Author Topic: bsa c11 frames.  (Read 541 times)

0 Members and 1 Guest are viewing this topic.

Offline tzar12

  • Newbie
  • Posts: 4
  • Country: nz
  • Location: invercargill
bsa c11 frames.
« on: March 02, 2019, 12:01:57 am »
did bsa c11 have different frames for different mtrs eg 1952 frame with 1953 engine,

Offline timsdad

  • Gold Member
  • ****
  • Posts: 7321
  • Country: england
Re: bsa c11 frames.
« Reply #1 on: March 02, 2019, 08:24:54 am »
In that period, the frames were all built in one department, Mr t, and stamped with their C10 frame number.The original 1938 C10 frames were based on the old B20 frames and quickly replaced that same year with the rigid frames still using the B20 girder forks. Post war, the head-stocks were updated to take bigger bearings for the new telescopic forks and this frame continued up to when the plunger frame was introduced as an option. The plunger frames were built alongside the rigid frames until the rigids were discontinued and replaced with the swinging arm frame as an option in 1957. The numbers were always stamped as soon as the frames were built and the prefixes show what they actually were intended for if the spec differed. The C11 always used the same frame so had a C10 prefix.

The engines were built in a separate department and would be mated up with a suitable frame on the production line so their numbers wouldn't match but would be from the same year build with the correct letters - Letter year or 'W' for war time, 'S' for sprung frame, '4' for four speed box, etc. There could be many numbers between a frame number and its original engine number if there were far more of one C model built than the other.

The 1953 build-year started in September 1952 up to August 1953 and, as far as I can make out, sometimes engines or frames may have hung around for a month or three before being used, especially if there was a problem with an engine after installation. The engine would be changed, scribbling out and alterations would show up in the build register and the original engine would be installed in another frame after rectification.

That's sort of how the system worked so your frame may not look like it has its original engine even though it actually has. Is that what your question meant?


Ray
Just a motorcyclist.

Offline tzar12

  • Newbie
  • Posts: 4
  • Country: nz
  • Location: invercargill
Re: bsa c11 frames.
« Reply #2 on: March 03, 2019, 08:08:21 am »
thank you very much so its a 1953 in a 1952 frame.we,ll call it a 1953.
« Last Edit: March 03, 2019, 08:11:31 am by tzar12 »

Online Owen

  • Administrator
  • Gold Member
  • ****
  • Posts: 7677
  • Country: england
  • Solutions not problems
  • Location: Hampshire
Re: bsa c11 frames.
« Reply #3 on: March 03, 2019, 08:45:17 am »
Please add your bike details to the C register. If you don't want the engine and frame numbers visible to the forum members, please email them to me for the private register which only Pete and myself can see.
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11
Anyone want a B20 in need of a lot of tlc

Offline cerullos1

  • Full Member
  • *
  • Posts: 10
  • Country: ca
  • Location: canada
Re: bsa c11 frames.
« Reply #4 on: March 04, 2019, 11:48:59 pm »
were is this registry  I have a 1947 c10

Offline John M

  • Full Member
  • *
  • Posts: 231
  • Country: england
Re: bsa c11 frames.
« Reply #5 on: March 05, 2019, 12:20:19 am »

Offline Pete

  • Administrator
  • Silver Member
  • ****
  • Posts: 2715
  • Country: gb
  • Location: Kennet & Avon Canal
Re: bsa c11 frames.
« Reply #6 on: March 05, 2019, 10:15:37 am »
1948 BSA C11
1932/56 C12Rudge
N.B. Andromeda
Volvo V40

Offline enfield49

  • Bronze Member
  • **
  • Posts: 1116
Re: bsa c11 frames.
« Reply #7 on: March 05, 2019, 12:26:43 pm »
I had been unaware that the girder head bearings were smaller than the tele version . I don;t suppose they are the same as early bantam ? Graham

Offline timsdad

  • Gold Member
  • ****
  • Posts: 7321
  • Country: england
Re: bsa c11 frames.
« Reply #8 on: March 05, 2019, 01:30:54 pm »
I can't remember, exactly, Graham. The yoke spindle/shaft thingy is thicker on the tele-forks, I think, and I believe the ball bearings are a different size. You need a different puller for the girder fork bearings, so they're not interchangeable, but it may possibly be that the head stock outer races have the same outer diameter. If so, then it's quite easy to fit tele forks into a girder frame and vice versa.

