# Transmission modulator replacement



## Spiritjohn (Nov 18, 2019)

Hello, this is my first post on this site and I am facing a unique mechanical issue.

 I have a 1995 cummins 12 v with an allison mt643 transmission. This transmission has an air modulator that worked in conjunction with the air accelerator on the cummins. I have taken this engine and transmission out of a rear engine bluebird bus with air brakes and it is now a front engine setup in a bus with hydraulic brakes. That being said I replaced the air compressor with a gear driven vacuum pump for the hydraulic brakes. I am trying to find a way to replace the air modulator on the transmission and am wondering if a vacuum or electronic one would be available and how these modulators would take into account how I am accelerating


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