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Discussion Starter #1 (Edited)
I've been wanting to build a killer offroad rig off of a 4bt/4bta and just recently I picked up a 1990 Ford Bronco xlt with a pretty tired w351 and the stock automatic tranny.
I got it from a repo yard so she's not the prettiest but for $500 I couldn't beat it.

  1. Now the 351 comes out obviously (might get rebuild and sold). I'd dearly like to get that auto out of there and put an NV4500 or something equivalent. Now we come down to the transfer case. From just looking at torque specs it would seem like I could keep the stock manual transfer case? However I've had some difficulty finding the actual model of it. Would it be a BW1356?
I'm trying to do this on a budget so any tips and/or tricks for sourcing would be greatly appreciated.
 

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Transfer case is a Dana 20, have to deal with the short driveshaft. 4500 is longer, so have to shorten rear driveshaft. There are several Bronco conversions around here.

Ed in CO
 

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Ed, the Dana 20 was only used from '66-77 Bronco. His 1990 should be a BW1356. The simplest swap would be a ZF S5-42 which came in front of that transfer case. Get one with the SB Ford bolt pattern out of an F250 with the 351 and a 4bt with Ford adapter plate and it's a direct bolt up. There may have even been some of the Broncos that had the ZF with the 351. The smaller engines I believe were the M5R2-OD Mazda transmission. If this is seeing a lot of off road use, the small block ZF has a lower 1st gear unless you get the '92-93 GM NV4500. That one can be a bit more expensive to adapt unless you happen on a 4bt with a GM manual setup.
 

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Discussion Starter #4
Thanks for all that.
I'm not set on a 4500 but if I were to get one it'd be a chevy/gm because of the 5th gear locknut issues.
I would imagine the ZF would be more common and probably easier to source locally but how long do they usually last?
 

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The ZF is every bit as strong as the NV4500. You mention something about the 5th gear locknut. As far as I know, the '94 up GM and Dodge NV4500 are the same. The odd duck is that '92-93 GM model with the very low 1st gear. The one issue with the ZF that often rears its head is the slave cylinder on the small block model. It's inside the bellhousing which means pulling the transmission and transfer case anytime it needs replacing. Big block Ford ZF's had external slaves but they are more expensive to adapt to a Cummins. If you stay all Ford you should be closer to a true bolt on deal. Since the Bronco and F series have the same frame width, you could get the transmission mount for the ZF so no custom work there. If you want to get a little fancy, you might change the dash instrument cluster for one from a 7.3 truck of the same vintage and have a diesel tach and fuel gauge that says "DIESEL". All kinds of possible fun.
 

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Discussion Starter #6 (Edited)
Ok, good to know.
It sounds like that's the route I'll be taking then.
There's a couple of junker fords around that I could probably pull the tranny and clutch assembly for pretty cheap.
Do you know about how many miles the ZFs usually last? Just so I have some reference on how much life they may have left .
 

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How long one lasts depends on how you treat it. The ZF S5-42 which came in gas and diesels if quite strong. Mine in my '90 F250 diesel has 323,000 miles on it. Still shifts smoothly and doesn't make any strange noises. You might contact member Eggman. He had the small block gas model in his F250 but swapped it for a 7.3 diesel model because he needed a bigger clutch for his higher HP 4bt. He may have that one for sale.
 

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Discussion Starter #8
Thanks for all that information.

I know there is a difference in the bellhousing bolt patterns for the 7.3 vs the gasser. But would they link up to the same transfer case?
My friend is taking his 7.3 and tranny out to switch to a 6bt and offered me the tranny
 

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It is not worthwhile to reuse clutch, throwout bearing, pilot bearing units because the large amount of labor involved vs. the reasonable price of new units.

Ed in CO.
 

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On your question about the various ZF's onto transfer cases the answer is yes. The small block, big block, and diesel models all came with the same transfer case. The small block, big block, and F450 7.3 diesel all have the same gear ratios. The model used on the 7.3 in the F250/350 was a close ratio model. Works better with a 4bt Cummins but cost more to adapt. Takes around $1500-2000 in parts to fit either of the larger transmissions to the engine plus do some minor grinding work on the block skirt.
 

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Discussion Starter #11
Yeah. As a general principle I try to replace clutch/throwout bearing every time I pull an engine.

Hmm well it looks like I got myself a difficult decision. I'd like to be working with the best and the price is going to be discounted.

But does that justify itself on my shoestring budget.

Lots to think about and consider. Thank you for all your information and help. There may be more posts to come as I get into the actual deeds of swapping.
 

