Quote:
Originally Posted by david.dgeorge07
I do know how to get six unlocked...more or less! I discuss the whole process on my build thread but the short version is that you get a letter from Thomas approving the change and then you take that to a certified Allison technician who gets a control code from Allison that then reprograms your transmission control module. If I remember right the process is set up to allow you to do it by the fleet. I only had one bus to do it to but the form and paperwork was definitely set up so that he they could approve multiple buses at one time.
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When you make the request to Thomas, it goes to their engineering department for approval. All I think they need is the VIN#.
If engineering approve they issue an approval letter. This can take a few weeks to a few months.
You send that letter to Allison, and you can do it direct or via a dealer. Allison also have to approve. If they do they issue a download link to the dealership (who have to have an authorised technician).
The code from that link is flashed to the TCM and it's done. It doesn't simply give you an extra gear. The new code remaps all the change points.
I have heard of a few restrictions. They won't issue an approval if the top speed will exceed 75 mph. They might put a rider insisting that engines are governed to 75 mph.
They may instruct the tech to only perform the work if the tires are appropriately speed rated.