Allison Transmission upshift problem

[DanK]

I am having a shifting issue with the Allison Transmission and I thought I would post it here to see if anyone had any insight on what it could be. The coach is a 2003 Newmar Kountry Star with the ISB 300HP motor and the Transmission is the 3000 series. The issue is that when I'm towing a vehicle behind the coach and I'm climbing a steep grade the coach downs shifts properly, but will not upshift properly. Example would be driving half way up a hill and the RPM will go to about 2400 after down shifting and would normally start to upshift at at around that RPM, but it goes in between gears. So the transmission tries to upshift, but doesn't actually upshift (I hope that makes sense). I have taken to coach into our Allison dealer and they could not simulate the issue, so they did not know what the issue is. The issue only happens when towing and only on very long grades. The other thing to mention is that when it tries to upshift is tries to do it every 1-2 seconds until I back off the on the gas pedal and then it will upshift. The problem is also starting to occur more frequently. I have owned the coach since new and it only started about 1000 miles ago. Coach have 67K milage if that is a factor. I would appreciate any insight you may have.

[usersmanual]

rgatijnet1 wrote:
The only way your Allison transmission would up shift is if the grade changed or if you were trying to accelerate and then let off of the throttle because you were happy with the speed. In that case, it would revert to the best gear to maintain that speed with the load. It would not up shift in to a higher gear if it could not maintain that speed because of the load and incline.

one would assume he knows this as he said:

I have owned the coach since new and it only started about 1000 miles ago. Coach have 67K milage if that is a factor.

[rgatijnet1]

The only way your Allison transmission would up shift is if the grade changed or if you were trying to accelerate and then let off of the throttle because you were happy with the speed. In that case, it would revert to the best gear to maintain that speed with the load. It would not up shift in to a higher gear if it could not maintain that speed because of the load and incline.

[usersmanual]

DanK wrote:
I am having a shifting issue with the Allison Transmission and I thought I would post it here to see if anyone had any insight on what it could be. The coach is a 2003 Newmar Kountry Star with the ISB 300HP motor and the Transmission is the 3000 series. The issue is that when I'm towing a vehicle behind the coach and I'm climbing a steep grade the coach downs shifts properly, but will not upshift properly. Example would be driving half way up a hill and the RPM will go to about 2400 after down shifting and would normally start to upshift at at around that RPM, but it goes in between gears. So the transmission tries to upshift, but doesn't actually upshift (I hope that makes sense). I have taken to coach into our Allison dealer and they could not simulate the issue, so they did not know what the issue is. The issue only happens when towing and only on very long grades. The other thing to mention is that when it tries to upshift is tries to do it every 1-2 seconds until I back off the on the gas pedal and then it will upshift. The problem is also starting to occur more frequently. I have owned the coach since new and it only started about 1000 miles ago. Coach have 67K milage if that is a factor. I would appreciate any insight you may have.

Hard to believe a actual Allison dealer has no idea?
One thing that to me does not make sense.You said on a loaded pull up a long grades? Once your on a long grade and its forced to downshift it should never upshift till the grade lessons?
it almost sounds like the engine governor(max RPM) is forcing the trans to upshift but the trans says no because of the load it feels
and wants to stay in the gear it selects for that load and pull
I assume your foots on the floor when it trys to upshift?

[wallynm]

When the last time you had the transmission serviced? Have you upgraded to Transynd fluid? Have you checked the fluid level? You can do that by using the shift. Allison has a recommended fluid change interval. Have you followed it?

http://dmaxstore.com/products/?route=product/product&path=12_31&product_id=41

DanK wrote:
I am having a shifting issue with the Allison Transmission and I thought I would post it here to see if anyone had any insight on what it could be. The coach is a 2003 Newmar Kountry Star with the ISB 300HP motor and the Transmission is the 3000 series. The issue is that when I'm towing a vehicle behind the coach and I'm climbing a steep grade the coach downs shifts properly, but will not upshift properly. Example would be driving half way up a hill and the RPM will go to about 2400 after down shifting and would normally start to upshift at at around that RPM, but it goes in between gears. So the transmission tries to upshift, but doesn't actually upshift (I hope that makes sense). I have taken to coach into our Allison dealer and they could not simulate the issue, so they did not know what the issue is. The issue only happens when towing and only on very long grades. The other thing to mention is that when it tries to upshift is tries to do it every 1-2 seconds until I back off the on the gas pedal and then it will upshift. The problem is also starting to occur more frequently. I have owned the coach since new and it only started about 1000 miles ago. Coach have 67K milage if that is a factor. I would appreciate any insight you may have.