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A friend with a dead stock '99 PSD is on his third OE 5 speed. It kills the synchros, and no, he isn't the type that leaves his hand on the shifter just going down the road. If that's a ZF then I for sure wouldn't go down that path.

Later Ford trucks came with NP271's (say somewhere about '08). Would be my preference over that electric shift 1356. I have a 96 OJB, so I'm just getting familiar with that electric shift t/c and I can tell you that so far it is not confidence inspiring.
 

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I've been wanting to build a killer offroad rig off of a 4bt/4bta and just recently I picked up a 1990 Ford Bronco xlt with a pretty tired w351 and the stock automatic tranny.
I got it from a repo yard so she's not the prettiest but for $500 I couldn't beat it.

  1. Now the 351 comes out obviously (might get rebuild and sold). I'd dearly like to get that auto out of there and put an NV4500 or something equivalent. Now we come down to the transfer case. From just looking at torque specs it would seem like I could keep the stock manual transfer case? However I've had some difficulty finding the actual model of it. Would it be a BW1356?
I'm trying to do this on a budget so any tips and/or tricks for sourcing would be greatly appreciated.
Im just finishing up my 89 Ford Bronco that had a 351 W with a C6. I opted to use a Big Block E4OD. I obtained a conversion kit from DCS. I started to do go with a NV4500 but decided based on it being a daily driver and some trail use to go that way. A manual will be easier because you dont have to run a TPS or a tranny controller on it. But man.... I would get tired of shifting. You can source a pedal set up at a junk yard that will work fine to run the clutch.

You should have the BW1356. The benefit for me was it bolted right up to the E4OD. As noted by other members there may need to be modications to drive lines.

Another thing to think about is to not mess around when mounting the engine in the frame rails. These motors are several hundred pounds more than a 351 W. I bought a set of legit upper mounts on-line and used 1/4 inch steel to make the lowere mounts. Also you will need to box the frame. I wnet one setp further and welded in 1/4 in steel in the frame channel to support the weight and prohibit the frame from fatiguing over time.

If you can find one get a P-Pump 4bta. These are intercooled and the pump can be turned up. I also picked up a vacuum/ hydraulic pump to run my brake booster and power steering. These are gear driven and can be found on e-bay and rebuild kits are cheap and they are easy to rebuild.

You will also need to get a kit to run a tachometer if you wanted to. I wanted a clean look and sent my whole gauge cluster to Autohack Guys. They provided a kit that uses magnets on the dampner to provide a signal for your tach. On that note most 4bts dont have a dampner/ balancer. You can source one off of a 5.9 on ebay for not much money. These will reduce the rattle from these engines.

Depending on what you want to do a uprgaded turbo is a good option I went with a turbo off of an 06 24 valve and it really woke things up.

I know this is alot of info, but I wanted to pass along my experiences. In my opinion the Bronco is a great conversion candidate. Good Luck
 

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Discussion Starter #14
Thank you so much. I'm still gathering as much info as I can.

I've pretty much scrapped the idea of using the NV. I've already got a couple of leads on a ZF. It'll save me headaches and money with the direct fit to my tc.

I'm still on the hunt for the engine though. I'm looking for something that ran on some old agricultural equipment (field pumps, small tractors .ect) as they'll probably have easier wear from being run at one speed for most of their life.

As for mounting I'd like to call myself a pretty darn good fabricator so I plannined to weld up a nice sturdy engine cradle. I've done similar work on a small dozer that pretty well crushed it's front end.

As for the tach I'd hoped to wire the existing gauge off the lead spark plug. Not entirely sure how that works but I had a friend who did that when putting in an aftermarket gauge.

Thanks for the tip on the dampener. Id like to have it not try to shake me to death when it's all said and done.

So far what I have sourced is a clutch peddle and master and a couple different zf trannys

Thanks again for all that information, I appreciate it immensely.
 

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As for the tach I'd hoped to wire the existing gauge off the lead spark plug. Not entirely sure how that works but I had a friend who did that when putting in an aftermarket gauge.
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May I suggest that you slow down an spend a couple of weeks reading up on diesel theory and operation. Diesels do not have spark plugs.

And tachometers for older spark plug engines get their signal from the primary (i.e. 12 Volt) side of the ignition coil. Attaching your tachometer to the spark plug will send thousands of Volts into the instrument cluster. It will not end well.

EDIT: Often, the tachometer signal on newer engines is provided by an engine management computer.
 

