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madcap1973 08-18-2010 03:53 AM

Got to fix this whine
My Jeep has got a tiny bit of whine coming from diffs, axles or whatever - I don't know what's causing it. The sound is constant from start to higher speeds, but not loud. If I put the radio on or turn the fan to step 2 it's almost not audible.

Between 90 and 100 km/h (around 60mph) there's a louder noise which comes when the car rolls without any tension on the driveline (when I let off the throttle). At first I thought it was coming from the roof rails - but it's not. This sound comes and goes, and it's not bad - only a touch annoying.

Question is:
How can I set up my driveline so it's silent?

My Jeep is a '99 4.0 litre, has the Dana 30 in front and the 35c at the rear, 42RE transmission and Quadra Trac II transfer case. Transmission and transfer case is in good condition. Milage is 130.000 km/81.000miles, and the car is very well kept.

I don't get off road much, and if I do it's gravel roads - it's not legal to drive motorized vehicles outside of roads here in Norway unfortunately... :(

I am on a budget here, so changing as little as possible is an issue.

Any suggestions? I will most likely be buying the parts from the US, so links will be greatly accepted.

Follow up questions:
Are driveline parts interchangeable between all 99 - 04 WJ's??

Could a synchronisation of the diffs fix this? Does this require any changed parts (repair kit?)

Does later model WJ's suffer from the same problems?

Much appreciate any input on this - I have read a lot about these problems and talked to my mechanic (at the dealers), and I understand that this is mostly a problems for my ears, not so much the car. There's nothing saying my WJ will have problems running for a long time with this, but alas - I would like it to be quiet except for the engine sound which I love :)

StoneCold 08-18-2010 10:06 AM

Re: Got to fix this whine
Sounds like it's just diff whine. If so just add some LSD to the fluid and you should be set.

There a a few good UK suppliers, which should keep down the shipping costs for you

madcap1973 08-19-2010 01:21 AM

Re: Got to fix this whine
LSD? Do you mean limited slip additive? As I have Quadra Trac II and not Quadra Drive, I thought that I shouldn't add additive? Anyone know this for sure?

Copied this from
(color me stupid, but why is it listed two kinds of oil for each axle??)

Rear axle, Dana 35C:
Thermally stable SAE 80W-90 gear lube
MoparŪ P/N 04874468

For heavy-duty or trailer tow use:
SAE 75W-140 synthetic
MoparŪ P/N 04874469 NOTE: Trac-lok and Vari-lok equipped axles require 4 ounces of Limited Slip Additive be added to the lubricant.

Front axle, Dana 30:
Thermally stable SAE 80W-90 gear lube
MoparŪ P/N 04874468

SAE 75W-140 Synthetic
MoparŪ P/N 04874469 NOTE: Trac-lok and Vari-lok equipped axles require 2.5 ounces of Limited Slip Additive be added to the lubricant.
Trac-lok for the front axle is available only with (and included with) all QuadraDrive systems

In addition I should mention that last time when I had the Jeep in for service, they added some Omega stuff to the diffs to silence it a bit (I know this cause the mechanic forgot his notes in the car...). Maybe I should try to change the oil and see if this helps?

StoneCold 08-19-2010 06:47 AM

Re: Got to fix this whine
When was the oil last changed? I've never heard of the omega stuff.

Frango100 08-20-2010 09:59 PM

Re: Got to fix this whine
As far as i know the limited slip additive is only needed for vari-lok or trac lok differentials (quadra drive). It is a friction modifier, which is necessary for the clutch inside the differential to work properly.
MY WJ has Quadra Trac II and i only put the 80W-90 in both diffs, according the specifications.

Frango100 08-20-2010 10:04 PM

Re: Got to fix this whine
Regarding the 2 types of oil mentioned for both axles, the 80W-90 is for normal use. The 75W-140 is for heavy duty use (trailer towing).
I always use the 80W-90 in my both axles.

Chaoul1 08-20-2010 10:43 PM

Re: Got to fix this whine
It's one of the differentials. Check both.

Escape 08-20-2010 11:30 PM

Re: Got to fix this whine
Does it clunk into gear and if so how bad?

Has the whine always been there or is it getting worse?

Sounds to me like you just have a bit of wear in your diff. Unless it is unbearable or getting worse I wouldn't worry to much about it. It all depends on how it was assembled to begin with.

Here is your correct mating pattern for your ring and pinion. If your a do it yourself guy and can stand the smell of diff fluid. Drain the fluid, take the diff cover off and using the correct grease check to see if your wear pattern is correct.

I'd recommend finding a reputable off road shop or axle builder if it gets worse and you just can't live with it.

madcap1973 08-24-2010 01:45 AM

Re: Got to fix this whine
Thanks so much for the input, guys.

As I understand it, mine is not the worst of problems - it's a very low to moderate whine, and there's no clunk or other noise. Just my sensitive ears ;)

No worsening either, so I guess I'll stick with it until I notice any difference, or my mechanic tells me it's time to do something about it.

Thanks a bunch for those drawings, maybe I'll open the diffs next year and check it out.

spgull 08-30-2010 04:02 PM

Re: Got to fix this whine
I had one of the first 1999 Grand Cherokee Ltd to come off the line. Jeep had to replace 3 sets of front differential gear sets before the whine went away. I still have the the Jeep with minimal whine but no major differential problems.

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