Rear End Noise '89 Cherokee

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  #1  
Old 11-13-06, 10:18 PM
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Exclamation Rear End Noise '89 Cherokee

This spring I began getting a metallic wail while driving under power - when I back off the throttle it disappears. I emptied the differential at a mechanic's suggestion and took a sample in a glass jar. There are a few small silver flecks in it, otherwise nothing seemed out of the ordinary, except perhaps a few small pieces of grit near the front end taper of the housing. I sprayed the housing out with Brakleen and refilled with Mobil 1 75W-140 and a tube of LSD additive but it hasn't quieted much. It reaches a crescendo at about 45 mph then gets quieter as I go faster. Any ideas? I keep my u-joints greased with synthetic. I had been using Amsoil synthetic fluids and grease and had not been adding LSD additive at Amsoil's direction but have recently gone to all Mobil1 products and back to using additive. I never noticed chatter.
 
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  #2  
Old 11-14-06, 07:21 PM
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Could be the pinion bearing/bearings. When you accelerate they would be loaded. When you let off the throttle the loading would decrease then increase to maximum backlash on the ring/pinion. The latter wouldn't have the same loading as the the acceleration.

Did you disassemble the differential? Is it a positrac setup?

You may be able to get an idea of the bearings by raising the rear of the SUV, taking off the tires, disconnecting the drive shaft and turning the yoke by hand. By the time you did that though, you may as well take the differential apart and look at it.

Hope this helps,

Bob
 
  #3  
Old 11-15-06, 05:18 AM
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Two possible diff's in this vehicle.........Looking at the rear pan. If it's basically round, it's a Dana 35......If the pan is sorta notched it's a Dana 44......The 44 was a much better unit than the 35 .......The 35 had bearing issues and yours sounds like the pinion bearings are failing
 
  #4  
Old 11-15-06, 06:07 AM
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x2 on the Dana 35 being a POS. Had several in Jeep Wranglers. They are not very durable. Bearings are probably wasted exspecially being an 89. Those axles are usually a dime a dozen at the boneyards. It would be much cheaper to swap in a replacement than to change out the bearings. 87 was the only year the dana 44 was offered in the Cherokee btw.
 
  #5  
Old 11-19-06, 01:06 PM
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Rear End Noise

Thanks! That's some excellent information. I've been told that the options of finding anything in boneyards around Fairbanks and Alaska is pretty nil and by the time one pays shipping here (FedEx or UPS only) it gets expensive. I may subscribe to that online shop manual site that gives total service info and TSB's for a yearly fee. But can one of you tell me roughly how hard it would be for a DIY guy to swap out those bearings, does it require special tools, and can it be done with the rear axle assembly in the vehicle?
 
  #6  
Old 11-19-06, 01:37 PM
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It can be done without remove the whole housing/assy. but you'll need a special tool to do it, a spreader is needed to spreads the housing out a bit so the whole carrier can slide out/in, if you can get the carrier out without the spreader, your side bearing reload is wrong, and when the side bearing reload is wrong, of-course your backlash also wrong and they will "sing a loud song" when your are cruising.
 
  #7  
Old 11-20-06, 01:33 PM
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OK -Thanks!
 
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