TY 175 fork preload spacers

[paul neilson]

Can anyone advise the on the maximum thickness that preload spacers can be before the forksprings will coil bind on a TY175.

Paul

[David Lahey]

Paul I don't remember exactly, but it is something like 5 to 8 mm. I'll have a look in my TY175 bike log and see if I wrote it in there.

[paul neilson]

Thanks David,
Much appreciated

best regards,
Paul

[David Lahey]

Paul my records said that:
In 1993 I added 7 two-cent pieces to each side and then took them out shortly afterwards and ran from then with no extra spacers. There were no comments about what it was like.
In 1999 I fitted 15mm spacers and commented that it was too much then tried 12mm and again I wrote that it was too much and then ran with no extra spacers. I didn't write why it was too much.
In 2000 I fitted TY250 forks.

[paul neilson]

Thanks David,
I might give it a go with 12 - 15mm of preload and if I can't get happy with it, I'll look for some TY 250 forks. I guess I'd need a set of TY250 triple clamps as well ? Is the front wheel and brake backing plate the same for both bikes ?

regards,
Paul

[David Lahey]

The hubs and backing plates are the same on TY175 and TY250. Only the rims are different. The TY175 clamps could be machined out to 34mm if you can't find TY250 clamps. Both types of clamps are made from the same casting/forging.

[paul neilson]

Thanks David,

The 250 forks sound like the go. Are they the same length ?
Mal Chapman has just built a 200 for himself and has used leading axle forks. Would there be a benefit in this for me ?

regards,
Paul

[David Lahey]

Paul I just measured them as being the same length.
Be careful and get the full info about Mals 175 because he might have made other changes to the geometry of that bike as well as fitting the leading axle forks.
I've seen a few TY twinshocks fitted with leading axle forks. Some are mounted in the TY twinshock triple clamps and some in the triple clamps from the bike that donated the forks. One TY250 I bought had been fitted with Bultaco Sherpa T (leading axle) forks! I guess the most common swap I've seen is to use a TY250 Mono front end, but on a TY175 unless you do something about the steering stops and the fuel tank, it reduces the steering lock severely compared with standard (because the TY250 mono clamps have less offset). Of course you can just get the TY175 clamps machined out to suit but then the trail dimension gets very small.
I've not heard anyone complain about steering geometry after doing their mods. Most fork swaps like that are to get better fork damping and springing because the TY175 forks are best suited to a lightweight rider.
I've found that a standard TY250 twinshock front end on a TY175 works well for me (95kg) and has the benefit of looking original because your eye doesn't pick out the bigger diameter tubes easily.
There is no doubt that the TY250 Mono forks and the forks from Fantics, Bultacos, OSSAs and Montesas have a better action than TY250 twinshock forks.
One thing I have in mind to try on the front of a TY250 Twinshock or Majesty, are OSSA MAR forks, and in-line axle Betors from a Pursang - but those are projects for next year.

[paul neilson]

Thanks again for your invaluable advice David,

I think I'll try some small preload spacers first and if I'm not happy then I'll search for some TY250 forks which sound like they might be the best option for me as I too weigh 95kgs. Are TY250 forks hard to come by ? Im not interested in putting on TY250 mono forks or any other later forks.

best regards,
Paul

[BOGWHEEL]

David, want do you think the result would be with a inline fork axle on the sherpa?