4bt Bronco Build

[dantheman222]

I decided it was time for me to post up about my build. I have been working on it for about a year and a half but I am in school so I have been working on it mostly over christmas and summer breaks. So here goes:

1974 Bronco
4bt Cummins
Mazda 5spd from F150
3" body lift to clear motor
Cut F-150 coils
NP205 T Case w/ Twin Stick
F150 front disc brake conversion
Hydroboost brake conversion

It was a disaster of a truck to begin with. I think I ordered ALMOST every possible replacement panel, including full floor pan set, rear bed floor, tail light panels, grill, front inner fenders, front wheel housings, rear wheel wells, inner and outer rocker panels, rear quarter panels, tailgate. And the windshield frame and hood are shot too so I need to order those. I also rebuilt the entire inner quarter panels using sheet metal stock. (Even the filler neck cutouts).

All of the body is welded together except the windshield frame and hood. The motor was fitted before the body repair and I am working on putting it back in permanently this weekend. The inside of the tub was coated with orange tinted bedliner and the entire underbody was coated with black bedliner.

To do list:
Install new windshield frame
One of the doors needs to be skinned
Air conditioner
Fab cage and bumpers
Interior
Body prep and paint

Anyways, hopefully I will post a full build up thread soon but here are before and now pics.

When I first got it.

Sagging Body

All the floor pans look like this.

New body panels

That is even brighter than I expected. We used some paint mixed without binder and tintable bedliner for the inside.

 

[Pa PITT]

HOLY smoke all that on your 1st post... Put in as a buddy Please ..I want to see your progress ..Your profile doesn't show where your from ...Let me know ..and send me any info or pictures you get ..I'm building a 4BT also ...My Bronco has been down since last SEPT ...My motor is in and I'm cleaning it up now ..But it's not running yet ..maybe about 2 more months ...

 

[robofig]

Seems to me that the mazda 5 speed trans may be too light duty for the torque of the 4bt. You may want to do some research on that.

 

[kancox]

What were your experiances with replacing the lower quarter panels and where did you get them? Truck looks solid now!

 

[malonejy]

Wow. That really is one hell of a first post. Keep up the good work and keep us updated with the progress. Oh, and welcome to the board

 

[sprdv1]

Welcome to the site Dan, looking forward to your progress. Great work so far.

 

[dantheman222]

Lower quarters: I ordered them from wild horses and I cut along the seam of the old ones, the top seam on the new panel is actually metal glued on like they do with new cars. It is pretty standard stuff you can get at auto body places. The side and bottom seams are welded from the inside.

Mazda Transmission: First I chose the M5R2 because they are dirt cheap and have very nice gear ratios for the Cummins. The Mazda gets quite a bad rap because the little rubber plugs on top of the tranny get hard and fall out or leak oil, then the tranny runs low on fluid and goes out. You need to keep new plugs up there or convert the rubber plugs to metal freeze plugs. A good synthetic fluid helps as well. The M5R2 was offered stock behind the 302 and the supercharged thunderbird v6 both which had around 315 ft lbs. Anyways, as long as you don't hammer on it too much in low range it should be alright. Besides these transmissions are plentiful, cheap, and have much nicer gear ratios for a DD than a ZF or NV4500. And to top it all off, if it fails someday a ZF can be swapped right in its place as it is exactly the same length and uses the same bellhousing and t case arrangements.

My dad has a 4bt F150 with a ZF and my grandpa has a 4bt F150 with the M5R2, no problems so far with either and the Mazda shifts smoother and drives real nice.

 

[Pa PITT]

So with the Mazda trans what adapter did you use to go to the Dana 20..and what did it cost..

 

[dantheman222]

I didn't use a Dana 20, I used a NP205 from a late 70's half ton

 

[Ohio Bronco 21]

Wow, some major time on that thing. way cool

 

[agent_orange73]

Hey dan, i'm finishing up a c4 to M5R2 swap in my 73 bronco and i ran into a problem when bolting on the t-case (also an np 205 like yers). Somethings holding me off between the tailhousing and the t-case. Ive got about a 1/4 inch gap between the two. Did you run into anything like this?

 

[DonaldDouchebag]

Very cool. Any updates? I'm another guy from Minnesota with 4bt aspirations.

 

[Bronco Ga]

Very cool. Any updates? I'm another guy from Minnesota with 4bt aspirations.

Add me to the list. I'm doing a 4bt swap a well.
Any updates on this project?

 

[Pa PITT]

I'm driving mine around the farm now . An I sure do like the 4BT other than the noise .. It is loud but It starts with only one turn .. Even in the 100+ if it's moving it'll stay cool . If not my cooling fan will drop it from about 210 to 150 in about 3 minutes. I've never had a truck that'll just Idle up such a steep grade. My mileage doesn't look good but I may have to run my mileage on an hour meter.
...After I see how it'll start and heat in the winter . This should be my final test. I hope it'll heat enough to hunt out of this winter.

 

[ssray]

...After I see how it'll start and heat in the winter . This should be my final test. I hope it'll heat enough to hunt out of this winter.

Get a weather front made for it like the big rigs. Some folks even use em on Diesel PU's. That should help if you do a lot of low speed idling around. The only thing to watch is if it happens to have a thermostatic fan with the temp sensor on the viscous drive. I've run across cautions on some of them about covering the radiator. FWIW I think that was on an older JD tractor so it might not be an issue.

Scott

BTW, Stephenville sounds familiar and I think it's because we blew a tire on a trailer while passing through there 10 or 12 years ago. It was really close to a Walmart that was towards the west side of town? That's where we pulled in to put on the spare.

 

[agent_orange73]

Hey dan, i'm finishing up a c4 to M5R2 swap in my 73 bronco and i ran into a problem when bolting on the t-case (also an np 205 like yers). Somethings holding me off between the tailhousing and the t-case. Ive got about a 1/4 inch gap between the two. Did you run into anything like this?

Disregard this question, i found the answer over on 4btswaps.com. Apparently the tailhousing on the M5R2 isn't quite as deep as the one on the ZF or NP435. Not a big problem though, I just put the input shaft bearing retainer off the NP205 in the lathe and took about 1/4" off the thickness around the edge. This should solve my clearance issue, i'll post pics if anyone wants em, this might come in handy for anyone who wants to run this setup in the future.