Bronco and Cummins 4bt.... Questions

[bkd]

so I purchased my 1970 project several months ago and have been researching/ planning/ dreaming about the direction I'd like to go with the build ever since.
Currently I have a build able 302 block, stock 3 speed and manual brakes, steering. there will be lots of rust repair but I've acquired 2 damaged bronco body shells with solid metal in places I can transplant to my rig.
I'm not keen on building a 302 or 5.0..... I had a 5.0 HO efi in a Jeep 1966 cj6 and while dependable it was less than stellar in the performance department..... so next option would be a 351 which is appealing in many ways. I think for the money I can go with a 4bt however which I'm really intrigued by. I've searched and read everything I can here and spent hours on the 4btswaps.com site learning and researching. My question comes to this, if I go 4bt and run 31" tires ( or a bit smaller) can I run a auto with satisfactory results? Am I obliged to go 5 speed for performance sake? Knowing tire size and power band of the Cummins what would be a optimal gear ratio?.......... any other tips or heads up about the swap?
not afraid of fabrication or alteration so really more concerned about best/ correct setup for best performance/ mileage/ enjoyment....... thanks for any help!!!!!

 

[bax]

7004r was a factory bolt up in many 4bt bread trucks / step vans. They worked good. I see no problems. Put an atlas behind the 7004r and your golden. Your broke but your golden.

 

[bkd]

Thanks bax....... most I'm seeing are setup for Ford, how are the AOD's suited for behind the 4bt?,,,,won't be wheeling this one much so a D20 will be fine for transfer case...........

 

[bax]

dont do an AOD do the 7004r Much better application and twice as strong.

 

[kholding]

I'm interested in this as well. I know there are a few members on here who have done this swap but I'm not sure what trans they are running? So is the 700r4 probably the best auto option for our short broncos?

 

[bax]

paired to the 4bt I think it is.

 

[SSDDBRONCO]

I'm interested in this as well. I know there are a few members on here who have done this swap but I'm not sure what trans they are running? So is the 700r4 probably the best auto option for our short broncos?

So are you getting second thoughts on swapping out your motor for a 4bt??

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[kholding]

No, I'm going to keep my 351 in my current bronco. Thinking about a second bronco project.

 

[SSDDBRONCO]

No, I'm going to keep my 351 in my current bronco. Thinking about a second bronco project.

That would be awesome... but you still have to get your first one up and running

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[Pa PITT]

OK I too think the 700 4R IS GOOD trans but BAX is it not a little too long.. I'd want the Allison it may not be a OD.not totally sure. BUT I think it's the last trans needed. Mine is a NP435 but your talking auto's not Manuel ..

 

[dnewman9]

I am looking at a diesel for my truck, swapping out the 4.6 DOHC. My candidates are the 2.8 TGV, 4BT and 4BD1T. the 4BT is the loudest of the bunch, by far. I am looking at the 700R4 but I also read that it takes a fair amount to make them stand up behind the torque of any of them. From what I have researched only, the later GM transmissions would hold up better, but also require electronics.

Based on what I have looked at, the 4BD1T is my engine with an expensive, built, but no electronics 700R4 or the later.

Just my 2cents with no practical experience, but a ton of research so far.
D

 

[lowbush]

47RH is also a good candidate depending on what you are going to do with the 4BT if you are going to turn it up both the 700r4 and the 47RH need a few upgrades.

Also you might want to consider an OM617 swap, you could put a 400HP rebuilt torque monster in your truck for the price of getting a 4bt out of the salvage yard.

http://www.transmissionadapters.com/Mercedes diesel.htm

 

[SSDDBRONCO]

Check out these guys. Yes it's a jeep site but worth to take a look. They use either the nv4500 or the 4l60e (auto). Would a 4l60e fit in the stock frame of a eb?
http://www.bruiserconversions.com/jeep-wrangler-diesel-conversion/

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[Dbteak]

This is another auto trans thread for the 4bt. I remember reading a few threads on the 700r4 failing behind the 4bt but they may have been heavier trucks.

Doug

http://classicbroncos.com/forums/showthread.php?t=218635

 

[68bronco4bt]

cummins swap

do the 4bt swap you wont regret it...i used a nv4500 but thats just because i like to shift gears 37 inch tires 3.54 gears

 

[lowbush]

This is another auto trans thread for the 4bt. I remember reading a few threads on the 700r4 failing behind the 4bt but they may have been heavier trucks.

Doug

http://classicbroncos.com/forums/showthread.php?t=218635

I don't recall the 700r4 being installed behind a 4BT on anything from a factory (I could be wrong) I have always found them sitting behind a TH400, that being said the 700r4 was behind the 6.5 diesel in the old Suburbans and it holds fairly well. But it's always a good idea to upgrade the 700r4 while you have it out, especially the sun gear. In stock form the latter year r4's where decent but the early years had some more glaring weak points. Later years are electric while early years where hydraulic (so you end up having to do mix and match parts on the later ones anyways). Personally I always rebuild them while I have them out and do the upgrades. If you plan to do the upgrades you can buy the older less desirable 700r4's and save a couple bucks.

 

[4BTEB]

I am running a t19 behind my 4bt, it came with the engine, no overdrive, 34" tires and 3.50 gears and plenty of power to spare. It'll run at least 75-80 on the hwy. I am getting about 19mpg.

 

[ET]

IMO. With automatic, stock gearing will work with 31" tires. You'll want overdrive and a 3200k rpm spring.

Eugene

 

[bkd]

all good info guys....... keep it coming

Pros and cons to the swap?
ease of adding PS/ PB/ AC
How about the Allison trans, suitable for a EB? able to mate to a transfer case?
Any other options I should look at, consider?

 

[4BTEB]

pros... great power and torque, great fuel mileage, it just keeps going forever, very upgradable, burn many alternative fuels, etc.
cons... very heavy, a little louder than a v8
power steering and brakes is fairly easy, they have gear driven p/s pump, I went hydroboost brakes easily, 4 wheel disks and stops really well.