BAC Forum

General Boards => Technical Support => Topic started by: Mark Beavin on March 03, 2019, 01:46:57 PM

Title: Allison transmission up shift
Post by: Mark Beavin on March 03, 2019, 01:46:57 PM

While making a trip towing my trailer using the cruise control on a slight incline the transmission will down shift to 5th and seems to stay there even after leveling off. If it then rolls downhill it will shift back to 6th. If I disengage the cruise on the flats it will shift to 6th and then I reset. Is this normal? Also has a delayed 3-4 shift when not towing. Anyone well versed in these 6 speeds. 1996 cat 2136 with Allison

Title: Re: Allison transmission up shift
Post by: Bill Lampkin on March 03, 2019, 04:47:12 PM

Might be you need to regain roadspeed. On my 05 Beaver, I have to exceed the speed limit (55) to get an upshift to 6th, it happens around 58 mph or so. Cruises quite happily at 59 or 60.

Title: Re: Allison transmission up shift
Post by: Gerald Farris on March 03, 2019, 05:26:04 PM

Mark,
There are many factors that will influence your shift pattern, but mostly they boil down to 2 parameters, and they are throttle pressure and speed. If you were driving very close to the shift point with a heavy load on cruse control, I would consider your first complaint normal.

On your second complaint of a delayed 3-4 shift, that will depend on throttle pressure. If the condition is pronounced regardless of throttle pressure, you need to visit the local Allison shop.

Gerald   

Title: Re: Allison transmission up shift
Post by: Dwight Lakusta on March 04, 2019, 06:27:10 AM

Do you push the economy/performance button on your gear selector? It should not kick down ever when the red light is on.

Title: Re: Allison transmission up shift
Post by: Mark Beavin on March 04, 2019, 01:58:37 PM

Have not tried that, thanks!!!

Title: Re: Allison transmission up shift
Post by: Mark Beavin on March 04, 2019, 02:04:03 PM

Thanks for the replies. Heading out tomorrow and will try both the economy mode and will try speeding up a bit with the cruise on. Got great mileage on my last tow of 10.3MPG holding 55-57 mph towing my Race car trailer

Title: Re: Allison transmission up shift
Post by: Mike Shumack on March 04, 2019, 02:40:58 PM

Quote from: Mark Beavin on March 04, 2019, 02:04:03 PM

Got great mileage on my last tow of 10.3MPG holding 55-57 mph towing my Race car trailer

That little engine is fuel sipper - lucky you.
Mine is a guzzler.

Title: Re: Allison transmission up shift
Post by: Dwight Lakusta on March 04, 2019, 05:49:26 PM

https://familyrvingmag.com/2012/03/01/allison-transmission-mode-button/

Here is a write up on it!