Halfway rearsets anyone? (2020)

[Fast Eddie]

Partly that, they could cast footrests into almost any position, but in ze old days we only had Avon Speedmaster and the Dunlop equivalent tyres.

My point was that it’s the gearbox design, and the exit point of the gearchange spindle, that largely dictated footrest location, not the footrest casting.

 

[splatt]

Very nice piece of work, makes mine look very massey ferguson

 

[robs ss]

Well - there's been a bit of a slow down as I try to figure out how to make the gear linkage. The linkage part is the easy bit, it's the curved arm that has to go down to the toe-piece that is the problem. It has to start behind the Z-plate, curve outward to not scrape the gearbox, fit inside the (RGM) kickstarter then finish outside the horizontal run of the exhaust pipe.
I have tried several approaches, the photos below being the latest (and most successful) so far - using 6mm aluminium rod (the rose joint, to link to the gearbox, will be just above the top right-angle bend.)
When I have the shape worked out I'll have the profile cut from 4140 then bend and grind to match the "dummy" in the photos.
Just thought I'd open up to some hopefully better suggestions?

On the upside, the shortened hangers which I ground, sanded and polished are still looking like chrome after 7 weeks - must be bloody good steel they're made from!
Cheers

 

[robs ss]

Well, some progress made on the gear linkage - just need to wait for my shift-working neighbour to have some days off for a spot of welding (toe-piece and lower pivot)
Then some judicious bending, test and adjust before final sanding ready for chroming.

 

[cliffa]

Well, some progress made on the gear linkage - just need to wait for my shift-working neighbour to have some days off for a spot of welding (toe-piece and lower pivot)
Then some judicious bending, test and adjust before final sanding ready for chroming.
View attachment 81341

Nice work Rob. Maybe I'm missing something, but may I ask why you need to have the lever mounted so far from the fulcrum? In one of your earlier posts the picture seems to have plenty of clearance behind the folded kickstart to have a straight lever pivoting near the footrest.

 

[Fast Eddie]

Rob, also ref that ‘far away fulcrum point’ you might benefit from more holes in the gearbox shaft arm so you can experiment with different lengths. I suspect you might need a shorter arm there to reduce the movement on that looong pedal.

 

[robs ss]

@cliffa & @Fast Eddie, the gearshift only looks long - it is 195mm from pivot to the toe-piece whereas the stock one is 150mm.
It has to be longer because the pivot has to be behind the footpeg whereas the sock (obviously) is in front - see photo with pivot below.
I have arranged the lengths of the two vertical links (up from pivot & up from gearbox shaft) to "undo" that length effect so that the "throw" of the toepiece will be identical to stock.
I do have a problem to solve though. The combination of the steel+rose joint+nut will currently be too wide to fit between the Z-plate and the frame plate behind it. I think I have a solution but...
Cheers

 

[cliffa]

Hi Rob, if we forget about the linkage for a second, Couldn't you simply have a curved lever straight from the pivot like this (excuse the crummy drawing)..

And then once that has the right shape attach the linkage so that it runs underneath instead ?

 

[robs ss]

Hi Rob, if we forget about the linkage for a second, Couldn't you simply have a curved lever straight from the pivot like this (excuse the crummy drawing)..



View attachment 81356

And then once that has the right shape attach the linkage so that it runs underneath instead ?

No Cliffa - That has no connection to the gearbox and, additionally, won't have sufficient "throw" to successfully change gear.
My design is not new - look at late 50's Works Nortons and "over-the counter" Manx's. Had similar linkages - I think, for a reason.

Edit: sorry Cliffa - didn't read your entire post before replying - see #151 below

 

[Fast Eddie]

The curve on the Manx pedal was to clear the ex pipe. if the pedal pivoted from the peg, clearance wouldn’t be possible.

Praps you didn’t read all of Cliffa’s post? He knows it needs a linkage and has suggested an underslung linkage. Worthy of consideration I’d have thought ?

 

[robs ss]

The curve on the Manx pedal was to clear the ex pipe. if the pedal pivoted from the peg, clearance wouldn’t be possible.

Praps you didn’t read all of Cliffa’s post? He knows it needs a linkage and has suggested an underslung linkage. Worthy of consideration I’d have thought ?

Yep - you're right - I didn't read that last line of @cliffa - but am still unsure of how, mechanically, an underslung linkage might work.
There's not much room between the frame rail and the exhaust system - still worth pondering!
I'll think on that tonight.

 

[robs ss]

Hi Rob, if we forget about the linkage for a second, Couldn't you simply have a curved lever straight from the pivot like this (excuse the crummy drawing)..



View attachment 81356

And then once that has the right shape attach the linkage so that it runs underneath instead ?

I've just gone to my workshop and had a look - your idea has substantial merit.
More work to do - I'll keep you posted!

 

[robs ss]

@cliffa & @Fast Eddie - there is a problem
When the footpeg is folded upward, to allow the kickstarter to work, there is no space for the "horizontal' gear lever.
I still like the idea, particularly the underslung linkage, so will play a bit more with your idea.
The problem with the "overhead" linkage is that it will have to operate in the confined (16mm) space between the inside of the Z-pate and the frame plate-work.
Thanks

 

[Fast Eddie]

Looks to be more room under than over to my eye Rob. Hope it works out.

 

[robs ss]

Looks to be more room under than over to my eye Rob. Hope it works out.

Yes - sort of...
By the time I put the downward links with rose-joints and tie-rod it's starting to get too crowded between the exhaust pipe and kick-start knuckle to fit the foot pedal.
So it appears to be heading for linkage below and pedal above.
Might not be able to quite achieve @cliffa 's dream (needs 40mm movement up/down at the toe-piece) but not as raised as my original attempt.
Thanks for the ideas blokes!!

 

[Fast Eddie]

Pedal over and linkage under was my thinking Rob (and Cliffa’s too I believe).

Praps you can use the same pedal just with a lever welded on for the ‘under’ linkage ?

 

[cliffa]

How about a spacer under the triangular mount for the footrest ? Maybe that would give you enough space the clear the folded peg?

 

[robs ss]

How about a spacer under the triangular mount for the footrest ? Maybe that would give you enough space the clear the folded peg?

A-La-MkIII?
That doesn't fix the exhaust to knuckle issue - thanks for the thought though.

 

[cliffa]

A-La-MkIII?
That doesn't fix the exhaust to knuckle issue - thanks for the thought though.

Yep.

 

[cliffa]

Rob, I've been busy mulling this over (sad isn't it) and have come up with another idea which would be aesthetically pleasing on the eye and I think would work. Excuse the rough drawing...

I suppose it all come down to space below the knuckle when it's fully at the end of the stroke. You mentioned you need 40mm movement at the toe piece, but remember that can be reduced by changing the lengths of the two linkage arms.