Thermostat thought...

[THEFERMANATOR]

James the automatic semi I have driven a few times at my work with an Allison has seen the same trans temp issues you have going down camp Verde hill at 80k.

It probably has a trans retarder in it, hence the really high trans temps. It's not uncommon to see 280-300 when you have a trans retarder and braking pretty hard. It was the main reason allison came out with transynd. It is not uncommon to see 300 degrees routinely in garbage trucks and other allisons driven in stop and go traffic with a retarder, and dex iii don't last long at those temps.

 

[hondarider552]

It has a Jake brake. No retarder in it. I try to never touch the brakes going downhill.

But yes with a retarder trans temps do increase, our cranes see this as most are Allison's too.

 

[THEFERMANATOR]

It has a Jake brake. No retarder in it. I try to never touch the brakes going downhill.

But yes with a retarder trans temps do increase, our cranes see this as most are Allison's too.

Freaks me out everytime I drive one with a retarder. It is unnatural how quick trans temps can go from 180 to 325 with one. I know the motorhome I drove with one and an 8.3l would heat the engine up on a long downhill grade.