I was looking through my old posts and came across this one. I stated that I switched from 3.21 to 4.56’s. I actually at the last minute changed my mind and ordered the Yukon 4.88’s and a TrueTrac. They’re amazing! Pulls like crazy, no downshifting on hills. RPM’s are in the 2600 range at highway speeds. Cost me about 1 to 1.5 mpg’s depending on how I drive it. I’m averaging between 16.5 and 17 consistently under normal driving conditions. I know this probably doesn’t matter much, but it just bugged the crap out of me that the information in the post was wrong! Anyway, at the end of the day I am thrilled with the 4.88’s and if I do decide to move up from 33’s to 34’s or even 35’s I’m geared and ready!

 

The 4.88's are really in their sweet spot with a true 35 inch tire. So if you do go up in size, you won't be disappointed.

 

"The first time they drove it the tech said that he couldn’t hear anything and," I just cannot believe how many deaf people work at dealers!! Must be a benefit to the dealers to save on shop hearing protection.

 

FWIW- TrueTracs don't always work well with synthetic gear lube. Anytime a customer had a noise with a Truetrac we could pin it down to the gear lube. We always recommend Lucas 85w-140.

 

Digger,

Thanks for the comments and you are absolutely correct! Let me say, I had one heck of a time getting a “recommendation” on lube from Eaton! After lots of time and many emails to various people at Eaton and lube manufacturers I had all but given up, then I got an email from Eaton recommending Mobil Mobilube HD Plus 80W-90. I verified this through Mobil as well. Both were in agreement that this lube had everything my TrueTrac needed and nothing it didn’t! I never dreamed that it would be that difficult to find the correct gear lube, but my patience paid off. I know that “most” non-synthetic gear lube would likely suffice, but I am somewhat anal (my friends say very) about vehicle service and maintenance and I do not put just anything in my vehicles! This was an expensive project and I was more than willing to spend the extra time getting the proper lube rather than ruining everything and having to replace the gears!

By the way, if you want to give it a shot Summit has it.

 

I agree! I did the swap with that in mind. I just put 285/7017’s on not too long ago, so it may be another 12-18 months before I step up to a taller tire but even with the 285’s the Jeep doesn’t seem to be “over-revving” at highway speeds. Soooo much more fun than when it had the 3.21’s!!!!

 

My factory unit came apart in pieces at...not sure...but when I cracked the diff at 26k miles, the bottom was full of broken teeth. I was only running 32.5" tires at the time, and the Jeep was not used for anything serious off-road (fire roads and such). The factory LSD is a steaming plie of dung. I talked to my local Jeep shop, and they said it was common to find broken teeth from those units.

I had a Yukon Dura Grip installed. It does not chirp the tires in a parking lot when dry. It the wet, it will lock up when pulling out and getting on the gas, so I disable the traction control. It is quite a bit more aggressive than the factory LSD but still has great road manors once you get used to it. Be careful because some LSD's have a different model depending on how much gear you are using.

 

For the oil I would use the selected viscosity spec in full synthetic.

 

I’m a believer in full synthetic products too, especially AmSoil, but Eaton says “No” to using it with a TrueTrac.