Slipper clutch conversion project

[GregT]

I just had a thought, what would be the results of an unsprung clutch? what if I just fastened the 550 primary drive gear to the gsxr basket without dampening springs? Clearly the clutch would behave in an abrupt manner, but would it be to the point that the bike is unrideable? We are also running a quick shifter and will not use the clutch on upshifts over 7000 rpm.

That is do-able...the clutch will not change it's characteristics (feel) but the box will see higher impact loads at changes. There should still be a shock absorber in the line - the rear cush drive.
Given that the bigger GS's are known to collapse the clutch cush springs after abuse - the drag race guys will confirm this - and the resulting slop puts more impact load on the box than a solid drive - and the box generally survives this, I don't think you'll have a problem.
Our roadrace 1000 is running what is for most purposes a solid clutch cush.The guy who modified it originally had it in a turbo'd 1000 which dynoed around 170 at the wheel. Unblown we'll never break it and the clutch feels fine.

[BigD_83]

This is a great thread. Nice and techy!

If I remember correctly, all of this trickery was to outrace your buddy at some future timepoint to be determined.

Has that happened yet?

[ashdricky]

This is a great thread. Nice and techy!

If I remember correctly, all of this trickery was to outrace your buddy at some future timepoint to be determined.

Has that happened yet?

Yes initially that is how we kept motivated, "we've got to do this because the competition is most certainly doing something devious.", the imminent clash with evil. I have since realized that I have nothing to prove to them as last I saw his machine I thought he was quite brave to ride it in the condition it was, also I doubt I could have persuaded him to take it to a track. Odd that you remember that.

[BigD_83]

initially that is how I kept motivated "we've got to do this because the competition is most certainly doing something devious.", an imminent clash sometime in the future, I have since realized that I have nothing to prove to that guy. lat time I saw his machine I thought he was quite brave to ride it in the condition it was, also I doubt I could have persuaded him to take it to a track. and in fact have not spoke with him in nearly a year. Odd that you remember that.

I have a mind like a steel trap...it's just a little rusty!

If only I had learned to use it to best advantage earlier in life

[ashdricky]

here are photos of where I am now, I am trying to find the best way to bolt the drive gear to the basket, as we will not be using dampening springs.

[GregT]

Is anything at all on the same pitch circle ? Hard to tell from the pics.

[ashdricky]

Is anything at all on the same pitch circle ? Hard to tell from the pics.

Im sorry what do you mean by pitch angle?

[Dogma]

Im sorry what do you mean by pitch angle?

"Pitch circle" is a theoretical circle on which nominal features lie. On a gear, this is the circle where gear teeth make nominal contact. On a bolt circle, this is the circle through which a group of bolt centerlines pass. In this context, I think it means where the spring pockets and bolt holes are. GregT is asking if anything lines up between gear and basket.

[ashdricky]

"Pitch circle" is a theoretical circle on which nominal features lie. On a gear, this is the circle where gear teeth make nominal contact. On a bolt circle, this is the circle through which a group of bolt centerlines pass. In this context, I think it means where the spring pockets and bolt holes are. GregT is asking if anything lines up between gear and basket.

Ahh thank you for the explanation, the answer is not at all. but I thought of possible using this solution, which was used to fit a gsxr clutch to a tl1000. The user that took these photos and created the original goes my the name of Manurewa, he is on the TL and GSXR forums, I believe he is fron New Zealand, but may be wrong.

[GregT]

Yes, Dogma got it right...The Kiwi who did that clutch conversion had way too much time and CNC machining available to him....

The shaped insert answer like he used - but simpler shapes - is probably the way to go. Aluminium inserts for the gear bored to match the pitch circle diameter of the 3 basket retaining fasteners should be do-able.

You're dealing with a lot less torque and horsepower than the TL so three 10mm retaining bolts will be adequate IMO. You may want to look at Button head or even countersunk head fasteners as room at the back of the gear will be limited. If you use the original steel back plate from the 550 gear and redrill for the new hole location, after assembly the bolt/screw heads can be spot welded (TIG) in place for security.

[ashdricky]

Yes, Dogma got it right...The Kiwi who did that clutch conversion had way too much time and CNC machining available to him....

The shaped insert answer like he used - but simpler shapes - is probably the way to go. Aluminium inserts for the gear bored to match the pitch circle diameter of the 3 basket retaining fasteners should be do-able.

You're dealing with a lot less torque and horsepower than the TL so three 10mm retaining bolts will be adequate IMO. You may want to look at Button head or even countersunk head fasteners as room at the back of the gear will be limited. If you use the original steel back plate from the 550 gear and redrill for the new hole location, after assembly the bolt/screw heads can be spot welded (TIG) in place for security.

So I was able to drop off the basket at my local race shop (Fast by Gast) and should get the opening in the basket enlarged so that the primary gear can be fit, once I get those pieces back I can look into locations for the bolt holes. I'll be sure to post updates ASAP.

[AJ]

I'm sort of wondering why in the world you feel a wee 550cc four cylinder engine needs a slipper clutch in the first place.

LOL! That's exactly what I was thinking.

Still, I admire the desire and the engineering initiative.

[GregT]

I'm sort of wondering why in the world you feel a wee 550cc four cylinder engine needs a slipper clutch in the first place.

There's no doubt that slipper - or back torque limiting - clutches have changed how you can ride in roadracing. Even the 550 has enough crank mass that corner approaches are done with some restraint - change down. run the revs down, change down again etc....Slipper clutches simply allow the rider to bang down the appropriate number of gears for the corner without worrying about rear wheel lockup or over revving.

Whether they're appropriate for Vintage or Post Classic racing is an argument which is just being aired here in NZ. Personally I say no as part of racing these dinosaurs is having to ride them in the fashion they were originally.

The OP here does not appear to have to worry about race regs at this point so i'm happy to offer advice. And of course if they do become legal here in NZ, I've seen some of the problems.....

[ashdricky]

Update: I stopped at Fast by Gast yesterday and the clutch machining is in line behind several other jobs. On a side note, I am leaving the country on Sunday, and will be over-seas for six weeks, So I don't foresee any developments on this project until I return.

Im a little surprised that Dansofield hasn't noticed this project as a BTL clutch would be a nice addition to the 550 he is racing in the UK.

[ashdricky]

So I have been in Europe for 6 weeks now working for my father, and the other day I got a call from my friend back in the states who picked up the clutch basket from the machinist. he then sent these photos, I appologize for the poor quality. Also GregT has informed me that the splines on the input shaft for the gear box are the same on the larger bikes as well.





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