Andy'S Comments About His Wheel Conversion

Viking’s comment: When Andy attempted his wheel conversion project, he hit a bit of a problem – the spindle is a different size.

Here is part of the conversation about it. (See the June, 2002 mailing list archive for the full details.)


> Ah, I see now why mine had no speedo problem, I must have the
> 15mm one.
> Since you had the bigger spindle, did you have to machine the ends
> where they are clamped on the end of the forks?

Andy then replied:

No,I didn’t. I think some further explaining might be required to save anyone else having the worries/headscratching/ages playing with a digital vernier and notepad,then that heartstopping moment when you go to put the front wheel in and hope you did your sums right!

Here goes. With hindsight (looking at bearing charts for Honda in the M&P catalogue), I think I’ve got VF750FG wheels, whereas Mr.T has FD or FE wheels. The bearings for the FD/FE wheels are identical to the RC17. The bearings for the FG aren’t.

When I removed the bearings from the VF wheel,they were 42 o/d,20 i/d and 12 m.m. wide. The RC17 uses 42 o/d,15 i/d and 13 m.m wide. This is where panic set in!

After measuring both wheels, I worked out that the RC24s bearing recess is the same distance apart as the RC17, so I could use the RC17 spacer, and by fitting RC17 bearings, I could still use the RC17 spindle, so the extra 2 m.m. created by the RC17 bearings comes in handy, as you dont need any modifications or spacers on the spindle.

By using the RC17 spindle and bearings, you can use your original speedo drive gearbox, but the RC24 drive dog doesn’t fit the RC17 gearbox. Bugger! Also the RC24 dust seal won’t reach the edges of the gearbox, but the RC17 seal is 5 m.m. too small to fit the RC24 wheel!

So I did some measuring and sketching and came up with what’s on the drawing. Off to work on a Saturday afternoon, turn up the converter, mill out the slot and go home to see if it all fits.

What you have now done is pull all the diameters of the RC24 wheel in by 5 m.m., so you can still get the bearing out (through the 42.2 m.m.hole), use the RC17 drive dog (the slots in the converter provide the drive, but be sure to file out the corners of the slots after milling, as shown in the ‘plan’ view, or you either won’t be able to push the speedo drive dog in to touch the bearing, where it’s meant to be, or if you drop it in and then fit the converter, you make it captive, so you can’t get the bearing out without whacking the converter and drive dog out first).

The 50 m.m. bore you have holds the dust seal, and by making this bore 7.25 m.m. deep, but the 55 m.m. dimension 8.25 m.m. deep, you regain the 1 m.m. you need to put the dust seal in its correct position (remember the RC24 12 m.m. bearing and the RC17 13 m.m. bearing, and there is the ‘lost’ 1 m.m. you’ve just got back with the converter!).

The 47.8 m.m. dimension is a clearance fit into a 48 m.m. bore, so you don’t have to worry too much about the concentricity when you turn it around to machine the second side on the lathe. Get it to run true to 0.1 m.m. and it’ll be fine.

Then I just smeared it with Loctite bush retainer, and gently tapped it into place, before having the wheels painted.

> You have the collars and spacers, did you have to machine down the
> original disc bolts to use the collars, like on my bike?

Yes, see the note in the top right-hand corner. Initially, I wasn’t too happy about the potential for ‘free-play’ (if you remember, I was going to mill up 6 different spacers, to make use of the lugs that help align the disc) but once I fitted the discs I realised I was panicking over nothing, as they run true anyway, so I’ve shelved that idea. I also didn’t want any bare ally showing to the sides of 3 spacers on each side of the wheel, so I also Loctited the collars to the wheel, then the spacers to the collars and wheels before painting. Now, you’d never know they weren’t meant to be!

As for the rear wheel, just roll it in (if only everything in life were that simple!).