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Discussion Starter · #1 ·
I am ready to buy a 4bt and zf 5 speed what zf 5 speed do i get big block or small block and what adapters do i need for the 4bt diesel to a zf 5 speed and dana 20
 

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You need a ZF-5 with the small blockpattern, you will also need the Cummins Ford flywheel housing to bolt up the ZF-5 if the 4BT comes with something else. Can't help you on the Dana 20, the ZF-5 4x4 will have the common Ford round 6 bolt pattern that bolts up to the tramsfer case.
 

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You can also do the big block pattern with an adapter from fordcummins.com. Or make an adapter from cummins work with a little machine work. This is how I did it, fordcummins couldnt supply me with an adapter in a timely fashion. I already had the tranny/x-case so this was the no brainer thing to do. Except it took brains to get all the dimensions correct to make it fit. If you decide to go this way let me know and Ill guide you along.
Carl

1979 F-250 crew cab 4 x 4
4 bta with modified H1C
Cold air intake
ZF S-42 5 speed
Borg Warner 1356 x-case
Dana 60 rear
Dana 44 front
3.55 gears
255/85R16 tires (33.5x10.5)
Hydroboost steering and brakes
Custom 40 gal. fuel tank
Much more later
 

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The only problem I have with it is that I have some gear chatter 1300-1500rpm in 4th gear. Even this is not really a problem on level ground or downhill. Uphill or towing,(all onramps in texas are uphill), I take 3rd gear to 2500rpm and 4th will hit at 1600rpm, right in the meat of the torque.
Carl

1979 F-250 crew cab 4 x 4
4 bta with modified H1C
Cold air intake
ZF S5-42 5 speed
Borg Warner 1356 x-case
Dana 60 rear
Dana 44 front
3.55 gears
255/85R16 tires (33.5x10.5)
Hydroboost steering and brakes
Custom 40 gal. fuel tank
Much more later
 

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On my ford with the 460 and zf5, a shift at 2400 RPM out of second puts me in third at 1300 RPM. I've pulled heavy loads with underpowered diesels before, and that's too low, you'll end up back in second climbing the hill.

The zf's have a dual mass flywheel from the factory. Using a regular flywheel causes gear chatter. It does not seem to be harmful, just annoying. The dual mass flywheels are expensive and fail much faster then the regular ones.
 

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Nice looking bronco Halfbreed!

Carl what kind of milage do you get?

I thought you could get a 4bt that was installed in a ford product and it will already have a plate on it that matches the small block ford or diesel bolt pattern?

Preston
 

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you can, but the small block bolt pattern has only wide ratio gears. My concern would be when loaded you'd lose your torque and not be able to upshift if you didn't use the diesel ratio gears.
 

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Discussion Starter · #10 · (Edited)
you can, but the small block bolt pattern has only wide ratio gears. My concern would be when loaded you'd lose your torque and not be able to upshift if you didn't use the diesel ratio gears.
so the zf small block is not a good choice cause that is what i was going to do i will never be towing just street driving
 

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I've had both transmissions, the narrow ratio in a diesel and a wide ratio in a gas.

I think you could get by with the wrong one for the application, but I think the right one will be smoother. As I said above, my truck goes from 2-3 and goes from 2400 to 1300 RPM. That's HUGE in a diesel, especially one that redlines at 2400. A 3k GSK would probably allievate the problem, but if you don't have a tranny I'd look for a diesel one and find a plate for it.

If you can't find what you need, send me an email. I bet I can make it for you. My problem is that I don't have an engine and tranny to fit it up.
 

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BC Broncos sells an adapter to bolt the bronco Dana 20 to a ZF.
Advanced Adapters also sells it.

The Bronco stuff I know better then the diesel stuff, at least for now (still learning about the oil burners)
 

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I am ready to buy a 4bt and zf 5 speed what zf 5 speed do i get big block or small block and what adapters do i need for the 4bt diesel to a zf 5 speed and dana 20
The NP205 will bolt directly to the ZF 5 speed without $$$$ adapters BC broncos can help you with a cross member or what ever is needed that would be cheaper than the adapter. You metioned that the vehicle is mainly on the street using the np205 would not hurt you, only the people that go off road would worry about the gear ratio difference between the two transfer cases. The dana 20 has a lower ratio for off road which you are not using your vehicle for. If you ever decide to go off road later on, the money you saved from not buying the adapter to bolt your dana 20 can go towards the Atlas or the Stack aftermarket transfer cases. NP205 are very cheap around $100.
 

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The NP205 will bolt directly to the ZF 5 speed without $$$$ adapters BC broncos can help you with a cross member or what ever is needed that would be cheaper than the adapter. You metioned that the vehicle is mainly on the street using the np205 would not hurt you, only the people that go off road would worry about the gear ratio difference between the two transfer cases. The dana 20 has a lower ratio for off road which you are not using your vehicle for. If you ever decide to go off road later on, the money you saved from not buying the adapter to bolt your dana 20 can go towards the Atlas or the Stack aftermarket transfer cases. NP205 are very cheap around $100.
Gpete;
I gota tell you, you have one beautiful truck. She is really sweet. In 1966, I bought the first Bronco that the dealer received. It was the full body, yellow and white with a 6 cyl. I guess it was a 300 cu in but thats to long ago to remember ha ha. My congratulations on your work.

Paul
 

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I didn't realize that gear driven boxes are even available. Anyway, I just figured that it came behind the zf5 and would be easy to fab up. You may need driveshafts modified, but probably will anyway.

As far as the gas vs diesel ratios, I'm sure that you can get away with using a gas one. But, since he hasn't bought one yet, why not get a diesel one? With the diesels I;ve driven, much more than a 500 RPM drop when shifting is too much. The power band of the cummins is relatively narrow, and proper gears are necessary to take advantage of this. The more power you have and the lighter the vehicle is the less this will matter.
 

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Discussion Starter · #20 ·
Gpete;
I gota tell you, you have one beautiful truck. She is really sweet. In 1966, I bought the first Bronco that the dealer received. It was the full body, yellow and white with a 6 cyl. I guess it was a 300 cu in but thats to long ago to remember ha ha. My congratulations on your work.

Paul
thanks man i really apreciate it i like it for a 17 year old it drops lots of panties my dad and i have been working on it for one year and i worked for it all my parents didnt pay a penny so that is a big acomplishment for me KNOW COMES THE 4bt Swap LOL
 
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