Modern Vespa

hello all,

I seem to have the wrong type of drum for my p125 so it doesn't tighten down.

I attached a photo of the drive shaft end. when I put the drum on, it will not go down far enough for the splines to be fully matched. Hence there is some wheel wobble.

The drive shaft has a 14mm end.

Any ideas which would be the right drum for this ?

thanks

Show of photo how your hub is seating on the shaft will help to give right answer.
Also measure the diameter on the hub where it goes into shaft seal. Correct hub diameter for you is 27mm.

Hello,

Picture attached. I believe it is the right diameter. It slides on, but will not go down far enough.

The shaft appears to be different to the others that I have seen for the p125x. the splines end rather abruptly. while on there they appear to gradually taper out.

I thought maybe the shaft is short, the bearings too wide (but the circlip would not fit) or wrong hub.

I have surfed the Web. I think the shaft is for an LML star.

Clearly , from you earlier posts, you have been riding this bike. Has the hub been loose all this time? What have you changed? That looks like a new hub. Does it match the old one?
According to the SM listing, the PX125 and LML axles are the same. https://www.scootermercato.com/Scooter-Parts/Drive-Shafts/112858

I may be late with my suggestion, but, with the seal removed, does that hub seat all the way down? Can you post a photo of the fitment when on the scooter without the seal in place?

Showing the rear hub from the back and sides and also from the front, focusing on the shaft and threaded area?

You probably got a 30mm hub and you just need to replace the seal to 30x47x6mm. All hubs are interchangeable expect the late PX with an internal seal. Measure the center of the hub to see if it's 30mm or 31.5mm…

last couple of years I used the bike in the summer, but barely as there were numother issues to sort on it. Now, the reason I have noticed this issue is because I had some issue with getting it running smoothly. it's now almost there, but I notices a sver3 vibration at certain points during acceleration. I jacked up the back, but noticed some play in the wheel. I took it all off an noticed that the nut had loosened and there was play. I tried to tighten, but noticed the hub doesn't go all the way down. Then I started to compare to my gtr parts etc, hut still could work out where the issue was. what I did notice is that the spline looks different.

I remember the shaft is one of those which has those circles on both sides of the gears.

I will dig out photos from my other phone.

Not sure what you mean by this.
The nut should not back off if the cotter pin is installed.

Circles on both sides indicate.to.me.a late type layshaft

sorry for typo I meant circlips not circles. and yes I thought it was a later shaft because of that.

Ok, found some pictures.

firstly- I was un correct. there is only one circlip so old type shaft.

However, the end looks different to the other I have. picture attached.

I can either get a hub that fits, or put a new shaft in there.

I don't see any major difference between the ends of those shafts although you don't show the threads of the first one....

sorry I wasn't clear. all these images are so far of the same shaft. this was before it was installed. I now attach what the other shafts for a p125x seem to look like.

the splines on the newer shaft, seem to not end abruptly. I am wondering if there is a length difference too?

Aftermarket shafts versus original shafts do have minor differences. But usually work quite well.

My advise before you spend any money is to measure the shaft at all it's critical points. Against the one you have been riding quite happily on

Ie where the bearings sit, overall length etc etc. I've seen some very poorly machined ones that I can only presume we're bought of the bay of fleas as seconds.

It's not such a problem if the end of the shaft sits lower in the hub. As long as you have a sufficient amount in there and you can lock it off with a washer/nut/pin combo. Tuned motors are where it really matters.

ok.

measuring done. I still can't work out what I am seeing tho.

It looks to me that the hub needs to slip on another 3mm. So what's stopping it? I believe it to be the inner 27mm wide part of the hub in this new picture. You can see on the inside if the sleeve that there is a part that is not really oily, that's how much further this hub should slip on for the splines to be in full contact. Why is that happening?

Actually, I think inworked it out. I got new bearings for this and my gtr. they are 14mm thickness. I have a feeling they should be 12. With the 14mm bearings, the circlip that holds the bearing in is bang on. However, if I look at the parts catalogue, it looks like there is bearing followed by oil seal followed by circlip.

pictures attached.

That last photo of he hub located and the spline slightly lower is nothing I personally would be concerned about

I've seen many many like that do thousands of miles with zero issue.

I would torque that to spec and call it good

The washer under the nut is not supposed to bottom out on the step on the shaft so there's a recess. The nut drives the hub against the bearing, against the stop, locking the whole assembly to the axle. Let's see a pic with the nut and washer installed.

Thanks chaps,

here we go with nut on pics. I put one nut on, tightened it and the threads stripped. I got to about 75nm. That was a new nut from sip. now I've come back to an old nut, it tightened up as much as I could and I put that old pin through to drive around the block.

Now, there is still some play in the wheel. when I push and pull the seat from side to side, there is quite a knocking. However, not so much vibration when I go through the gears.

feels kind of ok, or at least better than it was.

