Tmax drive belt snapped

[Pukmeister]

I knew I should have changed the Tmax drive belt at 10k (Dayco), bloody thing just snapped on me at 6:20 this morning in the fast lane of the M27 heading to work. I managed to coast to the Cosham exit and push it to the Marriot hotel, now stood awaiting recovery. Odometer shows 10,696 since I last changed the belt. Maybe I should stop riding it like I stole it, or do the belt every 9k from now on instead of the quoted 12k.

[Pukmeister]

Nearly three hours wait and then recovery turned up.

Now at work having garaged my scooter at home and grabbed my van keys, four hours wages lost today.

Spanners out this evening for a belt change.

[MrGrumpy]

I was wondering if you were talking about the V-belt or the final drive belt, but as you appear to have a mk3, it must be the V-Belt!

Oh bugger - I've not heard of many belts snapping - the Yamaha ones look like they are brand new after 12k miles! It so annoying to have to bin something that looks like its got years of life left in it.
On my mk6, I've just done what I said I've never do and bought an aftermarket belt - a'JT Max' belt via Wemoto, on the basis that Wemoto wouldn't sell rubbish - and it was only £72 compared to over £170 for the Yamaha article! Now you've got me worried that I should have bought a Yam one, though I guess that even if it does fail early I'm still quids in. Don't really fancy it failing in the outside lane of a M-way though.....

[knight2]

That could have ended a lot worse, glad it worked out o.k. Three hours for a breakdown not to bad, I had to dial 999 for a ambulance last week then wait 5 hours for it to turn up. It wasn't for me.

[Pukmeister]

Yeah. sorry its the vee belt on my Mk3.

I'll post a picture tonight of the carnage once I get the belt covers off.

[Pukmeister]

Right, advice time: Don’t let your belt snap, it’s a total pain in the ass. Two hours to remove the primary and secondary sheaves and pull/cut melted Kevlar string bundles from it, plus chunks of toothed belt. I was expecting an intact but snapped belt, instead I just found rubber shrapnel and Kevlar rope. Sheaves and variator all cleaned up ready for a rebuild with new belt over the weekend.

[MrGrumpy]

Snag is, its not an easy thing to inspect in-situ!
It seems odd that the belt hasn't snapped but seems to have disintegrated - I can only guess that the failure was relatively gradual rather than instant with the belt pulling itself to pieces. It would seem that an instant failure would have been better!

[Argyll]

I'd probably make a note to inspect the new belt after 6,000 miles just to see if something else is going on. Presumably the cover plate comes off fairly easily?

[roadster]

On my Piaggios the outlet duct for cooling air gave an indication of imminent failure because wispy bit of cord (kevlar?) began to blow out. On the other hand a neglected Burgman borrowed from dealer seized without warning when the belt went at 70mph. Stopped very suddenly and could barely be pushed at all.

[Pukmeister]

I'd say the belt was almost certainly slowly degrading as the bike felt a bit gutless compared to normal on yesterdays early morning commute. With me giving it the beans to join the motorway saw it throw in the towel catastrophically.

The failure was instant at motorway speeds in lane 4, with a lurch (presumably the Kevlar snapping) then silence, no engine, nothing. I coasted to the hard shoulder, put hazards on, had just enough momentum to crest the hill and then coasted at 15mph under gravity to the next motorway exit. The engine refused to restart with the engine warning light flickering when cranked. Giving it a handful of throttle got it restarted (phew, relief) but no drive to the rear wheels. I assume the rev-limiter caught the engine as the belt failed and it needed fuel and a positive TPS signal to reset the ecu and fire it up. Pushing the bugger up the motorway off-ramp and then a quarter mile to the hotel entrance nearly gave me a cardiac event !

As an engineer I see plenty of failed drive belts and almost 100% are still near-intact after failure with just one single point of failure visible on the belt when they snap (same as a broken link in a chain). In this case it was many chunks of toothed rubber that had delaminated suddenly from either side of the central Kevlar webbing band., The Kevlar 'string' then went on to mostly wrap itself around the secondary (driven) sheave pulley, with a little bit poking out of the air outlet vent in front of the primary (variator) sheave pulley. The old belt was literally a small pile of rubber shrapnel and Kevlar string.

If I could find a way to see the forum on Tapatalk I would post better pictures from my iPhone.