Custom Pivot Bolt

OnkelB wrote:

Well, if it was easy it wouldn´t be any fun, would it?

Ah hah! A man that understands!

Steell,

On the Gsxr arms I'm using on my bikes the bearings (#2) are the same on both arms. But the '91 750 arm uses a bigger spindle so that the races (#5) and dust caps (#7) have a bigger ID than the '86 1100 arm's spindle. I simply used #5 and #7 from the older arm as the olders arm's spindle is the same as OD as the Kz spindle.

Clear as mud?

Later, Doug

OnkelB wrote:

I posted a write-up about the swap over at KZ650.info, here´s a link - you might need to be registered/logged in to see the pics.

Hey OnkelB, I've browsed through your write-up over on KZ650.info many times.
I'm still looking for something to make the spacers out of. You used nylon correct?
I'll have to buy a length of nylon rod or a piece of sheet.

StreetfighterKz

Ah, I see! It's simply a matter of terminology, what you are calling races is what I am calling sleeve, because on the GPz750 (83-85), the sleeve extends from one side all the way through the needle bearings to the roller bearing on the other side. So the sleeve is actually the inner race.

Thanks for the explanation and pic!

I'm putting a ZR550 Zephyr arm on my Z650,

Does the sleeve go right the way through on the Zephyr arms? i.e. is it the inner race like on the GPz750 that steell talks about? Or is it separate bearings with a spacer tube between them?

I don't really want to drill my frame out to take the 17mm spindle, because the chances of getting the enlarged hole on exactly the same centre is going to be difficult to say the least, and just a slight bit off will put the alignment of the swingarm and back wheel out quite considerably at that end, so I'm thinking the cheapest easiest way to do this is to change the bearings, now if the bearings are separate and the inner races of each bearing pushes on a tube sleeve spacer that sits in the centre of the swingarm, then I reckon all that is required is replacement bearings with 16mm i.d, I reckon the sleeve spacer having an id of 17mm not 16mm would not be a problem.

Does any of this make sense to anyone? Or am I barking up the wrong tree??!!

I think I understand what you´re asking and yes, the sleeve goes all the way through the entire width of the swingarm - the bearings sit between the sleeve and the swingarm itself, so changing them won´t help you.

Hey Onkel, How would you recommend going about the drilling of the frame?

Don´t know if I´ll recommend it as such, but I just bought a 17 mm drill bit and used my electric drill, wasn´t all that hard. Since you´re only removing 1/2 a mm of material the drill will pretty much steer itself once you get it started right. The important part is to go slow and easy and let the drill do the work - don´t force it, take your time and drill as slow as you can, that way you minimize the risk of messing up and you won´t twist your wrists if the drill gets stuck. It´s also a good idea to use a cutting paste, Rocol or such.

Btw, the 17 mm drill bit I got is undercut to 13 mm at the end that fits in the drill, make sure your electric drill will take a 13 mm as many machines will only take a 10 mm.

Thanks for the tips.

I see a few places that sell the whole bearing set up, outer races and inner races (tube)

If I could find a bike that takes the same outer diameter bearings but inner of 16mm, that would be perfect, doesn't matter on the length of the sleeve as I could always turn that to the correct length.

I've thought about having a sleeve made up with the correct i.d., but chatting to some buddies at work, they've said as a bearing surface it would need heat treating and annealing etc...

I think perhaps I'll end up drilling it out, next thing is 17mm drill bits are damned expensive!

Where are you located?

I have a 17mm drill that has the shank turned down to fit a 1/2" drill motor, it was a MT2 shank. We used it to drill GPzInfested's KZ650 frame to fit the 17mm pivot bolt of the GPz750 swingarm.

I actually have two, but the second one is still an MT2 shank and I use it in my lathe tailstock to make bushings.

I'm in the UK, I'd be happy to pay for shipping, and return it to you when finished if you'd be willing to lend?

It would probably be cheaper to buy one locally than pay for shipping to and from the UK.

Try asking the folks at www.750turbo.com/forum/ where you can get a 17mm drill locally, most of the members there are in the UK, or contact Lorcan (the owner of 750turbo.com and a member here) where you can get one, I think he runs a shop and I know he has modded his GPz750 Turbo into a 211 mph screamer.

I haven't seen Lorcan post here in awhile, so contacting him through his site would probably be faster.