2nd Gen Non-Engine/Transmission Rear end clunk when shifting

[JGK]

Lately I've begun to hear a clunk when shifting. Not always. Not only when shifting hard. Not real strong. I've heard this before on other trucks. Got underneath and grabbed the driveline and tried to twist it. Only just a tiny bit of play.



What might it be? Is it serious? What and how should I check for to determine what is going on?



TIA,

Jay

 

[emjay]

Make sure that the driveline is not under tension when you check it. Do it preferably with the trans in neutral (and the parking brake set, of course) and check for rotational play between each yoke and check the middle bearing for slop if it is a two-piece driveshaft. Could be a motor or trans mount or something loose in the rear suspension (U-bolts, leaf springs, etc. ) Good luck!

 

[JGK]

That's it... 1 response?! (BTW: thanks, Emjay).



I'd have almost bet the rent Illflem would have chimed in and offered just what I needed to know



Anywone else?

 

[rspinks]

Probably not many responses because it could be any number of things. As per Emjay check the driveline for obvious play in u-joints, carrier bearing etc. U-bolts could be loose allowing the axle to twist slightly, overload springs could be tapping the mains springs under load. I had a bad clunk that turned out to be the spare tire hanging loose and thumping into the frame. Good luck

 

[rspinks]

I forgot a major one which is excess backlash in the ring&pinion, check this by popping the diff cover off and checking freeplay on the ring gear. I read somewhere that Dana recommends checking backlash every 20k for the 70 and 80 axles.

 

[klenger]

I had a bearing totally go out where the rear drive shaft splits. Dealer fixed it under warranty. It happened at about 1000 miles. It caused a loud "clunk" when shifting.

 

[redram]

I'll put my money on the drive shaft carrier bearing assembly. Check the rubber doughnut and see if it's cracked or it could be a bearing starting to bind / drag in the carrier assembly of the two piece drive shaft.



mine failed and it literally shook the truck as if I had blown out a tire side wall, thump, thump, thump.



This was before any after market parts were available. Ungain the Dodge boys, instead of using a standard off the shelf carrier bearing had to design a custom that was an arm and a leg from the stealer. Finally found when at a driveshaft rebuilder but they had to special order it. I think Napa and others may finally carry the bearing assembly.



Good luck.

 

[stg2500]

I had a 98 gasser that had a similar problem. It turned out to be a bad pinion beraing. Would have been real $$ without the extended warranty. A friend of mine had the same thing happen to his 98. Could be a likely answer.

 

[emjay]

Usually when gears are involved (i. e. pinion bearing), there's a lot of whine either on drive or coast.

 

[redram]

Might be your limited slip unloading as well. GM's have long been described as having a 'Chevy Posi-clunk" when the clutches unload say like on an off ramp when slowing down.



Don't know if this is common with the Dodge limited slip.

 

[Deezul1]

Does it clank pretty good when letting off throttle and getting back on it again? if so put it in neutral and slide under and rotate the shaft and see how much it turns from lock to lock and look to see where the slop is, rear end, u joints, support bearing?

 

[JGK]

rspinks,



I know it's not the tire. I recently replaced the spare with a larger one and had to rework some of the exhaust to keep it from touching, so I know all is tight.



emjay,



There is no discernable whine on drive or coast (other than the new PDR HX40!).





I will get under the truck and twist/wiggle/inspect the drive shafts as recommended this weekend and get back to you all. If that all checks out, maybe I'll pop the cover and try to check free-play in the ring gear.



The clunk is not real loud and not consistent. I'll try the throttle on/throttle off to see what that does. FWIW: I replaced the diff cover with a Mag-Hytec and filled it with Amsoil 75w-90 in June.



2 questions: should checking driveline lash be done with the wheels on the ground or jacked up? What is the preferred method of checking gear lash in the rear end (I have a manual and can look it up, but those with experience typically have better ways).



Thanks all,

-Jay

 

[emjay]

I could be wrong, but I doubt whether the ring gear backlash has anything to do with it, because there's no gear noise. Check the easy stuff first. The ring gear backlash spec is on the order of . 005" to . 008". If you're getting enough backlash to make a clunk noise, you would likely hear a lot of gear whine with it. If you're looking in the diff, the other thing to check is the end gear sideplay, and clutch packs if it's the limited slip variety. You can do a quick check of your limited slip by setting the parking brake, place the trans in neutral, jack up on rear wheel. If it turns easily or freely, your clutch packs may be worn out.



Good luck!

 

[Deezul1]

Both my Dodges had a bunch of back lash and made no noise at all. I asked a rear end guy about tighting it up and he said as long as it wasnt noisy dont mess with it. This seems to be another chronic DC problem as I have seen a number posts about it.

 

[Little Bill]

Make sure your spare tire is centered and cranked up tight.

 

[KYOUNG]

clunk

my 94 4x4 developed a clunk when you got of the throttle. it turned out to be the front right u-joint was worn out. replaced it and no more clunk

 

[C Schomer]

My 80 was getting loose before 50k miles. The carrier had about . 0015" slop and the pinion preload was almost gone - down to 1 in. lb. I had . 008 lash. An old timer at Dana told me the old spec was . 004-. 008 and he likes them on the tight side. I thought looser would be better (carry more oil) but he said the way Dana teeth are cut, they like to be on the tight side. I replaced all four bearings and cups. If you do it, better have the shim kits ready. I had to change some shims to get it setup like the Dana tech wanted it. Craig

 

[obert]

I read above about several ideas concerning the Carrier bearing. I have the same sound emitting from the under side of my bed, and i also have a bad carrier. If I change it soon I could post a result.



Butt, if i switch to dads truck my timing is usually poor on the clutching and shifting the first couple of times till i realize I'm not in mine, and it usually causes the same sort of chunk when tension is released suddenly off the drive line. So make sure your clutch is completely releasing.



JMHO