Griffon clutch pressure plate fit issue.

[46T Sprocket]

I got hold of a 6 spline clutch pressure plate recently that I originally intended to let me fit a Griffon clutch to a BSA A10 gearbox on the Greeves project I'm working on. I have now binned the idea of using the BSA box in favour of using a Griffon gearbox instead as this is more or less a straight fit on to the Challenger engine.

The Griffon box it have is 6 spline version No GB2C 2355. The 6 spline pressure plate I have that I got from Geoff Nunn doesn't fit. The I.D. is too small.

The o.d. of the spline on the Griffon mainshaft is .694" The i.d. of the pressure plate spline is .680" The two don't match.

I spoke with Geoff on the phone and he said that he has never came across an issue like this on all the gearboxes he has worked on.


Anybody come across this incompatable issue before? This issue has me stumped on how to resolve the problem. It's not as simple as buying another pressure plate or even a whole new clutch. Going down that route could still leave me with exactly the same fit problem.


Thanks,
David.

[Rob]

I've got a new plate in the shed but I think it is 5 spline. I'll go and have a look and measure it anyway. I have never come across this problem either.

Not that it is much help but the dimensions of the 5 spline are - Top dia = 0.750", bottom dia = 0.656", width = 0.305". That is from drawing G1459. I have not found a 6 spline drawing yet.

[46T Sprocket]

Thanks Rob, I managed t get it to fit today. I ground a cutter from a piece of tool steel and shaved each spline out on the clutch plate bit by bit by holding the clutch plate boss in my lathe chuck and then just worked away at by making repeated passes with the tool mounted in the tool post slide taking off a sliver at a time. An afternoons work! Job done though so a big relief.

Next job is to figure out a mounting for the rear of Griffon gear box in the Challenger frame. I need to modify the existing frame mounting for the original Albion box to something more appropriate for the Griffon mounts without effecting the integrity of the parts supporting the swinging arm spindle tube.

[Dogsbody]

David, I've just measured the o/d of the Griffon mainshaft on the box I have and it comes out at 0.687"! This is a late box GB2C 2632. Colin

[46T Sprocket]

Hi Colin,

I think this is just bad luck on my part that the parts - the mainshaft spline and the clutch pressure plate spline have been manufactured at the extreme end of tolerance.

David.

[Phil Hyde]

gearbox mount

I faced a similar problem with a Triumph engine in the MX2 frame. In essence, remove the existing mount and bronze weld two steel spool pieces. I have photos I can email if anyone is interested. My email address is in the 'LL. Please ignore any daemon email notices.

Phil

[46T Sprocket]

Can you not just post them on the forum Phil?

David.

[Phil Hyde]

Sorry I can only post a rather poor photo of a photo. Basically a spool piece. One on front of the frame tube and one behind. Basic triangulation.

[Brian Thompson]

Is this any help....

Phil's pic, cropped, enlarged and adjusted for contrast.

Brian.

[46T Sprocket]

Thanks. I see what you have done there Phil. In my situation I think I just need to cut off the existing mounts by about half way across both. Remove a half inch and then join them back together to give me clearance. Then make up some right angle brackets to let me securely bolt in the Griffon box..

Looking at my Silverstone, the factory has done similar on my RES frame to make room for the 5 speed box.

You can just about see the join in this picture below. The original hole in the mount is now half covered due to the forward section covering it when it was moved back.

David.

Now Honda CB400N less.......... Stolen in Edinburgh and found yesterday totally burn out.

[Phil Hyde]

photo

Brian

Thank you for assisting in improving the quality of my poor posting.

David

I understood your solution. As you will understand, locating the triumph engine is a bit more involved.