New Dry Clutch Spacers/Collars arrived today from Webike Japan (Parts 3, 16 & 17 as shown in Fig 1) from third party supplier DMR-JAPAN...
...and were fitted to the Primary Clutch Gear as shown in Fig 2 so measurements could be taken.
Net result was there was 0.15mm free play between the spacer and Clutch Primary Gear which can be seen in Fig 2.
I then fitted the Clutch Primary Gear onto the Gearbox Fig 3 and using a basic homemade Spacer, tightened it all up on the Gearbox Mainshaft and result, the Gearbox Mainshaft spun independently of the Gearbox Mainshaft (I know it should have, given the free play, but belts and braces!).
I took some measurements (see Figs 4a, 4b & 4c) of the old and new Spacers/Collars to give some basic measure of the wear, although I should point out that I was using a cheap Digital Vernier Gauge, the differences are very small between the old and new parts, but this small amount of free play must be significant.
Any wear on the Spacer (16)...
...which spaces out the Needle Roller Bearings inside the Clutch Drive Gear, is probably insignificant, as I don’t think there will be any lateral loading on these Bearings, as you can see in Figure 5...
...the Collar (17) sticks out just slightly proud of the 2 Needle Bearings and their Spacer (its even more pronounced on the Original Honda version)!
Several things baffled me though (not difficult I know):
- The Spacer (16) and its associated Needle Roller Bearings aren’t shown on the MC18 R6K Dry Clutch Diagram, although they use the same Bearings on both the Wet and Dry Clutches! Perhaps that's the reason why, but there is still no spacer shown!
- Why hasn’t Honda published any free play tolerance, as there must be an issue if a third party supplier goes to the trouble of making replacements!
- Leading on from that, if there are known issues, wouldn’t it have been better to provide some shims and free play tolerances as all the Collars/Spacers (except spacer (16)) are tightened up and rotating in the same direction (I understand when in neutral they can be stationary whilst the Clutch Primary gear rotates, but this shouldn’t cause an issue I would have thought)!
- Lastly, those of you would have noticed that the overall length of the New Collar/Spacer is shorter than the Old one. This is not a mistake as it’s the length of B which is critical (I hope!).
I hope you find this post interesting, but as always, any comments please. You can probably see from any of my previous posts I am a fairly newbie to the land of NSR250s and still learning and hopefully continue to learn all the time, as there is so much good stuff on this site.
Old New
A 45.08mm 44.91mm
B 40.14mm 40.8mm
X 17.91mm 18.0mm
Y 10.91mm 10.95mm
PS Couldn't attach all Diagrams on this post so will insert the other 2 Diagrams on the following Post
ADMIN: Edited to place the images inline to make the commentary easier to follow.