Allison at 545

[79gmccrewcab1t]

First off my project build is a 79 gmc crew cab dually. I have aquired a 1990 12 valve and alison 545 trans from a school bus. Of course I would love to do a allison 1000 but its just not in dueable right now. I've done some research on this trans, pro's and con's and all I can find is it doesn't have a overdrive but can be compensated some with gears and tires. My truck will see some highway but mostly city driving with little light duty towing. I plan to do some moderate mods to the engine, would be happy to see 300 to 400 pony's from it. Ive read people saying dont do it but haven't any rime or reasond other than hear say. If I go to another auto I'm back to where
I'm at now, alot of money to build it to handle the engine plus the exspense of adapters and such. Doe's any one have any prersonal experience with this trans in their own truck and what its your pro's and cons?

 

[nevrenufhp]

There are a couple places in the country that will do a performance build on a 545. Real world downfall of the non-lockup? heavy towing will make a lot of trans heat. MPG may be a little less than if it has a lockup. With mostly city driving, there's no reason to spend so much on a 1000. They have a pretty sporty shift, except the annoying gear whine at lower speeds. It'll fit in a puckup a whole lot easier than pretty much any other Allison. Run C4 hydraulic oil Allison recommends, not Dextron. Suncoast makes a lower stall converter for it that should allow you to get your power to the ground.
Only other close option there is would be an MT643/653, but you gain the lockup and beefier internals. They shift rather clunky too.

 

[lotzagoodstuff]

Don't know if you are planning on 2 wheel drive or four, but just keep in mind that you will be a bunch of money ahead using a Mopar transmission as you won't need an adpater. For instance, if I was to put a 12V in my truck, I'd need a 12V to ZF5 adapter, which is a cool $800 from Destroked. The 12V to ZF5 speed is a pretty common swap, and you might have lots of money and time getting a 12V mated to an Allison 545. I'd save the adapter money and get yourself a built 47RH or 47RE as it will bolt up.

Again, just my .02 worth.

Good luck whatever way you go

 

[79gmccrewcab1t]

Is there a lock up available for the 545 or am I stuck with the non lock up?
I do plan on running a large trans cooler so I dont think the heat should be a problem. My 12 valve come with the trans so the only mods will be is mounts and a ford style divorced 205. Thanks for the info

 

[nevrenufhp]

You can have a lockup, it's a different model, an AT1545. Very few and far between. While a novel idea, I highly doubt it would take much over the rated power(230 hp).

 

[zebrabeefj40]

Biggest issue I have with the 545 is the 400ft/lb torque limit. Of course that is with it installed in a MDT so it might work out ok in a lighter pickup truck. Me? I'd be looking for something better...

 

[crazytwo]

I have one in my bus. I HATE IT!. Non-lockup sucks mpgs. I cringe if I see the slightest grade, even if its an overpass. Temp rises dramatically on any grade. I will admit that my transmission might be getting tired. I plan on a swap for a mt643.

 

[towcat]

an alternative to the AT545 is the 4L80E. I have one living happily behind a industrial 6bt with a THM 400 adapter pillaged from a 4bt wonderbread truck. the truck is a Chev 2wd CCdually packing a Lance 10 ft slide-in. Gross is 12k wet. watching how this monster haul ass from a light and up a grade is a sight to be beholden.

 

[crazytwo]

I'm in a different boat. Mine is in a bus that weighs 18,000# dry and behind a DT466. It might be fine in a pickup.

 

[spg]

I swapped the AT545 in my truck for an Eaton-Fuller 6 speed out of a like truck. The AT545 generated way to much converter heat because I am towing a trailer as well. I think the AT545 would work in a pickup application with a tight converter fairly well. It is rated up to 22K GVW.