Modern Vespa

Has anyone on here any experience of these? I have had to split my engine to fit a new Crank and the area the clutch side bearing circlip sits has a small amount of damage meaning the circlip is not a tight fit.
I am nervous about having to drill holes in the casing to fit one of these repair rings and I'm hoping someone on here can give me some advice.

That's a new one to me, but the design seems fundamentally solid. Just need to be VERY careful drilling and blind tapping those holes, I'm guessing.

Got a link to the part?

Also, what kind of cases are those? Are they off your Douglas? The brass bushing in the main shaft hole is interesting, but I can't recall seeing it before. Aftermarket improvement?

Here's a link https://www.sip-scootershop.com/en/product/cluster-circlip-bearing-crankshaft-sip-clutch-side_87805000
That's just a stock photo from an ad Chandlerman. Yes I am worried about drilling and tapping a thread in the case

I have used the ring before. I ended up measuring the thickness of the case in that area, then drilled.

I would use two taps, one plug or taper to start tapping threads and a bottoming tap. End isn't pointed on a bottoming tap and can be harder to start. Wouldn't take any chances on just trying a bottoming tap.


https://www.cnccookbook.com/different-types-thread-taps-complete-guide-choosing/

Thanks for that Christopher. Very helpful. I have to admit I've not tried anything like this before. Any pointers as to what size taps I should buy?

Maybe Gick remembers what he used, but short answer is "Whatever matches the holes in the bracket."

Probably M5 or M6, if I were gonna guess. Your best option is going to be get it and see what fits.

Thanks. I shall order one from SIP and let you all know how I get on

Take a very close look at the photo you posted up at the very top of the page. Notice how the holes in the retainer don't line up whatsoever with the OEM holes that are drilled into the case? Also notice that you won't be able to install the auto-lube gear cog either. If both of those things aren't an issue for you, then proceed.

I think those holes have been drilled to show you how to fit it. Don't think there are any holes on any PX cases? Not on my late Super(early PX engine) No auto lube on mine so not a worry but thanks for pointing that out.

If you have a PX case, then yeah, there will be no holes. You get to drill your own. The early P series cases came with holes. And i can tell you from first hand experience that the SIP retainer won't fit a P series engine case without a bit more work.

Sorry I don't know a lot about Vespa engines. Mines a late VBC1M case. The listing includes my model so hopefully it will fit. Do you remember what size Tap you used?

I never followed through with using the SIP retainer. It was a few years ago that I was going to install it, so my memory is a bit hazy. But I would have had to TIG weld up existing holes in my case, machined off some other aluminum case reinforcement, and I thought one other thing as well, but I can't remember what. I contemplated on just chucking that POS SIP bracket across my shop, but decided to keep it around to laugh at its poor design.

I don't remember if the hole is a M5 or M6 (I think it was 6?). I'd have to search around my shop to find the bracket, and it will be a while before I can do that.


I'd be interested to know how and what case Mr. Gick has success with using that bracket on. Perhaps I was doing it wrong?

Rally 180

Christopher had a great tip.
If you can't find the bottoming tap - you can just grind or cut a tapered one.
Start with the tapered tap.
Repeat process with the bottoming tap.

Personally - I wouldn't be too freaked out about accidentally going through the case.
That area is low pressure.
In fact... and this might cause some tomatoes to be thrown - you might do a better job if you did drill through on purpose.

Hold your tomatoes y'all.
There is madness to the method.

Your cases have other through holes - that studs seal up.
It's a piaggio thing.
If you bore through - you can then thread really nicely the full depth.
then just use a generous amount of loc - tite when you put the bolts in.
You will end up with more threads for holding.
And it will seal nicely.
(of course you should always pressure test the motor).

So either way - you should be fine.
With or without going all the way through.

I did one of these not too long ago. that picture is a little misleading, in that I think it was only shot for context. I was able to flip the piece and still use the auto lube gear. the tabs and holes lined up fine (early P) so it was kind of a no big deal situation.

but yes, lock washers and all the lock tight.

if you're going in fresh, a point or starting tap 100% and finish it up with a bottoming. i used M7 to keep it all the sames, but really you could go M6 or 5 if that's what you go. shit, if you wanna be real farmer John, even a 1/4-20 would do if that's what you had.

No farmer Joe is a 1\4-28 and 3/16 - 24 bolt, that's what was in the Folgers can. I wanted to kick the supervisor I replaced in the nuts. He had guys storing hardware in fucking Folgers cans.

see previously Terrible Thursdays-

while I do have some coffee cans, pretty much everything is in bins or boxes or trays. and somewhat organized.

Hmmm....I'm going to have to take a second looksee at my bracket

I finally got my repair circlip from sip. Have had a mare trying to tap into the soft Alloy so ended up putting in two helicoils. 2 M5 Bolts & plenty of thread lock. Fingers crossed.

Nice n tidy! should hold just fine

Thanks mate, hope so