AT545 in a midsize bus

pkd1 · 07-07-2020, 05:41 PM

Looking for some focused comments here. I've tried to do my homework as a relative newcomer, and see the generally negative comments about the AT545 transmissions. I've found an 8-window, 1996 Bluebird with a CAT3116 and the 545 transmission, 180k miles, I have maintenance records and it's coming directly from a school district. Looks to be in great shape...I plan to confirm with a hands on visit. Seems to me that many of the negative 545 tranny comments relate to larger busses and maybe with folks that have a greater need for speed than I do (I'm trying to be tactful). Is the 545 transmission better suited, and perhaps reasonable for, a smaller bus and being completly satisfied with 65 mph? I would plan to install a trans fluid cooler and temp gauge. Let me have it!

EastCoastCB · 07-07-2020, 05:45 PM

A 545 doesn't necessarily limit speed. It limits the speed you can go and not overheat. My bus will do 80 and I've got a 545. But the moment you go more than 45 the heat starts building. This bus I have will hit a certain temp limit and stay, but others I've had require you to slow up and let the temps go down.
I've had 545's in short and full length buses and they always suck. But I wouldn't let it keep me from a nice bus. IF/when it ever fails I'm upgrading to a 643.
The real thing you need to look into is the condition of the fuel system on that 3116. they can get REALLY expensive if there are injector, cup, or rack issues.

pkd1 · 07-07-2020, 05:51 PM

Thanks EastCoast CB...but why do they suck, because they get hot? And I wasn't saying that I thought they limit speed, just that I won't be seeking it.

EastCoastCB · 07-07-2020, 07:00 PM

More heat, less efficient, no engine braking, weak in general. They're for low hp ratings, so only get the lowest hp rated engines.

Johnny Mullet · 07-07-2020, 07:21 PM

I have an AT545 in my bus and I have taken it cross country, down to florida, and all over the country. I have put about 25,000 miles on it so far and never had an issue.

cadillackid · 07-07-2020, 07:33 PM

I wasted 2 AT545s one in a 6 window shorty and the other in a 7 window shorty ..
Both busses have better transmissions now and are well worth the swapping in place of the 545.both busses now run cooler have bettter highway manners and get better fuel economy..

I still have a 540 in one full size bus and I ran it 2700 miles across the country. Overheated the trans on I-80 in Wyoming.. didn’t burn it up but did Cus it.. and that was climbing mountains at 30 MPH...

pkd1 · 07-07-2020, 08:59 PM

Quote:

Originally Posted by cadillackid

I wasted 2 AT545s one in a 6 window shorty and the other in a 7 window shorty ..
Both busses have better transmissions now and are well worth the swapping in place of the 545.both busses now run cooler have bettter highway manners and get better fuel economy..

I still have a 540 in one full size bus and I ran it 2700 miles across the country. Overheated the trans on I-80 in Wyoming.. didn’t burn it up but did Cus it.. and that was climbing mountains at 30 MPH...

Thanks for the reply--What was the power plant in those shorties...what transmission did you swap?

pkd1 · 07-07-2020, 09:01 PM

Quote:

Originally Posted by Johnny Mullet

I have an AT545 in my bus and I have taken it cross country, down to florida, and all over the country. I have put about 25,000 miles on it so far and never had an issue.

Thanks for the reply--I'm always intrigued by the spectrum of experience. I recall my father telling me about the difference between a "Wednesday Car and a Friday car."

cadillackid · 07-08-2020, 03:02 AM

Quote:

Originally Posted by pkd1

Thanks for the reply--What was the power plant in those shorties...what transmission did you swap?

One is a T444E , I swapped in a ”built” 6 speed allison 1000
The other bus is a DTA360, it now has a MT643

The one that still has an AT540 is a gasoline IH 392

Sraycwb · 07-08-2020, 08:45 AM

I've a 99 Bluebird, just under 30 foot tip to toe, with an AT545 off a T444E have yet to encounter any noticeable tranny related heat issue to date. I've also not gone over 60 and climbed no hills other than minimal grades of the south.

With that said, I do have a new radiator, thermostat, fan clutch, water pump, and hoses. Replaced it all on trip home when I blew radiator out, which I suspect was due to it being the original 20 yr old radiator.

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