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Ty175 Forks. And Yokes Rake


andy.t
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Just been giving my forks a go over as they felt a bit knackered, stripped them down to find the left fork bottom was binding real bad on the stanchion and after a few hours of poking at it with a bit of wet and dry on the end of a wooden curtain pole it looks like the things sliding nice and free now. Put it all back together and the suspension is now so much better. I noticed whilst playing around with the forks just how much rake there is in the yokes alone and was wondering if anybody has thought of a way to pull back the rake so that the stanchions are more parallel with the stem. I have a few ideas of my own buts perhaps you guys have a better idea and perhaps an opinion.(I know about the frame cut and shut to adjust the rake but I'm more interested in adjusting the yokes)

Cheers for any replies

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I tried what you are asking, by using a set a Montesa Triple trees machined to take the Yanaha stem with the fork tubes parallel

to the stem. It was not a fun ride. Felt like I was falling off the front of the bike all the time. And going down hill with it it felt like the bike was going to filpover the front wheel. If I was going to try it again I would use a set of forks with a leading axel setup like on the Bultacos.

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there are few people who understand the whole steering geometry thing including me... I made a top yoke for a 2011 Sherco with view to moving bars foreward.. I machined three holes (forks & stem) on same axis.... turned out OEM part is not by c.1 deg..fortunatly it improved the steering...just finished batch for France as (bless em .) Sherco changed colour scheme again. Give your idea a try

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  • 3 weeks later...

I found on my TY175 the steering head is at 28 degrees and the forks are at 31.5 degrees. Plus the handle bar mounts are in a real bad location. My question has anyone found a triple tree that will bolt right in to the steering head for these bike. At 31 degrees the bike is great for going in a stright line but very poor for turning. I don't want to put longer shocks on the back because this will mess up the geometry of the whole bike.

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All you do by altering the yoke offset is to change the trail and the wheelbase, does nothing to the steering rake angle. Steering rake is the angle of the steering head, not the angle of the fork tubes.

If you increase the trail by using different yokes, you will need to move the axle forwards (ie use leading axle forks) to regain a decent trail dimension.

Eccentric sleeves in the steering head or on the steering stem are used on other bikes to adjust the steering rake, but I suspect the Ty175 steering head is too small a diameter to fit eccentric sleeves.

Another issue to consider is that if you just make the rake angle steeper without also moving the steering axis forwards, there will be clearance issues with the front mudguard on the frame and exhaust.

Another issue with just steepening the rake angle is that you will shorten the already-short wheelbase

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You are mostly correct, when you change the fork rake angle you do shorten the trail and wheelbase some but you also change the fork angle. Most modern trials bike have around a 24 degree fork angle , that is why they can turn so sharp and under control. I have a plan now to change the angle and gain about 1.5 inches of wheel base . Back to my old Hodaka days.

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I thought this subject was going to confuse me, so changing the angle on the yokes will only change the Trail and not the Rake, was thinking it would give the same effect as changing the angle of the headstock, the idea was to try and reduce the easy rider chopper look and in doing so stop the front wheel washing away on a tight turn.http://www.hdforums.com/forum/attachments/softail-models/52894d1245721553-raked-triple-tree-causing-steering-problems-raked-trees-and-trail.jpg

Looks like its back to the drawing board then.

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yes swapping yokes is probably easier than making changes to the frame, but it can't achieve the desired result.

Apart from the theoretical reasons I have already posted, evidence for this is that if it worked, fitting different yokes to twinshocks would be a popular modification.

What is popular, is fitting the forks and yokes from a later model bike, which improves the action of the front suspension.

Making the steering more like a modern bike requires a steeper steering head angle.

Edited by feetupfun
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