Allisons gain popularity

Allisons gain popularity among converter rebuilders

Impeller with a green tag.

Impeller with a green tag. Note the number and angle of the primary fins and stator fins.
Impeller is designated by an orange tag

Impeller is designated by an orange tag. Note the number and angle of the primary fins and stator fins.
Impeller with a black tag.

Impeller with a black tag.Note the number and angle of the primary fins and stator fins.

With the growing popularity of the Allison converter found in many popular General Motors medium and heavy duty trucks, we decided to report on different phases of the inevitable Allison rebuild.

In phase one, we will help identify the differences between the Allison models, like the three highlighted in this article. With the number of potential component combinations, the number of Allison models seems to be growing.

For this article, we will focus on what we will refer to as the Allison Black Tag, Orange Tag and Green Tag, although other colors exist.

If you look closely you can notice the differences found in the angle of the primary pump fins of each unit. The black tag aporange pears to be a much lower stall than the other two models.

Also, the combination of this impeller, and possibly other stators, indicates numerous incorrect combinations and rebuilder errors that may result in poor vehicle performance. In future articles, we hope to inform our readers of part numbers and relationship to individual vehicles. Until then it is suggested to replace each customer’s converter with an identical unit.

We are aware and will continue to research the existence of a past TCRA booklet, which was distributed to members who attended the a past TCRA seminar.

We are hoping to have access to the original document, which will enable us to share more valuable information on this topic.

Found in issue October 2005