Author Topic: Gearbox Drama's  (Read 174 times)

Offline Superflash

  • Tony
  • A's Good Friend
  • ***
  • Join Date: Jan 2020
  • Posts: 108
  • Karma: 0
Gearbox Drama's
« on: 25.05. 2021 02:15 »
Have got a bit of a story for you, so find a comfy seat and beverage of your choice and prepare to be entertained....
So the project is finished more or less. Got it down off the work table and pushed it outside to tidy up the workshop. When I went to pull it back inside, it popped out of neutral. Waggled the gear shifter back into neutral and went to pull it back again. Popped out of neutral again. Ok, so can't be much that some adjustment won't fix. I then proceeded to confirm the clutch works by pulling in the clutch lever and pulling the bike into the shed. Sweet....
This is where I start to lose my mind.... Hopped on the forum here just to see if anyone else had had the same problem with neutral popping out when pulling the bike backwards and after 38 pages of various topics found zilch. What I did find though in one of the threads was one of the guys talking about there 4 thrust washers inside the box.... one behind the kickstart pinion, yep got that. one behind the 1st gear pinion on the layshaft, (yep, got that too). But then he goes on about another 2 on the layshaft!! one between the clutch end bush and the fixed gear, and another one between two other gears. What the hell is that all about?? There's nothing on the parts drawing, and nothing mentioned in the lists, so where did these spring up from? The only 2 I put in were 67-3161 behind the kick-starter, and 67-3203 behind 1st gear. Is he talking about some other model, or do I have to pull the gearbox apart again...? Advise and counselling gratefully received. Cheers 
68 Trophy
74 Trident
74 XLCH Sportster x 2
86 Liberty Sportster
07 FXDWG (current)
53 BSA SF (WIP)

Online Swarfcut

  • Wise & Enlightened
  • *
  • Join Date: Oct 2018
  • Posts: 1623
  • Karma: 32
Re: Gearbox Drama's
« Reply #1 on: 25.05. 2021 09:01 »
 Standard gearbox has the hardened steel washer  67 3203 on the layshaft. Fit with inner bevel towards the clutch side to avoid the smooth diameter transition on the layshaft. So that's OK. So is the other washer to support the kickstart ratchet spring.

 My Super Flash supplement shows no other change from a standard Plunger box other than the kickstart pedal and associated hardware.

 The only time other thrust washers are required is a when roller bearings are fitted to the layshaft, as far as I know. So for your box this can be disregarded.

 Jumping into gear is more likely an incorrectly adjusted, worn or sticky camplate plunger or possibly a worn camplate. Jumping out of gear under load  is down to plunger adjustment and/or  wear on the gear drive dogs. Worst case is the box has to come apart, but with the exception of the sleeve gear bearing, seal and camplate pivot the box can be completely dismantled in the frame with a bit of patience and gymnastic flair.

 The Camplate Plunger adjustment plays a part in rotating the camplate as well as indexing the gears. Starting point for adjustment is just a couple of threads showing above the locknut.

 Swarfy.

Offline Superflash

  • Tony
  • A's Good Friend
  • ***
  • Join Date: Jan 2020
  • Posts: 108
  • Karma: 0
Re: Gearbox Drama's
« Reply #2 on: 25.05. 2021 10:26 »
You're my hero  *smile* rather glad I don't have to pull it apart again. Mind you I've done it 3 times now so am getting more confident each time. The cam plate and plunger assembly are all new so as you say it's probably all down to adjustment. Cheers
68 Trophy
74 Trident
74 XLCH Sportster x 2
86 Liberty Sportster
07 FXDWG (current)
53 BSA SF (WIP)