Modern Vespa

I had the exact same problem with my first J. Costa, here's the evidence:

The damage; note the recessed area in the brass bushing that was worn by the washer, which was properly installed:

At WOT, once the scoot reaches its top speed and highest gearing, the highest gearing is limited by the two halves of the variator pulley touching each other at the hub (with or without a washer in between), instead of being limited by the length of the belt holding the pulley halves apart a little. Once the two pulley halves have touched, the belt is no longer being squeezed enough to keep it from slipping. Once the belt starts slipping, the inner pulley half will start rotating more slowly than the outer half because it can freewheel and there isn't enough friction to make it keep up with the spline-driven outer half. At this point -- since the hubs are touching -- the two pulleys start grinding away at each other.

I'm just speculating, but this is the only thing I can think of that might cause this wear pattern. The solution might be something as simple as a slightly shorter or wider belt to keep the driving pulley halves from ever touching at the highest gear ratio... or perhaps a thrust bearing between the pulley halves.

I checked out my variator tonight and it looks pretty good after ~3000 miles. However, I do see an indentation starting to form on the brass bushing where it contacts the washer. It's not as deep as the washer is thick (yet), but getting close. No wear on the outer pulley yet though, thankfully. I did notice some brass colored dust caked around the center of the pulleys, no doubt from the worn areas.

It sure seems to me that the brass is too soft for the steel washer, and the pressure that the variator is exerting on it at WOT is enough to slowly wear it away. Perhaps a harder material could be used for that bushing, or at least a harder ring could be used on the inside face of the pulley? Just thinking out loud here... anyone have thoughts to share?

I can't see why the belt should slip when the two variator half-pulleys make contact. Remember that the clutch contra-spring is under great compression, and it is pulling the belt hard down into the variator. So there is great tension in the belt pulling it down into the V between the pulley halves. Why would it slip?

Mike

Here's another theory; as you let off the throttle the pulley half engaged with the crank slows while momentum keeps the other half spinning faster until the rear pulley slows enough to pull the belt tight.

Polinis fall apart after 2000 miles, as I found out on the Cannonball, so I'll probably just go back to stock and try some Dr Pulley sliders after my current J. Costa is spent.

Actually, I'm still running the Polini that glasseye gifted to me in a display of selflessness on Day 8 in Cincinnati. I inspected it recently, and it's still in very good shape, except for the flattened rollers. Even then, the flattened rollers don't seem to be affecting performance nearly as much as they do on a stock variator.

And all this time I thought you were on a J Costa...
What is your experience with the Pollini. How it compares with J Costa in terms of performance and reliability?

I have the feeling that all those J Costas belonged in the same bad batch. How else to explain that all the problems surfaced around the same time and almost all were new installs?

I'm not so confident. I like the J Costa a lot, but I think this is a design issue and not a manufacturing issue. Granted, the problem probably doesn't affect those who aren't WFO all the time, but that's the very group that's likely to go for the J Costa in the first place.

I agree with Jess' analysis completely, but I'm wondering if a slightly shorter belt (if one could find one) might be an effective "band-aid" fix.

I agree with Jess' analysis completely, but I'm wondering if a slightly shorter belt (if one could find one) might be an effective "band-aid" fix.

By shorter, you mean not as tall, or not as long?

Interestingly enough, Xavier at JC suggests using the shorter GT200 belt with the LX150 version, Though he refers to it as being stronger and more durable, not shorter(and narrower in fact). In any case, I have a nearly unused (5 miles only) JC for the 150 (they sent me the correct bell). I'd love to sell it as the more failures I see, the less I plan on ever using it. Let me know if you want it. How's that for a sales pitch? For now it makes a really cool paperweight.

Costa variator and belt are in mint condition, the weights could easily do 5000 km more my dealer told, but he did put new in as I told him too. (got the old as a spare part now)

Can we not just add another washer to increase the pulley separation every 5k KM or something? Seems that this would solve the problem.

Charles.

If you ride at WOT all the time I am surprised that there is no wear. Did YOU actually see the variator. It would be easy to miss where the wear was happening if you didn't know what to look for. The J Costa writing will have disappeared off the brass bushing. If your mechanic didn't know what he was looking at he might miss it as well.

Until this apparent problem is sorted I will not be recommending it again.

J. Costa longevety report

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Well after singing the praises of J. Costa for 8000 very fun miles my J.Costa variator is now junk. I installed it at 9000 miles. My stock variator (at 9000 miles) has no sign of wear, the bush was still very tight inside the sliding pulling bushing and the weights were totally round.

At 17,000. I had a catastrophic belt failure. What a mess...

When I yanked out the variator, the bullet weights were worn flat on only one side. I also noticed that the innermost portion of the fixed and sliding pulleys appeared to be touching. There were wear marks on both pulleys like they were grinding together. I wan't sure how this was possible since I did have the 1mm shim sandwiched between the fixed pulled and the bush.
When I went to reasemble the variator, I realized that the bush had a TON of play inside the variator bushing. It turns out that the variator bushing had worn so much that the sliding pulley was slanting and grinding into the fixed pulley.

I wish I had realized this sooner since I bought a new set of variator weights from J. Costa to the tune of $60 and a new melossi belt. The bushing is pressed into the sliding pulled so I would assume that I would need to replace the entire pulley. Seeing that the weights cost $60 I can imagine the pulley would run well over $100.

So...
I can no longer recommend the J. Costa variator. Considering the condition of my stock variator at 9000 miles the J. Costa unit is not as reliable as stock.

I reinstalled my stock variator (with the original weights) and will probably order the Polini Variator later down the road. It uses a greased bush and has good performance reviews. From the variator article someone had posted, I can't run the Polini with the Melossi belt without messing with it so I'll wait and see if I keep the bike. As it stands right now, I think a Tmax is in my future...

Teflon is too soft, but might be worth a try. Actually the plastic material that Dr Pulley sliders are made of may be a better choice as it is hard and slippery.
Or change the brass sleeve for an oilite bearing.

Please help me the socker size for the nut covering the vairitor and the clutch.