I've never done it because it's sacrilege!
]

Ray
Just a motorcyclist.

Offline enfield49

  • Bronze Member
  • **
  • Posts: 1116
Re: bsa c11 frames.
« Reply #9 on: March 05, 2019, 08:34:32 pm »
I am going to use the girder fork , it is the best part of the bike, but the headstock bearings are beyond use. Graham

Online Owen

  • Administrator
  • Gold Member
  • ****
  • Posts: 7677
  • Country: england
  • Solutions not problems
  • Location: Hampshire
Re: bsa c11 frames.
« Reply #10 on: March 05, 2019, 10:19:57 pm »
The 1940-46 girder fork models use the same headstock bearings as the M20, which you can get a taper roller headstock bearing set from Dragonfly.

https://www.draganfly.co.uk/triumph-shop/twin-cylinder/product/13580-hawker-headrace-set-taper-roller-pair-a-b-m-not-b-1946-48/category_pathway-2 ::)
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11
Anyone want a B20 in need of a lot of tlc

Offline enfield49

  • Bronze Member
  • **
  • Posts: 1116
Re: bsa c11 frames.
« Reply #11 on: March 05, 2019, 10:52:10 pm »
Mine is late 38 ,There must be a suitable taper roller bearing somewhere. Graham

Offline timsdad

  • Gold Member
  • ****
  • Posts: 7321
  • Country: england
Re: bsa c11 frames.
« Reply #12 on: March 06, 2019, 06:57:17 am »
Tapered head-stock roller bearings are not the answer to everyone's dreams, as far as I'm concerned it's swings and roundabouts.

The main benefit from roller bearings is their bigger load-bearing area so they last much longer than roller bearings. The disadvantage of them is that they have much more drag, so make the steering noticeably heavier, especially when going in and out of roundabouts.

Cups and balls can usually be salvaged by spinning the old balls in the cups and cones with valve grinding paste and then fitting a new set of balls. This will last several thousands of miles, which should see most of us out, and is far cheaper and easier than sourcing, and perhaps modifying, tapered bearings. The freshening-up can probably be repeated if the steering gets notchy, and the cups and cones have got pitted again, but I've never had to on a BSA.

I just spin them together in my pillar drill, with a bit of paraffin as a lube, and it works for me. They don't have to be perfect to feel like new again and it can be done with wheel bearings too.


Ray
Just a motorcyclist.

Offline BSAc11g

  • Full Member
  • *
  • Posts: 487
  • Country: 00
Re: bsa c11 frames.
« Reply #13 on: March 26, 2019, 01:15:30 pm »
Quote
In that period, the frames were all built in one department, Mr t, and stamped with their C10 frame number.The original 1938 C10 frames were based on the old B20 frames and quickly replaced that same year with the rigid frames still using the B20 girder forks.

Interesting.
The parts book I have shows different part numbers but I happen to know some one trying to restores a B22 and he is having problems with the front forks.
It appears that a lot of C10 parts will fit the pre War B series or rather "almost fit" .
Bike Beesa
Trevor

Online Tman

  • Silver Member
  • ***
  • Posts: 2293
  • Country: england
Re: bsa c11 frames.
« Reply #14 on: March 26, 2019, 08:34:39 pm »
In my limited experience of fitting taper rollers to a bike originally fitted with ball and cups,  the taper roller bearings are deeper overall, and this then means the yokes sit further apart causing the headlamp brackets/fork shrouds to have a gap at the top.
I can see why the manufacturers fitted them on the assembly line but given most riders' use and mileage they seem unnecessary overkill to me. As Raymondo says above, they don't alter the handling for the better either.