How can I put a MT643 in my M35A3?

[ShrekA3]

I currently have a A3 with a AT1545P and want to upgrade to a MT643. How is it done?

 

[welldigger]

If I had to guess it won't fit unless you move the transfer case back. Then your in custom territory. Isn't the final drive 1:1 in the mt643? If that is the case then there isn't much benefit to retrofitting it in.

 

[ShrekA3]

My trans died so I've found a brand new MT643 on the cheap. I've heard it's supposed to be a superior trans. Just don't feel the 1545 is worth rebuilding due to its numerous complaints of reliability in the A3. Allison guru said 1545/545 are overloaded in a Deuce. Everyone claims MT643 is the trans to go to but I want to now how it's done.

 

[ShrekA3]

I agree the that the final drive is 1 to 1 and may have to move the transfer case. I'm wandering if the juice is worth the squeeze?

 

[jdknech]

Why not use a AT545 out of a schoolbus, they can be had for really cheap around here.. $400-500 range..

 

[welldigger]

If you haven't already purchased the transmission and are willing to take on moving the transfer case then I suggest finding something with an overdrive. Otherwise you will be going through a lot of trouble for not much gain.

 

[paradeduty]

I have an allison out of a school bus that can be had cheap - have to check on the model.

 

[goodguyzy]

here is one thread, there is another really good one but cant seem to find it.
http://www.steelsoldiers.com/showth...ssions-for-the-M35a3-with-the-cat-3116/page19

 

[steve6x6x6]

The 1545p has a lockup converter, the 545 does not, it is not really 1:1 it has 7% slipage. Your 1545p top speed is 52 to 53, you will have 7% less with a 545 or mt643.

 

[ShrekA3]

A bit off course here guys. I need to know if anyone out there has put another type of tranny in a A3? I have a MT643 available which is very close in size and can handle more power, torque, and GVW than the 1545 or 545. This is what I have to work with. Please help

 

[welldigger]

You have to understand that the prop shaft is already so short that without moving the transfer case backwards there isn't room for any bigger of a transmission. This very topic has been covered numerous times.

Bear in mind, moving the transfer case is no small task.

 

[quickfarms]

The MT 643 does lock up in 3rd and 4th.

 

[porkysplace]

A bit off course here guys. I need to know if anyone out there has put another type of tranny in a A3? I have a MT643 available which is very close in size and can handle more power, torque, and GVW than the 1545 or 545. This is what I have to work with. Please help

Ok so you have a cheap transmission that will need alot of fab work along with 3 new driveshafts . Price out the driveshafts , material to move transfer case ect. ect. , time and the fact that parts will no longer be common to other trucks . I think you will find you are puting less money for this used tranny to start with , but will spend more in the long run with alot of downtime.

 

[11Echo]

The Canadians had good success with the MT643 behind the Detroit in their deuce trucks.