Looks good to me. The outer bearing race should be captured in the case and the inner is clamped to the shaft. If there is any side-to-side play it is in the bearing. My Smallstate also knocks a bit the same way.

I agree with the previous posts. That is exactly how a hub arrangement works .
BUT... IF you are experiencing a lot of play in the hub after it has been torqued down, it's possible that the shift itself is very worn.

If you can video what you are describing that would help.. a picture is worth a thousand words and a video even more so.

ok,

here is a short I just filmed.

Does it sound normal?

?si=HL77Uj45wk7-Aq1x

That is NOT normal

I changed hubs and shafts for less than that

What have you replaced, that Is relevant to the drive shaft, bearings, hub etc

all the bearings were changed, I also made sure the gear shim under the circlip was at the right tolerance. the cruciform was also changed.

the play in the wheel feels less now, but the knocking feels like it's coming from inside somewhere. If the shaft is pulled right up against the bearing, i can't think where that play would come from.

Seems like ok for me. The bearing have heat tolerance that is where it have play.

That play would most likely come from the area where the shaft seats inyo the bearing at the gear change side, compounded with wear on the teeth of the actual shadt itself. I would change it out

I agree. There can't be that much play in the bearing. Unless it isn't captured in the case. Or if it the wrong one and too thin? If you hold opposite sides of the tire and rock/twist the wheel back and forth does it knock? Or does it move straight into and out of the case?
No way around it, you're going back in....I'm looking forward to the solution for this.

if I grab both sides of the wheel and push in and out I don't hear or feel anything major. if I push one side of the wheel and pull the other, I get a definite knocking. It must be the wheel /shaft connection. perhaps the teeth on the shaft are too done after me driving around with a wobble. The thing is, I would expect it to dissappear when the wheel is fully tight as there should be enough clamping force.

I found this video on youchoob. bloke reckons that some players normal.

?si=XAJ72bkAe9S9hSvX

I've just had another little look. So if I push the engine from the selector box side, it will rosk and make a knocking noise. Just pressing the tyre on the back side stops it. It almost feels like the shaft at the selector box side is not fully constrained.

I guess I will have to whip that off next to have a look.

Wondering of part or all of the FS bearing is missing.

I think you have it spot on here. Is there anyone local to you who has a p series so you can get a comparison?

It's been a few days as I've been working away so no chance to tinker. My plan is the following.
1, replace drive shaft
2, replace rear drum

I've seen an RMS shaft with all gears supplied with at at a very reasonable cost. So if anyone has had any experience with that I would love to hear. if it's real poor stuff, I will probably just go with FA stuff unless anyone has good experience with anything else.

While I'm in there I will of course check have a very good look at the bearings. something is clearly off as I replaced them only 1000km ago.

Now, along side my wobling wheel, I just noticed that the flywheel has some play in it which looks like it's crank related. I will have to check that too. Is a bit of play in the crank a normal thing?

This is getting a little bit more extensive than I had originally thought.

It's the way she goes man. One step forward, 2 steps back is normal for these things. Just keep plugging away you'll get it sorted.

Doh!

RMS / FA italia. Both good quality parts from respectable manufacturers

Thanks, I'm ordering today. I hope it arrives for the long weekend. Will keep this updated.

There was a time not that long ago when Piaggio drums would be a nice tight fit on the splines of the driveshaft. Now it's difficult to find one that doesn't rock on the splines from brand new.

If you ride it with that kind of movement between the drum and shaft it will only get worse. Usually it's the drum that wears the splines first. You can buy more time by doing it up super tight. Often they loosen up again by themselves. I had some success using a big spring washer which put off the inevitable a bit longer.

The last drum I bought that fitted well on the splines was a Scootopia. I still use a breaker bar to tighten it now with no issues.

A little update over here.

There is a bloke in my street who also has a vespa p125x. his is 1 year older than mine but in really great shape, he's had it from new. Anyway, last year he was having problems as his condenser kept going wrong. This year he's still having problems after fitting an external condenser as he keeps going through plugs. he rides like 30km and then he stalls and can't restart unless he changes the plug. Anyway, to cut a long story short, I stopped while he was tinkering and gave his rear wheel a shake. his also wobbles but not to the same extent as mine. So I will still go ahead and change up the pieces. incidentally - I unscrewed my mixture screw one turn and the scoot has more crappy acceleration, but doesn't vibrate so much. it's much smoother
feels like I'm doing one of those games when you pull one string and another one gets longer. Nice weekend all!

Sometimes it really helps to see another scooter to compare against to understand the condition of our own. Especially in the early years of the "hobby" - it's more a passion than a hobby.

I think in your friends case he should post on here to get assistance or more realistically change to electronic ignition with a new HT Coil.

As for the carb, my advice would be to strip and it give it a really good clean of all components.. ultrasonic clean if you can spring for it.


Good luck on all fronts and keep us posted!