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?

I started with a square plate. Then I drilled a 1/4" hole in the center of it. I had the trans with the converter in it sitting on the tailshaft. I laid the plate on the trans bellhousing and lined up the 1/4" hole with the center of the torque converter. (it had a lathe centering dent). Once it was lined up, I marked the bellhousing holes with a pencil. Then I drilled the bellhousing holes. I did the same with the back of the engine. Lined up the hole in the plate with the center of the crankshaft. Once all the holes were drilled, I cut the center of the plate out. I checked it several times during the process, it was right on the money. I drilled the holes just big enough for the bolt diameter, so it would not move much.

John

Not nearly as far as I'd like to be.

I've finished the trackbar (a.k.a. panhard rod) bracket, and reinforcing the frame where the motor mounts bolt in.

I'll be putting the finishing touches on my cross member/motor mount/engine cradle assembly this weekend.

I have about half of the custom exhaust manifold pieces made, and finishing them and getting the maifolds welded up will be next on the list - followed closely by the custom Y-pipe for the exhaust.

Then comes all the "little" stuff. Adapting the tranny mount, plumbing the vacuum stuff, doing the electrical, finishing the cooling system, modifying the rear driveline (if necessary), shifter for the tranny, etc., etc., etc.

Once she's road-worthy and I get to drive it and enjoy my work for a little while, then I'll be adding the turbo...

Was reading this thread and there are a few optical tachs out there that count flywheel teeth and Dakato Digital also has some items that may help as for as tachs or concerned . I used some of there other items to make a mechanical speedo drive run a digital dash on another conversion i did .

I like the idea of the Dakota Digital box, but I've heard it's pretty slow to respond. Any info on opticals would be greatly appreciated...

The way I did it was to use a stick bell, fab a pilot using plate with pipe welded to it then trued up on the tathe. It worked great! How much did you have to lift your jeep? I set the motor in to fabb mounts and it looks like it needs some. I saved the front coils from the benz, they look about the same size only larger wire.

Cool, how bout some pics! I'd like to see something different. Did you have to do a lift? Looks like I will be doing some major mods to get the steering issues sorted out.

I haven't taken many pictures yet, but I will be on Saturday. Stay tuned!

I'm going to build it with a removable Y-pipe that can be easily swapped for one that brings the exhaust from both sides up behind the motor - between it and the firewall - so that I can easily install the turbo later.

Got it all planned out...

I did not lift the Jeep. The engine sits high in the engine bay. It's going to need a hood scoop to clear but the hood does close,and the axle would hit the bump stops before it hit the oil pan.

John

I will try and find it again but for now look up tiny tach and this tach

2-1/16" 4K Universal Electronic Tachometer

http://www.egauges.com/pdf/vdo/0-515-012-037.pdf

Good info Cbum - thanks...

Try this an look under install if it fits your needs

Stewart Warner Performance

Thanks for all the links, very helpfull!! What project are you working on?

The begining stages of putting and lbz Duramax speed allison and all that goes with it into a 76 ElCamino

SWEET!! I'd like to see some pics of that!

Not much to see right now just got the donor stripped down and will get to stripping the Elky here shortly have the engine and tranny out though

I will start thread on it not to hi jack this one any further

Making a little progress! Here is my bell adapter and all bolted up. Next is the motor mounts, just trying to figure out the best mounts.

Nice!!! Looks like everything lines up nice!!!

VERY nice! Looks like you welded in one a couple of the studs at 11 a 4 o'clock...

Yea, I started the adapter by locating the allignment pins and them welding to the plate before drilling the holes (benz side). Then used the allignment tool I made with the stick bell, located and welded the GM dowels before drilling holes. After everything was done I re-checked with the allignment tool, perfect!

Good job!! That trans aint' going anywhere!!! I think your the first person to use the dowel pins on your adapter plate, smart. Did you figure out the motor mounts?

John

Thats what I'm doing now. I thought about using the stock benz mounts but as you found, they are a little to wide so I am going to fab my own brackets and possibly use the jeep mount. We'll see! I plan on setting it a little lower than you did as I will lift it to get clearance, and figure out the steering later. I think I have a few optins. Hopefully I can make some progress tomorrow!

thats some nice work on that adapter! :D gonna try and get a 6.2 TC so it keeps your rpms down? im sure it'll work well either way.

Thanks! According to the code on the converter I have, the stall is 1650. Seems like it should be about right, I guess we'll see!! BTW have you gotten your truck on the road yet? If so, what kind of fuel milage have you seen?

Progress!!!
 

Making progress!! Here are some pics of the motor mounts, they are the same as used in the 4bt bread vans. They worked out well. I decieded to forget about the benz mounts (too soft) and the pedistals put the mounts too close to the upper controll arms, so I made new ones. The motor is in, hopefully to stay, now the trans mount.

More Progress!!
 

Well I got the motor, trans& tc in, and with the stock springs it sits 1in lower than stock. This puts the pan 1in from the diff, so a lift is in order. I saved the ft springs from the benz, this gives 6in lift-too much! So after a few trials, I ended up cutting off 1 1/2 coils to give 3in of lift. Now for the steering issues!

I like the frame rail stiffeners for the motor mounts. They look pretty familiar...

Doing some nice work there man. Is the pan going to interfere with your steering? I remember that was one of Benzer1's big issues....

Thanks, so are you. I am in the middle of re-engineering the steering to clear everything. I am using a ps box from a 78 F150 2WD. It has 8 more in of drop from the pitman shaft than the jeep box. So far it looks real good, plus it gives me more room for the radiator. The horizontal portion of the box sits on top of the frame rail instead of beside like the jeep.

Looks good!!! I remember you mentioned this before, good idea!!


John

Hi John, how is yours coming along? The F150 box is looking real good, I should be done with the swap today. Still working out the trac bar and crossmember, but it looks great! The steering rods are near level with 3in of lift using the new box. I made bump stop extensions as well. I'll get pics up as soon as I can.

I got a new front seal for the trans, going to put that in today. I need to bolt the trans and transfer case together too. I would like to see the pics of your steering setup when you get it done, I will probably do the same thing to get rid of the hillbilly pitman arm. I used socket head capscrews for the flywheel bolts, they stick out too far and touch the new torque converter. I ordered new factory flywheel bolts, as soon as they come in, I will change them and start putting the trans and transfer case in. The 700r4 and it's case are almost identical in length to the 904 and it's case, I'm still hoping the factory Blazer driveshafts will work. I need to get a hood scoop too. Yours is coming along nicely, good job, it all looks professional!

John