Opinions on Transmission and Transfer Case Options

[Jeff10]

Hey,

Sorry if this is a poor post... I'm trying to think my way through some options, and nothing really makes a great deal of sense.

The long and the short of it... We presently have two Broncos, a '71 (the subject of most posts here) and a '70. We purchased the '70 late in 2011 thinking we would sell the '71 and be ready to wheel with the '70 pretty much as purchased. That wasn't the case. We now have both Broncos with different mods done/planned since earlier this year.

The '71 has a rebuilt 302, B-W T-18 tranny, D-20 transfer case with stock gearing (and 4.56 gears front and rear). The '70 has a fairly new 347 stroker, NP 435 tranny, D-20 transfer case with Tera Low gearing (also with 4.56 gears).

I also purchased a rebuilt C4 and D-20 from a Pirate member earlier this year.

Although I don't know which Bronco we'll be keeping (for moderate trails and around town), I am trying to figure out which combination of engine/tranny/transfer case will be best for us. (We could end up keeping both for a short time, or ever longer, too.)

I know there are strong opinions on both sides about manual versus automatic. I'm just not sure that I have read many opions of T-18 versus NP435.

I'm also not sure which transmission (C4, T-18, or NP435) is better suited for the 347 stroker.

I'm leaning toward keeping the T-18 in the '71 with the 302, and removing and re-installing the Tera Low gearing from the '70 into the freshly rebuilt D-20. A heavy duty output shaft came with the rebuilt D-20. I would also install twin sticks at that time. If I go that direction I would probably install the freshly rebuilt C4 into the '70 with the stroker and rebuild the D-20 from the '71 and install the gearing from the fresh D-20 rebuild. I would also install twin sticks at that time.

I know there probably isn't a right or wrong answer. I just need to bounce some of this off of some knowledgeable folks.

With the low gearing in the T-18, maybe the Tera Low gears aren't really a huge benefit? Would the Tera Low gears be better suited for the C4?

At risk of making this even more complicated, I have attached the options in a little different format.

Any thoughts would be appreciated.

Jeff

 

[.94 OR]

Sounds to me like you need to put it back together and drive it.

 

[Jeff10]

Hey,

Sounds to me like you need to put it back together and drive it.

You're right!

Actually they're both pretty much to that point. I only want to make changes to both one time... and try not to second-guess things afterward.

Pulling the transfer case on the red one to install the twin sticks is opening a few too many doors.

Jeff

 

[garberz]

I would put the C4 with the Terra low Dana 20, in the one I was keeping. But only because I like autos. Very forgiving, you tend to not abuse your drivetrain with a torque converter.
Mark

 

[Jeff10]

Hi Mark,

I would put the C4 with the Terra low Dana 20, in the one I was keeping. But only because I like autos. Very forgiving, you tend to not abuse your drivetrain with a torque converter.
Mark

Thanks for your opinion.

The whole auto versus manual preference thing is what makes this decision so difficult. My wheeling would probably benefit from the C4, at least short term. I have some friends who think the benefits of the manual are greater than the auto. I can see some of their points... just not sure they outweigh the auto.

Jeff

 

[Broncobowsher]

The harder you wheel the better the auto becomes. If you are starting to see teh benifit to a C4, then that is the better choice. Build that with the tera lows and good shaft.

Now for the engine choice. 347 can be great or worthless. completely dependent on how it was built. Most of the time they are built a bit too high strung to get an elusive HP number.

 

[Jeff10]

Hey There,

The harder you wheel the better the auto becomes. If you are starting to see teh benifit to a C4, then that is the better choice. Build that with the tera lows and good shaft.

I was sure leaning that way when I bought the rebuilt C4.

Now for the engine choice. 347 can be great or worthless. completely dependent on how it was built. Most of the time they are built a bit too high strung to get an elusive HP number.

I totally agree. The jury is still out on the build as it hasn't been driven much to speak of. I've been tuning the carb and adjusting the timing off and on the last few weeks. It is coming around a little but still not where I think it should be. This is the motor I'd like to convert to propane eventually... it may come to that sooner, rather than later.

Thanks for the input.

Jeff

 

[broncnaz]

Hard to say what one to keep but it sounds like the 71 is built a little better. As for transmission well even if you swap in the C4 you will still have a manual to swap back to if you dont like the C4. NP435 and t18 are basically the same with just minor first gear differances so there's no real differance in either. The 435 has a slightly lower first gear thats about it.