Modern Vespa

I was changing the clutch on my 2014 Piaggio Typhoon 50cc 4v 4t. I read that the torque on the bolt to attach the entire assembly to the shaft should be approx 30 ft lb. After hand tightening it, I used my torque wrench and didn't even come close to 30 ft lb. All of a sudden the nut because very loose. I tried to back out and remove it but it was just spinning. I eventually had to cut the nut off.

The threads on the shaft were destroyed. How difficult is it to replace that shaft?

Do I have to remove the back wheel and open the reduction case? Is there fluid in there?

Not your scooter but you can see how they get access to the drive gears. Start watching at the Hour-25 minute mark. If the typhoon doesn't access the gears behind the tire, look behind the clutch for the access nuts and plate.

Here's a trick you can try. With the shaft exposed wrap some cereal box around the shaft and hold it with some vice grips. Best to grab where the shaft is not machined(if you can). Find out the diameter of the threads in inches. This depends on what side of the pond you are(hint hint). You can go to ace hardware and buy a hex die and recut the threads. lots of metric threads are just a little larger than standard threads. Buy a nut while your there.
This is how I fixed the front sprocket shaft on my SR500 30 years ago.

Sorry to hear it What kind of torque wrench do you use?

30 ft-lb sounds about right (at least based on the specs for my LX 150), so is there a chance your torque wrench is defective?

breaknwind
Yeah I thought about getting a hex die to do that. I have a spare nut already, so I was thinking of bringing the spare to the hardware store to find the exact size of a bolt that would fit in it. My concern with doing this is safety. Will there be any risks of a less strong secure hold on the clutch? Will I have to go a size down from the existing nut?

berto
It's a cheap brand clicking type. It's entirely possible that the wrench is faulty/broken. But that being said, it didn't feel like I was much over. I would think that a shaft thread would be able to withstand quite a bit more force. My torque wrench is small, and it felt like I was using very little force.


Once I fix or replace the shaft, I'm going to be pretty paranoid about not overdoing it again. Could I go as low as say 20ft lb?

No
If you fix the thread you need to google a torque chart to find a recommended value for that size thread. As long as you cut a new thread and not just chase the old one, you should be able to use the recommended torque. So get a decent torque wrench for that.
If you don't have a way to check the thread diameter, sometimes an Ace or other hardware/auto parts store will loan you some calipers. All you have to do is post a picture of the calipers on the threads and I can read what the size is and tell you what hex die to get and what the max torque is.

$65 part + simple R&R. Not typhoon manual but gearbox is same, see engine section page 75.

http://www.wotmeworry.org.uk/manuals/Vespa/S50/S50%204valve%20Workshop%20Manual.pdf

Every cloud has a silver lining? Have you any plans to upgrade to 80cc anytime in the future?
For about the same money you could get a primary gear up kit. Same job different parts.

bluecloud I have the typhoon manual (which looks like the same steps as the vespa manual). The steps show the job getting done from inside the crankcase. The video from MJRally show access from the other side. I assume the book is correct, but it doesn't say if the wheel/brakes need to be removed. Do they?

Also, it sounds like a lot of special tools are needed. Kind of makes me feel like I should get the local vespa service shop to do this job for me.

Can this be done without special tools?

waspmike I might be interested in upgrading to 80cc however isn't this scooter restricted some other way? And if I get this done at the service shop, I assume they wouldn't do the install.

bluecloud I have the typhoon manual (which looks like the same steps as the vespa manual). The steps show the job getting done from inside the crankcase. The video from MJRally show access from the other side. I assume the book is correct, but it doesn't say if the wheel/brakes need to be removed. Do they?[quote}

The book is correct. I mentioned above that if it wasnt behind the tire, itd be inside. I dont know all the particulars of the Typhoon.

Also, it sounds like a lot of special tools are needed. Kind of makes me feel like I should get the local vespa service shop to do this job for me.

Can this be done without special tools?

If you already can remove the clutch, it should just be as simple as removing the gear cover from the inside via the 5 screws. Replacing the shaft and gasket, buttoning everything up and then re-torquing the clutch again.



waspmike I might be interested in upgrading to 80cc however isn't this scooter restricted some other way? And if I get this done at the service shop, I assume they wouldn't do the install.

All the restricted 50cc scooters that ive seen had a washer in the variator, smaller main jet and exhaust cone. Have you dealt with all those?

Is the shaft held in by any special clips or something that will need a special tool?

Will the shaft be attached to the plate that I remove? Because then I could just bring that plate in and have the shop switch the shaft (if a special tool is needed).


Do I have to worry about any of the other gears or components in there falling or getting out of alignment?

Wheel doesn't have to come off for the 50, cover is behind the clutch. Special tools? Yeah, the manual is kind of confusing. I suspect what you will find when it comes apart is that bearings are pressed into the case and cover but shafts and gears are slip fit and can be removed by hand, 150 motor is like this. Worst case if shaft is pressed on can take it to a machine shop.

Last night I got ready to try and open the plate inside the crankcase. And the book is wrong, it is like the video. There is no plate. It has to be accessed from the other side meaning the tire and brakes have to come off.

So my question is with bikes that are this "style" (access from other side) is the shaft normally removable without a tool? And do I have to worry about misaligning something/gears?

Yeah, that's messed up, parts and service book both show 2T style motor. Had to dig to find a good pic. Looking at the pic, should come apart like the 150, shafts should just drop in. No shims in the 150 but if you find any insure they're reinstalled in the same place. I think also no gasket, sealant only at flange.

I finally received the replacement shaft late last week. I replaced it over the weekend.

The gears fell out when I opened everything up. The shaft had to be hammered out and the new one hammered in. But everything seems to be working fine now.

Thanks for the help everyone.