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while i'm waiting, more Cub questions - forks #773903 05/16/19 11:30 am
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MartinBuilt Offline OP
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everything's good in the machine shop, so i've been looking at the front end of the bike.

The stanchions are tired, a little rusted, possibly bent.
What i'm finding is that the forks on the C models are different than the other lightweights, and there are no replacement stanchions available.

I wrote to Greystone to see if there were any other options, or common alternatives, said "no."

I don't want to fit a modern front end on this bike. I tried an oif fork on the c15, but it was just too tall.
I ended up using some unknown BSA rig, it might be from a Victor. it works, and looks like it belongs.

i am open to any suggestion, thanks very much.

Last edited by MartinBuilt; 05/18/19 2:06 am. Reason: wrong letter
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Re: while i'm waiting, more Cub questions - forks [Re: MartinBuilt] #773950 05/16/19 10:43 pm
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Whats the current stanchion diameter ?
Some early cubs had some funky undersized stamped triple trees .


Later and last cubs ... off the line in 1967
Ran these " heavy duty " forks .
They are 1 5/16 ... 33 mm +/- [Linked Image]
This looks like a very good set
But the price is kinda up there .
https://www.eBay.ca/itm/97-1880-FORK-ASSY-T20MT20SH-1966/133026391335
Ive read somewhere ... that the cub HD-forks are same/similar to some early T100 or pre-unit T120 forks ?




Re: while i'm waiting, more Cub questions - forks [Re: quinten] #773962 05/17/19 1:47 am
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yikes. $1100 is over-budget for this project.

I'll have to look into the other models. Might be that i can luck into another set that will fit.
The forks on my bike are the smaller lightweight forks, stanchions are about an inch in diameter (i didn't measure them) but i think i read 27mm somewhere.
There are replacement lightweight stanchions all over the place, but two suppliers have told me they won't work on a "C" front end, but neither explained why.

Possibly, it's the length, or they way they are drilled. I can't imagine Triumph designed something entirely different for this one model, though.
I'll keep digging...

Re: while i'm waiting, more Cub questions - forks [Re: MartinBuilt] #774030 05/17/19 7:23 pm
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Had a quick look at the parts books.
The forks seem to be the normal heavy weight forks fitted to Cubs
Basically that are Triumph 3/5 TA stanchions and lowers plus top yoke. The bottom yoke is also similar but is the 3/5TA casting with a different stem as the cub frame is smaller
You can normally pick up a set of forks in ok condition for about £250 in the uk

Once you have the HW forks you need a new front spindle and a pair of adaptors to shim the spindle up to the 5TA spindle size
plus a HW front brake plate. (Or buy a plate that you fix to the old plate)

Or you can assemble a set of forks from odds and sods

Re: while i'm waiting, more Cub questions - forks [Re: MartinBuilt] #774052 05/17/19 10:56 pm
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Incidentally the forks in your picture look like the later outside sprung Triumph forks . Although I think by that time bsa /triuumph forks were the same?

Re: while i'm waiting, more Cub questions - forks [Re: MartinBuilt] #774070 05/18/19 2:21 am
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so, Greystone got back to me on the stanchions.

They say the lightweight stanchions they offer won't work, but a set suited for the supercub/bantam will.
Diameter is right, length is different. Approx 1" shorter, which i can live with. I also need to find a set of gaiters, the correct ones are out of stock everwhere.

I would like to use as much as i can from the front end i have. The lowers are really nice, and i have a cool T20 trials fender that fits perfectly.

to add to my confusion, a company called 'BritishBikeBits' sent a note saying the stanchions Greystone warned me against would be perfect.

For now, my plan is to put my faith in Greystone, order a bunch of parts, and see what happens. I'm just waiting for the invoice...

Re: while i'm waiting, more Cub questions - forks [Re: MartinBuilt] #774269 05/20/19 6:29 am
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I think you should be able to use the standard Cub stanchions in the T20C, I believe the originals were thicker material for added strength. The Bantam Cub ones will fit, as already suggested, but you may find that as the Bantam type top yoke is thicker, you may need to grind or cut off some of the top chamfer. The top nut thread might be different as well, so you may need to drill some Bantam onesThe gaiters for the T20C are tricky to find, but you may be able to improvise using something off a mini bike or similar, you will just have to hunt around.


1966 Triumph Thunderville
1968 BSA B40M Roughrider
1970 TR6C
Re: while i'm waiting, more Cub questions - forks [Re: MartinBuilt] #774277 05/20/19 9:11 am
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Why not get the original stanchions straightened and then hard chromed.

Re: while i'm waiting, more Cub questions - forks [Re: MartinBuilt] #774311 05/20/19 4:57 pm
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MartinBuilt Offline OP
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well, we'll see what happens. I ordered a bunch of parts today. I imagine it will be a couple weeks before they arrive.

Greystone tells me everything is compatible, including the top nuts. I'll report back when i get a chance to try it.
I can't be the only person working on one of these cubs, the information might be useful.

as for saving mine, the one tube is hopeless, It's very badly pitted (i'll put up a photo later), and would require a bunch of welding and tooling to be round again. Even if that were the only problem, Chrome shops are few and far between in Pennsylvania.
With shipping, the replacements are about $75. I couldn't get a plating shop to answer the phone for that money.

Re: while i'm waiting, more Cub questions - forks [Re: MartinBuilt] #776045 06/10/19 11:52 am
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an update.
I'm still waiting for my parts from Greystone, so I've been drifting around eBay looking for good photos, and small parts.
Yesterday, i bought a set of heavyweight forks identical to the set pictured above.
They were much less $, though.

Should be here tomorrow.
I had asked a couple questions that were already answered above, my apologies for not going back to check.
Looks like i'll need a spindle, at least.

Last edited by MartinBuilt; 06/11/19 11:17 pm. Reason: Added info

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