FORK CHANGE
Tony Phillips is planning to build a trail bike based around a Triumph 5TA basket case he’s picked up, but wants to do it on a reasonable budget. With this and practicality in mind, he’s thinking of fitting 1970s Japanese front forks. “In the old days we could just pop to our local breakers and trial-fit possible solutions, but it’s not so easy today and I wondered if you have any thoughts?”
I’d say it’s a good idea. You’d certainly get more travel and better action with Japanese forks and they are usually not too expensive, either – although, being chromed, you may struggle to pick up any that don’t have pitted or scored stanchions.
Most British forks are a taper fit in the top yoke, while Japanese are usually clamped, so you’d need to fit Japanese yokes and that may involve replacing the stem with a custom one made from CDS tubing – as I did last month on my Rex Acme restoration. This is a tricky job, though, and instead it’s worth looking into the possibility of adapting the bearings to fit. So long as the stem is not too short, it can probably be spaced and maybe sleeves can be made to take the Triumph cones – a lightweight Japanese fork should have a smaller diameter stem than the Triumph. Or maybe some taper rollers could be ground internally/ externally to suit – that’s how taper roller conversions for Triumphs are made.
I’d guess forks from a 250cc bike would be about right for the Triumph’s weight and one advantage of the clamp top yoke is that if the forks are too long, you can slide them up a bit in the yoke.
‘JAPANESE FORKS ARE USUALLY NOT TOO EXPENSIVE’