transmission /gear setup

[mdshore]

Hi all, much delayed- im back into my bronco build.
ive been bouncing all around on what to use in my build so finally ill get a general consensus and go with your recommendations ---

this 72 bronco has a 351 with a 3sp manual trans, stock 3.50 axles , front w disc brake conversion , and hydroboost to be installed ,3.5 in suspension lift.

I was considering auto trans but Im thinking simplicity /not dealing with computers etc its best to go with 5 sp manual ?

i.e.
x15 trans ?

where best place to get complete setup ? or should i source out a rebuilt unit ,they seem to be half the price . are new x15's different from vintage yrs?

I also have a set of built 4.56 axles I could use, planning on 35 in tires. would this be preferred over the 3.50 gears? I plan on little to no rock crawling , mostly beach /highway /mud use.
thanks.

 

[broncnaz]

Definetly want at least 4.56 gears might need even lower gearing 4.88 or 5.13 for 35in tires and offroading. As for the AX15 I dont believe there are any differances. A rebuilt unit would probably be a good idea since most tranmissions will be over 15 years old and no telling what they've been thru.

 

[Wyo4x4er]

Definately want to get a later year model. Earlier year had a shitty internal slave cylinder that was prone to breaking.

 

[Broncobowsher]

No way to use an overdrive with 35s and 3.50 gears. Even with the 351 you can find yourself struggling on some grades with a direct 1:1 drive.

My last one was a 351 and 33s with 4.88 gears. It was actually a good highway gearing. It was a little overgeared as it did play on rocks, but did amazingly well on the highway. All thanks to overdrive.

4.56 gears and 35s will be a nice overall driver with an overdrive transmission.

 

[mdshore]

thanks guys for the clarification ! it makes me feel better knowing im doing it the right way as I hate R & D !

 

[kkhammer]

Mild hijack... I'm leaning this direction myself... What are the best donors to be looking at for the ax15?

 

[DirtDonk]

If you're preferring the idea of an automatic trans mdshore, the old AOD is a non-electronic overdrive 4-speed auto from Fords.
Yes, it's the weaker version of the later updated electronic versions such as the 4R70W (a very popular swap from Exploders), but if you're not beating on it, I bet it could live long and well.
Especially with a few mods done to it before the install.

Just sayin' in case you're wondering. I'm a manual guy myself, but the AOD seems a decent swap.

Paul

 

[DirtDonk]

Mild hijack... I'm leaning this direction myself... What are the best donors to be looking at for the ax15?

Not sure, but just so you know, the similar NV3550 is still available new.
For now...

Paul

 

[WorkerBee]

Going a slightly different direction here but I'll throw in a vote for the Mazda trans out of an F150. I got mine for 100 bucks at Pick n pull and couldn't be happier. Other than a really tall reverse gear I love it for my style of driving which is similar to what you're planning.

I have an NP205 so I did not need any adapters which was cool.

It took me a whole day to clean and paint it but I'd say it has been worth it.

I cannot say how strong it is because I don't abuse it. I just cruise around and only romp on it every now and then. If you have any specific questions about it just PM me and I'll try to help out in any way I can.

 

[mavereq]

Going a slightly different direction here but I'll throw in a vote for the Mazda trans out of an F150. I got mine for 100 bucks at Pick n pull and couldn't be happier. Other than a really tall reverse gear I love it for my style of driving which is similar to what you're planning.

I have an NP205 so I did not need any adapters which was cool.

It took me a whole day to clean and paint it but I'd say it has been worth it.

I cannot say how strong it is because I don't abuse it. I just cruise around and only romp on it every now and then. If you have any specific questions about it just PM me and I'll try to help out in any way I can.

Lower gears at the TC and axles will help avoid breakage. What's the OD ratio?

 

[WorkerBee]

What's the OD ratio?

Pretty sure it's .75