That is correct if my memory serves me right

 

That is correct the 4cyl came with 4.10s, great build up looking forward to some more pics.

 

Actually the 2.5L 4 cyl with the A904 automatic came with the 4.10 gears, and as far as I've been able to determine, it was the only model XJ that did. The 2.5L 4 cyl with the 5 speed came with 3.54 gears - as did the 6 cyl with the auto. The 4.0L with the 5 speed did come with 3.07 gears and so did the MB 300D automatic.

HOWEVER, the AX-15 is a 5 speed with a 3.83 first gear, a 1:1 fourth gear, and a .79 OD 5th gear. The MB722.3 automatic tranny is a 4-speed and has a 3.68 first gear and a 1:1 fourth gear. So the AX-15 has a slightly lower first gear, but a significantly higher high gear (5th). That's why 5th isn't very useful - its out of the range of the powerband of the motor.

The other adjustable factor is the tire size. The stock tires on the MB are 195/70/14"s - roughly 25" in diameter. The stock tire size for the Cherokee is 215/75/15"s or 225/70/15"s - roughly 27-1/2" in diameter.

The slightly lower first gear of the AX-15 will just about compensate for the larger stock tire size, and let the engine use 5th gear under flat smooth highway cruising conditions only. With the 33"s and stock 3.07 axle gears, 5th will be useless and even the lower first gear of the AX-15 isn't enough to give you the same acceleration in the Jeep as what it gave in the MB 300d either.

Put some 3.54 axle gears in it and 5th still probably isn't going to be very useful with 33" tires. Maybe with a set of 30"s or 31"s, but not with 33"s.

I think you pretty well hit the nail on the head. The only way you're going to get to the point of making 5th gear really useful is with a set of 4.10s...

 

I have 410's and 30in tires, the tallest tire I belive you can use with this motor, gear,and od. I an toying with switching to a 29in tire to get it in the "sweet spot" more often. I am finding that in 5th and locked up down the freeway, anything below 60 and it will bogg down and want to downshift. It really LOVES 70+ and doesn't even start to run out of power above 90. So I think a set of 235-75 15's would be perfect, and I think my mileage will go up as well(it's @ 25+ mixed running hard)

 

2.1 Diesel came with 4.10's too. And possibly some cars with towing package or off-highway package.

Seems normal for the 5th not to be useful compared to 4th in the Mercedes. It's overdrive, a more honest comparison would be with 4th in the ax15.

Ignoring the difference in gearbox ratios, going from 25" tire and 3.07 to 28" tire on the Jeep, 3.54's would be a good match.

 

Don't worry about the gears.
There are some Cherokee Diesels with 31' and bigger tires rolling around in germany. Of course you will lose a bit of bite. But you won't recognize after a while getting used to it. Most drivers with 4.10 claim to loose to much mpg with too small tires on the Autobahn. so 31 and bigger will be fine.

 

Correct me if I am wrong, but those euro Cherokee's aren't running OM617's, so they may act a little different. No way could I get away with anything larger than 31's unless I was planning on driving 80+ all the time!

 

Hmmn, according to my research the 2.1 diesel came with 3.55s too, but since I've never actually seen one so I can't say for sure. They are so rare that they aren't even worth talking about anyway, since finding one is almost impossible. There was one engine/tranny combo that came from the factory with 4.10 axles - the 2.8l V6 with the manual tranny - also a fairly rare combo.

Yup, I agree with that.

 

Here are some updated pictures. We need a paint job now. We have 3 more sets of adapters being made and 1 commited.




We are working on technical page on website to assist others in conversion. See web site OM617 Mercedes Diesel Conversion Jeep Wrangler YJ Engine Adapter Swap by next week.

 

Very nice!!