4bt axle gear questions

[R0kcrwlr]

To all the 4bt owners.

1. What gears are you running with a 4bt to accommodate 37's? zf5 trans.
2. what front diff are you using? HP44 or Dana60?

Thanks

 

[Pa PITT]

Mine is all stock Bronco stuff.
4BT MOTOR.
NP435 4 SPEED TRANS. 3:54 FRONT AXLE &
3:55 REAR AXLE..
Stock Dana 20 t/c .
If I'm on the hyway I only run about 45 to 50 mph.
But then I really only use mine on the farm. I bring fuel to it in 5 gallon buckets.
.. SINCE IT GETS 16 TO 20 MPG. I ONLY have to add fuel about once each 2 or 3 months.

 

[R0kcrwlr]

Thanks PA PITT. I saw some of your posts but I noticed you mainly use yours on your farm. I am looking to go 37's with zf5 so I am thinking 4.10 gears.

thanks.

 

[kinder]

I run 4.10s with a 4BT/ZF5/NP203-205/D60/37 combo. Mine is P pumped with a few mods (PDD AFC Live and Max Travel Kit, valve & gov spring mods are next) and the 4.10s are a good compromise for the type of driving I do daily. When I'm running loaded I do wish for a bit deeper gear, but that is only a couple of times a year. The gas ZF doesn't have the best gear split for the 4BT, the next planned mods with help overcome the gap in the 3 - 4 shift.

 

[R0kcrwlr]

Thanks Kinder. Yea, I noticed the big drop from 3-4 gear on the zf trans. I have ve pump 4bt. I am in the build process so I appreciate your feedback. My combo will be 4bt/zf5/stack TC/D60/37's so it seems pretty similar to you minus the p pump, etc.

I just order a 3200 spring and fuel pin. it has a split manifold and I took the baby h1c intake and used a h1c exhaust side and just make one turbo 12cfm exhaust housing and the 42intake.

I plan to run 75 on freeway so based off conversations I should be around 2k rpm or so. Does that sound right to you? I think 3.92 would be a good gear if they had it for the dana60.

Thanks again.

 

[kinder]

I plan to run 75 on freeway so based off conversations I should be around 2k rpm or so. Does that sound right to you? I think 3.92 would be a good gear if they had it for the dana60.

Thanks again.

I think my 37s are a bit undersized so I see around 72 mph (based of GPS) when I'm at 2k rpm. I was thinking of going down to 3.73 or so when I was trying to figure out my axle ratio, I agree a 3.92 would be nice. In the end I'm happy I tried the 4.10s that were already in the axle in the real world and didn't rely solely on a gear calculator. Without the 4.10s pulling mountain passes fully loaded would likely push my EGTs above 1200 when trying to keep up with traffic.

 

[R0kcrwlr]

i was looking at the calculator again and here is what i am coming up with.

3.73 / 36" tire size
70 @ 1850
75 @ 1984
in 4th gear @ 65 its 2263rpm

4.10 / 36"
70 @ 2036
75 @ 2181
in 4th gear @ 65 its 2485