Crankshaft damage - advice needed.

[sharpeyie]

Hi all.
The images below are from the end of my ’75 Z1B crankshaft which I am in the process of restoring. This is the rotor end and as you can see there’s been some damage to the slot for the woodruff key. I pulled out what looked like some small pieces of epoxy so I am guessing the last guy tried to fix it that way!
My question is this; to what extent is this going to cause problems and what would be the best approach to addressing it?

It's difficult to figure to what extent the key itself (and by association the slot in the shaft) would come under regular pressure once the rotor and starter clutch are in place and all torqued up (I say this based on the effort it takes to get the thing off in the first place.) It’s also difficult to imagine how this has occurred. As you can tell, I just dunno.

Your collective input would be very welcome.

Thanks.

Stewart.

[MrDavo]

That looks pretty brutal - I wonder if the alternator stator fouled the rotor very suddenly (ie to a dead stop). This could possibly happen in a crash if the case got bashed in, or even if the stator wasn't installed correctly - the clearance is pretty fine.

I'm sure that could be fixed by someone with the right skills, whether you could get away with not doing is open to debate.

[KeithZ1R]

Rob is your man he will be along presently with advice or bad news you could send him a pm to speed up the process his usename is zed1015

[z1bman]

buzzard is the man to speak to. it can be repaired but could be expensive send him some photo's & get his professional advise as an engineer

taken from his facebook page. buzzard1425@gmail.com

https://www.facebook.com/BuzzWorkz

[moizeau]

May be talking cobblers but my understanding of the woodruff key is simply to locate the rotor whilst it's being tightened. I'd guess that the rotor bolt wasn't tightened properly and when the starter button was pressed it sheared the key. Regarding the repair, if welding it, make up a copper disc that fits snugly that way the weld doesn't run into the slot and makes it easier to dress back. If enough of the slot still exists, enough to hold the key perpendicular and secure, you may get away with it as is.
As first mentioned, this may be cobblers.

[FOZ1A]

Padders has one for sale

Foz

[ADRIAN H]

Whilst it’s out send it off for a full strip and rebuild. Buzzard as mentioned before, or Ray Debben @ Debben Performance.

[sharpeyie]

May be talking cobblers but my understanding of the woodruff key is simply to locate the rotor whilst it's being tightened. I'd guess that the rotor bolt wasn't tightened properly and when the starter button was pressed it sheared the key. Regarding the repair, if welding it, make up a copper disc that fits snugly that way the weld doesn't run into the slot and makes it easier to dress back. If enough of the slot still exists, enough to hold the key perpendicular and secure, you may get away with it as is.
As first mentioned, this may be cobblers.

Your logic about the woodruff key rings true to me regarding it being a locating pin effectively, rather than a stress bearing piece. But also (like you) I am not sure I’m not talking cobblers because it suits what I want the outcome to be.

Anyone else wanna row in behind or refute this notion?

[sharpeyie]

Whilst it’s out send it off for a full strip and rebuild. Buzzard as mentioned before, or Ray Debben @ Debben Performance.

Worth a thought alright. Have to see how the budget looks.

[sharpeyie]

Padders has one for sale

Foz

Where will I find Padders?

[FOZ1A]

He is on here, but he tends to sell on Facebook these days

Foz

[baz]

put some fine lapping paste on the taper and lap the rotor to the crank and forget about the keyway.........nothing tighter than a good taper fit

[sharpeyie]

put some fine lapping paste on the taper and lap the rotor to the crank and forget about the keyway.........nothing tighter than a good taper fit

Someone else suggested something similar. I think it has merit. Perhaps a combination of approaches including repairing the break and the lapping approach. The mist is lifting.....

[chrisu]

any z1/z900/z1000 (not mk2) will fit fine.

If you get stuck i've a few spares. mostly z1000 though. Buying from the UK will be expensive though due to weight/postage costs.

But having said that probably cheaper than getting this one fixed

[z1bman]

you will be wasting your time if you just lap the rotor to the crank the problem is you just cannot get enough torque on the 8mm bolt that holds the rotor on ( 18ftlbs ) that's why the z1000 has a bigger bolt 10mm thread unless you repair the keyway it will just come loose again