4 replies to this topic

[BPilgrim]

Hello Everyone,

I've just taken on a 1959 Triumph 3TA barn find, and I hope to turn it into a trials machine. My sort of riding is just having a bit of fun on the white route, so I'm not after much competitiveness, but I am interested in keeping it period, and I'm hoping to do as little (if any) permanent modifications as possible. Here's some pictures of the bike in question:

Triumph 3TA

My first question is the hubs, before I get the bits to lace the planned 21" WM1 and a 18" WM2, what hubs would be appropriate? From reading around it seems a Tiger Cub front hub is common choice, do these come in 36 or 40 hole (or does it vary, if so, which is better?).

With regards to the rear hub, can I get away with using the original, as it already has a very small drum? It is the type where the sprocket and drum are cast as one, but it bolts to the hub itself, so the sprocket could still be changed without difficulty, albeit taking the drum with it. From reading the threads, it appears alignment of the sprocket is an issue with a trials conversion, which is why I'm keen to keep the original hub on the back. Also, I don't suppose anyone knows if a 18"x4" tyre will fit the swingarm on a 3TA. I'm sort of guessing here, but I think it's the same frame as the 5TA, which I'm assuming is quite a bit bigger than a tiger cub series? I'm hoping the chain won't hit the tyre.

For the lacing bits, could anyone recommend a good place to source the rims and spokes from?

Another question I have is about the oil tank, what are the side affects to having a smaller oil tank, I think it's got a 2 3/4 pint tank on it, would a 2 1/4 pint make any difference? Also, is a 'froth tower' recommended for trials?

Other bits which I should mention;
-exhaust will be twin high level pipes, inspired by the Triumph Metisse, bit heavier than the siamese system, but it'll look fantastic
-forks... I hope to leave original... I'm planning to just heat treat the springs to suit, and have a play with the oil to make them work.
-fuel tank, tiger cub, or terrier tank, as the newly made pre-65 trials tanks I found were really expensive.
-mudguards, universal alloy ones, would you recommend the 6" D shape rear (for the B40) or the 5" C shape rear (for the Tiger cub)? (will be from trialsbits)
-Handlebars - Although I love Renthal bars, the brace looks too modern for this bike, so I'm looking at the Pre-65 bars from Sammy Millers, are they any good?
-Seat - I plan to make
-Air filter - are pancake filters ok for trials? As mentioned, I'm only riding white route, so they're shouldn't be any deep water.

I think that's enough questioning for now!

Many thanks,
Ben

[totalshell]

as inspiration and a cracking source of knowledge / direction dave at http://www.dcclassicmotorcycles.co.uk/ i ve had a ton of bits and hours of help and advice from him in the past.

[Big_Red_Bike]

Hi your problem with keeping the rear hub will be gearing,you need a lot bigger rear sprocket about 64 teeth,a 14 tooth front sprocket and also a small engine sprocket from dave mentioned in above post.To fit the engine spocket you have to grind some metal away from the main bearing housing to provide room for the primary chain.

[CVGMmartin]

Hi Ben, The triumph twins are great fun to ride, but like any other pre-65 bike, only as long as the engine runs cleanly without spitting back, and stalling. I would strongly recommend putting a PVL electronic ignition system on and get rid of the old points and mechanical advance/retard mechanism. I ride a 500 in a frame of my own making so can’t help with many of your questions, but as far as the engine is concerned I would go with a siamese exhaust, it will be easier to make it reasonably quiet and I think it will run better at low rpm. When I first built my bike I was told to put the 3TA cam in it to soften it, unfortunately this made it gutless and no fun to ride, I now use a standard T100S exhaust cam with normal timing and an E3134 inlet cam but rotated a couple of teeth such that the inlet opens around 30 deg BTDC. This combination seems to give plenty of power and ticks over very cleanly. Mick Andrews tried it once and commented that he liked the engine. In answer to your previous question about rear shocks, NJB are fine for pre-65 bikes and if you give them your and the bike’s weight they will select appropriate springs. Good Luck with the build.

[Andy M]

Here's a well sorted one, the riders not too bad either.....