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Lawrence
Dodge Dakota
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1/26/2004
19:18:04
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 Subject: Rear differential
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Message:
Hello there,
Last August I bought a 94 dakota quad cab 4x4, and soon after I bought it noticed a clank sound when I let off the accelerator. I've asked a few people, even my mechanic and not one of them seems to give me an explanation that I'm happy with. Nothing seems to be loose, and the U-joints are in fine condition. I suspect the ring and pinion are getting worn out and sloppy. Can anyone provide me with some ideas of what to do? I could use some ideas, thanks.
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.boB
Dodge Dakota
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1/26/2004
23:44:21
|  RE: Rear differential
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Message:
Could be a lot of things. When the pinion gears start to wear, you don't often hear anything. It's possible, but I would look in other areas first. When you let off the gas, a lot of dynamic changes occur which allow weight to shift. Anything that isn't tight will shift around and make noise. I could be as simple as a loose spare tire, or as difficult to find as a broken spring leaf. You have to be a real detective, and really look at everything closely. A little bit of slop by hand movement translates into a lot of movement with CG shifting.
Get the rear end up in the air; support it with jack stands on the frame, not the axle. Now check for anything that might be loose: shocks, spring shackle, axle bearing, etc.
Now do the same with the front suspension.
Now use a jack to test for loose or broken transmission and motor mounts.
Looke everywhere for anything that might be loose or broken. Ride along with a friend and recreate the sound. A second set of ears can really help to localize strange sounds. Who knows, maybe there's a beer bottle in the door panel. Anything smell funny?
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Lawrence
Dodge Dakota
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1/28/2004
19:22:54
| RE: Rear differential
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Message:
Thanks boB, I did what you said and checked those things out. I didn't notice anything broken like a spring shackle or anything, but I did notice that when I twisted on the drive shaft there some slop in it without the tires turning, what exactly is CG shifting? Thanks agian for your help.
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.boB
Dodge Dakota
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1/28/2004
22:53:13
| RE: Rear differential
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Message:
CG just means Center of Gravity. When the vehicle takes off and when it slows, the CG shifts from front to rear. When turning, it shifts to the outside of the turn. That's a lot of mass shifting around. Which can amplify any small problem.
Since all the easy stuff seems to be tight and in order, now you end up with the pinion gear. There should be a little bit of gear lash (play), but not much at all. Take it to a drive train shop and have them put a micrometer on it. It's best done with the drive shaft disconnected.
The mid 90's trucks had a common problem with carrier bearings. But AFAIK that generally did not cause the kind of problem you are describing.
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ugh what
Dodge Dakota
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1/29/2004
17:41:39
| RE: Rear differential
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Message:
When you accelerate the center of gravity does shift to the rear, but when you stop it shifts to the front.
I bet you will find a majority on here that has the clunking that you refer to. My 99 has done it since new, even took to a well respected driveline shop, their opinion was even with a complete rebuild they could not guarantee the noise would be eliminated. 50k later it does not seam to have gotten any worse.
BTW, mine does not have carrier bearings.
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Vapor7
Dodge Dakota
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3/09/2004
12:46:05
|  RE: Rear differential
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Pull the differential cover and check the pinion shaft. I had an old Mopar once that the pinion had elongated the holes in the carrier and were letting it slap forward and back on accel decel.
Had to replace the carrier assembly. You can tell if it's in the differential by droping the ujoint at the rear then grab the yoke and turn. See how much play is in it.
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ugh what
Dodge Dakota
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3/10/2004
19:41:47
| RE: Rear differential
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You have been sniffing to many of those vapors, did some digging to find this ?
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Sephiroth
Dodge Dakota
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3/11/2004
01:44:30
| RE: Rear differential
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Message:
I bet it's the joints on your drive-shaft. I heard a clank when I let off the gas in my '92 V6 4x4 CC for ages. Then when I'd start putting it into gear after a nights' rest, it would 'snatch' into gear making a loud clunk. I was an idiot teen who ignored it back then, and eventually it developed into a high-pitched squeal (like metal on metal) when coasting. After several trips to Virginia, I had it taken to my dealer when they had a recall to replace some aluminum valves in the transmission with steel ones. The mechanic called me early the day it was supposed to be worked on. Apparently the joint up front on the drive-shaft was COMPLETELY shot. The rear one had no pins or bearings in it, and he had no clue how I drove it so long without dropping the shaft.
Check those joints ASAP. If you can still grease them like you can on the '92 and '95 models, do it! If not, and they are the problem, I'd get them replaced ASAP. I think the fee was around $200, but this was back right after I graduated HS, so I may be wrong.
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