Kawasaki 750 hard tail (was rear end ratios)

[minimutly]

No, its one more local to me (2 miles down the road actually). I can count and it is a 3.5, and the casing is different, with a drain plug smackin the middle of the diff cover.
More info as I glean it
Huw

[Manky Monkey]

The 750cc jobbies had the plug in the middle of the diff casing. The 850s had it to one side. It's a fill plug, rather than a drain one -you're supposed to fill it with oil to the bottom of the plug hole. No idea how you're meant to drain it -I think the seals just leak so much it's never been an issue!

[Olds]

Sorry, when you mentioned that it was different, I thought you meant different. 

[spanners]

bond bug ? ? has it had coil over shocks ?

[BikerGran]

The 750cc jobbies had the plug in the middle of the diff casing. The 850s had it to one side. It's a fill plug, rather than a drain one -you're supposed to fill it with oil to the bottom of the plug hole. No idea how you're meant to drain it -I think the seals just leak so much it's never been an issue!

When you turn the axle over as you have to with some bike engined trikes, apparently you don't fill it to the bottom of the plughole, you fill it your finger pushed right into the hole and down, just touches the top of the oil!

[hunter]

Bobbie,What if you got short fingers.
Or long one's.

[minimutly]

Tee hee, as if it matters how much oil is in this axle..
No I dont believe it had coil overs. I've given up trying to trace its ancestry, not much point really, I'm just surprised there isn't a definitive list out there, but hey ho.
Anyway, I've decided to make some new tubes for my original axle, reweld it together with the offset required for a straightish propshaft. Probably go with the 3.5 ratio which will raise the axle and help with the prop alignment as well as improving the ride quallity.
I'll get some pics up asap.
Huw

[hunter]

Huw,
Maybe a pic will help identify.

[minimutly]

As I said, no point trying to trace its identity, especially since i will only be using the shafts, I'll call it a 750 axle. It's so rusty I've decided to use my original axle, with new tubes to replace the bent ones. Bought a length of tube on line, seamed 2 inch nominal dia.  I'd "measured" my mangled tube at 2 inch, but when I pushed out the end from the casing tonight found it was something like 1.975, lucky it wasn't the other way round. Anyway the new tube is thicker wall, which adds much needed strength, so tonight I machined up the salvaged bearing carrier to fit inside the tube, ready for welding. Tomorrow night I'll cut to length and machine for press fit, still time to cock it up yet...
The plan is to take 75mm out of one side of the axle, shift the diff across half that amount to closer line up with the Z750 output shaft, and add 12.5mm spacers to both hubs when I replace the wheel studs with bigger dia ones to line the PCD  of the axle to the 100mm wheels. This will restore some of the lost width, the trike will be 25mm narrower each side - barely noticable. I could of course be tempted to add the extra length to the other side, the only added work would be lenghening one shaft. Need to make that decision before cutting the nearside tube I guess, otherwise the diff will be too far across. Decisions decisions.
I've done a mock up using the 750 axle, and allowed the rear of the trike to drop by 25mm or so, again this improves the prop alignment. It looks Ok I guess, even with the original low profile tyres, so I may drop it some more since the planned tyre profile change will raise it back up. Picks to follow tomorrow night, too late tonight.

[minimutly]

Not had much chance to do anything, other than measure this up again - measure twice cut once etc.
The more accurately I tried to measure this the more I struggled, with a real discrepancy from centreline measuring (plumb bob hanging down from the frame spine), as opposed to measuring in from the insides of the frame. Well eventually the light came on - the frame is offset, essentially because its a shafty! Stupid bugger me.
So allowing for not needing to get any closer than 40mm (the vertical offset), means I need to move the diff over 60mm. I've decided I don't want to narrow the axle, so I'll be shortening and lengthening by 60mm. So later on I'll be machining the end of the tube at goes into the diff casing, also drilling and turning a stub in one end of the shaft so I can weld it. Anyone want to guess at the interference fit of 2 inch steel tube into aluminium? About 4 thou would be my guess?
Huw

[morrag]

It's worth mentioning again here,I feel, that a truly straight aligned prop.as in this instance, is not only unnecessary, but actually not desirable, as there is then a possibility of 'brinelling' of the universal joint needle rollers occurring. Indeed, consider the attitude of many industrial and agricultural prop. shafts, and you might see what I mean, so, ensure your wheels line up! ,of course, but prop. alignment, motor output shaft to axle pinion flange, don't be over critical!! Morrag

[morrag]

Something else you might also consider. The track of the orig. axle suited a 4 seater car application! whereas your application will be considerably narrower. I find that a 6" overall narrowing of the standard Reliant axle width, an advantage when filtering in road use, and I believe is ascetically,gives a more balanced look, although that's down to personal taste of course! but as your making new axle tubes, now is the time to consider it......... Morrag

[BikerGran]

Morrag - can you explain 'brinelling' - wonder if that's what happened to my shaft drive.

[Olds]

Brinelling is where the needle rollers indent into the spider or the bearing cups. This is caused by the needle bearings always transmitting the load in the same place.
Offsetting the axis of the gearbox output and the axle input, reduces this by causing the needle bearings to rotate.
While my axle and gearbox are in line vertically, they are purposely not on the same plane horizontally.
The same problem happens to headstock bearings and causes the familiar notchiness feel on worn steering.

[morrag]

Couldn't have said better myself,Olds!!! ...Morrag