Suzuki T20 selector drum
Posted: Fri Jan 22, 2021 3:24 am
Dear all,
While I wait for my crank to come back from SEP, I've been checking the gearbox over. Due to the state of the engine I couldn't test drive so I want to make sure all is well. I assembled and found that the selector mechanism is too stiff to turn. I thought I had done something wrong but careful inspection reveals two problems;
1: With the selector drum sitting on the spring detent it protrudes slightly on the neutral switch side. Thus, bolting up the neutral indicator case pushes the drum slightly inwards. I carefully flatted down the neutral side plate on a surface plate and it is clear that two of the screw heads were rubbing slightly against the end of the selector drum (see pic). It helped a little now I have a fresh smooth surface but bolting it up pushes the selector drum towards the change mechanism side.
2: The two selector drum plates have been modified to reduce selector drum float (see pic) which makes things even worse. The end of the right hand plate has been bent over slightly whilst the stopper plate has been ground so it fits in closer to the cases (its worse than it looks on the pic). The upshot is that there is no side float whatsoever and the whole thing nearly locks when the neutral plate is bolted up tight.
If I have the screws on the neutral switch plate loose then the selector mechanism works great so proving I have insufficient end float. I will attend to the selector drum plates which should restore some clearance but that still leaves the selector drum sitting hard against the neutral indicator plate and slightly pushing the detent plunger out of its groove. I'm tempted to chuck the selector drum in my lathe and take off just enough material so it sits flush with the end cover. I guess the alternative is to try and shim the cover out a little.
This is all a little baffling as I cannot see how the gearbox could have worked in the state it is now! Can anyone supply any advice please before I resort to modification? Is there a specification for selector drum end float that I can work to achieve?
Thanks!
Keith
While I wait for my crank to come back from SEP, I've been checking the gearbox over. Due to the state of the engine I couldn't test drive so I want to make sure all is well. I assembled and found that the selector mechanism is too stiff to turn. I thought I had done something wrong but careful inspection reveals two problems;
1: With the selector drum sitting on the spring detent it protrudes slightly on the neutral switch side. Thus, bolting up the neutral indicator case pushes the drum slightly inwards. I carefully flatted down the neutral side plate on a surface plate and it is clear that two of the screw heads were rubbing slightly against the end of the selector drum (see pic). It helped a little now I have a fresh smooth surface but bolting it up pushes the selector drum towards the change mechanism side.
2: The two selector drum plates have been modified to reduce selector drum float (see pic) which makes things even worse. The end of the right hand plate has been bent over slightly whilst the stopper plate has been ground so it fits in closer to the cases (its worse than it looks on the pic). The upshot is that there is no side float whatsoever and the whole thing nearly locks when the neutral plate is bolted up tight.
If I have the screws on the neutral switch plate loose then the selector mechanism works great so proving I have insufficient end float. I will attend to the selector drum plates which should restore some clearance but that still leaves the selector drum sitting hard against the neutral indicator plate and slightly pushing the detent plunger out of its groove. I'm tempted to chuck the selector drum in my lathe and take off just enough material so it sits flush with the end cover. I guess the alternative is to try and shim the cover out a little.
This is all a little baffling as I cannot see how the gearbox could have worked in the state it is now! Can anyone supply any advice please before I resort to modification? Is there a specification for selector drum end float that I can work to achieve?
Thanks!
Keith