Best trans and trasfercase combo behind a Cummins 4bt

[GoldenEagle36]

Ive been kicking this idea around for a long while now...... i want to put a Cummins 4bt in my dads Tj (since it has 226,xxx on the old tired GM 151 ) and i just want a beast of a Jeep. anyway, what would be the best combo behind it? if i do follow this build up, i will keep the stock axels, and just get new driveshafts. but im looking for ideas, manual or automatic, and transfercases. i greatly appreciate it guys, ill always love this fourm site

 

[Busted Knuckles]

There is a website, on 4BT swaps, you might do some reading there, Ive considered the swap, did some back ground on it, and a common denominator on the 4BT supposedly, it shakes terribly. Not sure if the proper mounts are not being used, or if its just the stroke of the motor, physics, anyhow, Ive read that time and again.

Ive got a 6BT in my pickup, with 410k on it, runs like a top, and its all original, so Im not knocking the motor, just what I read. Consider that a Caveat on the swap, as far as I know, there are no real other "down sides".

Personally, when I think of trail "crawling" or moving at low speeds on a trail with the top off, or half doors, windows down, or what have you, the thought of choking on diesel exhaust does not excite me. Ive got 7.3PSD, a 6.5 Turbo, a 7.3L IDI, and the 5.9 cummins, so Im in the diesel camp, but cant bring myself to put one in a trail rig, even if its a part time trail rig.

Id agree that torque is where its at, for wheeling, and the fuel efficiency would be great. But the shaking and smell, keep me at bay.

Good luck if you take it on, if neither bother you, I dont think you could find a more ideal set up to build.

If I was going to do it, Id get a NV4500 out of a Dodge Truck, and swap a Dana 300 behind it.

 

[3QuarterTon CJ]

I'd get the 4BT out of a retired bread van, They are plentiful here in PA. Plus they have the adapter on the engine already to run a Chevy Transmission .

I installed one in a customers Jeep TJ, I used the bread van engine and adapter, then put a 700R4 Overdrive automatic behind it with a S-10 Transfer Case . This way we didn't need to spend extra money for adapters and whatnot. We used a console out of a upscale S-10 blazer with the console mounted shifter, that mated perfectly with the 700R4 Transmission , and the Transfer Case shifter obviously didn't require much modification to work either.

He mainly wanted a commuter vehicle with good mileage, and still keep his Jeep a 4x4. So that's why we went the automatic route. Yes it did shake the TJ pretty good, mainly just when it was idling tho. I used first gen cummins engine mount brackets with the poly rubbers in it, so maybe the poly mounts made it a little stiff and shaky.

Good luck with the swap if you do tackle it, just take your time and don't rush it, and it'll all work out just fine as many people have done this swap with great success.

 

[GoldenEagle36]

i was actually thinking about taking a 4bt out of an old case skid loader, but like you sad i would need to buy some adapters for the Transmission i want to put behind it

 

[ken98k]

Personally, when I think of trail "crawling" or moving at low speeds on a trail with the top off, or half doors, windows down, or what have you, the thought of choking on diesel exhaust does not excite me.

I thinking the folks in the next couple jeeps behind won't like it much either.

 

[Tubediesel]

I am working on this swap myself. I have done lots of research and have gathered lots of parts trying to make sure I do things only once I want to have all the parts at hand.

The things I have found are yes they shake a lot at idle, the bread van I have has fluid dampers and this seems to help tremendously.

The Transmission adapter and flywheel is where guys have the hardest time. The 4bt comes in such a wide array of vehicles, including the CONSTANT rpm model in the tractors. This constant rpm is not conducive to throttle response as the engine is designed to run at idle or against the governor. With so many transmissions (sae bell-housings chevy bell-housings and ford too) it's hard to find the right conversion parts and the trial and error is very expensive. Destroked.com sells a conversion kit for around $1300 for the flywheel and bell-housing adapter. So you can see the rest of the parts will only add.

My recommendation is get a running driving machine and take EVERYTHING. sell what you don't need after your jeep is complete.

Also there are 256lb-ft of torque available as you release the clutch so Dana 20 or 30 axles don't live very long behind the 4bt.

 

[Tubediesel]

My jeep is a 1970 Jeepster Comando with full width Dana 44 from 1982 grand wagoneer detroit locker in front and aussie locker out back running 5:38 gears 300m axle shafts and adjusted 102 inch wheelbase.

I have removed the factory Dauntless Buick 225 V6 oddfire, GM Turbo 400 and Dana 20 Transfer Case in preperation for the 4BT.

it will have the 4bt followed by the ranger torque splitter and sm465 (yes 8 gears forward 2 reverse!) then following all that is a twin stick Dana 300 . The whole running gear is shorter than stock.

The tires are H-1 beadlocks adapted to the Waggy 6 lug pattern, and the h-1 37x12.5 goodyears.

 

[Tubediesel]

I thinking the folks in the next couple jeeps behind won't like it much either.

Just convert the thing to biodiesel and it will just make them all hungry for fried chicken or donuts!

 

[adamkuhle]

Ive been kicking this idea around for a long while now...... i want to put a Cummins 4bt in my dads Tj (since it has 226,xxx on the old tired GM 151 ) and i just want a beast of a Jeep. anyway, what would be the best combo behind it? if i do follow this build up, i will keep the stock axels, and just get new driveshafts. but im looking for ideas, manual or automatic, and transfercases. i greatly appreciate it guys, ill always love this fourm site

What axles do you have on it? If you plan on doing some heavy off-roading, that much torque behind weaker axles will just shred your differentials