Buddy 170i Rear End Shaking

[BuddyGuy170i]

Hi all, new to the group and hoping someone here can help shed some light on a problem I've had with my 170.
Bought a used 2012 with 3k miles on it and riding it this summer, noticed the entire scooter starts shaking starting at about 25-30mph and getting worse the faster I go. Googling turned up mainly that it could be bad tires, bent wheels, so I replaced the front and rear tires and wheels, and still have the shaking just as bad as before. Nothing is obviously bent or warped to my eye. Swore it was coming from the front end since I felt it so much from the handlebars, but when I got it up on the center stand then even at low speeds I do see the shaking coming from the rear. I read that it could be a bad bearing in the final drive. I would take it to a dealer but I'm up in BFE northern Idaho where there are none.
Then I read it could be something related to the drive belt, but took off the cover and nothing seems wrong there.
I took this short video, hoping someone has run across something like this:
https://photos.app.goo.gl/sLGsX73M1DT1morg8
Thanks in advance,
Andy

[MTermine]

Link didn't work for me.

I have been around mopeds for a few years, but I just got my first scooter (this summer and a 170i too!), so take this suggestion with a grain of salt, but could it be a bent axle?

[DeeDee]

i'd take a look at the cushions for the engine mount, #13 on this drawing: http://www.scooterloungeonline.com/buddy125frame

[ohiomoto]

I would consider the wheel movement in the video "normal". My 170 does that on the stand and rides perfectly fine. I point this out simply so others won't throw their bike up on the stand and think something is wrong with their scooter. Nearly every motorcycle, scooter, and bicycle I've owned would do that on a stand with that much wheel speed.

But you do have an issue. If the "shaking" is a frame or suspension issue, it could play in the wheel bearings, swingarm bushings, and steering stem bearings. If it's more of a vibration and the scooter rides fine otherwise, I would look at engine mounts, bushings, or possibly a varator problem.

[BuddyGuy170i]

Thanks for the info. It's enough that even on center stand, it shakes the handlebars, and it's in just the same way as when I'm riding.
The shaking seems to match the wheel RPM. Since it's a brand new wheel and tire, I think next step is to replace the drive shaft and bearing and take it from there. Should be under $75 if I do it myself. I think one of the previous owners either hit a pothole or took it off a jump or something.

[scootERIK]

I took this short video, hoping someone has run across something like this:
https://photos.app.goo.gl/sLGsX73M1DT1morg8

Is it just me or does it look like the engine/swingarm are shaking not just up and down but also left to right?

Here is a video of my Buddy 125 running on the stand. - https://www.youtube.com/watch?v=2lKc8S0OEas

[ohiomoto]

Thanks for the info. It's enough that even on center stand, it shakes the handlebars, and it's in just the same way as when I'm riding.
The shaking seems to match the wheel RPM. Since it's a brand new wheel and tire, I think next step is to replace the drive shaft and bearing and take it from there. Should be under $75 if I do it myself. I think one of the previous owners either hit a pothole or took it off a jump or something.

I'm curious if you solved the problem.

[BuddyGuy170i]

I ended up ordering a new axle drive shaft. Today I took apart the gearbox and inspected the old drive shaft, and it seems perfectly straight. I spun the wheel on it, and there is no play... it's solid. The gearbox bearings are good as well. So my focus has shifted to the engine mounts/cushions, will see where that leads.

[BuddyGuy170i]

I inspected the engine mounts and they seem fine. There is no play where the engine mounts to the frame.
So I guess next to look at is the variator, clutch and belt.

[BuddyGuy170i]

The variator, rollers, clutch and belt all look perfectly fine.
I ran my impact wrench at full speed directly on the clutch bolt with the belt removed, and it was just fast enough that the shaking started.
That rules out the variator, rollers and belt.
Looking closely at the wheel as it's spinning, it has a visible wobble.
So it's definitely a final drive issue, but given that the rear axle is quite straight, I am starting to think that all 3 of my rear wheels are bent: the one that came with the scooter, the one I bought used on ebay, and the "brand new" one I ordered from a Genuine dealer and had it shipped to me.
I know that the 170i wheels aren't normally balanced because it shouldn't even go fast enough to require it, but I'm going to try getting it balanced and see if it improves the situation.
Manufacturing defect, or possibly getting bent as the tires are mounted? I've got no other ideas.

[BuddyGuy170i]

Verified my "brand new" $175 wheel from the dealer is warped.
Looks like at some point after 2014, Genuine switched from steel wheels to aluminum alloy wheels.
As part of that, they went from a 2 piece wheel (inner hub + outer wheel) to a single piece.
FWIW, the part number for the "new style" alloy wheel is P64071007703.
The old steel one was C24071067700.
I'll end up ordering the alloy and will follow up. What a saga.

[DeeDee]

I've ran into all kinds of problems with alloy wheels and the tire bead leaking over the last few years. I've never had this type of problem with a steel wheel. Once your new wheel is on and the smooth ride returns, you'll forget the details of the brain damage it took to get there in no time.