Gotta a question about the OEM Allison. I found out we have ally's in our freightliners at work, and must say, all the hell we put them thru daily, they keep tickin and never break down. But when we mod our trucks and give em more power, they tend to crap out shortly thereafter. So why is it the tranny can take all the abuse in the world daily under hard driving conditions, but when it comes to putting more power to it, it craps out? Just wondering......

From now on, keep the titles appropiate and on topic or they will be deleted..

I think he ment "Hard on them" meaning abuse vs. adding more power. Why can they take abuse, but not power?:confuzeld

I think he ment "Hard on them" meaning abuse vs. adding more power. Why can they take abuse, but not power?:confuzeld

that is what i meant, people being hard on something, vs. putting more power thru it......

Do you know the nature of the failures? Unless parts actually break from the additional power, they most likely are friction failures. Shift calibration is crucial to getting life out of a trans that has to handle more power than it did from the factory. I doubt that there are shift kits available for Allisons other than the 1000 or 2000, but I don't know. The older allisons that weren't electronic had trimmer valves in the valve body that could be tweaked to improve shift quality.

I think one of the big problems is the RPM we can run in our trucks as compared to the bigger trucks. Notice where we are capable of making power (RPM range) and where the bigger trucks make their power. RPM kills clutches.
mike