Help and advice needed

[Veg]

So my Scottish has a 20inch wheel fitted I’ve bought what is stated to be a genuine 21 inch Scottish wheel.
Ive measured the hubs on both the 20in seems to have a 5 1/2 in hub and the 21 has a 6in hub.
the 20in brake plate was attached to a bolt half way along the fork arm, the 21in plate seems to want to bolt to the pivot bolt on the bottom of the forks. The bolt though is not long enough for this.
Ive looked on line for an exploded image can’t find one the parts catalogue isn’t clear.
any advice please.
thanks
Tim

[johnrunnacles]

There were a variety of locations for the anchorage point/pivot point for the brake plate. Early models had an open-ended fork on the anchorage arm which pushed onto the extended pivot bolt for the swing-arm, the open fork was closed at the bolt-hole on some models, but then a later mod was for the closed, shorter anchorage arm to locate with a dedicated bolt through the swing-arm (which sounds like what you had with your 20-inch wheel). Maybe the brake plate on your new wheel is intended to be the pushover type of the earlier design, in which case you may need to fit the extended form of pivot bolt, perhaps?

Hope this helps?
Good luck!

[Veg]

Thanks John that’s exactly what I thought it’s a bit of a mongrel tbh as I’m discovering and with so many bodges it makes me a touch concerned as to what else I’ll uncover. Is the bolt an m20x175? Do you know? I’ll remove what’s there and see what I have.
thanks
Tim

[johnrunnacles]

Bolt would not originally have been a Metric size, Tim. Will look out what factory drawings I have to see if they give proper Imperial dimensions, perhaps (?)

[iansoady]

Please don't use metric bolts. The one on mine is 5/16" BSF (I think - or may be 3/8" - too unwell to go & look). My 1958 Hawkstone chassis has what John calls rhe early type with an open ended slot on the extension arm.

[johnrunnacles]

Have sent you a PM, Tim.

[Veg]

Thanks for the replies, the reason I quoted the metric size was it appears listed on British bikes 1970 as an m20. I’ll get some pictures posted. I assume that the right hand bolt that holds the bottom arm is longer to accommodate the brake plate in place.

[johnrunnacles]

Gary's reference to M20 is more to do with the factory drawings filing system (I think?), Tim. Does not relate to the bolt sizing. M20 components look to have been those drawn for the 24MDS scramble bikes. You are correct in your assumption about longer length of the bolt, by the way. It needs to be of a "special" construction, though, to allow the brake plate to float but at the same time tight enough to keep the side plates firmly in place. Note the collar under the bolt head in the drawing I have posted to achieve this ...........

[Veg]

Thanks John ok that makes total sense. I have removed the bolts and botch again a totally threaded metric bolt has been used I’m going to buy some imperial sleeved bolts and I’ll make a bush for it to float on and see how we get on . Thanks yet again Tim

[garybam4711]

John you are so correct I list by greeves part numbers And the m20 is MDS the first time that item would of been used of course it would also be used on other Greeves models after
Gary

[Veg]

Ok it appears that I need to order the correct spacers and bolts . I’ve emailed British bits 1970 as I’ve used them before and been impressed unlike the other Greeves company who still haven’t supplied or refunded my purchases

[Veg]

I’ve just realised who you are Gary. Thanks for the reply to my email
tim

[garybam4711]

No problem with sort Monday

[John Gresty]

Maybe the 'bodges' were an attempt to make the machine more competitive.
John

[Veg]

So the vast majority of new nuts and bolts are all metric, the front wheel spindle spacers are alloy tubes with nuts hammered in and the thread drilled from the nuts so they fit the spindle, the reason the front brake didn’t work is the wrong size shoes were fitted and the brake pivot is totally elliptical that’s just the front wheel and brake the only performance benefit I can foresee is the need to keep the front wheel off the ground at all times.