Modern Vespa

On the way home from AmeriVespa in New Orleans, I had not one but two belt failures.

Sunday, in Arkansas, I thought I felt something funny from the transmission. I got off on the next off ramp and took a quick look in from the back inspection port. At first I thought I wasn't seeing clearly, so I grabbed my flashlight and looked again.

Not only could I see kevlar threads on the belt, all of the outside teeth were just gone!



I had a spare belt with me along with my Buzetti. What I was missing were the sockets and wrenches to take the transmission apart. Since there wasn't anything at that exit, I had to pussy-foot it down to the next one 5 miles away. They sent me another 8 miles to the AutoZone in Lexington, MS. The employees there were really great. They had several wrenches, including a torque wrench, and even helped me with a few of the steps where you really need more than 2 hands.

Today, just about 200 miles from home, my backup ate itself. I'm guessing it was the same thing that happened before, with the top coming apart from the bottom, only this time it went completely instead of just partially. My dad came to pick my bike and me up, so I only got home a few minutes ago. I haven't been able to take the trans apart yet, but I'm too wiped out to do it yet tonight. I'll try to get it done tomorrow and post some pics.

But, from the previous pic and the description, does anyone know why it would have done this? Two failures in 2 days is symptomatic of a larger problem that I really need to fix before I put on my new belt...

whats your setup

the belt is sitting to high did you loose a washer in between the vario disks?

or did you changes the springs on the clutch ?

Did you check to see if that little black roller is still rolling free? The tensioner pully? I'm just glad that you're safe.

really hard to speculate with out some good pics. need ones of it just opening it up. vari as its being disassembled, clutch as its being removed, case shots to see what its rubbing against. ect ect.

Maksor, I had a Fuzzy washer in but recently removed it. And I did change to a clutch with a white Malossi spring in it. At my last work on it, I had just changed back to a set of Dr Pulley sliders I've used before. I'm pretty sure they're the 21g set. I think all that was about 1500 miles before I left for New Orleans, too.

mvtroiano, I did check the idler pulley when I changed belts on Sunday, and it turned fine.

OAD, I'll try to get some good pics when I get it apart.

What washer size did you left in between the vario disks and how much did you needed to push the malossi spring in to Fit the 55mm nut on the clutch

iff the clutch spring is to strong it will push the belt out

Wild guess here, but did you happen to Grease the large Brass Bushing that sits at the center of the variator? (Shown at center of right image below).

I mistakenly did that last year... the grease turned to wax after some months, which then inhibitated the sliding movement of the variator half, which caused Vibration, which resulted in Belt Failure (breakage). After removing the grease, it has worked Ok ever since.

I talked to OAD on the phone today as I was opening the transmission up. We're pretty sure that I pinched the belt in the variator during reassembly on Sunday (and probably the last time, too). That would have caused it to not get the outer pulley half on quite as tight as it should be. And I probably didn't get the belt down far enough in the clutch, either, both of which caused the belt to ride high and either fully come out of the variator or just rub itself apart on the transmission casing.

Maksor, I left in the stock 2mm washer. I didn't replace the stock clutch spring with the Malossi one myself , so I don't know. It was on the clutch already when I got it, so I'll probably swap back to my stock one on reassembly, if y'all think that might be part of the problem, too...

Alex, I didn't grease the bushing. I can't guarantee that I didn't get a tiny bit of anti-seize on it rubbed off of my hand, but I didn't knowingly put anything on it.

I've got pics, but I haven't gotten them off my phone yet. I'll probably do that tomorrow.

Makes total sense.

Yeah, makes sense. I had similar happen to me early on and notched the belt where it scraped the case. After that botched belt change I always rotate the belt well after tightening the variator nut, and then recheck the torque on the nut a second time with belt riding properly. A little extra work but no more scraped belts.


. . . .

I too rotate the belt after the change. Even if it rolls a tiny bit I'm happy.

