86 Cherokee OM617/700R4/NP231
 

Ok, I finally got started on the conversion. Picked up the Jeep for 350, drove it home and sold the 2.8/TF904/NP207 for 300! Bought the 300sd and parted it out and hauled the rest for scrap, 100 more than I paid! Free motor and then some. I took the benz t-converter and cut it in half to use as an adapter. Hopefully I can get the pics up. Working on the bell adapter next.

Good Job!
 

Nice Work!!!! That looks nice and beefy, should hold up well.

John

N-I-C-E-! Very clever idea to make your torque converter adapter out of the front half of the MB converter! Did you have to ream the inside of the pilot of the MB converter shell to make it fit snuggly onto the pilot of the 700R4 torque converter?

To give you a comparison of what to expect, the Jeep's curb weight is roughly 3450 lbs. Unless it has the towing package with the D44 rear and 4.10 gears (pretty rare) it will have a Dana 35 rear end with 3.55 gears. The 700R4 has a 1st gear ratio of 3.06 so your final drive ratio in first gear will be 10.86:1 and the stock tires are I believe 225/75/15 - roughly 28" in diameter

The SD weighs in at around 3700-3800 lbs. It will probably have 3.08 rear axle gears and the 722 tranny in it has a 3.68 low gear, so your final drive ratio will be 11.33:1 and I think the stock tires are 195/70/14 - roughly 25" in diameter

So you'll have about a 4% lower final drive ratio turning roughly 14% larger diameter tires. Bottom line, you'll have about 10% less low-end acceleration.

On the upper end the 700R4 has a .77:1 overdrive vs. the 722 having a 1:1 4th gear. So your final drive ratio in 4th gear would be 2.73:1 in the Jeep vs. 3.08:1 in the original MB setup. That's about a 13% reduction in RPMs which when combined with the 14% larger tires gives you a total of a whopping 27% RPM reduction at the same speed. Really good for fuel mileage IF the engine has enough power for it to hold 4th gear when cruising. If it doesn't have enough power to hold 4th and its constantly downshifting to 3rd (which is 1:1 ratio in the 700R4) the OD won't help much with mileage - because in 3rd your final drive ratio will be 3.55:1 - 15% lower than the MB - which with the 14% larger tires makes it pretty much a wash.

If you have the 4.10 gears, or even can get a set of axles with the 4.10 gears, that would be ideal. That would make your final drive ratio in first gear 12.55:1 - almost 11% lower than the MB. A much better match for the 14% larger tires - you'd only loose about 3% on the low end - hardly enough to even be noticeable. Your 4th gear final drive would be 3.16: vs the MB final drive ratio of 3.08:1 - 2% lower, but with the 14% larger tires you end up with a 12% reduction in RPMs at cruise speed. Not quite as good for fuel mileage as the 27% reduction of the previous example, BUT you'd certainly be able to spend a lot more time in 4th and probably end up with a net improvement in mileage.

My Jeep that I'm doing the 4.3L V6 Olds diesel/700R4 swap into has the 4.10 gears. I'm hoping that its going to work out just like the 4.10 gears example above...

Thanks for the words of encouragement! John, the benz t-conv is 1/4 thick, plus tough (had to use a carbide bit to turn on the lathe!!) I welded a bead up on the inside to turn out a pilot for the GM snout. I have the 12in t-conv with the large snout, bigger than the benz snout, so building up with weld and turning down was the only option. The second pic shows the weld. Thanks Cheeper, I got 410s

AWESOME! Let me know how those 4.10s work for you - assuming you get yours on the road before I'm able to drive mine. I'm prepared for anything OTHER than the 4.10s not being low enough. I have sets of tires in 30", 31" and 33" diameters to try and I even have a set of 3.55 axles to swap into it if the 4.10s turn out to be too low...

Yea, I plan on getting this on the road before too long but it took twice as long to part out the Benz and haul the hulk away than I told my wife!! She is pretty cool, but between her the kids and o-ya my JOB, time flys by. It always seems to take longer to these projects than we think! Although I do get alot of engeneering done in my head on my projects while I'm rolling down the road! P.S. My neighbors think I'm nuts!!

When I tell people about my diesel Jeep project, they usually say "why would you want to do that" How do you plan on doing the starter. Put studs in the factory engine plate?

John

The Benz starter bolts from the back, so I am using shorter bolts through the bell adapter and lucky for me the bell on the 700r4 has a huge access below the starter, enough to get a wrench in there. In other words the starter wart on the trans is lower than the Benz starter. Also the bottom half of the trans bell comes off. Yea none of my neighbors work on their cars, I guess I'm a little too "redneck" for the neighborhood.

Yeah, non-gearheads have trouble understanding the satisfaction of driving something you built yourself! I make biodiesel too ,and a couple of my neighbors are worried I might blow up the house!!LOL!! I forgot that the 700R4 is open at the bottom. You will have an easier time hooking everything up that way. The bellhousing on the 904 is sealed ,so it was tricky getting everything lined up. What type of metal and what thickness are you using for the bell adapter?

I am using 3/16 steel, that is the space I needed to make up for proper t-conv clearance so steel was the only option for strength. I ended up not having to alter the stock flywheel cover, so this will be a total no-mod adapter. In other words GM from the plate back and Benz from the plate foreward. BTW how did you get the proper center line on your plate?

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Yea, I plan on doing alot of tire swaps till I find the "sweet spot". I think the lock-up will make the difference on how it will perform. How far along are you?