GSXR Wheel Swap

[Grey runner]

Going back to your first post, it should not make any difference what goes inside the swinging arm if the yamaha axle bolt ain't long enough you done something wrong, the Yamaha swing arm has to be under compression to work properly (about 4mm) so any thing that won't allow this is bad news. Chain allignment is crucial and the wheel should site central in the swingarm.

[DB Cooper]

Hey Greyrunner.
Thats the problem I'm having. I"m stuffing in almost 4mm more wheel and hub than what was originally in there, which is just about what I'm short on the axle for the cotter key to go through.  I've since learned that the inner spacer between the cushdrive hub and the wheel is in fact too long, by same the amount that I need on the axle. After a quick mock up tonight, everything seems to fit fine. The chain alignment looks good to. I should have the spacer back from the machinist in a day or two, and I'll take it from there. Also, after taking some measurements tonight, from the factory, the FJ wheel is off center to the right by almost 2mm! Go figure on that one. I will try and set up the GSXR wheel to the same offset.
Kevin
 

[Dazza57]

Hey Greyrunner, what is this about 4mm of compression on the swingarm? I have done this mod on my 90 3CV, and used 4mm washer each side and did nothing else. There might have been about 1-2mm gap when I tightened the axle. All appears to line up nicely, 180/55 tyre clears chain etc with a flat sprocket. I sourced all parts from the same bike, 1990 GSXR1100.

The one thing I have not done is to check alignment with the front wheel. Been scratching my head on how to do that, I'm not an engineer. Can anyone shed some light on how to check front/rear wheel alignment?

All help appreciated as always.

Dazza

[tmkaos]

The one thing I have not done is to check alignment with the front wheel. Been scratching my head on how to do that, I'm not an engineer. Can anyone shed some light on how to check front/rear wheel alignment?

All help appreciated as always.

Dazza

Grab yourself a broomstick or anything long and straight. With bike on the centre stand, lay the broomstick alongside the rear wheel so you have 2 points of contact on the rear tyre, with the broomstick extending towards the front wheel. Try doing it on both side of the wheel, you should have an even gap as the back is wider than the front. If the gap aint even your rear is offset to the front.

Whatever you use may have a bend in it so also rotate the broomstick when it is in position and that will tell you if the stick has a bend in it.

You could also use a stringline. the old Mk 1 Eyeball is pretty good at detecting curves and bends.

Happy riding,

James

[Dan Filetti]

Piece of string, stretched tight works well too.

Good luck.

Dan

[markmartin]

OK, I took off my 1990 GSXR 1100 wheel, mounted the FJ wheel, measured as accurately as I could, compared both wheel assemblies for width, and where the FJ wheel sits in the swing arm, and the following is what I got.

Disclaimer: Measurements were not performed by NASA, just me laying on my garage floor with a set of vernier calipers.  I also don't own a surface grinder.  If I did, I could get the spacers closer. And machine the cush


The FJ wheel assembly (Wheel, spacers, caliper bracket) is .349 " wider than the GSXR wheel pack.  This means we need to make up .349 or so in spacers.

Also, the FJ wheel sits .050" left of center to the swing arm.  (there is .100" difference comparing the measurement of one side, to the other side.)

Using the spacers and shims I had available, I put .057" spacer on the sprocket side, and .287" spacers on the brake side on the GSXR setup. (I know I'm .005 short, but this is what I had available.)  This put the GSXR wheel .035" to the left of center . Also, with a JT rear sprocket flipped over, with this spacing, the sprocket is .014" closer to the swing arm than the FJ stock set up.  All in all, pretty darn close.

I suppose one could get shims and move the wheel over to the left another .015" and mill .029" off the face of the cush drive if you wanted to get the location of the wheel and sprocket perfect.  

I hope this helps someone else when they do theirs.

[markmartin]

Kevin, I measured the spacers while I had the GSXR wheel off.  

FYI

Flat spacer, sprocket side, thickness:  0.450"

Spacer in Cush drive length: 1.867"

Brake side spacer:    0.829"

[DB Cooper]

Mark, you are awesome dude!
With your help, I've found the major source of the problem. My sprocket side spacer is .649" thick, that's almost 5mm wider than the spacer you have!
Thanks again Mark.
Kevin

[markmartin]

Glad to hear it.  You're welcome.  I've been using your posts and of course Craigo's and the Kit Kat Black write up and other members posts to get this done, so I'm happy the information was useful. Contribute where you can.