Topic: Length difference between 750F1 and K3-K5 rear axle?

[nayto550]

I've got a hardtail frame that was set up for a K rear end, but I'm trying to use an F rear axle.  The axle is about a 1/2" too long.  The part number are 42301-300-010 for the K and 42301-392-000 for the F, so I'm assuming (probably incorrectly) that there is some difference between the two.

Just hoping there is a length difference and there's not something screwy with my frame.  I really don't feel like building a new axle for it.

[Tugboat]

Weird.. I always thought that the pre-76 K's and F0/F1 rear ends were the same, except for the swingarm having the brake stay on top for the F and on the bottom for the K. So there's a half-inch difference? The 77/78 K & F bikes have swingarms/sprocket carriers that are 10mm wider than the earlier versions.. maybe you have a later F axle?

[MCRider]

In general, the last 3 numbers of the part number are for small modifications which don't keep you from using the parts interchangeably.

The middle 3 numbers are for major changes (usually corrresponding with a model change), which, in general mean you can't interchange with another. Personally i know of no exceptions to this but there may be.

If in fact the early axle could be used on the later bike it would still carry the 300 center digits and just the last digits would change.

In general.

Specifically, i have nothing else to ad to your question. Other than one wouldn't assume a 300 part could interchange with a 392 part. Could be i supose, but highly unlikely.

For example the CB750 Clutch cable adjuster at the handlebar carries the 268 set of center digits. These digits are primarily for a CB77 305 Superhawk last made in 1968. But Honda used the same part on the CB750.

[nayto550]

So there's a half-inch difference? The 77/78 K & F bikes have swingarms/sprocket carriers that are 10mm wider than the earlier versions.. maybe you have a later F axle?

Not sure if there is a half-inch difference, I only have the F1 axle and nothing to compare to.  All I know for sure is that the frame is supposed to be set up for a K and the F axle is too long.

The axle is definitely for a '76 750F.  It was the original donor bike for this project.

The middle 3 numbers are for major changes (usually corrresponding with a model change), which, in general mean you can't interchange with another. Personally i know of no exceptions to this but there may be.

If in fact the early axle could be used on the later bike it would still carry the 300 center digits and just the last digits would change.

Hmmm, if anyone can get length measurements (non-threaded length and total length) from a K rear axle it would be greatly appreciated.

[Jerry Rxman Griffin aka MuthaF'er]

Can't compare as I haven't done K stuff. I do know there is much interchangeability between models AND bikes.

If you end up with a leftover F0/F1 axle and it's decent+ I'd be interested in purchasing it.

[MCRider]

So there's a half-inch difference? The 77/78 K & F bikes have swingarms/sprocket carriers that are 10mm wider than the earlier versions.. maybe you have a later F axle?

Not sure if there is a half-inch difference, I only have the F1 axle and nothing to compare to.  All I know for sure is that the frame is supposed to be set up for a K and the F axle is too long.

The axle is definitely for a '76 750F.  It was the original donor bike for this project.

The middle 3 numbers are for major changes (usually corrresponding with a model change), which, in general mean you can't interchange with another. Personally i know of no exceptions to this but there may be.

If in fact the early axle could be used on the later bike it would still carry the 300 center digits and just the last digits would change.

Hmmm, if anyone can get length measurements (non-threaded length and total length) from a K rear axle it would be greatly appreciated.

I can measure a K axle. Got some laying around. It'll be later tonight.

[78 k550]

Can't compare as I haven't done K stuff. I do know there is much interchangeability between models AND bikes.

If you end up with a leftover F0/F1 axle and it's decent+ I'd be interested in purchasing it.

Jerry, You looking for one. Axle as in swing arm or just the axle bolt?

Paul

[MCRider]

Nayto:
A CB750K <K7 is 10 3/4 not incl the butt to the beginning of the thread: 11 3/4 incl the thread (but not the butt) and 12 1/4 total length, incl the butt.

[nayto550]

Well, it turns out that the F axle is 1/4" longer than the K axle, just enough to be a pain in my ass... so it looks like I'm in the market for an axle from a K. 

Thanks for the measurements, MC.

[MCRider]

Well, it turns out that the F axle is 1/4" longer than the K axle, just enough to be a pain in my ass... so it looks like I'm in the market for an axle from a K. 

Thanks for the measurements, MC.

In the market? See your PMs.