Hello there...

Having noticed a few months ago that my revs were a little higher than they had been, (but no noticeable loss of power / accleration, and fuel economy much the same) I recently inspected my S'wing's drive belt with a view to changing it thinking it may be on the way out.... but upon inspection (drive belt at approx 15k miles) found the belt to be in good condition, seemingly not any worse for wear when I last looked at it about 5-6k miles ago when I had the J costa Variator fitted. So I decided to leave it on until after winter when my S'wing will need its next service. Another interesting point is that there was very little in the way of dust debris in the casing. Much less than when my Swing had the stock variator.... Have a look at my photos /videos and see what you think. Also, When I measured the width of the old drive belt compared to the new one, it was the same!!
The first two pictures are of the old drive belt, still fitted, with the new one underneath for comparison




The next two photos are of the outer and inner drive belt casings..... There was much less dust / debris than I expected and the filter was failry clean too....




Finally a short video clip.... You can hear the rev limiter cut in briefly (about 17seconds in) before I throttle back a tad. If you listen carefully I think you can gear the exhaust popping as I let it throttle right back
[url=http://s410.photobucket.com/albums/pp188/willbernardo/?action=view¤t=P1010750.flv][/url]


Clicking on the picture doesn't work so click on the web link below for the video

http://s410.photobucket.com/albums/pp188/willbernardo/?action=view&current=P1010750.flv


Bearing in mind that I had my S'wing souped up a little when I had the variator changed I had expected that there would be more wear on the belt? (with power commander and dyno tuning plus free flow exhaust, now 45bhp at the rear wheel as opposed to 37) So the big question is, despite the increase in power and a more assertive rather than laid back riding style, the drive belt seems better than expected....

So, Is it possible that it has stretched despite looking in good condition?

Could it be that it looks good, but really isn't and I should change it anyway (approx 15k miles) No rips tears or jagged bits.... some wear marks visible in the side of the "teeth" but nothing to worry about...

Perhaps its the pins in the variator that have worn, making the engine rev higher, but they have only done about 5-6k miles, so I wouldn't expect this? Could it be wear on the the clutch?

Does the belt wear less with a J costa variator? I mean, I think it definitely cuts out the belt slap and is a bit more responsive, but I had expected more wear not less?

Anyway, any views / opinions appreciated..!!

Hey bernardo,
thanks for the pics and video.

I put a video of the variator in action on youtube over a year ago.
below is the link.

http://www.youtube.com/watch?v=-tdVY6Kone4

paul

Bernardo, while looking at the pics of your old belt, I noticed little striations in the rubber on the sides of the belt.
These are indications of rubber delamination. (little hairline cracks in the solid rubber) these are caused by heat and pressure). The cracks will get bigger with each compression/decompression cycle (going around a pulley). These microfractures also make the rubber softer in the area of fractures. (solid vs siped, and have a lower durometer measurement, hardness)

I cannot tell how deep the striations go from the pictures.
These are the first indications of belt failure. As they get deeper, the belt looses strength. We have all seen pictures of belts that have grenaded/shredded. It is usually due to delamination.

That belt may last for many more miles or it may not. kinda like loosing knobs on an off road dirt bike tire. the rubber comes apart and separates. This may be where your higher RPM's are coming from. The belt stretches under load and is not visible at rest. (like a rubber band)

I personally would change it soon from your pictures.

MaxB (30 yrs of industrial belt use and a couple on scooters)

PS: those are some of the best pictures I have seen of delamination.

Hi Everyone,

I have now since had the belt replaced.... Alas I wasn't around to get pics of the J Costa Pins, though I did have a new set in case... My friendly mechanic however examined the existing ones and said they were fine and just changed the belt.....

The revs are now back to normal pulling around 200-400 rpm less than they had been on the old belt, and match with my original figures rev/speed that I posted about 6 months ago.... I have it written down someplace, will post them when I find them....

Here they are:-

40mph 4,000 revs
50 4,500
60 5,100
70 5,600
80 6,200

My S'wing seems a bit more torquey with the new belt, especially from a standing start or slow speed, and it seems that you need to give a bit less of a handful with the throttle to get the same acceleration and power.... It's a mitsuboshi belt....
So the moral of this story..... I think I was right to change the belt when I did......

Thanks again Max for your advice

It's hard to tell when a belt of this type is shot just by looking at it. By the time it's visibly damaged you've already been living on borrowed time for quite a while. If your revs are increasing that's said to be a sign that the belt is worn.

If you do your own wrenching I see no reason not to replace it pretty frequently, in terms of mileage. If you do 4K miles per year, as I seem to do, just replace it every other winter. It gives you something to do, and you'll never have to worry about the belt again.

Back when I used to be heavily involved in VW TDI diesel we would debate endlessly over the minutiae of cam belt lifespans, but that's because changing the belt was an all-day ordeal and the risk of NOT changing it was a mechanical Armageddon that not even Federal disaster relief could assuage. But these things? Cheap and easy. Change it.

Your revs were up because of the width of the belt being worn down. If the belt width is below spec (It is in the service manual service limit 27.0cm (1.06in) the belt doesn't ride up on the pulley as far thus your rpm is turning faster. The manual tells you to measure the width and look for cracks, separation, or signs of excessive wear. It is my opinion that belt replacement is based on width. I suspect the Honda limit of 16000 miles is their careful estimate as to how log the belt will run before reaching the service limit. Sure belt age can contribute to delamination and failure, but at the rate I am putting miles I will go through belts much faster than they will age.

I noticed a big difference when I replaced my belt, mine was less than 1in. It acctually got a little slower acceleration wise as it was essentially running in a little higher gear ratio. Belt slap went away as well. To get the acceleration back i am running with 4 rollers instead of 6. The lighter weight in the variator keeps the rpm up while accelerating. The drive face and ramp is quite robust and I have had no issues of warping or accelerated wear.

There seems to be quite abit of discussion on mixed rollers and such deviant activities, but I don't believe there all that much pressure on the rollers pressing the front pullies together. It just needs enough pressure to get the belt to climb the V. If you take your cover off squeez the belt together in the middle and see how easy it is to get the rear pullies to open up.

Thanks for all your thoughts!

As per my last post, I've had the belt changed now and the revs are back to normal, and my average MPG is a tad over 50, a little better than it was before. It seems the higher revs were indeed indicative of a worn belt I could probably manage a lot more, getting on for near 60MPG on a longer run as at the moment most of my mileage is around town. As to the rollers I have a J Costa variator and the pins / weights were fine with too little wear to warrant replacing them. The width of the old belt by the way was the same as the new one!

I think in the future I will continue to replace the belt at the recommended 16k miles or before, and in any event check it every now and then to make sure its OK.