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Rebuild or replace rear diff?
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zmasterflex
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Aug 3, 2010, 6:57 AM
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Rebuild or replace rear diff?
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Im not sure where this posting belongs...... Rumbling rear diff on 98 grand cherokee laredo. Is it cheaper to rebuild it or buy a used one? I have time and tools but little money. Local yards here want 400-500 bucks for a replacement. Is it cheaper to rebuild it myself if I can find replacement gears/bearings or does it require special knowledge and special tools? Advance DIYer, thanks for any advice.
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Hammer Time
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Aug 3, 2010, 7:06 AM
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Yes, I'm afraid it does require some advance knowledge and special tools. It requires some tools I don't even have. You'll be looking at substantial investment in parts also. I would say your only options are to either replace it with a used one or have someone else that is equipped, repair it for you. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
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Aug 3, 2010, 12:31 PM
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Hmmm? I'd take a look inside to see if it's just a bearing or something simple first. If sure it's junk you should be able to find a good whole used one for lots less than you said. Just count revolutions of drive yolk to how many wheel turns to match exact ratio as yours if not sure or speedo will be all wrong, T
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Sidom
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Aug 3, 2010, 5:17 PM
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It depends on what you are doing to the rear end. If you are just putting new bearing in it, you can get by with minimal tools. If you are putting new gears as well then the rear end will need to be set up again and that requires special tools. The bearing set is around $100. There is just a few thing you need to take note of before tearing it down. 1st is to see how many threads are showing on the pinion gear on top of the nut while it's tight. The pinion depth is already set to the ring gear with the old crush sleeve and you will be reusing this to keep the same setting. The sleeve is between the 2 bearing on the pinion gear. When tightening the nut make sure it doesn't tighten down to show more threads or you are pulling the pinion gear out of the ring gear. Also take note of what the torque is on the carrier caps before you remove them and torque them back to the same specs. Have a good punch to take out the bearing races for the pinion. If you don't have a bearing race installer, you can go old school & use the old races to drive the new ones in (small end to small end, just make sure the old race doesn't start in the bore or you'll have a hell of a time getting it back out). The last thing to be careful on, is the shims for the carrier when reinstalling it. They always go in very tight and are easy to break. A brass hammer works good to gently tap them back into place. If you use a regular hammer, plan on going to the dealer to get new set. I've seen some guys pull them in with the carrier caps but I was always a little leary of that, but it worked good for them......And it goes without saying but don't mix up the shims, reinstall them on the same sides that they came out of.... The bearings are pretty straight forward. If you have a press and axle bearing adaptor you can pretty much get all of them easily. About the only one you'll fight is the bearing on the ring gear side of the carrier, no real easy way to get that one. Axle bearings do like you would normally do, just slide hammer them out. If you don't have a slide hammer, just get a really long piece of pipe and put it down the tube for the axle & drive them out the backside. The carrier is already out so you can get a good shot at them.....
(This post was edited by Sidom on Aug 3, 2010, 5:39 PM)
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zmasterflex
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Aug 4, 2010, 7:33 PM
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Thanks for all the information, I will try to find a cheaper used one I don't think I would be able to discern a bad bearing from a bad gear just by looking at it. I will keep the old one and take it apart so the information you gave won't go to waste..... thanks for all the advice.
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Sidom
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Aug 4, 2010, 9:02 PM
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It would be a good learning experience. The bearing set isn't that expensive. You could always rebuild that one & have it ready to go. Once you get it apart, you'll see they're pretty easy to work on. Unless of course there is an outrageous core charge on the old rear end. Then you might just wanna take it back....
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Tom Greenleaf
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Aug 5, 2010, 10:50 AM
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Bearings and gears should be mirror smooth. No "galling(SP?)"no freeplay but would have some in and out motion pushing/pulling on axle. Leaks could be clue of bearing failures but not always. Two local salvage yards could give you a quote over the phone........ Rich's Auto Parts, Inc. 566 Main Street. Hudson, MA 01749. Phone: 1-978-562-6393. Toll Free: 1-800-541-0280. Another generally will install what they sell! I don't have the exact address but is Post Rd Used Auto Parts, Boston Post Rd, Marlborough, MA 01752 Ph: (508)- 485-1414. I have no affiliation with either but both are excellent at judging used parts. Both are inventoried and deal with other yards all over the US. Can't speak for quality of others. Laugh but not funny - have replaced TWO whole units. One was BENT - housing and all from backing into a pipe stronger than it! Other rusted out so bad it wouldn't hold coil springs! T
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Hammer Time
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Aug 5, 2010, 10:58 AM
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Those guys are a long ways from Waterbury CT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
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Aug 5, 2010, 11:24 AM
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Guess 2+1/2 hours or have those places connect with a more local one. 99% of rear differentials here get squished with the vehicles when down to metal value. Know folks in Putnam, CT and Tolland, CT which only cuts an hour off and neither specialize in this vehicle. Unless I missed something we don't know if this differential is something easy or a total mess yet?? T
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Hammer Time
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Aug 5, 2010, 11:30 AM
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About the only thing he could easily do without getting into a total can of worms with presses and setup would be the outer pinion bearing and even if it's only that, he likely has a differential full of metal filings doing further damage. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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