champ198
Active Member
hi everyone, I've had my XB21 for about a year now. I've recently experienced a hard "clunk" in my Engine or Sportmaster when I'd come off of pad and goose the engine to get ahead of the following wave. When I'd trailer the boat and right before I'd ease up on the bunks, it would "clunk" while I gave it gas.
Turns out, the Allison shifter was slipping out of the fwd gear notch and sliding slightly toward neutral during runs down the lake. This was pulling the gear back out but there was enough of the gear that it would catch and make the clunk.
I took the shifter assy apart and tightened the nylock nut that the shifter lever pivots on. If you ever have a shifter issue, check this.
To remove the shifter assy:
1.) Unscrew by hand the gear shifter knob from the lever. It is two pieces with one that has the bolt embedded.
2.) Remove the plastic gear shift cover. This is either wood grain or carbon fiber. It is held in place by two phillips head screws.
3.) Take an allen wrench and remove the four screws. Remove the plastic plate.
4.) Remove the assembly by unscrewing the four large screws with a phillips head (be careful not to drop these into the inside of the boat.
5.) Turn the lever to reverse. This moves the internals forward to allow you to work the shifter mechanism out of the hole.
6.) Adjust the nylock nut at the base of the shifter a few turns so that it has slightly more friction. You want it tighter but not too tight.
7.) reverse the process to re-install.
One thing I appreciated was the custom aluminum brackets, all of the machined screws used and the compact design in general.
Hope this helps someone in the future.
Turns out, the Allison shifter was slipping out of the fwd gear notch and sliding slightly toward neutral during runs down the lake. This was pulling the gear back out but there was enough of the gear that it would catch and make the clunk.
I took the shifter assy apart and tightened the nylock nut that the shifter lever pivots on. If you ever have a shifter issue, check this.
To remove the shifter assy:
1.) Unscrew by hand the gear shifter knob from the lever. It is two pieces with one that has the bolt embedded.
2.) Remove the plastic gear shift cover. This is either wood grain or carbon fiber. It is held in place by two phillips head screws.
3.) Take an allen wrench and remove the four screws. Remove the plastic plate.
4.) Remove the assembly by unscrewing the four large screws with a phillips head (be careful not to drop these into the inside of the boat.
5.) Turn the lever to reverse. This moves the internals forward to allow you to work the shifter mechanism out of the hole.
6.) Adjust the nylock nut at the base of the shifter a few turns so that it has slightly more friction. You want it tighter but not too tight.
7.) reverse the process to re-install.
One thing I appreciated was the custom aluminum brackets, all of the machined screws used and the compact design in general.
Hope this helps someone in the future.
