Airhead 5-speed tranny conundrum

[TEXASYETI]

A friend of mine is having some tranny issues and could use some help:

81 G/S, recent tranny overhaul - did it himself.

Input shaft turns nicely and the output shaft turns with the input shaft. He had an old airhead guy take a look at the finished product, i.e., run it through the gears and he said it felt fine.

Puts it in the bike and with spark plugs out he cannot turn the rear wheel - and therefore the engine cannot be turned over either. He says it is locked up.


Thanks!

[mark1305]

My first thought (As I am learning these boxes myself) is to ask, "Did anyone shift through the gears up AND back down?" Apparently it is possible to get them together and shift up, but not be able to shift back down.

Second thought is, disconnect the driveshaft at the flange again and try to turn the rear wheel/shaft by themselves. That will either isolate the problem to the gearbox (or motor, or both) or isolate it to the driveline.

Third idea is to leave the drive shaft connected but disconnect the swingarm and slide the gearbox back off the motor as if doing a spline lube and trying to turn the gearbox by turning the rear wheel.

And naturally trying to shift gears whenever you can manipulate either transmission shaft to facilitate shifting.

Edit: Before dismantling anything, can he rock the rear wheel back and forth and really rattle on the shifter to work up or down through the gears back to neutral?

I found when test shifting mine through the gears, that I couldn't shift it firmly enough with just my hand on the shift lever (with the gearbox still open and on the bench). I used a small length of tubing (actually a two-ended stamped steel sparklug socket) over the lever end and had to kind of snap each shift to get it to kick to the next detent and actually get the gears to slide into engagment.

Good luck. It may get discouraging if it comes to pulling and reopening the gear box. But perservere.