Allright I have looked for the answer to this question and can't seem to find a definitive answer. I'm putting an Allison 6 speed GM 2007 in my ford it has the 261 manual Tcase and I'm going to use a medium duty TCM program, the TCM has two shift schedules I believe my question is if I engauge 4 low range in the Tcase which is around 2.73:1 will it shift correctly?
Stand alone Allison
- Thread starter Dieselwiesel
- Start date
Haven't run the Allison standalone, but:
If you aren't marrying it to the GM ECM and/or auto Tcase, it doesn't know you're in LOW range. There is no signal AFAIK. It reads input RPM and output RPM.
Make sure you use the Dmax Calibration. Other diesels will shift way too early, and the gas calibration is going to make you unhappy (no WOT 4-5 shift, elevated shift points, bizarre downshifts, etc). Medium duty calibration ain't so sweet for a daily driver, but is usable. I've run both gas and 6.6 medium duty calibrations during testing, and they aren't better than the pickup calibration, just bizarre and harse.
If you aren't marrying it to the GM ECM and/or auto Tcase, it doesn't know you're in LOW range. There is no signal AFAIK. It reads input RPM and output RPM.
Make sure you use the Dmax Calibration. Other diesels will shift way too early, and the gas calibration is going to make you unhappy (no WOT 4-5 shift, elevated shift points, bizarre downshifts, etc). Medium duty calibration ain't so sweet for a daily driver, but is usable. I've run both gas and 6.6 medium duty calibrations during testing, and they aren't better than the pickup calibration, just bizarre and harse.
Thanks for your input, this tcm runs off of the J1939 instead of using the gm ECM and uses an old style bell housing w input speed scensor. The out put speed is taken from the t-case but I just don't know if it will wig out when put into 4 low at 2.42:1 since medium duties are only 2wd. Also I'm aware of the poor shift qaulities of medium duty apps but I figure my trucks no cadillac. The tcm is From a 2800 governed rpm md app.
I'd be stunned if it did anything odd in low range. Not all medium duty Dmaxes are 2WD btw, nor is there a difference in 2wd/4wd calibration that I know of. If it did do something odd in low range, you'd just have to figure out how to lie to sensor. Relocate, resistor, etc.
when i was playing around with the DeStroked allison stand alone box basically all i really did was adjust how much defueling i wanted during shifts.
Thanks for the input I wasn't sure as if all medium duty apps where 2wd interesting to know some were 4wd. I wonder if this tcm is from a 2wd app if it will work in four low? I had one person tell me to install a tone wheel and output speed scensor in the output shaft of the tranny instead of the tail shaft of the Tcase so it always scensed 1:1? just wish somebody had been there and done this.
I can run you through some of the problems you will have. I'm assuming this is going behind a Cummins. No it won't care if you're in 4-lo. You should get the TCM for something similar to what you have. Scott's kit has one. You will have to get a 5 speed valve body and bell housing. The 6 speed won't work. I have an '09 Allison 6 speed sitting due to some poor information on that issue. You will need a tone ring if you want a speedometer and ABS. The Allison harness will occupy the output sensor in the 261. Unless Ford uses the hubs for speedo and ABS you will need a tone ring.