A bit of an unpleasant surprise today. The Bike went along for its first MOT at 3 years old with 11,500 miles showing and failed as a result of badly warped front discs. Apparantly there is a 60 thou variation out of true and the permitted for MOT is no more than 30 thou. I have owned it from new and it has been ridden mostly two up, with 3 piece hard luggage and not aggressively.Has anyone else experienced a similar problem? This is going to be a costly MOT!!
First of all check that all the bobbins are free to move.
How free should the bobbins be? rattling or not?
Well clearly not really rattling, but should be able to turn freely.
I’m afraid they have had it. Mine were running 0.4mm(0.016") out at 17000 miles . They were vibrating at high speeds and jerky at low speeds.
Check out this guy for replacements.
http://www.blackshadow-uk.co.uk/Moto%20Guzzi.html
Also change to EBC HH sintered pads you will have to replace the pads anyway. The new discs need setting up to run within 0.1mm this important to prevent further problems. The Blackshadow web site is a mine of info on the subject.
Also have a look at this video.
http://www.youtube.com/watch?v=2GaYqJYhCB0
I replaced and set up my discs for £230 including pads and happy to help if you are near the Grantham area.DaveM2012-10-10 11:59:23
did the tester show you the run out on the disc. Reason I ask, is 2 years ago one testing station told me my Norge had warped discs, cos his machine told him that was what was wrong, although he said they were just within limits. I did say to him I thought it would be the pads not the discs. He just looked at me like i was dog s**t. I checked them with a dti at home and found no run off. I did have Brembo pads in at the time. This year when I went to another testing station, I had fitted EBC pads. The bike sailed through the test with no problems. Afterwards I asked the the tester if he had detected nay signs of warping. Non at all he said, brakes are perfect.
So either they un-warped themselves, or it was as I already knew the Brembo pads grabbing causing the machine to believe the discs were warped.
Are you actually getting any symptoms when riding? Such as described above. if not I would check the bobbins and try another MOT station.One place I took mine too just pushed the bike along and grabbed a handful of brake, it stopped and he was happy . I think it was on some sort of inertia platform thingy he was using. Certainly not a rolling road or anything sophisticated. Others use a winch to pull the bike along whilst you sit on it with the brakes on.
I must admit 60 thou/1.52mm does sound a lot and you would notice it when braking for sure.
There is another check worth doing. Using a micrometer measure the disc thickness in 90 degree segments there should be no more than 0.03mm variation, mine were this far out and you could feel it.
I would say pick your MOT garage - I watched mine being done and at no point did they do more than put the bike on the brake tester… no check of the discs at all.
I am sure many garages go to the enth degree to spot things like this to earn ££££
The problem you have now is all MoT centres are connected by technology, so you can’t just take it to a more pragmatic test centre
By the way - re your original point, it is a known problem - search for the problem on www.1200sport.com and you will find loads of people have had the problem
Adam
Thanks to all for the helpful advice and information given. I am now a lot wiser.