View Full Version : rear end clunk/clank
I got a '99 Chevy 2500(new body style). When you put it reverse you here a clunk/clank noise. The truck has 60,000 miles on it. Took it to the dealer, mechanic said he sees alot of 3/4 ton Chevy trucks with that noise. Said most likely its backlash/slop in the rear end from heavy use/snow plowing and that its normal. he said that he wouldn't worry about it until it started growling. My question is does anyone else have this problem with their Chevy 3/4 ton pickups? truck shifts good and makes no other noises, just when you go from drive to reverse.
08-12-2005, 01:45 AM
Said most likely its backlash/slop in the rear end from heavy use/snow plowing and that its normal.
"Most likely??"....So he doesn't know for sure, or at least didn't confirm it.....Any sort of noise like this is NOT normal....I'd take it to another mechanic and get it double checked.....it could be a u-joint going bad, for example. If it is the rear end, I'd get another one on hand before winter....(or sooner.)
08-12-2005, 04:26 AM
Sounds like the U-joint for sure .It's on your driveshaft,have somebody look underneath while you keep your foot on the brake and put it into reverse.Leave your foot on the brake and dont take it off at all then put it back into park then back into reverse.The person will see slop in the driveshaft at the U-Joint if it's that.Change your differential fluid and look for lots of metal in it.If there is PIECES of metal in it it is your rearend thats the problem...some metal shavings in the old fluid is normal.
08-12-2005, 06:15 AM
A mechanic that says it MOST LIKELY this or that, is an idiot, either it IS or it ISNT. go to a competant mechanic and get it looked at. it sounds to me like you've got a bad U joint as well, better replace BOTH front and rear U joints on the drive shaft, probably they're both pretty close to going, so replace both. save the hassle. also check the differential for pieces of metal, change the fluid probably, and clean it all out some. probably repack the bearings on the wheels too while you're at it.
I have replaced all the u-joints ecently, they are all new.
08-12-2005, 02:40 PM
Check your engine idle RPM's and have them reset lower. Check transmission & engine mounts for damage, loose bolts. Pull the differential cover yourself, make sure you have limited slip additive, rear gear oil, and a new gasket on hand. With wheels off the gound, engine off, tranny in park, you can grab the ring gear or tire and turn back & forward. The ring gear to pinion gap while cold is known as "backlash". If it's excessive due to wear, a shim can be installed on the ring gear side of the carrier bearing. This is best left to professionals with factory tooling rather than the corner gas station. It's also possible one of the carrier bearings is worn, or the pinion bearing.
08-12-2005, 04:07 PM
I'm not sure if the guts in the rear end are the same as pre 99, but if they are, yank off the cover and check the gear faces on the spider gears. At about 99,000 in a '94 GMC 3/4 ton, we saw the machined faces had begun to self destruct and turn into a pitted surface looking like deep sandblasting. I got a spider set for about $350.00, and alot of that clank you describe went away. A very easy to fix problem, there is only one retainer bolt on each side. But, if it is shims, (pretty rare I may ad) best taking it to the dealer and gauging it out properly.
08-12-2005, 08:05 PM
Is this puppy a diesel? If so, then the noise is relatively normal, just a little rearend slop like your mechanic said. If is a gasser, then you need a new ring + pinion.
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08-12-2005, 08:28 PM
Klank And Klunk Are Not Normal Noises. Its Is Either A Broken Motor/trans Mount, Ujoint-cv Joint Or Excessive Backlash In The Rear. I Agree That The Mechanic That Said Dont Worry Is A Moron. Get I Fixed Before It Fails.....i Had One (differential) Go Bad Before A Snowstorm.......almost Cost Me 10 Grand In Missed Plowing. I Did Get Mine Fixed In Time Only Because I Had A Spare Axle Ready To Go Just In Case . Not To Mention Tools, A Warm Shop And A Few Good Friends That Are Mechanics.
Dont Let It Bite You. Nip It In The Bud Before Hand. A Local Speed Shop Usually Is The Place To Have A Diff Fixed.
08-12-2005, 08:52 PM
Mine too. Mines a 1/4 ton but same noise. Dealer told me it was a common on this year. Said it was the slip joint but I'M not buying it. I paid for the extended warranty and will be taking mine in soon. If I find out any thing I will let you know.
Thanks guys for the advice. I'm going to tear into it tomorrow and have a looksy. Just for kicks, I checked my wifes 2004 Tahoe and hers makes the same noise but not near as loud.
Keep me posted as to what you find out.
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