Author Topic: Bronze headstock on T35īs / Plus Models  (Read 269 times)

0 Members and 1 Guest are viewing this topic.

Offline douglas1947

  • Master Member
  • ****
  • Join Date: Feb 2014
  • Posts: 477
  • Location: Germany
Bronze headstock on T35īs / Plus Models
« on: 23 Oct 2022 at 17:33 »
Is it known, why the Douglas factory used on some bikes bronze headstocks insted of the iron headstocks?

Michael

Offline franky

  • Full Member
  • **
  • Join Date: Jun 2012
  • Posts: 36
  • Location: Bathurst Australia
Re: Bronze headstock on T35īs / Plus Models
« Reply #1 on: 24 Oct 2022 at 06:25 »
When checking the authenticity of a local 1950 Mark1V prior to purchase I checked that the frame and engine number matched but was miffed by the frame number which included a B. Let's say it was 7592 /4B no that's actually not my correct frame number, just too lazy to got out to the shed and check.
I asked the question in late 2016 of a LDMCC member as to why was there a B incorporated in the frame number. Apparently the headstocks could crack so the Marks were supplied with bronze ones. Now I know other models have the same features.
Does your T35 have a B stamped into the frame number?
Frank

Offline eddie

  • Master Member
  • ****
  • Join Date: Mar 2006
  • Posts: 1785
  • Location: Hampshire, UK
Re: Bronze headstock on T35īs / Plus Models
« Reply #2 on: 24 Oct 2022 at 10:06 »
A lot of early Mark series machines suffered frame breakages that necessitated repair under guarantee. Douglas made several attempts at overcoming the problems - one was bronze lugs (denoted by the 'B' suffix to the frame number). Another was post-production stress relieving - some late Mk3 and early Mk4 frames had an 'HPN' prefix - evidently this stood for 'Heat treated, pickled and normalised' - this treatment seems to have been short-lived. Whilst these changes reduced the frame breakages, some still occurred in later years. A lot of breakages occurred around the rear lug/swinging arm pivot - these could have been caused by poor lubrication of the pivot - the pivot pins were hollow (wih a small hole allowing grease into the bearing). If grease is allowed to congeal in the small hole, pumping more grease into the bearing just succeeded in blowing the sealing plug out of the inner end of the pivot. I have seen Mark pivot pins with blind holes (to ensure all the grease actually gets to the bearing and does it's job.

  Regards,
               Eddie.

Offline douglas1947

  • Master Member
  • ****
  • Join Date: Feb 2014
  • Posts: 477
  • Location: Germany
Re: Bronze headstock on T35īs / Plus Models
« Reply #3 on: 25 Oct 2022 at 07:07 »
I have a Mk5 with bronze headstock (1009/5B). I think that is an original headstock.
The bronze headstock on my 80+ could be a frame repair. The brazing looks a bit rough; there is no "B" in the number.

Michael

 

motorcycle