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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I just replaced my chain at 16k. The oe chain lasted well first then stretched very fast and was making a clanking noise now and then. Just fitted a did gold x ring chain - wow its like a new bike! Amazing what you get used to when it degrades slowly.

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check out www.redbikejohn.com for all the latest race reports from the CHEC and enduroland.

Jess thats a bit of bad luck.

I was lucky as a similar thing happened on my old XTR, had been out for a good 45min ride on country roads so was on and off the throttle alot and the chain was slightly more slack than standard but nothing overly bad. Came around a corner asked for the power and a massive racket. Lucky enough i was only doing about 30mph, free wheeled and pulled over straight away to find the chain had come off and was rolling over the hub of the wheel. No real damage apart from a few bits of paint on the chain stripped.

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Plough on

for me the moral of the story is, if yamaha want to build an proper overlander/offroader. build it properly - add a chain guide, even a dt50 from the early eightys had one!

hi irish guy, been in donegal enjoying the trails over the weekend. absolutely brilliant!

Glad you enjoyed them... did you find the 200 yard long "swimming pool?" Lol...

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200 yard swimming pool? i certainly found long slurry pits!.

the sunday i was out on my exc doing peak to peak, will add photos later, else where, really should keep on topic

That's the thing though init? .... Yamaha haven't built an overlander/offroader. They have given us a bike with firm foundations to do either.

Overlanders are a funny bunch, and you would be hard pushed to find two riders who would want the same thing from a bike. But you only need to look at how straightforward it is (with a little engineering skill) to modify these bikes to suit individual needs. That's the strength.

I've seen a chain come off a bike (in front of me) once, it run out the back and slid down the road like a snake, nice and neat, no damage to anyone/thing. I've seen the aftermath (in the flesh) on another occasion, and the chain destroyed the engine case on it's way out. Now I have seen a third, and it destroyed the swing arm, but this sounds less like a broken chain and more like a derailment. However you look at it, had the chain been tight, it couldn't de-rail (unless there was something else wrong with the chain at that moment), as the chain wasn't recovered it's all really just theory. My point here, is that, certainly in my experience, chains are very unpredictable when they 'go', at speed with load this becomes even more unpredictable.

Theorising here a little, but what if a chain snapped between the guide and the sprocket (however unlikely)? then it's possible the same guide could momentarily grip the chain, leaving a flailing steel chain whipping around at the back end of the bike. It's all conjecture of course, just trying to point out that modifications could make things worse. We will never know why Yamaha decided to avoid fitting a chain guide, could be cost, could be they just forgot, could be aesthetics or it could be that they had some data suggesting chain guides create more potential problems than they fix? It would be nice to know though.

A few months ago, my own chain stretched, probably enough to do the same as as happened here, I noticed it because it was 'banging' on the top of the swing arm during throttle-back. I stopped and adjusted it. As the chain is approaching 30K, I think I'm pushing my luck somewhat now.

Chain guides have a specific purpose, I'm not sure they suit everyone. On the road, they provide a sense of security, but as we humans go, this means we just push things a little more, maybe carry out less adjustment. On the other side, a dirty chain guide is going to wear a chain - I have seen this, especially with a spilt link fitted....... As I say, we all have different needs/wants and these bikes provide one of the best platforms to build the bike of our needs/wants.

Nearly everything can be modified on these bikes, where they really fall down is the Stator, it just doesn't give enough Uuumph! And there isn't much we can do about that. But that's another discussion.

Like Keith though, I pay close attention to my chain each ride, Scottoiler and weekly maintenance on top. Between that and the rubber, the two (or rather three!) most important checks on the bike.

You were very lucky with the traffic, and good skills in bringing the bike home all alive. Motorcycling is a dangerous business, every day we survive it is a bonus!

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Never underestimate the power of stupid people in large groups.

Blimey you were really lucky as anything could have happened. I once had my rear wheel of my CBR1000 block at about 70mph on the motorway in the middle lane, and how on earth I was not taken out by another vehicle as I made my way across to the hard shoulder I will never know. And good point about the chain guide, would that have helped?? The drive chain on my 07 XTX did 15.000km and is still good, and I now have 6,000km on my 11 XTX and so far I have only needed to lube it, which I do every 2 weeks or so. I have never fitted a Scott Oiler, are they a good idea??

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(Now sold on, sob) 2011 Blue XT660X with gold wheels, was 26,500 km.
Engine mods: K&N Stage 1 filter, DNA Stage 2 filter, snorkel removed, Kev fuel mod fitted.
Plus: smoked Puig screen, Yam aluminium sump guard, Yamaha / Acerbis handguards, Givi Trekker aluminium side cases, Leo Vince X3 cans plus Kev front fork mod and Fender Xtender. Just fitted Michelin Road Pilot 3 tyres.

SOLD the XTX for a Super Ten 1200. And just bought a Raptor 700 so staying on here for some tips....

Assuming the chain is about 1.5m long, you'd need a temperature rise of about 55 degC to make it 1mm longer.


Pedantry aside, I'm with Gulgo on this one. Not enough information to say that it was the lack of chain guide that caused the problem.


Glad you came out of it unscathed!

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I spent a lot of money on travel and racing motorcycles - the rest I just squandered.

XT660Z - Commuter, Adventurer...Racer?

www.dashmoto.net

Other bikes >> MT-03 / CG125BR-J / ER-6F
Departed >> ZXR400L3 / EC300 / DR-Z400E / DR800S / GPZ500S / GS400

Well done, good save.

Thanks for posting as it reminded me to check and adjust my chain. I clean it regually but occaisionally fall into the trap of my own lazyness of thinking that 'I will do it next time' and as most of my everyday trips are short I convince myself that this is ok but know it not to be. Thai serves as a good reminder regardless of the reason.

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DickyC

Gun Metal Grey 2014 XT660Z
'Advice is sought by someone who knows the answer but doesn't like it'

'The adsence of alternatives clears the mind marvelously'