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Funky vibration in my rear end.

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Sorry if the title is a little weird, but I thought it was funny!



I need a little help in diagnosing a weird shudder in my truck. I am sure it has something to do with my limited slip rear end. I am getting a bit of a shudder when I go real slow around corners. I am talking parking lot slow. I have never experienced the "chatter" from a differential without the proper amount of friction modifier.



I will give you a brief history of my rear differential.



1) 0-100,000 km's (62137 miles) factory diff fluid.

2) 100,000 km's (62137 miles) Changed to Amsoil 75-90.

3) 130,000 km's (80778 miles) pinion seal started leaking.

4) 139,000 km's (86370 miles) Added 1L ( 1 quart) of another brand of Synthetic diff fluid. Motomaster 75-90. It's a Canadian thing eh!

5) 140,000 km's (86991 miles) replaced pinion seal and topped up with Amsoil 75-90.

6) Added aprox 4 oz of friction modifier. This was not the original Mopar stuff but a generic friction modifier from NAPA. This did not help at all.



So this is where I am at. I am almost embarrassed to say I let my rear diff get about 1. 5L (1. 58 quarts) low. I am not sure if my "shudder" started after I added the Motomaster synthetic diff fluid or if stupid me has wrecked my limited slip clutches. I have also replaced all 3 u-joints and the steady bearing was replaced last summer if these are items at which could cause a slow speed shudder.



Should I just drain the diff fluid and start over?

Buy the Dodge stealer friction modifier?

Could it even be me applying a light amount of brake and I have an out of round drum?

I talked to Darren today from DTT to eliminate the possibility of the transmission. I am sure it is in the rear diff.



When I pull the diff plug the magnetic plug has very little of that gray metal paste from metals floating around in the fluid. Any tests I could do with the wheels off the ground? 100 figure 8's in the parking lot? That is another weird part of it. It does not do it when I do tight figure 8's. Only at slow speeds in forward and reverse, maybe 1-2 mph. Even does it in gravel/low traction conditions. Never when I am going straight ahead or straight backwards. I know it is kind of an odd problem and hard to describe unless you are driving the vehicle but give me your ideas or theories or ask about anything you are unclear about and I will see what we can do.



Just don't tell me I am a meathead for running 1. 5L low on diff fluid and have wrecked my limited slip!



Dana 70 3. 54... ... ... .....
 
My truck has the same shudder at low speeds. It started when I changed the diff fluid. I put stalube gear lube in and the same friction modifier from NAPA. I don't think that friction modifier works.



Dana 70 4. 10



Rob Alley
 
My '02 had the same shudder (and symptoms) after putting on my MH diff cover with Synthetic 75-90. It started about 2 days after the fluid change - that's how long it took to "clean" the clutches of the original fluid... I put in 2 bottles of the Mopar friction modifier to quiet it down - but it did take another 2 days for the friction modifier to saturate the clutches again - everything seems ok with the rear end now.



HTH

Joel
 
Do a couple of tight figure 8s in a empty parking lot to circulate the modifier faster than just normal driving. I won't say you need to use Mopar modifier but it seems to always work, not all others do.
 
SD, great title!!!

Had the perv's running to see this one!!



OK, I doubt you hurt anything by getting it a quart low IF it was for a short time and you were completely full to start with. By completely full I mean jack up one side and let it down, refill and do the same to the other. The LSD on my truck is extremely tight, I have tried up to 42 oz of the store brands from Napa and autozone, it was still chattering. When you are sucking out a quart of oil to get your modifier in it is junk. I drained the diff and started over. I put in one bottle of the Mopar modifier and the chatter is only very slight right now. The mopar stuff works, the rest I have tried is garbage. Mixing the oil is not a big deal at all. Add the mopar, turn about 10 figure 8's and then give it about 50 miles to get all mixed in and where it needs to be. BTW I have the same chatter you describe right now, and another half bottle or so of the stuff will ge rid of it as soon as I get off my butt and get to the dealer.
 
I was under the impression that I would be getting an audible chatter and more jerky than mine is. I guess it is off to the stealers for a bottle or 2 of the friction modifier.



Joe,



Thanks for the tip, but for alot of things it is easier and cheaper to get locally. Being in Canada is kinda a pain sometimes with dollar conversion, waiting for product to arrive and duty at the border!
 
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