[soutthpaw]

Ha, another question in my own Forum
This truck has the Allison AT545 tranny and it upshifts at 2600rpm.. is there any way I can get the thing to shift higher at like 3000-3300rpms ??? Cody??? I think it has a speed limiter too. seems to just back off the fueling as I reach around 70mph which is also around that 26-2700rpm mark. are these trannys electronically controlled independent of the engine controls or is the engine and tranny combined like our light duty 7.3's
Or are they mechanical that there is something I can tweak or adjust to get the shift points higher

[cleatus12r]

Sorry, DJ, I know nothing about these except what I just "google'd".

I'm going to assume that the '00 year AT545 is a mechanically shifted transmission that uses fluid pressure on valve body valves and an electronically controlled line pressure system based on accelerator pedal position.

The speed-limiter setup you speak of is an engine defueling strategy based off of either road speed or output shaft RPM.

As for the shift points, that's not something I can accurately answer. I think you're looking at either a governor pressure, line pressure, or mechanical alteration (like valve spring) requirement to fix that since I don't think it's electrically shifted.

[soutthpaw]

Thanks, I was thinking it was a mechanical shifted unit too. From what I have read these trannys really rob a lot of power from the engines. a nice road ranger or similar manual with 10 speeds or so would probably be the way to go

[soutthpaw]

was chatting with Bill over the weekend and it hit me as to what the tranny shifting issue was... Bill confirmed it. when the truck starts to defuel around 2600rpm it makes the tranny think there is less load so it shifts up... thus raising the max rpm limit should solve the shifting issue. Kinda obvious
anyway we may try some prototype tuning on my truck if he can scrounge up another PCM for it... Bill said the defueling on these trucks is real agressive ... and it sucks but I guess if I was a business owner I would not want my employees hot rodding around in the company truck heh!

[westdouglas]

south paw u hit it rt we employers do not want employees hot rodding around in our equipment.I am a school bus owner/operator and the buses I run are the 466 and the 466e the 466 has an allison mt643 and the 466e has the mechanical at545 a (MECHACHANICAL TRANSMISSION) it would be great if there was a fuel milage tune for the 466e for the school bus industy I know if it would increase the milage from 7mpg to something greater i would buy one.Some of the other owners here in my neck of the woods would too.The Other engines to consider would be the Cummins brand (I dont like the Cats so lets leave them out LOL).International's 466e and 466ht are great motors in school buses there are alot of 7.3's out there on the road in buses too.International buses are going to the new allison trannys that are all electronic in nature so staying up to date on all the mods is challenging.There are bus bodies out there such as bluebird,thomas,ih,minataur etc that run the gamut of engines and I dont know if a 466 in one brand would be different from the next. Also there are hundreds of the e350 ford van bodies that run the 7.3 would the tune be the same as the edge evo? and if so would it be legal to run on a school bus? or any bus come to think of it?

[Power Hungry]

We have tuning for the 94-97 T-444E and DT-466 equipped vehicles. With a little help from Southpaw, we are will be testing new tuning for the 1998+ vehicles. Mileage is the main goal, with smoother power a close second. I understand the argument about hot-rodding around. However, a natural byproduct of improved efficiency is not only economy, but performance.

In earlier models we have reported gains of up to 6 MPG (from 10 to 16 MPG) with the average gains being about 2-3 MPG (from 11 to 14). This makes it well worthwhile.

Stay tuned for more information as it's released.

[westdouglas]

Hey!!!! thats what im talkin 'bout i will stay tuned for that i need the tune for a 99-00 dt466e for a school bus.The other bus a own is a 96 model dt466 that has the older style fuel delivery sys.I do have a few more people in mind for the 466 tunes any word on the cummins tunes? thanks for your hard work keep it going.

[Power Hungry]

There are plug-in controllers (pressure boxes) for the 3126 Cat and ISB/ISC Cummins, but we don't have anything in the way of programmers.

Will keep ya posted on the Navistar stuff.

[soutthpaw]

Found a good parts breakdown for the AT545 here. These trannys have governors that fit into the valve body they come in up to 2800 rpm, 3000-3400 and 3600-3800 rpm versions.. Boy I really need to take an automatic tranny class to get a better understanding on how these work... do the govenors modify the flow or pressure to change the shift points???

I just got another Medium Duty truck with the same AT545 tranny too

I really want to find an OD trans unit for one of the trucks. do they make overdrive gear splitters that are divorced from the transmission that I could just drop on behind the tranny???