I have a five speed allison on my Southwind/Workhorse chassis and sometimes, not always but it is getting to be more and more there is a wierd noise when shifting but once it has shifted the noise stopsand everything sounds normal.
It is when I start off, in overdrive and it is in first gear. When the shift is complete the noise stops and all is well. It is hard to explain what the noise sounds like...it is not a sudden sound or thud it is an even sound/hum or?
Does anyone have any ideas.

Welcome to irv2.com! That sound can mean several things. Don't wait until anything worsens, get your RV to a Allison authorized repair center ASAP!
The Allison FAQ page may be of use, but an Allison authorized repair center will read the computer codes and narrow the focus to specific areas of concern.

How long since you've had your transmission serviced and inspected? If the transmission is slipping the computer will cause a "limp mode" condition, limiting engine RPM, speed and gear selection until the fault is rectified.

Thanks for your response. I will make an appointment tomorrow. The last time I took it to our local Workhorse/Allison service center, I had to diagnos the problem myself and they never agreed so I took it a distance to another Workhorse service center and they fixed it for me. Of course that was Chassis related and not transmission, so I can only hope that they do a better job for transmissions.
We'll see what happens.

By the way, I should mention that my rig does not seem to be in "limp mode" or at least the RPM is good and I have no problem with power but I will take it in and have them read the codes at least.
Thanks again, Ray.
joco/carol

[QUOTE]Originally posted by Ray,IN:
Welcome to irv2.com! That sound can mean several things. Don't wait until anything worsens, get your RV to a Allison authorized repair center ASAP![QUOTE]

I did what you suggested and found out that all is well. I left the rig at the service center and a few hours later they called and said it was the fan clutch. Well, I know better than that..the fan clutch ROARS and does not Hummmmmmmmm. So I went to them and together we took a test drive. As it turns out, the service guy was stumped but after a longer conversation about it, he turned off the AC and we could never duplicate the noise. So his conclusion is that it is an AC noise..it is either the fan or possibly the compressor but his attitude was not to worry brcause it is definitely NOT the transmission.
Soooooo I guess my only concern now is to hope the AC does not go out. The service guy seemed to think that this could on for many months without a problem.....but who knows since I hear it more often. I guess the roof air will be sufficient.
Thanks for suggestion and concern.
Carol