Author Topic: C11g fork legs  (Read 247 times)

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Online AdamM

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C11g fork legs
« on: June 26, 2020, 09:49:20 pm »
Hi all
Just finished taking the forks apart on my 54 C11g. Once I put the two legs together I noticed a difference. Both legs were the same length but the mudguard brackets were at slightly different heights.
Is this normal?
The bike didnt come with a front mudguard so i couldn't use that to check alignment.
I cant find any part numbers on the fork legs.
Any help is appreciated
Thanks

Adam

Offline BSAc11g

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Re: C11g fork legs
« Reply #1 on: June 27, 2020, 12:21:29 am »
Obviously they are not a pair
One is for a 19" front wheel & the other is for an 18" front wheel
Bike Beesa
Trevor

Online chaterlea25

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Re: C11g fork legs
« Reply #2 on: June 27, 2020, 01:17:17 am »
Hi Adam,
The difference is between A/ B and C models,
I came across this when I wanted to use a C fork bottom on an A7,
The C legs I had have now gone to a new home, but  can measure some A/B ones tomorrow (memory permitting ::))

John

Online Owen

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Re: C11g fork legs
« Reply #3 on: June 27, 2020, 09:18:23 am »
The black one is not a C fork leg.
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11

Online AdamM

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Re: C11g fork legs
« Reply #4 on: June 30, 2020, 11:42:15 pm »
Thanks everyone. I did assume the black one wasnt right. But wanted to check.

Adam

Online chaterlea25

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Re: C11g fork legs
« Reply #5 on: June 30, 2020, 11:59:31 pm »
Hi Adam and All

An A /(B?) series leg measures 85mm from the bottom of the seal threads to the centre of the mudguard mounting

B31/33's were also maroon and some C's were Black so colour is no indication
The lug for the brake plate was common to the 7inch brake C11G, C12 an B31's

John

Online Owen

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Re: C11g fork legs
« Reply #6 on: July 01, 2020, 07:16:51 am »
It's the wheel spindle hole on the black one that looks odd to me, but not sure if a C12 leg is similar?
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11

Online AdamM

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Re: C11g fork legs
« Reply #7 on: July 01, 2020, 07:51:13 am »
The wheel spindle hole on the black leg is threaded. Not sure if that helps with identification.
Havent had a chance to measure yet. Although a replacement leg for a C11g arrived yesterday and the mudguard brackets line up but the spindle hole is smaller and not threaded

Adam

Online chaterlea25

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Re: C11g fork legs
« Reply #8 on: July 01, 2020, 10:05:32 am »
Hi Adam,
The 7inch brake fork leg is threaded
9/16 x 20 left hand for the stepped spindle
C11g, C12, B31 Tec

John

Online AdamM

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Re: C11g fork legs
« Reply #9 on: July 01, 2020, 10:42:15 am »
So the fork leg should be threaded on the C11g? The replacement I got that said it was for a c11g doesnt have a threaded spindle hole.
In the pictures the one on the left is the replacement I bought and the one on the right is the incorrect one for a C11g that was already fitted.
The measurement of the incorrect one from the bottom of the seal threads to the centre of the mudguard bracket is 85mm.

I have also added a picture of the spindle I removed and the wheel that was on the bike. Am I correct in thinking that the spindle is for a 1955 c11g and that the 1954 should have a nut and bolt spindle?
The wheel rim is 20 inches diameter but the brake plate is 8 inches.

Just want to make sure I've got the correct set of fork legs for a 1954 C11g before I start painting and reassembling them 

Adam
« Last Edit: July 01, 2020, 11:03:16 am by AdamM »

Online Owen

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Re: C11g fork legs
« Reply #10 on: July 01, 2020, 12:35:12 pm »
Early C11G's with the 5 1/2" hubs had the plain hole. Later C11G's had a larger front brake with the threaded spindle.
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11

Online AdamM

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Re: C11g fork legs
« Reply #11 on: July 01, 2020, 01:23:11 pm »
So it appears I have a 1954 frame with half 54 and half 55 forks. With a 55 front wheel?

Does that mean the other fork leg (maroon colour one) is also incorrect for a 1954?

Adam
« Last Edit: July 01, 2020, 01:43:13 pm by AdamM »

Online AdamM

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Re: C11g fork legs
« Reply #12 on: July 01, 2020, 02:13:35 pm »
Any ideas why the later wheel would be fitted to the earlier bike? Was this a common occurrence or upgrade?

The only issue I can see with it is the mudguard wouldnt fit due to the brackets being at different heights

Apologies if questions seem stupid but the bike is nearly 40 years older than me and is my first old brit bike.

Adam

Online chaterlea25

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Re: C11g fork legs
« Reply #13 on: July 01, 2020, 05:35:55 pm »
Hi Adam,
My last reply seems to have gotten lost?
55 models came out in September 54
The  wheel rim is measured at where the tyre beads seat so probably 19in.
Brake drum inside measurement is 7in.
Yes it is a Well worthwhile upgrade
I have one on my 500 Ariel HT5 and properly set it is a two finger effort
Making up an odd mudguard bracket might be the easiest solution???
John


Offline timsdad

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Re: C11g fork legs
« Reply #14 on: July 02, 2020, 07:23:11 am »
In answer to your other question, Adam, Back in the Day, it was commonplace to fit whatever you could get hold of to keep an old bike on the road. I bought a '54 Matchless 350 Jampot in 1965 for £2/10s (£2.50p in this newfangled money) and, to get it on the road, I fitted a new set of clutch springs and a Panther seat. The springs, I remember, cost 10d each (4p) from Chapmans in Norwich and the seat cost me nothing. Maybe you'll understand more when I mention I earned £20 a month, quarter of which went to my mother for board. I also had a forty mile round trip to work in Norwich every day.

A later 500 Matchless G80, bought in the mid '70s, had been converted by the previous owner to automatic advance on its magneto so had an AJS timing cover over the magneto chain because that's what the parts came off. I paid, I think, £140 for this bike, including a pile of spares, and the mismatch of logos on the cases devalued it not a jot.

The C models fall in with this type of old bike and no one worried about matching numbers or forks. This huge problem was a later invention by investors and speculators.


Ray
Just a motorcyclist.