Modern Vespa

I recently had my engine rebuilt and now the flywheel rubs the fan cover, when the clutch is disenguaged. It rubs in a couple of spots as I can see the evidence left behind when fan cover is removed. Split the cases to ensure that the bearing retaining clip was installed on the clutch side (it was and is). After reassembly the flywheel still rubs the fan cover. I cannot see any lateral movement of the when pulling the clutch lever but must be moving slightly as it does not make contact with the cover when the clutch is fully enguaged.

Any thoughts?

Under no condition the clutch engagement would have anything to do with the flywheel touching or not touching. The flywheel is in one side of the engine and the clutch on the other side and the relation between the two we all know it.

As far is the flywheel touching the fan cover (the metal shroud), have you isolated the exact spot? It can be tricky, did you put all of the shroud screws in? even when all of the screws are in there is some play when adjusting the shroud.

The idiosyncrasy of the flywheel is making sure that the stator is well installed, that you are using a star washer, a fresh woodruff key and using the proper nut and torquing it. With the crankshaft having a conical shape mating surface it is a perfect match to the conical shape of the flywheel. the only time it can go wrong is if the flywheel is not perfectly aligned to the woodruff key and there is a small slot for it.

I would say this though, as crazy as it sounds you can still literally bolt on the flywheel wrong missing the woodruff key slot and it would have enough pressure into the crankshaft to rotate the engine but it would likely not start because you would need the stator to match the flywheel.

Some reproduction flywheel covers aren't the best fit. You also can't mix and match PX covers with P series covers.

Cheapest answer is to find where it's rubbing and hammer the cover so it doesn't rub.

Next cheapest is to add a washer in the corner where it's rubbing. That acts like a small spacer.

Find a used OG cover on the interwebs and replace.

Last would be to buy a new cover and try again.

On disengagement, the plunger loading the clutch springs can actually force the crankshaft to the FW side. I'd think the bearings would have to be shot, though.

"Some reproduction clutch covers aren't the best fit. You also can't mix and match PX covers with P series covers."

I doubt the clutch cover is an issue here.

The key indexes the flywheel to the crank shaft and, therefore, the piston's location. The points cam lobe or the electronic trigger are fixed in position on the FW so the stator, which is mechanically independant is adjustable.

As you can't see lateral movement when you pull the clutch, lap the crankshaft taper if you haven't already. Lots of videos out there on how to.

You have to be at the razor's edge if it only rubs with the clutch pulled.

I like the lapping it to move it in a hair, but would take a LOT of lapping if it's already a good fit.

Here's another approach that might solve your problem - how about pull the cover and fire it up, then use an angle grinder or sander, or even a manual sanding block to lightly skim off any high spots on your flywheel? I've done this before mostly for the sexy brush finish but should also work well here.

So I guess under no condition is what happened to me (and a few other people I know) possible?

https://vimeo.com/333532695

And here's what the crankshaft looks like when it's pushed to the right and touches the bearing on a T5:

I'd just slightly elongate the mounting holes in the shroud and pull it out a bit before tightening the screws. It doesn't have to go out very far and will probably take care of the interference.