Hey everyone, I am new so please be nice and merciful on my stupid question. I would like to get a full size Bronco and get a 4bt conversion, I want a full size truck with 4x4, automatic, that gets above 25mpg,ac & can pull my pop up camper. This will be a dd.

My question is this. What is the most cost effective way to do this?

With the cost of adapter plates and transmission controllers for auto trans with 4/5 speed I was wondering would it be easier/cheaper to use a Dodge 767 trans with Dodge transfer case and cut down drive shafts?

 

Not to ruin your plans but you will be much happier if you swap in a 6bt. The swap will be cheaper especially if you purchase the entire donor vehicle. The 4bt is a great motor but I dont think you will be happy with the power, my buddy put one in his 84 bronco it went ok but forget pulling a trailer unless you are planning to do some serious power upgrades. Needless to say he sold the 4bt (p-pumped) he bought an entire 1995 dodge 12 valve for what he sold the motor for. Also I would recommend getting a p-pumped motor whether it be a 4bt or 6bt. My recomendations (what I did) I got a 97 12 valve (215hp but any 94-early 98 will do) with a nv4500 5 speed. I did mine piece-meal, bad idea, depending on your abilities and what you find a truck for you can do everything for around $3,000 however this number can easily triple or more depending on what you can do. You need to remember all the little things that will add up like intercooler, radiator etc. If you want standard go with the nv4500 for a cummins, if your going auto it really doesnt matter.

 

What year of Bronco were you thinking of using? The 80-96 all used Fords TTB(Twin Traction Beam) system front axle based off the D44 Center section, and can be prone to lots of issues if abused and not maintained. The 78-79 used a solid axle D44 front. I agree with oldmansimek and highly reccomend getting a complete truck with the 94 and up P-pumped, A VE pump is not for everyone.

I have a 79 F250 I put a '90 Cummins in and love it! I bought the donor truck for $2500, took it home and stripped the parts off I needed witch was nice cause I didn't have to run all over looking for them at wreacking yards.

There are a lot of things that go into a swap that you can overlook. To start, if you live in an area that gets below 40°F you might want to get the relays and wiring for the intake grid heater....ect.

The 4BT weighs just a little more or less than a BB Ford, The 6BT depending on the gen weighs from 950lbs and up to 1100lbs+. Don't hold me to the numbers, they are close but not exact. As far as the Dodge T-case Im no expert but I believe the are all passenger drop(front output to axle) where Fords need the drive drop. I got around this because I had a divorced mount np205 that a friend gave me. I mounted it right behind the NP205 on the Getrag 360 trans(really wish I had an NV4500!!) That helped me with the front drivline angle problem I had from the 6" lift.

I don't know your skills or trades, so depending on your mechanical ability this can be a huge PITA or a fun weekend project......If I can help in any way let me know. HTH

 

Thanks for the help! I was really hoping to do the 4bt over the 6bt for the mpg. What kind of mpg are you getting with the 6bt?

I did see one 6bt Bronco build where the guy used his stock axles on a 96 Bronco( I believe) and he was not having any issues.

I am looking at having one of my jiu jitsu students due this for me, he is a mechanic, I am good at arm bars But I would like to have a plan and start collecting things I need.

 

IMO If you want a 4bt, then get a 4bt. I have settled for less then what I wanted in my other hobbies and was not truly happy with all of them. If you can source a good deal for a 4bt, I'd say go for it. Keep in mind that a lot of the componets will swap over from the 6bt to the 4bt, some will not. The main reason I say go with a used truck donor is the ability to see where everything fits and having parts nearby that you may need but didn't know you needed.

As for my milage, I get 11mpg with my 37's and 4.56 gears. With 3.54 gears and 37's I got 16mpg pulling 10k. Your resualts will vary, You have less weight and if you dont tweak the pump too much I think you can get 20-28mpg. Some may call BS on me for this, but my friends 89 W250 gets 30mpg!! I know because I borrowed it for a bit one week when I was working on mine.

I dont think it will be a big problem, I'm just saying to be mindful that the TTB system is higher maintaince system. When you go Bronco shopping look at the tires and all the steering componets, and suspention busings. If anything looks worn, replace it. Believe me, death wobble is no fun!!

It's Always good to have friends to help you out!! My swap would have taken a lot longer without some help from my friends who were already running diesels!

 

+1

The 6BT and 47RH is quite ideal if you want an auto. Keeping the the power down will keep the mileage up, and the auto won't need to be built to the hilt.

 

If you do decide to go with the 80 and up full size, there is nothing wrong with the ttb front end you might need heavier springs but you would need the same for 78-79. Also the bronco I previously mentioned was getting about 15 mpg with the 4bt he now gets on average with the 6bt 24mpg, he gets almost 30 on the highway. And for some reason the 6bt is about half as loud in the cab.