New Dynamos - Problem

[mini_surfari]

Has anyone one on here bought a new dynamo?

Ours arrived but the shaft is too long so the fan doesn't sit on the woodruff key, I have made contact with seller and waiting on a reply.

Just wonder if its a bad one, or we need to run a different fan / pulley?

The original



The new





The Fan





Cheers, Oli

[Peter Laidler]

If you want me to turn you up a 3 or 4mm spacer to take up the difference, send me the o-d of the shaft. It'll take the fan part the same distance from the dynamo. But will that make any difference?

OR, thinking on my feet, willl the tight pulley hold the fan by shear friction

[surfblue63]

Wouldn't a spacer put the pulley out of alignment with the crank and water pump pulleys, thus leading to a fan belt breakage in double quick time?

[111Robin]

Doesn't the pulley clamp the fan in place ?. As long as the pulley is engaged on the key and the fan is clamped against the shoulder it will be fine. The fan has a keyway so you can assemble it, not so it can be driven (I think, but probably wrong)

[mini_surfari]

With the fan over the key it just rubs on the body, and not being engaged on the key will mean the shaft will just spin and the fan will remain stationary.

I have just noticed this though, http://www.minispares.com/product/Class ... o%20search

'Fits early dynamo pulleys with a spacer built in back to fit the dish of this fan - this fan has a keyway slot.'

Do these new fans have a built in spacer to allow for the longer shaft on the aftermarket dynamos

[EMOKID]

The fan has a key way slot to allow it to fit over the shaft with key way fitted. I have been looking at some C40 dynamos and none have the fan / key way together. Add the pulley and tighten nut with spring washer and I suspect all will work ok.

[111Robin]

With the fan over the key it just rubs on the body, and not being engaged on the key will mean the shaft will just spin and the fan will remain stationary.

I have just noticed this though, http://www.minispares.com/product/Class ... o%20search

'Fits early dynamo pulleys with a spacer built in back to fit the dish of this fan - this fan has a keyway slot.'

Do these new fans have a built in spacer to allow for the longer shaft on the aftermarket dynamos

The fan isn't driving anything therefore as long as it is clamped by the pulley there are no external loads on it that would cause it to slip. As far as rubbing on the body is concerned, by how much ?, a bit of tweaking with a lever should resolve this unless it's tight against the body and won't turn at all.

[jcr227e]

I had the same problem with the one I bought from mini spares. I ended up putting a spacer in as Peter suggested

[Andrew1967]

From memory, even with the original spacer on my 65 dates dynamo, the fan slipped over the key and spun round. Once the pulley was fitted it all clamped up and was held tight.

So I’d certainly agree with Robins post.

[mini_surfari]

I see what you guys mean, so the bushing/ spacer is too short on the new one.

This is how the originally sits... up against the spacer, causing the fan to sit on the key way, and then the pulley will push it all together. But leaving a gap.




However this is the new one, bush is too short, causing the fan to bind against the body if you bolt up the pulley.




The solution would be to spin up a new spacer.

However I have found someone supplying reconditioned ones with warranty. So this one is going back, and hopefully a correctly dated rebuilt one will be arriving Tuesday. Hopefully in time for an MOT Wednesday .

[Peter Laidler]

Maybe that's not a bad idea to send it back........ Is that a crack in the bearing housing?