Modern Vespa

76 VBC Super.

I was going to adjust the timing and when I tried to remove the flywheel by unscrewing the nut the circlip popped out of the grove before the flywheel came loose. I'm sure the clip was seated in the groove.

I stepped back and ordered two new circlips and a crank nut.

I can't be the first one that this has happened to. Now I know why the later ones use internal threads and require a puller.

Recently kitted with a 177 Pinasco but that, obviously doesn't have anything to do with this but what could have been a factor is that the flywheel came loose a few months ago and sheared the key. The slots in the crank and flywheel looked fine so I put some valve grind compound on the shaft and lapped it to the flywheel. I cleaned the compound off, of course.

I have had the flywheel off three times since this happened with no problems. I have been torquing the nut to 45 ft/lbs.

What are my options? Should the new circlip get it off? Should I apply heat? Any other ideas or advice?

Thanks.

Not uncommon...
New circlip (or even 2 circlips if you can fit 'em.)

Then slow even pressure, voodoo chants, and 3 hail Mary's.

I've had the same problem. Number one make sure the circlip is installed so the sharp edge is pointed out so it fits into groove and square sides meet when the nut applies pressure on removal. The rounded side will drift out of the groove easily. Once you put pressure on the circlip with the nut use a rubber mallet and give a few love taps on the flywheel hopefully this breaks the interference lock. If the circlip keeps popping out I've used a small screwdriver in the circlip gap to keep it from closing when excessive pressure is applied this has also helped.

I always do the thing with the sharp edge of the circlip out.

Fitting something between the clip ends sound like a good idea.

Edit: I think they should have made it so you don't have to pull the flywheel to adjust the timing. It would not have been hard to do.

Give it a try can be tricky when a socket is on the nut. Don't be shy use rubber and a few love taps.

I was thinking of getting the nut tight against the clip, putting some wooden wedges between the flywheel and the case and then hitting the end of the shaft with a punch.

What do you think of that idea?

Never tried but once the nut is backed out and even marginal pressure is on the clip the flywheel can move conceivably a love tap will rock it off the taper.

+1 for 2 circlips, I've been there

A few ideas:

Take nut off, turn it over & screw back on till outer edge is flush with end of crank thread..l smack it with a mallet.

Turn circlip over & try again... it kinda bends when pressure of nut pushes against it, thrn is warped a bit, so keeps popping off... turning it over means it straightens when nut is against it

The new clips and nut are due tomorrow so I'm not doing anything until then. I'll try flipping the nut and smacking it. I am also going to try wedging a screwdriver or something in between the clip ends.

I asked about heating it but no one responded. I have a non contact thermometer and I think I should be safe if I keep it below 250° or so, right?

Is there anything else that I should be or should not be doing so this doesn't happen again? I can tell you that this is all rather disconcerting.

My VBB engine didn't have a circlip installed. I bought a few different non metric sizes from the hardware store and put in the biggest size I could fit after cleaning the groove.

Not quite an answer, as my first thought was "put a shot of PB down the keyway and then heat it with a propane torch". However, a faint bell of high-school physics is making me think that heating is not good for magnetic bits. Someone more familiar might chime on on that, hopefully?

If it is a 2 inspection hole flywheel, the factory tool can be used. that late in the Super range it may be just the 1 hole inspection type.

Unfortunately just one inspection hole.

I should have thought of cleaning the clip grove and trying a slightly oversized clip. I'll do those.

I'll see what the new clip, wedging between the clip ends and smacking it some more does and go from there.

I'll hold off on the heat unless I run out of options. If the heat takes out some of the magnetism I can have it remagnetized. That would mean at least a couple weeks downtime.

2 clips and Bob's your uncle.

Do you mean two clips at the same time? Can you do that?

I only bought two because they are cheap and I wanted a spare.

I actually had an Uncle Bob. And I didn't even know what circlips were back then.

^ Generally speaking yes. I suppose there may be instances where the space for the circlip will not accomidate two. But, Poidog turned me onto that trick and it worked a charm for me on two seperate bikes. (Space the opening of the circlps 180* apart if ya can.)

get one behind the one in the groove. it may end up seated in the groove or it may just push against the one in the groove. depending on your circlip pliers, it can be a MF to get it to close the ends up enough to do it. but it can work.

I would never have thought of that.

That's why I come here.

It seems that what I need to do is put the first clip behind the groove then put the second one in the groove. When the nut pushes up against the inside one it should align itself and hopefully drop into the groove behind the outside one.

That has to work.

Famous last words.

Cleaning the circlip groove usually does the trick. Get a dental pick and make sure there's no grime or crud keeping it from seating.

Tapping the crank *gently* once the nut is loose will also help loosen the taper.

there's so much mass on the flywheel that I imagine a heat gun used with care before the love tap might also prove helpful and not so dangerous

That's what I was thinking.

The center steel part with the taper is not right up against the magnets.

I have a non contact thermometer and I can keep a close eye on the temp if I decide to do it.

I'm going to try the other methods listed here first. I'm most optimistic about the double circlip method. Using heat will be my last resort.

Am I the only one here who (careful, slow, rotate, repeat) used two big opposing screwdrivers and rags when this happened?


As on the clutch.

Got it.

It took cleaning out the groove, a fresh circlip, crank nut, love blows from a dead blow hammer and an inordinate amount of grunting.

No heat.

I celebrated with an adult malt beverage and a Marie Calendar pot p.i.e.

I've removed this type of flywheel about a hundred times and nothing like this has ever happened before. I'm positive I didn't over torque it. It did seem like I had to use a lot more effort than usual to get it off.

I tried to do the two circlip trick but was getting frustrated and wound up using just one.

When I got it off I noticed that the clip that I used to do it is now a little bit smaller than the other new one I bought. I don't know if it is recommended but I'm going to get a bunch of them and put a new one on every time I pull the flywheel.

cheap insurance, or just keep a few on the shelf for when you need them. i have some in my smallframe engine parts box that I go rob every now and then.

Outstanding I'm also having a malt beverage in celebrating your success plus it's my daughter's birthday so it's a good day!

Love taps right place right time do wonders.

Congratulations. And you now know you have a good tight fitting flywheel.