On a weird note. I always let my belt hang on a hook long before the change to oval it out. I purchase my belts about 2,000 miles early so they will be ready for the change. I don't know if the belt hanging things works, but it does for me.

At rest, the radius of the belt in the variator is quite a bit smaller than it is in its 'packaging'. I wouldn't worry too much about 'relaxing' it first.

OK, here's some pics.

More pics

And the last set.

I've done a little cleaning inside the trans casing, but not a whole lot yet. It'll either happen tomorrow night or Saturday, I think.

I'm still amazed at how much it ground the belt down. The whole area is covered like the lint trap on a dryer...

OAD has recommended that I put on a dust mask and take my air compressor and blow it clean. Then I should clean it with some brake cleaner to get all the rest of the kevlar dust out.

seen a few belts that broke but never like this what brand/type off belt did you use?

It looks like you had the washers in the right place, and about 1 1/2 threads showing. That's pretty much normal. Was it an OEM belt or aftermarket?

Both were OEM belts. The first one was an 849090. The replacement was an 832738.

hmmm


Think maybe they where old stock or something like that

Wow that really asploded.

The 849090 is both an OEM belt, and OK for the MP3-500.
http://www.scooterwest.com/item_details/Drive-Belt-MP3-500/8212

The 832738 is also an OEM belt, but NOT OK for the MP3-500. Note that (SW)Scooter's West told me that yes this belt "Fits" the MP3-500, and it's OEM because it's Made By Piaggio, but it is NOT RECOMMENDED FOR THE MP3-500.I'm going to repeat that last insight, so that y'all get properly shocked as I was when speaking to SW:
-OEM simply means that the belt is made by Piaggio. It does not mean that it's recommended by Piaggio for use on the MP3-500.
-Scooter's West web listing merely shows that this belt physically fits the MP3-500, yet they recommend that you do not use it on one!!!
-The ONLY belt that SW recommends for the MP3-500 is the 849090


I looked very closely into this issue after having had a belt failure (not using either of the above PN's), wondering if I used the wrong belt.

Generally, OEM is used to describe both the Manufacturor and The Suitable Application for a part. Yet as SW advertises it, they are only claiming that Piaggio (the Mfr) makes this part, and that it Fits the MP3-500 (based on Dimensional Characteristics). I think that this is STUPIDLY MISLEADING advertising ...for which they could sell you a right-size-belt made (by Piaggio) of marshmallow paste, and rightly claim that it's OEM, while ignoring the difference in material strength.

Cubs how many miles were already on the spare belt when it was reinstalled also how old was it?

I don't know. Probably close to 6k, and I know it wasn't my most recently replaced belt. It was visually OK, but age and wear certainly could have been contributing factors.

Another thought... was belt installed Backwards? Some of them have a directional arrow printed on outside.

That would be hard to tell on an old belt since those marks usually get warm away.

I was going to say there wasn't one for this belt. But I just went and looked. Lo and behold, there is an arrow on it, at least on the 832738 part number.

I've ever noticed that before!

So, it's possible it was on backwards. I didn't know it was directional, so I didn't check, and it's blown to smithereens now, so there's really no way to say...

If you are going to do your own maintenance, it is a good idea to keep a 3-ring binder with important info. I have done a dozen belt changes on my scoot and others, but I always refer to joe bulva's "[url]j costa install - mp3 400 - with pictures[/url]" In that thread, he included detailed pictures with all needed tools and torque values. You can ask any Folsom local, and they will tell you I have that info out with every belt change. Having the correct info is a time and money saving way to get the job done properly.

https://modernvespa.com/forum/topic47985?highlight=costa+install

I have that thread marked as one of my favorites. And I've changed belts enough times I have the torque specs memorized, too.

Though, I will point out that I just searched that thread and there's no mention of a belt direction arrow...

But, that's part of the point of this thread. Hopefully the things I've learned the hard way will keep someone else from making the same mistakes.

