"clunk" noise when shifting in reverse Auto Transmision

[cybergrizzly]

I have a 1999 Jeep Grand Cherokee Laredo with a 6 cylinder 4.0 liters engine and a Select-Trac Automatic Transmission (4x4). The engine runs idle at around 700 revs and the car runs perfect in in all respects. The only problem that I encounter is that when I shift in reverse I notice a "clunk" when engaging the reverse...other than that the vehicle reverses ok and when put in "Drive" it does not gives the noise. Since this transmission allows me to run the vehicle in 4x4 Full Time year around, I opted to leave this selection as the "clunk" noise is noticeably diminished maybe because the torque is distributed to the front wheels as well. Again, when driving normally (forward) there is no noise when shifting either up or down. The noise comes seems to come from the rear. Someone just told me that he also heard some noise coming from the engine bay...maybe a broken engine mount. Could it be possible that a broken engine mount create such a problem by not managing the twisting torque of the engine ? Is it possible to program this automatic transmission to lessen the initial torque when reversing ?

[mcs219]

My 94 Laredo with the 6 cyl does the same thing...loud clunk and slight jerk felt throughout truck when engaging reverse. As far as I know, this is normal; Jeep has 120,000+ miles and has been doing that ever since purchased used at ~70,000.

[Caribbean ZJ]

it is common on all early models, never heard of this on 99-02 models.

[Clownboy610]

im pretty sure that the tranny mounts get a lil loose cuz it happens on my 97 gjc also and all my friends that have jeeps they also have the clunk.

[Krazed Jeep]

The only thing I can think of to check first would be the transmission mount, or the engine mounts. When in reverse the transmission will twist the opposite way than it would in drive, possibly causing the clunk only in reverse. Besides that check your yoke at the rear differential and make sure it is tight and if your really bored check the free play of the crown and pinion in the differential. You may have worn gears that need attention.

[cybergrizzly]

Ok, guys...thanks for your ideas. I had no other choice than to take it to a transmission repair shop. They checked the rear end (opened diferential cover to check things out), U-Joints, Transfer Case, Torque converter turbine, and finally the tranny. Yep, the damage was there. The gear/discs housing unit mounted at the rear shaft of the transmission. A ring-gear was wearing out and had too much play. The car is still at the shop but the mechanic says that that definitely is the problem. We will see after everything has been assembled. It is weird due to the low mileage, but maybe a bad shifting at the wrong moment.

[Goldfishy]

Mine is a 99' GCL also, with over 110,000 mi. on them. The clunking started around the 40,000 mi range. The dealers mechanic (2 separate places) said it was a "normal" sound due to some design flaw but nothing to worry about.

The tranny runs fine otherwise. The tranny mounts were checked, etc like some previous posters, nothing found. It is very annoying tho'. I've watched and heard other GCL owners from 97-02, still the same noise.

Changes in the tranny fluid and filter does not make a difference.

But I hope that tranny mechanic fix will do the job and get rid of the noise. Definitely keep us posted on your repairs.

I wonder if Jeep's head mechanic honcho's know about this situation, given it affects so many years of production. Keep your receipts and my thoughts is to see about a recall to get the bad parts replaced at their cost. I think Jeep should make good on their part if they "knew" of this.

[99hdlady]

I have a '99 JGCL and I my jeep also makes a clunk noise when put in reverse only. I purchased the bearing kit and had them replaced. I was told that I would probably have to have a complete rearend job performed later because of the gears that I waited too long to have the bearings done. Now I am wondering is this the clunk noise I hear or is it my transmission?