A442 shift point question for the HDJ81 guys (1 Viewer)

[c2dfj45]

Need some input from the A442F HDJ81 guys......doing some shakedown work in my recently swapped 1hdt/A442 out of a 91 so a full hydraulic trans.......I 'think' the trans has an issue when it shifts from 3rd to 4th but I don't know as I have never driven one of these trucks. Figured I could get some input from guys that have logged miles behind the same combo.

I get a big drop in RPMs from 3rd to 4th. If I'm moderately driving(full boost but not pedal to the floor) on my way to 55mph.....the shift from 3rd to 4th happens at say 2600(I can't remember what it is exactly...maybe 40-45mph)....when it shifts to 4th, the drop occurs(the tach will indicate 1400-1500RPM) and it comes out of boost(well, technically it lowers the boost)...then it has to build boost and while it's building boost, there's black smoke. Not a cloud but for sure it's dumping fuel at that lower RPM until boost comes on and it cleans up by 1900-ish. Power and smoke in the other gears is under control. It's just that 3rd to 4th.

1st to 2nd, 2nd to 3rd don't have a big drop....they stay above 2000rpms so the turbo just keeps going and all is good. It's just that 3 to 4 shift....maybe something with the torque converter lockup? Maybe I need a G-turbo to spool up earlier ? Good thing that's on order already.

34.5 tires, 4.10, 15psi....nothing very unusual from what I can tell. I like the auto box....drives nicely and I like that it's full hydraulic...just not so sure something funny isn't going on.

Thanks in advance for any input....

 

[AirheadNut]

Sounds a lot like my brother’s HDJ81 when it shifts into torque converter lockup, usually around 40mph unless under heavy throttle. Rpm’s drop to around 1500 and it feels like you’re being propelled forward by a wall of torque. Lockup can be adjusted to happen a little later by adjusting the kickdown cable, but too much and the shifts get harsh.

 

[c2dfj45]

Sounds a lot like my brother’s HDJ81 when it shifts into torque converter lockup, usually around 40mph unless under heavy throttle. Rpm’s drop to around 1500 and it feels like you’re being propelled forward by a wall of torque. Lockup can be adjusted to happen a little later by adjusting the kickdown cable, but too much and the shifts get harsh.

Thanks AirheadNut......maybe the problem with my truck is the guy behind the wheel

 

[Outono]

Just chiming in here with the same answer as @AirheadNut. What you're describing is just the torque converter locking up. Now, if its excessive, it could be a bad TC, which happened to me. You'll have other symptoms if that happens though.

 

[c2dfj45]

Just chiming in here with the same answer as @AirheadNut. What you're describing is just the torque converter locking up. Now, if its excessive, it could be a bad TC, which happened to me. You'll have other symptoms if that happens though.

No other issues for me. Truck shifts nice. No weird noises or vibrations.

 

[Tanner H]

Dusting this thread off to avoid making a new one:

1990 hdj81 with fully hydro trans.

My question is the rpm drop between gears when giving it light or medium throttle.
1-2 has a slight rpm drop, but 2-3 almost has no rpm change on the needle (around 2100 with light/city driving throttle). I can feel it shift from 2-3 but man that tach barely barely moves. Is this normal?

I should note it shifts and drives great, so not a complaint post haha