Hello,
I'm the original, sole owner of a 1999 TJ Wrangler w/4.0 engine and AX15 Manual Transmission. I have always maintained the original stock Dana 30 (front) and Dana 35 (rear) axles on it - never any mods to them - just regular lubrication changes is all. This car has always been a pure California highway driver as well - no "mods" of any kind. Several years ago - after hundreds of thousands of miles - the rear Dana 35 diff started making a lot of noise. Upon examination by my mechanic at the time, he found that at least a few of the (original) four bearings involved were heavily worn - understandably! - and they were starting to move about and spin in unnatural ways causing the noise. So, I had him install a new BEARING KIT which he supplied (all Timken brand bearings) - but LEAVING the existing Ring & Pinion gears in-place; those original gears were still in very good shape, even after all that mileage. Although, the carrier and spiders needed replacement too as it turned out - which the mechanic did at the same time as new pinion & carrier bearings. After that work was done - again with the original OEM ring & pinion gears REMAINING in-place - ALL was quiet again... No whine, no unusual noise of any kind coming-out of the rear diff now. I was very happy with the work.
Fast forward another 150,000 miles... During one of my lube changes on the Dana 35, I noticed an unusual amount of metal shavings. So I'm thinking... those ring and pinion gears have been real troopers! They've lasted for 350,000 miles now. Well, it's time to retire them with honors (smile). R.I.P. fellas. That's what I set out to do.... and did VERY recently.
I took my jeep to another local shop that's rebuilt a million jeep diffs. This time, I got the mechanic's advice on new ring and pinion gears: A Yukon Gear set which matched my car's existing ratio: 3.07. We decided to swap-in a new carrier and spider gears at the same time, also from Yukon Gear. The mechanic secured all that for me, and I provided him with one of those Motive Gear Dana 35 bearings kits with.... Koyo bearings. At the time I'd had the choice of getting the same kit with Timken bearings, but thought there wouldn't be much difference. The mechanic took all that and did the work.
Almost immediately after I picked the jeep up, I noticed this phenomenon: From 0 to about 60 mph, all very quiet. Then anything >= 60-65 mph, INSTANT WHINING upon DECELERATION... mostly. But possibly some whine on acceleration as well. To be sure though, the whine is most obnoxious on deceleration at those > 60 mph speeds. I got in touch with the mechanic who did the diff bearings replacement from years before. His first question was: What brand of bearings were used? I told him Koyo. He insisted he ALWAYS used Timken bearings for that application. From what this mechanic said, and from some other online resources, I decided the following: I went back to this last mechanic with the same Motive Gear Dana 35 kit BUT WITH TIMKEN BEARINGS instead. I'd see if that made any difference...
And... it did not. I just picked the car up a few hours ago. The Timken bearings substitution made no difference. The whine still manifests itself in the way I describe above.
Any ideas on what the real culprit is here? Is it possibly a pinion NUT not torqued on tight enough and/or a faulty pre-load? Appreciate all your ideas!
Thanks very much,
Mike
I'm the original, sole owner of a 1999 TJ Wrangler w/4.0 engine and AX15 Manual Transmission. I have always maintained the original stock Dana 30 (front) and Dana 35 (rear) axles on it - never any mods to them - just regular lubrication changes is all. This car has always been a pure California highway driver as well - no "mods" of any kind. Several years ago - after hundreds of thousands of miles - the rear Dana 35 diff started making a lot of noise. Upon examination by my mechanic at the time, he found that at least a few of the (original) four bearings involved were heavily worn - understandably! - and they were starting to move about and spin in unnatural ways causing the noise. So, I had him install a new BEARING KIT which he supplied (all Timken brand bearings) - but LEAVING the existing Ring & Pinion gears in-place; those original gears were still in very good shape, even after all that mileage. Although, the carrier and spiders needed replacement too as it turned out - which the mechanic did at the same time as new pinion & carrier bearings. After that work was done - again with the original OEM ring & pinion gears REMAINING in-place - ALL was quiet again... No whine, no unusual noise of any kind coming-out of the rear diff now. I was very happy with the work.
Fast forward another 150,000 miles... During one of my lube changes on the Dana 35, I noticed an unusual amount of metal shavings. So I'm thinking... those ring and pinion gears have been real troopers! They've lasted for 350,000 miles now. Well, it's time to retire them with honors (smile). R.I.P. fellas. That's what I set out to do.... and did VERY recently.
I took my jeep to another local shop that's rebuilt a million jeep diffs. This time, I got the mechanic's advice on new ring and pinion gears: A Yukon Gear set which matched my car's existing ratio: 3.07. We decided to swap-in a new carrier and spider gears at the same time, also from Yukon Gear. The mechanic secured all that for me, and I provided him with one of those Motive Gear Dana 35 bearings kits with.... Koyo bearings. At the time I'd had the choice of getting the same kit with Timken bearings, but thought there wouldn't be much difference. The mechanic took all that and did the work.
Almost immediately after I picked the jeep up, I noticed this phenomenon: From 0 to about 60 mph, all very quiet. Then anything >= 60-65 mph, INSTANT WHINING upon DECELERATION... mostly. But possibly some whine on acceleration as well. To be sure though, the whine is most obnoxious on deceleration at those > 60 mph speeds. I got in touch with the mechanic who did the diff bearings replacement from years before. His first question was: What brand of bearings were used? I told him Koyo. He insisted he ALWAYS used Timken bearings for that application. From what this mechanic said, and from some other online resources, I decided the following: I went back to this last mechanic with the same Motive Gear Dana 35 kit BUT WITH TIMKEN BEARINGS instead. I'd see if that made any difference...
And... it did not. I just picked the car up a few hours ago. The Timken bearings substitution made no difference. The whine still manifests itself in the way I describe above.
Any ideas on what the real culprit is here? Is it possibly a pinion NUT not torqued on tight enough and/or a faulty pre-load? Appreciate all your ideas!
Thanks very much,
Mike
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