Author Topic: Bevel Pinion Damage on Plus Gearbox  (Read 411 times)

0 Members and 1 Guest are viewing this topic.

Offline douglas1947

  • Master Member
  • ****
  • Join Date: Feb 2014
  • Posts: 518
  • Location: Germany
Bevel Pinion Damage on Plus Gearbox
« on: 21 Mar 2023 at 09:59 »
Unfortunatly I have again pitty with my Plus restauration.
Today I have noticed a broken tooth on the gearbox final drive bevel gear.
I know, normal I should change the bevel gears as a pair, but Im afraid it is not easy to get a pair.

I have a spare bevel gear (from a Dragonfly), looks kike the same. Has someone experience with changing only one pinion?

I have added pictures.

Michael

Offline douglas1947

  • Master Member
  • ****
  • Join Date: Feb 2014
  • Posts: 518
  • Location: Germany
Re: Bevel Pinion Damage on Plus Gearbox
« Reply #1 on: 21 Mar 2023 at 10:01 »
Photos with 2nd pinion

Offline eddie

  • Master Member
  • ****
  • Join Date: Mar 2006
  • Posts: 1860
  • Location: Hampshire, UK
Re: Bevel Pinion Damage on Plus Gearbox
« Reply #2 on: 21 Mar 2023 at 12:05 »
Michael,
             As far as I am aware, Douglas used the same large bevel pinion on all postwar machines. The small pinion - whilst carrying the same part number - was altered on the later Dragonflies. It was nothing that would affect the interchangability of the gears - it was just the O.D. was reduced to clear the beefed up casting around the rear mainshaft bearing.
  Whilst it was common practice to suggest that the gears should be changed in matched pairs - that goes for all gears, not just bevel gears! Having said that, Douglas only provided one adjustment for the mesh of the final drive gears (by shimming the output bearing housing). Normally, bevel gears have some adjustment for the small pinion as well. Without this adjustment, and no mention in the handbook on the correct procedure for shimming the large pinion, I would suggest the majority of surviving machines are running quite happily with less than ideal adjustment of the final drive. If it was on my bike, I would swap the damaged pinion, shim it up the same as the original, road test it, then by trial and error, adjust the shimming to get the quietest running.

  Regards,
                Eddie.

Offline douglas1947

  • Master Member
  • ****
  • Join Date: Feb 2014
  • Posts: 518
  • Location: Germany
Re: Bevel Pinion Damage on Plus Gearbox
« Reply #3 on: 22 Mar 2023 at 07:25 »
Hello Eddie,

many thanks for your advice.
I will use the spare bevel pinion to repair the gearbox.

Michael