Allison MT643 for 1,500+ hp??

[JQmile]

Some of 'em came behind Cummins, right? I talked to a shop today about them, huge shafts, four gears, lockup, can be controlled manually.....think one would work without breaking in a mega-hp street truck? Oh yeah, and only $2K for a rebuild. They also said they weigh about 500 pounds, which is a good amount, but maybe not for ultimate reliability.

[ETH/DEE]

sounds promising... What are the physical dimensions like?

[1-5-3-6-2-4]

the at545 and mt643 are decent trannies, I don't know about for that much power though. I know a drag truck up here used a mt643 and had to rebuild it often. it was behind a 1000ish HP 2stroke detroit though.

[Signature600]

the at545 and mt643 are decent trannies, I don't know about for that much power though. I know a drag truck up here used a mt643 and had to rebuild it often. it was behind a 1000ish HP 2stroke detroit though.

In what though?

Weight could be a big factor in the life span...if you're talking 1000hp truck engines pushing 10-12K lb semi's, then in our trucks at say 6-7K lbs (or less) they might hold up to a tone of abuse?

Chris

[skidooman]

I used to work at an allison distributor and have thought about this, the problem I see is the size of the the dang thing.They are much larger than a Allison 1k or a 47/48.

[1-5-3-6-2-4]

In what though?

Weight could be a big factor in the life span...if you're talking 1000hp truck engines pushing 10-12K lb semi's, then in our trucks at say 6-7K lbs (or less) they might hold up to a tone of abuse?

Chris

that is entirely true. it was in a stripped out bigrig race truck. I say go for it. Cryo treat the shafts and gearsets. and let 'er buck.


the mt600s aren't that much bigger than the 1k/2k units. they are larger, but not gargantuan. the ht740 750s are fully 3 times bigger though.

[blacksmoke83]

I used to work at an allison distributor and have thought about this, the problem I see is the size of the the dang thing.They are much larger than a Allison 1k or a 47/48.

I have 3" body lift on my truck and I think that is plenty of room for any of those Allison who goes behind 5.9 cummins.

I have an AT545 seating in the back of my shop that I wanted to try a couple years ago and that was not even a challenge to fit in there !

My NV5600 is the same or bigger than an AT545 and I have lot's of room around the dam thing still !

Just my $.02

[dirttymaxx]

lets see some pics of that bad boy!!!

[smc953]

well you are going to have to change out your flywheel housing for the big thick one !!!

[Bustedknuckles]

They will shift slower too i would think.

[Knoberman]

Anyone know if any of these were available with overdrive? Im sure some were but how do you identify them?

[DieselWrencher]

Anyone know if any of these were available with overdrive? Im sure some were but how do you identify them?

As far as I know, no they weren't ever built with an overdrive. I thought about using one once, but they are big and heavy, and do shift slow. I'm sure someone could get them to shift faster, but I heard they won't shift real fast just because of how they're designed. Here is one next to a standard sized pressure washer for an example.

http://i181.photobucket.com/albums/x155/Dieselwrencher/000_0003.jpg
http://i181.photobucket.com/albums/x155/Dieselwrencher/000_0004.jpg

[2wpuller]

I had a MT40 in my truck it was a 6 speed that was the hardest hitting trany I had it broke almost all of the rear springs from slamming sohard.i weight was almost 400lb was cast iron.Now I'm putting in a 06 allison 6sp.can't wait.Tired of shifting the 10sp.