rear wheel sliding ???

[jerryz]

went out for a ride today on the S4  , road was bone dry , no diesel , some sand and wind blown grit as usual in Thailand but rear wheel broke traction and slid several times in bends and when pulling away , also rear of bike felt unstable at times even at gentle speeds ??tyre is Pirrelli Diablo corsa 3 only 2000m and in good condition loads of meat on it , 34psi , suspension is all set up same as usual , and seems all in order but on large bumps and speed humps there is a clunking sound from the rear end ??

any ideas ?
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MONSTERMAN

[Howie]

Swing arm bushings, shock bushings, suspension rocker bearings, tie rod bushings, wheel bearings, even cush drives.  Don't forget the easy cheap stuff like a loose fastener.  You will need to support the bike so there is no load on the rear suspension and start wiggling.  You may need to unbolt the shock.

[FrankenDuc]

I've had that feeling a couple times before. In my case both times it was chain tension. It seems when my chains go they go quick - like start of a ride it's fine, slack is perfect, end of ride it's about to hop off the sprocket. My last chain I had to retension three times in four rides while waiting for the new chain to arrive, each adjustment was about 1/5 of full travel on a dual sided swingarm.

If lose the chain will smack the swingarm good time or two over bumps, as well as whenever there's a reversal in torque (when braking especially), giving a good loud knocking noise. The extra slack will give an impulse of torque each time you get on it. Depending on how hammy your fist is, it can make the rear a good bit squirrely.

In addition to Howie's suggestions:
Axle nuts tight? Have had these loosen up on single sided swingarm, both wheel and sprocket sides, sure it could happen on either type of swingarm.
If standard swingarm, double check the chain tensioner caps/bolts/blocks, etc., if single sided check the chain tensioner eccentric clamp bolts.
swingarm pivot rod - check the clips are secure on both sides, heard of these coming loose, and there rear will get really funny if it slides halfway out.
Check endplay between the swingarm and the engine at the swingarm pivot.

Keep looking till you find it, Good Luck!

[jerryz]

I have stripped the rear end  and checked all bearings atc , all is good , regreased and cleaned it all
cant find anything wrong at all , all torqued up to spec , chain not loose .

have to suspect the tyre but it LOOKS perfect ?/ mind you I have never had total faith in the Pirelli Dibalo corse 3 ,
my other Ducatis in UK now have Dunlop Sportmax Q2 and Roadsmarts and they seem to have better feel ,grip and turn in , changing tyre in TRhailand is very expensive a rear costs $300+ and availability is limited to Pirelli, Bridgstone ,Metzler and Dunlop  and even then usually to order , 

I suppose it could be the road conditions but its weird I have done 25,000 miles o n this bike and in the past the only thing that caused slides was road conditions

[FrankenDuc]

Not a fan of the Diablo's either, but that's just personal preference ...
Do you still have the "clunking" noise over bumps? 

Also, don't know what region you're in or the weather out there, but if the seasons are wet and dry like out here in central California, I know after the first rain of each season, even when sunny and well dried out, I have to go slower even than when riding in rain after several heavy rains - the first rain takes the oils collected over the dry season to the surface and it takes a little while for them to run back, run off, and/or wear off...

[Dirty Duc]

how old are the tires?  They get hard after a few years and may look fine, but grip is compromised.

[jerryz]

roads here are either really hot 90f + or wet  its tropical weather , one gets a lots of dust in corners , the tyre is 2 years old ,
it has been raining solid for 3 days so no riding , should be dry wednesday then i will give it a run ?

[hillbillypolack]

I had something similar a few years ago on the M900.  Coming into a left hand 3rd gear curve I felt the rear step out what felt like 1".  I had been progressively leaning, smooth throttle in dry & cool conditions.  I had a set of Metzelers on the back at the time.

So, I'm also unsure if it was a local spot in the road surface, some debris, oil etc.  Just glad that I wasn't snapping the bike into a quick turn which might not had the bike regain grip (!)