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Rick
Dodge Dakota
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6/06/2008
23:26:15
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 Subject: 99 Dak rear differential rebuild/replace
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I see several posts on the front page about Dakota rear differentials. There must be something in the air this year, because mine just started growling again. 99 Dakota 4x4 ext cab 318 v8 Sport package; I can't tell you off hand the gear ratio in my differentials, but I'm certain they're stock and no LSD.
I'm hoping someone can recommend quality replacement gears, or even a matching axle from another vehicle. Whatever I have to do to fix this problem, I want the repair to make the truck BETTER than it is now, because I just replaced the gears in the rear differential three years / about 10K miles ago.
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well
Dodge Dakota
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6/06/2008
23:44:25
|  RE: 99 Dak rear differential rebuild/replace
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"mine just started growling again"
so they were replaced before?
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Kowalski
GenIII
6/07/2008
07:14:24
| RE: 99 Dak rear differential rebuild/replace
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Did you replace the carrier bearings when you replaced the gears ? What brand gears did you use ? Are you sure they were set up properly ? They should last longer than that.
Lead, follow, or get out of the way
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Rick
Dodge Dakota
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6/07/2008
13:55:30
| RE: 99 Dak rear differential rebuild/replace
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I suppose I did imply that I did the work myself; in fact, I had the local Dodge dealership fix the differential in 2006. They replaced all the axle bearings (4 different ones, I'm told), spacers, and the cup drive (whatever that is). I suppose the mechanic used stock Chrysler Dodge Mopar parts.
I know the truck originally didn't have LSD. I don't even know if it's possible, but on the chance the mechanic in 2006 put in LSD, I'm going to try adding some friction modifier to see if it helps.
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Rick
Dodge Dakota
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6/07/2008
14:17:44
| RE: 99 Dak rear differential rebuild/replace
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Here's more info on my truck:
The rear axle is an 8.25" with 2 stage longitudinal springs. It has anti-spin differential. Also, it has 15x8.0 5-spoke wheel hubs if that matters.
Since anti-spin differential is the same as limited slip, I'm going to add friction modifier (as noted in my previous post) before anything else.
For the record, the repair in 2006 included these parts:
52067595 seal driv 201066
2070316 bearing d 2011087
2070317 cup drive 2013018
3507575 spacer dr 2011386
2800485 cup drive 2013018
1800484 bearing d 2011087
3723569 cup diffe 2013018
1790541 bearing d 2011087
5010320-AA lubricant 1081033
5013477-AA sealant r 1081003
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dakota49
Dodge Dakota
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6/07/2008
14:41:26
| RE: 99 Dak rear differential rebuild/replace
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They didn't add an LSD, if they did it would have cost a lot more, like 300 dollars or more.
Looks to me they didn't change the gears, just the bearings, and seals. Still it should have lasted a lot more than 10,000 miles. Its possible that the housing its self is bad, that could account for it not lasting very long. They should have found something wrong though if that were the case.
Good Luck
Dakota49
1988 3.9 4X4 5speed
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jjj
Dodge Dakota
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6/07/2008
20:01:25
| RE: 99 Dak rear differential rebuild/replace
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Do you tow with it?
Not sure if the oil they put in was synthetic gear lube, I would use Amsoil, Redline, Royal Purple, etc. gear lube.
You could swap in a 9.25 rear fairly easily as they also came stock for your truck.
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Rick
Dodge Dakota
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6/08/2008
23:46:43
| RE: 99 Dak rear differential rebuild/replace
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The friction modifier did not alleviate the problem, which specifically, is that I hear a grinding noise when I let off the gas pedal. That is, when the driveshaft engages the rear diff, everything's fine; when coasting, I hear and feel the grinding.
Can I swap out the 8.25 rear axle for a 9.25 and not mess with the front axle?
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jjj
Dodge Dakota
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6/09/2008
08:22:05
| RE: 99 Dak rear differential rebuild/replace
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As long as the ratio is the same - yep. Just get one from the same vehicle. ie. newer dakota
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jayb
Dodge Dakota
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6/09/2008
19:29:05
| RE: 99 Dak rear differential rebuild/replace
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believe it or not, i had the same sounds come from my rig when the u-joints were going. replaced them and good as new...
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Rick
Dodge Dakota
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6/10/2008
21:38:57
| RE: 99 Dak rear differential rebuild/replace
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Today I noticed gear oil from the rear differential dripping from the rear u-joint. I can tell by the smell. I'm thinking that my problem might be solved by merely tightening the pinion nut. But now I'm worried that the vibrations have caused the pinion oil seal to fail. So, I'm going to try replacing that seal and tightening down the pinion nut an extra 1/2 turn or so when I put it back on.
The Haynes manual says to remove the wheels and brake drums from the rear axle to replace the pinion oil seal. Is this to get the torque on the pinion nut correct when putting it back on?
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jjj
Dodge Dakota
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6/11/2008
09:07:56
| RE: 99 Dak rear differential rebuild/replace
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You can replace the seal and use a NEW nut and torque to spec - usually.
If doing correctly, you should disassemble the rearend and check pinion bearing preload after torquing. If it is too high you must replace the crush sleeve also.
You CANNOT just give it an extra 1/2 turn :)
If it is noisy the damage is probably already done, either the seal leaked and that caused the failure or the bearings are gone and that caused the seal to leak.
To torque the nut you have to hold the pinion flange in one place.
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Rick
Dodge Dakota
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6/13/2008
11:23:46
| RE: 99 Dak rear differential rebuild/replace
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I like to close out my original questions with answers, so here's what has happened:
The rear differential only made grinding noises when coasting, so I took that as indirect evidence the gears and bearings in the dfferential itself were mostly or entirely OK. So even after reading jjj's advice about the bearings, I planned to install a new oil seal and pinion nut and hope for the best.
I was driving to the auto parts store to buy the stuff to do the job, and the pinion nut came off. The immediate result of which was, things came loose and the rear u-joint broke. I had it towed to a shop I trust for a professional evaluation. They looked inside the differential and said everything looks ok! Driveshaft looks ok, too, after being dragged about 50 meters. I still need a new seal and nut, but now also need a new pinion yoke.
I'd say I was lucky nothing worse happened to the truck or to me; and in the future, I won't off repairs I know need doing.
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jjj
Dodge Dakota
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6/13/2008
18:03:34
| RE: 99 Dak rear differential rebuild/replace
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The noise you heard was the pinion moving in and out due to the loose nut :(
That is why you use a new nut OR good loctite :)
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