Is this a VFR750 rear axle in a VFR400?

[StrayAlien]

Hi all,

I recently got a VFR 400 race bike to join the crew in the garage and my other VFR400 race bike. It came with a 5.5" VFR wheel on the rear.



So, I figured I swap the modified axle over to my current race bike and give it a go. But, hey, what it this? It doesn't look like a VFr400 axle - from what I can tell it is a VFR750 (or 800) axle. I have three 400 axles here (including an RVF) and they are all the same, but this one is different.

Besides having no 'stake' channel on the axle for securing the hub nut there are other differences.

Here a pic of the 400 axle. Note the 'nipples' on the casting and the position of the wheel studs.:



Here is the one on new bike:



Note lack of 'nipples' and where the wheel bolts are - closer to the circumference but rotationally in the same place as the 400. I thought the modified rear axles put the bolts in a different place.

Here is a photo of a 750 axle I saw for sale on ebay. It looks like this one:



In the spare parts 'box' I got was a complete rear swingarm so I also suspect the swingarm must be modded in some way to fit the 750 axle.

Anybody know more about this modification?

Is the swingarm modified? etc etc.

Greg.

[Neosophist]

Yes the bolts are different to the nc30 pegs, so it looks like a standard 750 axle.

Stick a 30 axle back n and see if fits, will soon find out what has been changed.

Either.

1. Axle has been modded to fit
2. Hub has been modded to fit the axle.

The VFR750 has cushdrive etc on it, do you have any of that?

Perhaps its a modded axle, it would also let you fit NC30 wheels too with an NC30 axel which is easier to swap than changing the swining arm.

[StrayAlien]

Thanks,

Ok. Axle out now. No cush drive, and it seems at first go (nothing tightened and wheel not back on etc) that a 400 axle will go back in.

Here are the two. They are not the same animal.



Here are the two relations again - 750 on left, 400 on right. Note the (2mm) spacer on 750 axle (I have separated it out just a little for clarity).



They do seem very similar. I am not sure if the 2mm spacer is there to make the axle fit, or there to push the wheel 2mm to the right so as to allow a slightly larger tyre. 2mm on one side I guess is 4mm overall. At a guess (and I am no expert), I'd say the latter. Dunno.

All comments welcome.

[Drunkn Munky]

I would of said its a modified NC35 axle if it wasnt for the lack of cut outs to stake the hub nut so i dunno, NC35 axles do not have those nipples you mention, that is the only difference between 30 and 35 axles.

How is the spacer on the wheel side fixed to the axle? it looks to me like its always been there like the 750 axle you also pictured.

What ever it is you must be saving a fair bit of weight over a NC axle, can you weigh it?

[Drunkn Munky]

Im pretty certain thats a 750 axle, heres one

750 rear axle.JPG

That spacer you mention goes on the outside of the sprocket carrier not the inside

[StrayAlien]

Bewdy, thanks.

So the pic above is of a 750 axle (plus spacer) that you've used in a 400?

Is that all that is required? No other mods to the hub of swingarm or anything?

[Drunkn Munky]

No its one i found on ebay, ive never used a 750 axle.

At a guess tho id say the 750 axle you have there has been modified in some way to fit the 400 hub as if it was a straight fit then i doubt Rick oliver would have bothered with the axle conversion for 400's. Does it look as if the diameter of the axle where the bearing fits has been turned down?

[StrayAlien]

Yes, I had done that calculation as well. That is, if it only needs a vfr750 axle with a 2mm spacer then why bother will the other engineering on a 400 axle. So, I am figuring it has been modified in other ways.

However, it doesn't seem to be machined. Well, both are machined but the machining marks on both look the same. Interesting eh.

[StrayAlien]

That spacer you mention goes on the outside of the sprocket carrier not the inside

Oh, and it is not the spacer you are thinking of under the hub nut (on the outside of the sprocket carrier), it is another spacer. It is positioned as shown in the above pic where I have dislodged it slightly for clarity. It is on the axle as it is inserted from the right, not put on the left under the hub nut after insertion.

[Fifer5]

Found this thread just browsing for some other stuff - I owned this bike for a while and raced it a couple of times. I bought it with the 800 wheel in it, I understand it was a 750 hub and a guy here in Melbourne had done it originally (he was either Canadian or American) as an alternative to paying for overpriced RVF400 17 rims. I saw it advertised for sale a while back at least once I'm pretty sure, so it has gone through a few hands again. Pic of it as I got it, I then ran it with a 5" 95 VFR750 rim and also a pic of it on track. Can't remember when I sold it, 2010 maybe? Certainly didn't need a 5.5" rim and even a 5" was plenty.