Bsa c12 front forks

[Clitheroe kid]

HELP!
I RECENTLY BOUGHT A C12 1957 (OR SO IT SAYS ON THE LOG BOOK) but I'm now thinking I've bough a mixture of various models.
The front left side fork sometime siezes, so I bought some used forks off ebay, supposedly for a c12.
However after reconditioning and fitting , I find that the wheel mounting is different with a seemingly straight through rod: 0.8inch dia at both forks
My "original" forks which were on the original the bike when bought have a 0.57inch lh thread at the lhs. And are 0.8inch dia. at the lhs with a hole through this end for screwing the mounting rod  into the lhs fork.
I have several questions    ------
1) Are these  forks as purchased the correct forks for this "1957" c12?
2) If I need to purchase replacement slider tubes, which should I ask /search for?
3) Is there anyone out there who is near E Lancs who can advise?
4) Where's the best place to buy or repair?
Any hel would be much appreciated.

[jodie89]

There is a forum specifically for these bikes. Just type in C10 C11 C12 forum. Knowledgeable and very helpful people on there.

[JulianS]

The front wheel setup should be like this, with screw in spindle with left hand thread.

[Clitheroe kid]

Well at least I have the correct forks which I have stripped down and found a bit of a dinge at the bottom of the RH slider.
Now the search is on for a replacement, but can I heck find anything.
Are C12 parts difficult to get hold of, cos Ive tried most of the more popular suppliers. but these sliders are rarer that  rocking horse s--t.
has anyone got any ideas?

[idie]

How long is the slider. I wonder if they are the same as a B series. Also measure how far the fork brace bracket is from the top of the slider. I have a feeling that the only difference is the bracket position.

[Clitheroe kid]

At first glance, the B series is much like the C 12 slider.  However, the spindle for the B series seems to be with a clamp at the base of both Lh and Rh sliders, whereas the C12 slider which I have here is an 8/10" clamped hole on the rh base and the        L handed  thread on the left slider base.
I'll get those measurements  for you in the morning.
I've found one slider in Australia  on ebay, it's a bit steep and so is the carriage.
One other idea I've had. (and this will make you frown); I've thought about turning the bottom brass bush down by a few thou for the bottom 1/2" so that it doesn't catch the dinge and sieze. Desperate measures needed though.
Another alternative is to remove the welded on clamping assembly from a B series, and replace it with the one which is on the damaged C12 slider.
Honing the inside dinge at the bottom of the slder is difficult owing to the reach and also the centralising peg.
I bought a pair of forks with sliders on ebay, thinking they were correct, only to find that after sand blasting and painting etc. the wheel wouldn't fit, because unknowingly, I had bought forks which were for a C11. Hence my original confusion.  You can Imaging my language, but I'm glad to say my wife is now speaking to me again after dodging the flying spanners !!!!!!!!

[DAVE BRADY]

Hi,

Is it possible to put a steel tube in to the slider that will just fit past the ding and over the locating pin?  Some light hammer work could then used to repair or deduce the ding.  Nothing to loose in trying if you cannot use it as it is.

Dave.

[Clitheroe kid]

It's an idea, I could turn some steel down to exact dia of the tubing, possibly give it some heat to harden it.
From what I can see looking down the tube, the ding internally is minimal, possibly abot 15 thou, so it might work.
As ive explained, it's kill or cure.

[idie]

The B31 has a split bush in the right hand leg which when removed enables the eight inch brake to be fitted like on the B33. The left hand leg, the left hand thread is the same. I think both C12 and B31 use the same length legs the difference being the distance the bracing lug is from the top. That is why I asked if you could do the measurements to see if I had one.

[Clitheroe kid]

Thanks for your responce.
The slider I have here is 11.5" long ( absolute bottom to end of thread with a thick welded lug on the inside of the tubing.  This lug is 1.5" wide/long, it has 2 x 5/16" holes  and is 7.5" from the bottom of the slider. (not shown on Dragonfly p/li.
This prob is driving me nuts, and she is complaining about motorbike parts on the kitchen benches.st)
The stanchion is 22" from end to end, and the oils seal holder is 47/8" long.
The dinge is about 3/8" sgare, and 3/4" from the bottom of the tube where it is welded to the spindle lug.
There are 2 x mudguard tags on this spindle lug

[idie]

I have played this game with dings on the slider. Bear with me on this and I will check in the garage tomorrow and measure the ones that I have. I will get back to you then.

[Clitheroe kid]

I've prepaired and polished a 38mm hole saw so that its a good tight but slideable fit down the slider.  All I have to do now is to devise a method of accuratey getting it down.  I  think I might weld a 14mm steel bar onto it with a 12mm hole for the spindle peg.
However, I'll wait in hope for any news you might have.  Fingers are crossed.

[idie]

 When you say right hand are you standing facing the bike and is it the one with the bush and clamping screw. If it is this then I have the one, it fits all your measurements. I fitted it to my B33 and then found that the bracing lug was higher. The clamping screw thread is weak and the clamp is a bit chewed up, not by me, so will need a nut on the bolt. All works ok comes with the bush. Yours if you want it. Just pay postage.

[Clitheroe kid]

Oh dear!
It's the wrong one! the one I need is the threaded side. It hasn't been my week.  I'm sorry I've put you to so much trouble, my fault and I'm a bit embarrsed.
So, it's back to route 1, I'll try to bore the thng out.
I can't thank you enough for your help.

[idie]

No problem, good luck in trying to get rid of the ding. I have never been successful. If you are not a rivet counter you could use a pair of sliders from a B31 or B33 and fit a longer brace and stays. The sliders are the same length. The B31 stanchions are 1/2 inch longer.