Allison 4 speed tranny question

[LetCook]

I just purchased a 1999 Winnebago Vectra GT with an Allison 4 speed transmission from a private seller. I noticed when I run at about 60mph, the RPM's hover around 3000. Is this normal? Thanks for any help/info!

[AFlugstad]

No that is not normal for flat ground. It sounds like you have OD locked out. You should have a switch on your dash.

[tderonne]

Sounds normal.

Discussed here.

(Your Vectra is on a Chevrolet P12 chassis. Gas engine with a 4 speed Allison. Not too many out there. You need to filter out the non-P12, non-Allison related information, it won't apply to your setup.)

[SmilingSimon]

not likely an allison but a gm 4l80e trans. and if so then 60mph when it has gone into '4th' gear should be 2100 rpm or so, depends on rear axle ratio some, a more or less good rpm for cruising - ~2000rpm.


the 4l80e trans is really a 3 speed with a lockup torque converter for 4th gear, when it goes thru the 3 gears it will then lockup and be in '4th' gear, the 1:1 ratio gear, no OD really, unlike the real 5 & 6 speed allison trans.


but i would turn 3000rpm in NON locked up D, but really it was in 3rd gear, and i would ease off throttle and it would quickly lockup in 4th.


so you are not getting into the locked up 4th gear for some reason, check your fluid levels and such, but sounds like you need a mechanic to check it out.


i never had any issue with mine so no insight, sorry, i did always check my fluid levels before driving.



GL!

Originally Posted by LetCook

I just purchased a 1999 Winnebago Vectra GT with an Allison 4 speed transmission from a private seller. I noticed when I run at about 60mph, the RPM's hover around 3000. Is this normal? Thanks for any help/info!