TA Fork Top Yoke

[Stuart Wigmore]

Hi All, can someone please offer some advice, what year did Greeves start fitting cranked top yokes to their trials and scrambles models, I am building a TA, should it have a straight yoke?

[johnrunnacles]

I no longer have it, Stuart, but I'm pretty sure my 1959 TA had a cranked top yoke.

[Brian Thompson]

Hi Stuart and John,

Hope you're both keeping well.

Stuart, there's some excellent info on this thread, provided by Peter Rotherham, that should clarify things, hopefully.....!

https://www.greeves-riders.org.uk/forums/forum/general-forums/general-greeves-chat/360-greeves-leading-link-fork-geometry

Also, this thread has Andrew King's incredibly useful guide to the various Scottish Trials models and their development and key differences. I'm with JR, I'm pretty sure the TA had a cranked top crown plate, with the 'v' pointing backwards towards the tank.

https://www.greeves-riders.org.uk/forums/forum/gra-members-area/help-advice/3603-greeves-scottish-articles-from-ll-43-post-1-of-3

Hope this helps Stuart.

Brian.

[johnrunnacles]

Thanks Brian.
You won't find better information/advice than that, Stuart!
The reason I have this point burned into my memory is that I once scrambled an otherwise standard-framed 1959 24TAS, and I was constantly being advised by those "in the know" to turn the fork yoke round to get better scrambles handling from the bike.
Hope all going well with you, Brian? All's good over here, thanks.
JR

[David Muir]

Interesting reading-are the top plates interchangeable and if so do they alter the steering on their own ? (I've got a straight top yoke currenly but would prefer the trials one-can't remember which way the 'V' goes!)

[johnrunnacles]

As Brian has said in his response, David, the Vee points backwards toward the tank on the TA for the trials setting, presumably to push the fork stations into a more upright stance and give a tighter steering lock (?). A straight top yoke was usually fitted to road bikes. Incidentally, I was always reluctant to turn my existing Scottish yoke round for a scrambles setting (as advised) because I could not see how existing top and bottom bearing races might line up if I did …………………….. ………………………... or was that just "me"?.

[David Muir]

Yes John , that's exactly what I was wondering! Putting on a different yoke or turning one round seems a bit too easy!

[IanCordes]

I don't know about the TA, but the TE also had an offset bottom yoke, which is of course not easy to change around, as it is bronze welded to the fork legs. Hence, if you simply turn the top crown plate around, the bearings will indeed be mis-aligned. The MDS bottom yoke is different, central to the fork legs. Also, the scrambler crown plate is not just a reversed trials one; the offset is different. However, these may be later developments, which may not apply in the same manner on the earlier models. 3 years was a long time in Greeves competition development back then.
See photos, one showing the difference in offset between the crown plate on the trials; bottom of picture; and scrambler. The other picture shows a roadster top plate at the bottom, trials in the middle and scrambler as it should be fitted; rider's view; at the top. The other pictures show the trials offset on the bottom yoke, and the scrambler, which is the one with bearing fitted.

Ian

[David Muir]

Very interesting and illuminating, thanks Ian. So I can't just put a Trials tope yoke on my scrambler forks and have the trials steering/angles!

[IanCordes]

If it was a TE then I would say no; but as I said, I have no experience of the 1959 models. It needs someone who has a scrambler and trials bike of the period to have a look and see what's what.

[IanCordes]

Disclaimer!! For clarity, I think it is possible that the scrambler crown plate in my pictures; the one with the shallower 'V', may be off banana scrambles forks, not rubber ones. This could mean they are different to those on an MDS, for example. This doesn't affect your original query, Stuart, but you didn't mention what model you have, David?

Ian

[David Muir]

Hi Ian, I have a 1958 SA scrambler BUT it has a straight top yoke! I'm building it up as a trials machine.

[IanCordes]

Hmmm, can't help you there David. I have no knowledge of that era. Plenty on here who do though, I am sure. No doubt one will be along in a minute!

[Stuart Wigmore]

Thanks all, sounds to me that I am now looking for a cranked top yoke for my 1958 TA with a 15/16" dia boss to carry the bearing cup, if anyone can help?