Hi everyone,

I had an interesting trip to France in the summer of 2011 which resulted in having to replace a fractured suspension arm... The story follows...

The bike in question is a 2010 XT660Z (in fetching blue ) and had approximately 15000 miles on it, I had replaced chain and sprockets prior to the trip.

It was a lovely hot day typical of mid France in August and we were travelling on the motorway at about 80mph or so (legal in France). I was overtaking a lorry on a long uphill incline when without any warning I lost drive, rear wheel more or less instantly locking up for a couple of seconds, then one hell of a bang as the wheel began to turn again. After crapping myself I managed to freewheel between the lorries to the hard shoulder to take stock of the situation. No sign of the chain at all, Brucetopher1 (from this forum), who was following, said it just missed him as it flailed across the motorway and out of his sight... He towed me to the next service area which was only a couple of miles away so i could have a good look and arrange recovery.

Close inspection revealed the rear suspension arm badly damaged forward from where the axle spindle is located as well as chunks of alloy missing from the cush drive housing. The cast alloy bracket that supports the rear of the chain guard was also badly damaged. The photo below is of the arm after it was removed from the bike and the fracture had extended after being ridden. Once the wheel was removed the fracture opened up.



Recovery was arranged and eventually a replacement chain was sourced and fitted. The French Yam dealers were not keen to let me ride the bike with the fractured arm but the engineer in me could see where the fracture was and that it would be mostly in compression if it was treated carefully. I off loaded much of my luggage to the rest of the guys and rode the bike gently for the rest of the trip. It got me home to Northern Ireland but the fracture could be seen extending as the days went by.

Once home I replaced the arm with a new one and fitted Stoic Bloke's chain guide mod, there should be no repeat.

So... What happened?

Initially I just assumed a broken chain was the cause, but... I now have a much clearer picture after inspecting the damage in detail and talking to those who were following me.

I had noticed at the fuel stop an hour before the chain let go that it was quite slack but hadn't worried too much about it, intending to adjust the chain at the end of the day, probably a mistake on my part. The temperature was low 30's so it was a hot day, and sustained motorway running at high speed would have caused the chain to be a lot warmer than usual too, and no doubt have expanded a bit more as well. As I was passing the lorries I had throttled off then accelerated as traffic in front cleared , this most likely caused the by now very slack chain to derail from the rear sprocket hence the loss of drive. It then caught on the bracket for the chain guard and snagged, bunching up between the cushdrive housing and the inner face of the suspension arm causing the wheel to lock and the pressure breaking the inner face of the arm and causing the damage to the cushdrive housing. The bearing in this was also damaged. Once the chain broke it was thrown clear. I would have loved to have seen the remains of the chain but it was impossible to retrieve.

Why do Yamaha not fit a chain guide to these motorcycles? It is such a glaringly obvious omission. The mod I have carried out was quite easy to do and should prevent any re-occurance. I am also watching the chain more closely on long motorway runs.



I sincerely hope no one else has the experience I had, the cost of the repairs was bad enough but the outcome could have been a lot worse.

On the plus side, I can thoroughly recommend RAC European breakdown cover, they recovered me from the motorway (the french police initially do this but it was the same company that was sent by the police as the RAC use so they paid the recovery operator directly rather than me having to do it then claim it back). They arranged for onward transfer of the bike to a Yam dealer, I got a hire car for a couple of days, taxis to and from the hire car premises and there were several phone calls to check that everything was going ok for me and to keep me up to date with what was happening.

Next big trip for the Z is Nordkapp at the end of June, bring it on

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