Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 06, 2025 ...

Shifting on the Allison 3000 was very much the same on all three of our coaches: Caterpillar 3116, Caterpillar 3126 and Cummins ISL.

Wonder how old the fluid is and if it is Transynd 668?  The better fluids from Allison do shift smoother than the old Dexron.

And, no diagnostic codes, correct.

What was the wire hanging down in one of your earlier posts?

Probably worth disconnecting, cleaning with Deoxit and reconnecting all connections at transmission, ECU and shift pad.

As to trans fluid, I do not know what is currently installed but will be replacing fluid and filters in the Allison next week and will use Allison parts and fluid.

Yup, get the filter kit from Allison-- it will have instructions/torque specs.

Buy the 5 gallon pail of 668. That will leave you about one quart left over from the change.

Just throwing this out there but could the idle rpm be too high causing a rough shift,had that happen on a car.

Just throwing this out there but could the idle rpm be too high causing a rough shift,had that happen on a car.

Sounds like you are talking about starting from a stop.  All of my starts from stop are at WOT until speed limit.  At the speed limit I let up and the trans will upshift and it will be a jerk.  First gear shifts at 2000RPM, 2nd has a torque converter lockup, then a shift to 3rd at 2650RPM. 3rd RPM drops to 1900, then winds up to 2650 to shift into 4th.  4th RPM drops to 2000 and then winds up to 2650 again to shift to 5th.  My top speed towing my HHR is 62-63MPH, in 5th the engine is turning 2300RPM.  If I let up on the throttle during the takeoff/start  with speeds less than 40MPH the trans will upshift and it will be strong.

Our U300/Allison HT747 with stock ATF shifts OK on upshifts also with WOT with the final 3rd to 4th shift at highway speeds OK. Not glass smooth but OK. Heading upgrade, the 4th to 3rd shift is OK with 3rd to 2nd harder. The rough shifts are the partial throttle down shifts and the downhill shifts where the coach starts to coast and then suddenly goes into 2nd gear.  The 747 is a transmission used in garbage trucks and is very durable as it may start and stop several times in one block. The 4 speeds on coaches have a pretty good gap between gears so will not shift as smoothly as the 6 speeds with closer ratios. Our larger 6V92TA only turns 2130 rpm max.

I've never seen an Allison that was anywhere close to perfect. We had Allisons on smaller rigs on the FD with the City using Allisons on the small Mercedes buses. They shifted so hard, that they would chip the ring gear in the rear axle third member. Lots of complaints from the riders. Said that the drivers could not shift the transmission . This was the reason they sold all the small buses.

Got to experience the auto/manual Detroit DT12 (12 speed transmission) for a good automatic. Even skip shifts and can use GPS for the right gear for any highway and grade in the U.S.

Pierce

Upgrade to the trans synd fluid if u can

Yes, any Allison dealer will have not only the correct filter kit (both filters plus gaskets and instructions) but also the Transynd 668.  As mentioned, the 5 gallon pail is the most economical way to buy it.

I set the pail up on a ladder and start a siphon into the dip stick tube to fill.

Tell us about the turbo leak?. A picture if soot trail from leak.

And, if hard shifting continues after fluid change, I would sure have the transmission's throttle position sensor checked for proper adjustment. For example, it the throttle position sensor tells the transmission that the engine is at WOT and you are at part throttle, the shifts WILL be harsh.