I have a few questions regarding regearing my XJ. I have a 98 XJ limited 4.0L, auto with 4.5 inch lift and currently running 32's. I have the HP Dana 30 and the Chrysler 8.25. I was doing some reading about gear swaps and found a few things I was curious about.

1) I recently discovered that the carrier needs switched on the Dana 30 if it has 3.55 gears. I have a XJ limited and do not know if that is the gear ratio, how do I find out?

2) I'm looking to go the cheapest route, so I will probably find a carrier at the junkyard. I read that YJ's with 3.73 gears have the carrier I need. What other vehicles will have a carrier that I can swap into mine?

3) I am buying tires soon, so I was also curious what size would be better for the 4.56 gears that will be swapped in the future. I am down to BFG km2's 33x10.5 or cooper discoverer 32x11.5. I am choosing between these because I don't want to go to wider since I don't plan on trimming fenders.

Any feedback would be greatly appreciated, thanks

 

1. Take your VIN to a Dodge/Chrysler/Jeep dealership and tell them you want the printout of the build sheet from the factory.

2. No clue

3. from what i've read if you go 33 you'll want 4.88's, 32 you'll want 4.56...but i'm sure I could be mistaken, so others will have to comfirm or debunk my findings LOL

 

should have a small tag/plate on the diff bolts stating the gearing inside. or pull cover and start counting teeth on ring n pinion.

X2

X2

 

if you plan on offroading at all with 33s you will have to trim your fenders 33s will not fit in stock wheel wells

 

You can also email Chrysler your VIN and they will send it to you that way. I did that and had it in a couple of hours.

Most of what I've been reading, people say that if you go 33's, you'll want 4.56's at least, and 4.88s are good for 35s but the pinion for the D30 on 4.88s is very small. I have no experience with either but was planning on going with 4.56's with my 35's when I get them.

I think it's pretty safe to say you have 3.55s if you have an automatic. 3.07's if you are manual. Also, this is the first I've heard that a D30 with 3.55's will need a new carrier with a gear change. Can anyone else confirm that?

 

Yes, you will need a 3.73 and up carrier

 

I do plan on doing some off roading, but I was under the impression that I would not have to trim the fenders if I added the proper amount to the bumpstops. Will that not work?

 

I'm told: 4.56 if you plan on staying at 33. 4.88 if you plan on going with 35s in the future

 

That is what I heard as well. I plan on staying in the 32-33 inch tire range, so I figured 4.56 would be the way to go.

 

I have 33's with 3.55's. I'm only going to go up to 4.10's. 4.56 and higher will just murder my fuel mileage.

 

false

 

Maybe not 4.56, but 4.88's won't be gas friendly.

 

where did you get that chart. what speeds are those RPM's recorded at. I have 33's at 4.56 and I definitely dont cruise at 3000rpm

 

Man, now you're testing my memory. I cannot who posted it. It was posted just a couple of weeks ago. I think it's from quadratec.

What are your RPM's at say 65mph?

 

Found it, Morris 4x4. Doesn't give any details.
http://www.jeep4x4center.com/calculators/index.htm