The following points are the ones that have stuck out to me:

* Make sure you don't pinch the belt when torquing the front pulley. Rotate it several times to make sure it moves freely.
* Make sure the belt is installed down in the clutch like an inch, not just flush with the edge. This goes along with the previous point.
* Check the belt direction arrows.

Mark

And don't forget that the belt arrow points counter clock wise

Those bits of the outer teeth don't look particularly worn through rubbing the outer casing so I don't think incorrect variator behaviour or assembly is responsible. You didn't particularly draw attention to wear on the casing so I guess you only had normal scuffing which is usually present.

I would be very suspicious of a non-standard rear spring. This component is responsible for correct belt tension and this would place extra stress on the belt if stronger than OEM. I am particularly concerned with Malossi products after a bad experience with their kit on a 250 Yamaha engine.

Another requirement for the transmission is adequate cooling through the variator fan and exiting at the back, so grills etc. should be checked for obstruction.

I agree with Maksor...
When I order belts, I check the date stamps.
If I am sent something that is too old, I send it back.
What a mess to cleanup.

Keith

I'm still shaking my head on this one - as in the UK at least the old 849090 belt is marked as superseded by the 832738 for all the '500' Master engines. The 832738 is all I've used in several X9 500's and my Fuoco for some many years, with zero problems due to the belt itself (though I did have a belt fail due to a worn J Costa bushing).

The outer teeth are also slightly less proud of the working surface of the belt, which gives an extra millimetre or two of clearance from the casing for those using Fuzzy washers etc.

no problems with the white malossi clutch spring . have had mine in for 20k miles and a couple nelt changes. Also know of a few others who have had one in for more miles than me and no issues.

First off - JAY-zus!! That's quite a mess. Looks like you mowed a sheep in there.
Second: Glad you're safe and made it home ok.
Third: a backwards belt would take more than a few miles to eat itself like that - if ever.
Lastly: It could be a combination of pinched belt and a too-strong clutch spring. But you should have been able to tell by it acting like it was stuck in a lower gear (excessive revs).

I actually noticed the exact opposite. It seemed to be doing LESS revs than I'd expected. At 60 MPH indicated (about 55 GPS), it was only doing 4800 RPMs.

Last night, I cleaned it all out and put my brand new belt in. I went back to my stock clutch and changed to 19g Dr Pulley sliders. As I was reassembling it, I made sure that when I rotated the variator, the belt came off at the bottom at a consistent angle. Is that the best way to tell if it's pinched or not?

I rode it up and down the block, and it seemed fine.

This morning, I did about 50 miles going to and from a 5K run. The revs were even lower than before! Now, at 60 MPH indicated, it's only about 4700 RPMs. 70 MPH indicated was about 5200-5300, and 120 KPH (appx 70 MPH real speed) was only about 5800 RPMs. After the Interstate when I got back in town, 30 MPH was about 3200.

Do those sound really low to anyone else, or are they fairly normal for a bike without a Fuzzy Washer?

I'm going to open the transmission up again and check it out.

I'm also thinking about putting the Fuzzy Washer back in. Or would that exacerbate the problem?

This is my understanding of how a CVT works, vis-à-vis the Fuzzy Washer: (Please correct me if I'm wrong!!!!)

* When starting out, and at low speeds, the belt is at its farthest inside on the front (variator) pulley and the farthest outside on the rear (clutch) pulley. This is "low gear".
* When cruising at highway speeds, the belt is at its farthest outside on the front pulley and farthest inside on the rear. This is "high gear".
* The Fuzzy Washer makes it so that it gets farther down in the front pulley in both low and high gears.

Mark

A backwards "USED" belt could self destruct really fast though

OK, here's some pics from my new belt after 50 miles.

And a couple more pics.

I never did hear. Do you think putting in a Fuzzy washer would help keep it from rubbing, or might it just make the problem worse?

You need to find out where it's rubbing on the casing, and tweak accordingly.