Rear Axle Noise

[petersonj]

I have been experiencing a rear axle noise when driving. The noise occurs only under acceleration (light or heavy). It is a steady whine that changes in pitch with vehicle speed. The noise has become more prominent over the last several months.

I disconnected the driveshaft and I can move the pinion shaft by hand up and down and side to side a small distance. My understanding is that there should be no free play here. I also removed the differential cover and drained the oil. There was the normal amount of fine filings on the magnet, but there were no chunks or pieces of metal in the bottom of the housing - in fact, it was very clean for the miles (386,000 miles). The ring gear shows a normal wear pattern and the teeth surfaces do not appear to be worn.

According to the FSM:

I am inclined to believe that I do have a worn rear pinion bearing because of the pinion shaft movement and the symptoms match the FSM description.

The knowledge (and tools) needed are far beyond my skills for a differential repair on the Dana 80 axle. Can anyone recommend a competent differential repair shop in the Boise, Idaho area?

Any thoughts or suggestions are welcome.

- John

 

[BigPapa]

This was the pinion bearing in my '98 when it started howling., @ 275K miles.

 

[petersonj]

@BigPapa , in your case, did you just replace the pinion bearings, shims, and seal? Or, did you do a full rebuild?

- John

 

[BigPapa]

My gear head buddy and I did a full rebuild. We replaced all bearings, R&P, and LSD Clutches. The truck had 185K on it when I bought it, so I don't know how it was maintained before I bought it. We popped the cover and he inspected the gears. He recommended I replace them.

 

[Ozymandias]

@BigPapa He did a fantastic job setting up these gears, wonderful pattern.
I would have loved to see this from the workshop that did mine...

 

[petersonj]

Thanks for the replies. I have decided to go with Jim's Drive Train Specialties in Boise. I have already spoken with them and hopefully just new pinion bearings and a seal will fix the problem

- John

 

[petersonj]

Just a followup. Jim's Drive Train Specialties finished the repair on my truck on two days ago.

Jim's crew installed a Dana 80 differential overhaul kit which included axle shaft bearings, pinion bearing and pinion seal. He said that visually the ring and pinion gear looked to be in very good condition. However, after setting up the gears and checking the pattern, he said the pattern was where in should be, but there was some wear on the ring gear. He said that it would not be a problem, but it will be noisy - just not as noisy as it was before the repair. It turned out not to be noisy at all - quiet under all operating speeds on the 150 mile trip home.

I am very pleased with the service from Jim's Drive Train Specialties. If anyone is needing drive train or axle work done in the Boise, Idaho area, I highly recommend these folks.

- John

 

[NIsaacs]

Just curious, what gear oil did they use? What gear oil have you been using and what were/are your service intervals? Is it limited slip?

 

[petersonj]

It is an open differential. I supplied the repair shop with Amsoil 75-140. Previously, I had used Valvoline 75-140 synthetic oil. The actual oil changes are listed below.

44,000 miles
110,000 miles
256,000 miles
386,000 miles

Pinion seal was replaced at 206,000 miles.

Obviously, the oil change interval for the last 250,000 miles was not frequent enough - my own fault.

I brought the old differential bearings and the pinion bearings home with me. This morning I inspected them and took some photographs.

The first photo below shows the carrier bearings. Appear to be normal wear (to me).

The next photo shows the pinion bearings. They also appear to have normal wear, until a closer inspection is performed.

The smaller outer pinion bearing race definitely has some brinelling going on. It is difficult for the camera to show, but there are four brinelling depressions that can be felt (shown in the next photo).

One cause that comes to mind is driveshaft vibration under load? too long of interval for oil changes? using an air gun to install the pinion shaft nut? Any thoughts are welcome.

Edit: One more thought regarding use of air tool. Originally, I tried to replace the pinion shaft seal myself. I broke three 3/4" drive sockets. I took it to a repair facility and the owner said the repair would be done by noon. He ran into problems. I showed up at his place at 5:00 pm to find him still working on removing the nut. He wasn't faring any better than I had. All his guys had gone home. I helped him. We rigged a brace to hold the end yoke. With me managing the brace, he was able to remove the nut with a 3/4" impact gun. So maybe bearing damage was done then?

- John

 

[NIsaacs]

Since you got 180k after the seal change, I would guess you didn't hurt anything. Just for fun, cut the cages off the bearings and inspect the inner race. Since they are smaller, they will usually show wear, before the larger outers will.

My brothers Ford sled puller, 1200 HP big block 565 cid and D-70 spooled 5.13's. Note the small pinion, he would be better off to go to about a 4.56 gear and change ratios in his drop box. But he would need to change the front too, so too much work. The 5.13's went in way back when he was running a slightly modified 400, it couldn't hurt the gears, Lol.