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Discussion Starter #16
Ahh yes my bad there.
It's been a long day of course diesels have glow plugs. And run on compression ignition. (I swear I'm not an idiot)
And yes hooking up a stock tachometer to a coil would just make some unpleasant smoke.
I was referring to something i believe friend had done with his truck that didn't have a tach gauge. I believe there is an aftermarket guage that'll count how many times the lead plug fires and give you a reading in rpm.

And yes obviously that would work with glow plugs.

Sorry for the idiot moment
 

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Discussion Starter #17
A friend with a dead stock '99 PSD is on his third OE 5 speed. It kills the synchros, and no, he isn't the type that leaves his hand on the shifter just going down the road. If that's a ZF then I for sure wouldn't go down that path.

Later Ford trucks came with NP271's (say somewhere about '08). Would be my preference over that electric shift 1356. I have a 96 OJB, so I'm just getting familiar with that electric shift t/c and I can tell you that so far it is not confidence inspiring.

Hmm well I'm not entirely sure if that was a ZF or what. From the people I've talked to and what I've read they seem to be very reliable trannys.
One of the ones I'm considering buying has over 300k miles on it and is still in working order.

As for the tc. It's a manual shift not an electric. I have no personal experience with that case but my friend's 1992 f250 is pushing 200k miles without complaint and I believe it has the same model.
 

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Ahh yes my bad there.
It's been a long day of course diesels have glow plugs. And run on compression ignition. (I swear I'm not an idiot)
And yes hooking up a stock tachometer to a coil would just make some unpleasant smoke.
I was referring to something i believe friend had done with his truck that didn't have a tach gauge. I believe there is an aftermarket guage that'll count how many times the lead plug fires and give you a reading in rpm.

And yes obviously that would work with glow plugs.

Sorry for the idiot moment
I'm a 75 year "old guy" gently trying to get your attention and get you to focus....

1. Cummins 4bt and 6bt engines do NOT have glow plugs.

2. Diesel engines that use glow plugs only use them to heat the combustion chamber to start the engine. A timer turns off the glow plugs after a few seconds. The glow plugs are continuously powered for those few seconds and are NOT a source of a timing signal for a tachometer.

3. I have to eat my words - There is a digital tachometer that senses the spark in a spark plug wire. New to me:


4. The same folks make a diesel tach


I have one of these, first used it in my bread van, and now have over 70,000 miles on it in the Ford F150. Highly recommended. You will have to measure your injector lines - there make a unit for 6mm and 1/4" diameter injector lines - the transducer clamps on an injector line - proper fit is necessary.
 

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Discussion Starter #19
I'm a 75 year "old guy" gently trying to get your attention and get you to focus....

1. Cummins 4bt and 6bt engines do NOT have glow plugs.

2. Diesel engines that use glow plugs only use them to heat the combustion chamber to start the engine. A timer turns off the glow plugs after a few seconds. The glow plugs are continuously powered for those few seconds and are NOT a source of a timing signal for a tachometer.

3. I have to eat my words - There is a digital tachometer that senses the spark in a spark plug wire. New to me:


4. The same folks make a diesel tach


I have one of these, first used it in my bread van, and now have over 70,000 miles on it in the Ford F150. Highly recommended. You will have to measure your injector lines - there make a unit for 6mm and 1/4" diameter injector lines - the transducer clamps on an injector line - proper fit is necessary.

Well thank you for that.
I'm still a ways out from undertaking this project. Probably sometime late summer.

I enjoy the mechanics of building and swapping but I'm not a fan of the electrical systems and the detail it often involves. That's part of why I chose the 4bt. Less complex electronics required and no computer.

My primary concern is getting a drivetrain assembled and mounting hardware installed.

I'd really prefer not to have to muck around under the dashboard, but I may If I decide I want a working tach. As mentioned earlier in the thread I could pull a whole dash cluster from a Ford 7.3. Would there be a similar procedure for hooking up the tach on that?

Thus so far I've been focused on transmission and tc. Partly because I'll need to wait until I get some more work coming in this spring before I'll have the funding to buy an engine.

Duly noted that I need to do more research and look into various aspects on this engine, this will be my first in-depth project on a diesel.
 

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One of the first things you probably need to address is finding an engine. You have a known vehicle to put it in but don't yet have the engine. Until you find one it will be kind of hard to figure out what else to do and how much it will cost. As for cost, probably need to plan in the $8000-10000 range if no major issues crop up. You might beat those numbers but we've seen guys go way beyond that. You can easily have $6000 in the engine and that nothing very fancy.
 
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