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Topic: Allison 4000 upshift with jake brake (Read 582 times) previous topic - next topic
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Allison 4000 upshift with jake brake

Yahoo Message Number: 66870
I've been following a thread on the yahoo CAT forum about what happens when you turn on your jake brake. It all started with a person that threw a rod and thought his 4000 transmission was supposed to upshift if the engine rev's got to high and apparently it did not. Anyway, there seems to several responders that don't believe the 4000 upshifts when the jake brake is on.
I'm new to the 4000 transmission but my 3060 on my previous coach upshifted if needed. Does anyone have experience one way or the other about the 4000 upshifting?

pete, 2000 magna
Pete
 2000 40'  Magna #5892  CAT C-10

Re: Allison 4000 upshift with jake brake

Reply #1 –
Yahoo Message Number: 66871
I've occasions when I have manually shifted into first gear to keep the engine brake engaged . But after comming to a stop I had forgotten to reset the tranny to drive so when I started again and accelerated then engine would not upshift, but the rev limiter would engage slowing me down. I have also had the same experience shifting manually into second. But the Tranny started in first went to second and then the torque converter locked up so when I hit the rev limiter the coach really almost ground to a stop. I don't do that any more. Its a noisy and jolting experience.
TWI 2004 Intrigue 11731