G: Gearbox (Twin) Five Speed Gearbox, Clutch Shaft and Carrier

[bmetcalf]

Me, with all this metric talk!

 

[Bill Thomas]

And you with that German Bike ?, .

 

[bmetcalf]

I gave my '77 BMW to my son in 2012. My other bike is a Buell, but It does have some metric fasteners on it.

 

[Bill Thomas]

We forgive you, Just wish I had one .
I knew it was a Buell, but could not spell it .

 

[highbury731]

I follow your comments with interest Vic, I wish I had your experience and skills, that you use so often, solving, even problems we never though we had, like the BMW style shift detent modification

What is this 'BMW-style shift detent modification' by Oexing? I am aware that John McDougal modified a cam plate by deepening the index notches a little, but no more detail than that.
Paul

 

[oexing]

The thing with the BMW - or other brands - type shift detent was a matter I read in this forum when it deals with slick gear shifts on Vincents. So I studied the gearbox components for a long while and did not like the camplate sitting on the selector forks plus the pointed spring loaded pin that engages in the camplate vees. So then I bolted the camplate UP onto the alu block that is often found to be cracked. So no standard camplate pinion in my bikes.
The detent pin was not my kind of design as it gets high side loads when shifting gear and does not want to move in its bore when it is a bit short and the bore not very deep, causes some friction from this. So that is why I wanted a lever for detent, like on other brands. The camplate is mostly standard, just I did some hard welding in a few places when I found there could be a bit more engagement of drive dogs. I don´t use jigs for checking gear positioning on all bikes as on most you can assemble all components in one side and see engagements for all gears to be acceptable, with a dentists mirror in doubt. So maybe this could be helpful for assembling gearboxes. And yes, I have only one ball bearing next to the clutch imperial standard, all other bearings are modern roller bearings with fits changed to metric o.d.s and inner races i.d. ground to go with imperial gearbox shafts. Roller bearings with rollers and cages in outer race plus plain inner races are very nice for assembling an engine.

Vic

 

[Monkeypants]

John told me that he altered the Vincent camplate by copying the AMC cam plate as much as possible. After that the bike shifted like an AMC.
Or you can just get the 5 speed, they already shift like an AMC.
You do lose that nice Vincent 3rd gear ratio which is awfully good for hills, two up or solo.
The new 5 speeds have a lower 4th which seems a better choice for everything other than racing. The first 5 speeds were made the way John Surtees and Rod Quaife wanted them, ideal for racing.
Iirc 4th was 1.07, so for the road it's almost like two top gears.
At some point they started to offer the 1.13 fourth gear. This seems more useful for the road.

Standard Vincent third gear is 1.19 which puts the engine at 3300 rpm @ 60 mph and 5500 rpm @ 100 mph. The stock or near stock bike seems to pull hills very well in that gear without over revving.

Glen

 

[andrew peters]

The Surtees 5 speed that I bought recently has 1.134:1 4th gear… 1:1 top gear, same as stock, shame really, I may have liked an overdrive top gear.. The aftermarket 6 gear sets available for Harley’s have an overdrive top, even the 06 up stock Harley 6 speed gearbox has a (sort of, high) overdrive top gear. Harley overkill… 7 speed gear sets are available for those needing to spend more money or just to be one up in the barstool racing…

 

[andrew peters]

For the amount these bikes get used now, no need to stress.....these bikes have been going for years, although many of Vic's ideas seem good, we have no proof as of yet if they are actually any good........many a Vincent has clocked up many miles without the need to reinvent the wheel.......we all see the short falls, but it takes years of experiance in my view to come up with better solutions.........No offence Vic, im just not 100% convinced all your mods are worth the effort........only you and you alone have that sort fo time/effort to carry out these mods........I do the same and much more, but mostly for racing not on stock bikes........simply no need.

 

[Cyborg]

The Surtees 5 speed appears to have the Series D clutch shaft, G3/1 with a shoulder (approx 5/16) between the spline and the clutch nuts fine thread, looks like a Series D style shaft to me (from looking at pictures) and my old G3 is different... Am I correct in thinking I should use the clutch shoe carrier C3/2, seal C18/2 and nut C20/1

Any chance you could post a photo of that shaft showing the 5/16 shoulder?

The VOC Spares site shows G3 being used for series D as well and doesn’t show an updated clutch shaft, yet KTB states that in order to change to the o-ring, you need the updated clutch shaft, carrier, and nut. The fact that it shows a G3 for series D suggests you don’t need those parts, but no idea if that is correct. At this point I’m guessing no It’s not correct. However, if you use a C3/2, then you need the C18/2 and C20/1 to go with it.

edit…. I found the G3/1 updated shaft on the Spares site. It’s a bit weird. If I go into Series D gearbox internals, it doesn’t show the G3/1, but if I do a search for G3/1 it comes up.

dagnabbit…. Your 5/16 shoulder comment tells me that I’m screwed again.