Alternator rotor shaft damaged

Previously dean_miller wrote:

Hi all

The 1968 fastback I am restoring came without an alternator rotor or stator. The shaft looks like someone removed the rotor with a meat cleaver (probably had a blue and white apron on when he worked on this bike)

The problem is after lightly cleaning up the damage the shaft measures up on size 0.75" horizontally but 0.012" smaller 90 deg around (in line with the key way)

I am after opinions on thoughts if I can run it like this (maybe with locktite) or if I need to get it repaired, maybe by plating.

I am thinking it would be ok as there is no load on the rotor but am concerned cos it does rotate fast.

I am intending to run a belt drive primary.

cheers

Dean

I had worse damage on the other end of the crankshaft (oil feed). I had it welded up and reground. It is like new now.

How are you measuring the diameter at the keyway? doesn't your caliper drop into the keyway and give a false reading?

hi dean

I've recently had to strip and re-build my stator/rotor, I also noticed that the fit of the shaft to the rotor was like a dick in a shirtsleeve,Try the fit of the crankshaft tubular nut to the rotor,mine took out the slackness and pulled the rotor up true and square

steve

Three options here.

1) Replacement Crank end.

2) Hot Metal Spraying plus regrind.

3) Plating plus regrind.

Of the choices .......1) is the hardest to find....as this is the side that most people damage. 2) will cost around £50 to £60 but will give the best result. 3) could be the cheapest with options of copper, nickel or chrome plating. The latter being the more costly.

I think that Steve's comments above are pertinent here. Assuming that the taper for the engine sprocket is in order, you only have to concern yourself with retention and centering of the alternator rotor.

The shaft is parallel and the keyway is for location of the timing marks. The rotor itself is retained by the sleeve nut and clamped tight against the rotor spacer. The sleeve nut provides centralisation for about 1/2" of the rotor depth so it may be that a new nut is all that you'll need.

Personally, I'd be disinclined to Loctite the rotor as it might make future removal impossible.

Perhaps try torqueing up the centre nut and checking for air gap of the rotor against the stator. If this is OK then I can't see why it would move, regardless of shaft damage on one part.

Hi Dean, I use Loctite 660 for securing loose rotors with damaged keyways and splineson clutch centers, that is what660 is designed for! I'd go along with what Steve and, in part, whatRichard said, the sleeve nut will pull up the rotor centrally against the spacer. In my experience, the 660 doesn't glue the parts together, only fills up the gaps, therefore isn't any more difficult to remove than a tight factory fitted component. Just make sure the parts are scrupulosly cleaned before the fit up to ensure complete cure strength. Follow the Loctite instructions down to the 'T'.

Paul.

Previously dean_miller wrote:

Hi all

The 1968 fastback I am restoring came without an alternator rotor or stator. The shaft looks like someone removed the rotor with a meat cleaver (probably had a blue and white apron on when he worked on this bike)

The problem is after lightly cleaning up the damage the shaft measures up on size 0.75" horizontally but 0.012" smaller 90 deg around (in line with the key way)

I am after opinions on thoughts if I can run it like this (maybe with locktite) or if I need to get it repaired, maybe by plating.

I am thinking it would be ok as there is no load on the rotor but am concerned cos it does rotate fast.

I am intending to run a belt drive primary.

cheers

Dean

Hi Dean,

I suspect that rather than having been butchered, your bike has had the same problem I had with mine - an exploded rotor (they all do that sir!). This would explain the damage to the crank and the lack of alternator, as this fault completely munches the stator and rotor. They frequently weld themselves together and drag in the alternator leads and wiring harness. Mine has also written off the inner timing case, so check the alternator mounting studs for cracks at the base and any other cracking around the mounting hole that fits over the boss on the crankcase.

The comments from the others inspire me to simply bolt mine back together with Loctite (once I have managed to remove the remainder of the key, which has welded itself into the keyway, the rotor having spun on the crank and "smeared" the key and keyway).

All the best

Steve