low humming strumming type noise from front end?

[md21722]

Glad it is helping.

Because of some transfer case noise after using 4wd the first time after the transfer case, some question about chain slop, a few pieces of metal "glitter", a nice sheen to the fluid, and this strumming noise, I opened up the transfer case and took a look inside and bought a few new parts to compare stretch. I found that the oil pump seal had dislodged and the shaft was wearing a groove into it and the pump body. I believe this was because some RTV got between the pump and the speedometer gear housing. When I first put the SYE in, I had noticed the oil seal was hard, cracked, and missing pieces and there was RTV around the ears of the pump. This time I put it back together with RTV as far away from the pump as possible. I also replaced the filter because even after spraying it with brake cleaner, I couldn't see through it like a new one. I put the two chains side by side and put the sprocket on and compared length. My old chain was within 1/16" of new so I put the old one back in.

When I replaced my front axle shaft seals, I noticed one my front differential carrier bearing was pitted. It very well could be the cause. I plan on replacing the bearings.

 

[md21722]

I swapped with the rear axle with one I rebuilt and the problem remains, though the noise is less. The rear axle I removed had some roughness to the pinion and some extra backlash. Next I plan to replace the front axle carrier bearings and see what happens.

 

[md21722]

Rebuilding/replacing the front axle smoothed out the front end. All bearings/cups showed bearing issues and the drivers side carrier bearing was also .100" thinner than the new bearings. However, this work did not change the strumming I am having in any way. I am starting to think it is the rear R&P. When I rebuilt the axle I changed the bearings but did not change the gear set as it looked OK. The noise comes on around 65 MPH and continues through legal speeds. It is noticeable on light throttle to maintain speed and also while acceleration. It seems to quiet down on deceleration. I will replace the exhaust since I planned to do that anyway and also try a spare driveshaft. If those don't help, I will replace the rear R&P gears.

 

[paddlernate]

What a pain in the neck! Props for your tenacity.
I have a similar noise, and am nervous about starting to diagnose it. The more I drive on it, the more it seems like a unit bearing.

 

[md21722]

I took out the new driveshaft with 5,000 miles on it nd found a bit of play between the splines. I put in "good spare" I bought off a forum member. On the highway through town at 65-70 the noise is gone!

If the noise doesn't come back in a few days, I'll contact the driveshaft shop who sold me the new driveshaft.

 

[mikerhyne]

Glad you got yours solved!

I'm still fighting my similar noise. I have removed my front drive shaft and it didn't help at all. I have the rear pinion and drive shaft angle about 2 degrees apart but I am going to play with that more to see if I can change the noise.

 

[md21722]

Well, the noise came back for a few miles on the way to work then disappeared the rest of the way to work. Then was present all the way home from work. But its so minor at this point, I could leave it alone. I will double check the replacement driveshaft and go from there. Right now I'm doing some work on my other XJ so next update probably won't be for a few weeks.

 

[md21722]

I believe I kicked this problem.

Back in December I rebuilt the 8.25 which greatly reduced the noise. Turns out I damaged the inner pinion bearing on install. I redid the bearings and for the past 400 miles there have been no problems with either driveshaft.

 

[md21722]

The noise came back. This time I found that that swapping in balanced driveshafts makes it ride very smooth. Now I doubt how much my rear axle was really contributing to the problem. I hadn't though the rear driveshaft was a contributing factor since it was new and supposedly a very good unit. I'll update again after I put a few thousand miles on the current setup.

 

[mikerhyne]

I was just about to pull the trigger on having my axle rebuilt when I decided to swap the front drive shaft to the rear this weekend and almost all of the noise is gone! It was almost odd how much quieter it was. I'll be taking the shaft back to the shop that built it to have them fix it. Not sure if it has a bad joint or was out of balance. I'll put some miles on it to see if this is my solution too.

 

[mikerhyne]

I took the rear shaft back to the shop and they rebuilt it saying that I probably over torqued the straps and caused the u joint to fail. That had caused the CV joint to fail as well. So they "repaired" it for me no charge. I picked it back up and bolted it being very careful and using a torque wrench to verify everything in and have the exact same noises. So I ordered a Tom Woods shaft today and I'll deal with the other new shaft when I have the patience and time to drive over to that shop.

 

[Hypoid]

What shop did you go to?

Not to disparage your purchase decision, but Bill's Englewood Driveshaft does quality work.

 

[md21722]

I moved the front DS to the rear and swapped in the old front driveshaft from my other Jeep. Basically swapping out what I identified as the likely problem, the 4 month old rear DS. I've driven at least a thousand miles with my current driveshaft setup. The problem has not come back. I was careful not to change anything else while testing. Upon hearing that a driveshaft change made the problem go away, the shop that built the shaft agreed to pay shipping both ways, replaced the centering yoke in their shaft, rebalanced, and repainted it. When I sent it back I dropped a note in the box asking them to use a Spicer non-greaseable if the centering yoke was found to the be problem and call me if there would be an extra charge for the Spicer part. They opted to use what I think is a Neapco non-greaseable at no charge. So far I haven't tried it. Its nice to drive a hum and vibration free Jeep. I guess I need bigger tires and more lift now. ;-)

 

[mikerhyne]

Hypoid, Englewood is who built the shaft that I'm having issues with. So my shaft from Tom Woods is like my second opinion. One will become the spare. I'm paid hourly so the 4 round trips so far to drop off and pick up from them has cost me 6 hours.

 

[Hypoid]

Bummer! Keep us posted, on how this works out.

 

[mikerhyne]

My new rear shaft is working great and quiet so far.

The front that I had rebuilt and put on the rear is less happy back up front and seems to be vibrating over 55 MPH so I'll pull it at some point and see if the vibration goes away.