Author Topic: C11 rigid frame  (Read 270 times)

0 Members and 1 Guest are viewing this topic.

Offline Sidslug31

  • Full Member
  • *
  • Posts: 5
  • Country: gb
  • Location: Leicester
C11 rigid frame
« on: March 07, 2019, 06:35:56 pm »
Hi, I’ve just acquired a rigid C11 project and on examination the front down tube appears to be slightly bent forward, the alignment seems ok still.
I have studied online photos and it’s hard to tell if this is the norm as some appear to have a slight forward bend?
Can anyone confirm if this is the case before I send it off in a panic to be straightened.
Much appreciated thanks.

Offline chaterlea25

  • Silver Member
  • ***
  • Posts: 2548
  • Country: ie
  • nr Cork Rep of Ireland
  • Location: Nr. Cork
Re: C11 rigid frame
« Reply #1 on: March 07, 2019, 06:49:33 pm »
Hi and welcome Sid

The best thing to do is see if the engine cases and frame fit together before any surgery

John

Offline Owen

  • Administrator
  • Gold Member
  • ****
  • Posts: 7562
  • Country: england
  • Solutions not problems
  • Location: Hampshire
Re: C11 rigid frame
« Reply #2 on: March 07, 2019, 06:51:02 pm »
Have a look at the frame dimensions on the following link https://bsac10c11c12.co.uk/smf/frame-forks-service-sheets/frame-dimensions-11927/msg99751/#new
What year and suspension does it have?
Please post your bike details in the C register. https://bsac10c11c12.co.uk/smf/'c'-register/
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11
Anyone want a B20 in need of a lot of tlc

Offline Sidslug31

  • Full Member
  • *
  • Posts: 5
  • Country: gb
  • Location: Leicester
Re: C11 rigid frame
« Reply #3 on: March 07, 2019, 07:29:29 pm »
Thanks I will check the measurements very useful info.

Offline Sidslug31

  • Full Member
  • *
  • Posts: 5
  • Country: gb
  • Location: Leicester
Re: C11 rigid frame
« Reply #4 on: March 08, 2019, 04:30:30 pm »
Thanks after checking measurements all are correct. But it definitely has a slight outward curve ? but all measurements spot on.   

Offline enfield49

  • Bronze Member
  • **
  • Posts: 1115
Re: C11 rigid frame
« Reply #5 on: March 10, 2019, 05:46:48 pm »
Which bike had a lightweight 4 speed box and a rigid frame ? Graham

Offline Pete

  • Administrator
  • Silver Member
  • ****
  • Posts: 2618
  • Country: gb
  • Location: Kennet & Avon Canal
Re: C11 rigid frame
« Reply #6 on: March 10, 2019, 06:40:11 pm »
Which bike had a lightweight 4 speed box and a rigid frame ? Graham
None. I believe that drawing was made for anyone considering a mod.
Pete
1948 BSA C11
1932/56 C12Rudge
N.B. Andromeda
Volvo V40

Offline chaterlea25

  • Silver Member
  • ***
  • Posts: 2548
  • Country: ie
  • nr Cork Rep of Ireland
  • Location: Nr. Cork
Re: C11 rigid frame
« Reply #7 on: March 10, 2019, 06:50:15 pm »
Hi All,
Quote
Which bike had a lightweight 4 speed box and a rigid frame ? Graham

I'm fairly sure this conversion drawing was made by a forum member from Switzerland,  Paul de Groot

https://bsac10c11c12.co.uk/smf/technical/swap-from-3-to-4-speed/msg9037/#msg9037

I posted a photo of a converted rigid C10 a while ago,
It has a modified saddle tube and custom engine plates as far as  can see

John

Offline Sidslug31

  • Full Member
  • *
  • Posts: 5
  • Country: gb
  • Location: Leicester
Re: C11 rigid frame
« Reply #8 on: March 10, 2019, 07:59:09 pm »
I took the measurements from the drawing supplied for a 3 speed rigid 11 31/32” from centre of engine plate mounting points all seem to be spot on to these drawings, bikes a 3 geared version and seems very original in most aspects.

Offline Paule

  • Full Member
  • *
  • Posts: 245
  • Country: ch
  • Meggen, Switzerland
Re: C11 rigid frame
« Reply #9 on: March 11, 2019, 04:45:26 pm »
Hi All,
attached you'll find the final drawing of the mod to make a '49 rigid 4 speeder and a few more pics. Really much better for riding here in Switzerland. No more reving the engine up too high to get into 2nd and higher gears!!
It was quite a job to get there, last year i had it the mod technically checked by the authorities. They had no problem with my build, so now it's road legal here in Switzerland :-)

Here's some brief information about the mod:
I have used a later frame which i bought from Peter Long (http://cornucopia-enterprises.de) and stamped my correct frame number onto it.
The lightweight 4-speed gearbox has same width as the original 3-speed gearbox. The genuine 3-speed gearbox plates can be modified to fit. The sprocket alignment is perfect! To keep the original drive ratio, i had to modificate the gearbox sprocket as well (from 19T to 17T).
The rear brake rod has tendency to fowl the gearbox if using the brake. This should be checked carefully!!!

Hope this helps, Paul

PS: Not visiting this forum as often as i used to, because i've started working on a bike, i've been dreaming of for a long time... '52 500cc OHV sloper, 28HP, full sprung frame, what could it be, possibly? ;-)
This forum is still such a great place with very very helpful people, one more time thanks to all for their help.

Offline enfield49

  • Bronze Member
  • **
  • Posts: 1115
Re: C11 rigid frame
« Reply #10 on: March 12, 2019, 06:10:45 pm »
It is nice to see modifications such as this so well thought out. The main problem over here would be registering such a bike , frame modifications are frowned upon . As for the spring frame sloper , that sounds nice , for years there was a spring frame rudge ulster being used as daily transport round here , an excellent bike , it has probably been rebuilt as standard and will be identical to all the other rudge ulsters which have survived. Graham