be the pinion bearing..

This does make a lot of sense to me. I'm betting he hit it on the head for diagnostics.

[Born_To_Travel]

I have seen when a bearing goes bad, the material coming off of them look like small pieces of aluminum foil, Thin sheetlike chips... If that is what they look like they could be from a bearing... Check your pinion for looseness by gripping the driveshaft where it meets the pinion yoke and try shaking it around.. If there is any movement of the pinion where it comes out of the case then it could be the pinion bearing..

[1969SSCamaro]

Mike,
I assume you are referring to the primary pinion attached to the driveline? The primary pinion bearings appear to be fine. I removed the pinion a few days ago and inspected it. Or are you referring to the differential pinions? I plan to remove the differential assy tomorrow and inspect the differential assy. Apologize if I'm asking silly questions, but I am a novice working on differentials.

Anther strange thing is the ring gear at the root-heel (very outside edge of the ring gear) gives an appearance like the pinion is meshed too tight; the edge of ring gear has slightly splinterd edges. I expected the pinion to be too close to the ring gear; meshing too close/deep, but the mesh patterns in the photos do not indicate that.

[Mike_Hohnstein]

Drive side is supposed to be more centered, suspect pinion bearing failure.

[APRSRVer]

Also not an expert but considerable experience, the ring and pinion appear OK. The metal pieces look to me like chunks of the axle gear bushings and/or spider gear bushings.