I picked up my fluids and filter for my tranny fluid change on my '03 with a 42RLE. I checked with two dealers and even talked to one of their mechanics. They said there is no pan gasket for the 42RLE. They said it calls for RTV. I could have sworn everyone said I need the pan gasket. What's up with that?


Also I picked up a bottle of friction modifier for my rear diff. It's a 4 OZ bottle. Can anyone with a service manual verify that I need all 4 ounces? For some reason I remember reading somewhere I needed 2 ounces.

Thanks!
Doc

No gasket listed in the Parts Manual and yes, the 8 1/4 should use all 4 ounces of the additive.

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#074642

I think it depends on whether the fluid you use already contains friction modifier material. In my case, I used a Schaeffer blend oil that has FM already. I found though that there still was some grabbing or unsmooth operation, so I added some aftermarket FM -- maybe about 1-1/2 ounces.

In the last 2 weeks I have just replaced the fluid recently again. This time I have not added any additional FM, and it seems OK without.

I'm probably going to use the Mobil 1 gear lube. The Mobil 1 web site says that it does have friction modifier in it, but if the highest level of limited slip performance is needed that the OEM friction modifier should be added. So I'll probably go ahead and give it a full dose.

Another question. Anyone know why the front diff calls for 75w140 synthetic while the rear calls for 75w90? It seems to me that in normal driving (2wd pavement) that the rear diff would be under much more load than the front.

I think it has to do with the gear drag and related vibes. since synthetic is generally thinner in relation to dino lube, it doesn't affect the driveline as much. The 8 1/4 rear has been using the same fluid in it for close to 40 years.

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#074642

Yeah, I'm actually going back in tomorrow to have the shop RE-RTV the tranny pan since it's started leaking around the edges. They said there's no gasket.

JP

Well after doing some more reading on the subject I found that friction modifier makes the gear lube more slippery. Too much friction modifier makes your limited slip act like an open diff. Too little friction modifier makes your limited slip clutches chatter.

So since the Mobil 1 gear lube already contains some friction modifier, I probably won't add any of the mopar friction modifier unless I get clutch chatter. I'd hate to add the full bottle of the mopar modifier and end up with effectively an open diff.

My manual strongly recommends using synthetic 75W-140 in the rear if you tow. The limited slip works best if you add the friction modifier even though the synthetic already has some.

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June 2001 Liberty Limited 4X4
Frankenlift II Premium, Al's Upper Arms, 245/75R16 C Silent Armors on Moabs, RL Skink Super Sliders, Rear DTT, Riddler Diff Cover, Fastman Throttle Body, Profinish-Proglass Hood, Borla Dual Outlet Exhaust, TransGo Reprogramming Kit, APS Stall Converter, 4.10 Gears, B&G Chrysler PCM, Lots of Line-X, etc...

The dealer seems to love RTV. I personally hate it. I always end up with some kind of leak. However, I've never had a problem using a gasket. You can find gaskets if you look elsewhere besides the dealer, which I recommend.

You can get a rear diff gasket at just about any auto part store.

BTW, Detroit Doc
I have an extra pan gasket and filter for the 42RLE if you want it. The kits cost about 20 bucks, I'd let it got for 10. PM me if you are interested.

Thanks for the offer Eddo but I just finished changing all the fluids. I used RTV. I'm keeping my fingers crossed.

The only problem I ran into was I didn't have a torx bit to get the filter off. I had to run up to the store and pick a set up.

I'm waiting for the RTV on the trans pan to set up before I dump the ATF back in.

RTV is used by the dealer because that is what Mopar specifies for the job. It is important to note that there are different types of RTV for the different applications. You should use ATF-RTV (P/N 5010884AA). There is also Engine RTV, Axle RTV and Silicone Rubber RTV for other applications.

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#074642

Elwenil-

The dealership sold me RTV that said it was Engine and Gear RTV. I used that for the diff, but suspected it might not be the right stuff for the trans pan. So I picked up some Permatex Ultra Grey RTV which said on the back it was recommended for trans pans.

You should be good to go with that. The axle stuff I don't quite understand myself, but appearently DCX has issues with using the same stuff all over now.

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#074642

I am going to do my differential fluids tomorrow. I am wondering if I should use the Mobil1 syn or the Mopar fluid. I have the Trak-Loc and know I need to know if I need the friction modifier or not.

Here is what I am thinking. Go with the Mobil1 and FM from Jeep. What Mobil1 should I use?

2002 Jeep Liberty Sport 3.7L 4x4 Offroad/tow pkg.

Also what RTV should I use?

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02 KJ Sport w/ tow group, offroad package.

Barto,

I ended up going with mobil 1 75w140 front and rear. You do not need to use friction modifier with the mobil 1 lube. If you want to save a few bucks and you aren't towing you can use mobil 1 75w90 in the rear.

Yeah I tow a few times a year, got the trailer brake controller installed so I will go with the 75w140. Thanks for the quick response, much apreciated.

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02 KJ Sport w/ tow group, offroad package.

Changed it out today. Everything went smooth and no leaks (yet). Front diff was way easy even with taking off the skid. The back kinda sucked since I didn't have much room, but nonetheless its back together.

One thing I noticed is that the Engine skid is a bit damp with oil. I just got it changed at a quick lube and I am hoping they were just sloppy. It is all wet and the axle that goes to the transfercase seems wet as well. Any body see this before.

-BTW: I live in Fowlerville, MI. Thought I would let you know Detroit_Doc.

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02 KJ Sport w/ tow group, offroad package.

my manual doesn't say to use 140 in the front, it just says Mopar gear oil and it mentioned to use 140 in the rear for towing. Where is everybody coming up with the fact the front needs 140?

My service manual sez so. You can use 75W-140 syn. in both.