5 Speed Lockup Clutch

[truk4u]

Does anyone know if the Lockup Clutch function on our 5 speeds can be programmed for different parameters? Since the lockup is controlled by the ECU, I thought Allison may be able to make changes. Mine free wheels through 1st and 2nd gear when retarding the throttle, sometimes at speeds close to 30 mph and requires constant brake action when coming out of lockup. Obviously, the jake is inoperable during lockout and is only good for 3rd, 4th and 5th gear.

[Jon Wehrenberg]

Tom,

Talking different vintages here, and a 1st generation computer vs your more modern one, but in my 87 I was told lockup was in first or second. I do know that the Jake dropped out around 20, a feature I did not like because when it dropped out it felt like you had gotten a push.

[truk4u]

Thanks Jon, I checked with Allison and it can't be done. The older 5 speeds are not electronic and parameters can't be changed.

[BrianE]

That was my understanding also. It was also my understanding that the "heavy shift" that occurs around 10-20mph is the tranny going into lockup where it remains until leaving lockup at about the same speed decelerating. Lack of jake at low speed seems to be a common complaint of all the 92 owners I've talked to.