Wildguzzi.com
General Category => General Discussion => Topic started by: NorwegianRider on August 18, 2026, 08:44:36 AM
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Hi,
First time Guzzi owner and first time on this forum.
Recently had a breakdown doing 80 km/h on a highway when I suddenly lost power/transmission (with some horrible noises included).
Managed to get the bike on a trailer, where I've dismantled it and found that the grade 10.9 bolts connecting the crankshaft and flywheel had snapped.
Unable to find any other faults: Engine turns fine by hand, gearbox turns fine by hand (all gears OK), drive and cardan OK.
Current plans are to just get new bolts from Stein Dinse, put the bike back together and hope for the best. But is the damage/marring on the mating surfaces a problems? I can always replace the flywheel, but worried about the crankshaft surface.
Are there any other things I should check for damage?
And any advice on other things that would be smart to check/replace while I have the bike apart?
Any advice is greatly appreciated, thanks.
(https://i.ibb.co/gZTBsP0r/PXL-20260627-134314786.jpg) (https://ibb.co/gZTBsP0r)
(https://i.ibb.co/KzpV1JS1/PXL-20260627-134336015.jpg) (https://ibb.co/KzpV1JS1)
(https://i.ibb.co/sdZL4RGD/PXL-20260628-091526354.jpg) (https://ibb.co/sdZL4RGD)
(https://i.ibb.co/gZ2dCWM6/PXL-20260628-091603607.jpg) (https://ibb.co/gZ2dCWM6)
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The flywheel does not look like it should be used again. Perhaps if you have a machine shop than can skin cut the surface it might be saved, but the divots in the face look deep. A perfect mating surface is critical here.
(https://i.ibb.co/3mR8KFPD/Screenshot-2026-08-18-at-09-15-27-PXL-20260627-134336015-hosted-at-Img-BB-Img-BB.png) (https://ibb.co/3mR8KFPD)
The crankshaft looks like it should clean up sufficiently using finishing stones after the bolts are extracted.
I can come up with no reason for the bolt failure other than improper torque being applied the last time apart, and/or lack of proper locking tabs or correct Schnorr washers.
Welcome to the forum and keep us informed on your progress.
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Thanks for the quick response Dave.
I'll order a new flywheel, and do my best at dressing up the crankshaft.
The bolts were installed with these washers;
(https://i.ibb.co/bMymRXMC/PXL-20260627-134324628.jpg) (https://ibb.co/bMymRXMC)
Is it usual practice to use locking tabs?
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Thanks for the quick response Dave.
I'll order a new flywheel, and do my best at dressing up the crankshaft.
The bolts were installed with these washers;
(https://i.ibb.co/bMymRXMC/PXL-20260627-134324628.jpg) (https://ibb.co/bMymRXMC)
Is it usual practice to use locking tabs?
Locking tabs are the old way of doing it. Those Schnorr washers are correct for the application. Do you know if the correct torque was applied last?
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Thanks for the quick response Dave.
I'll order a new flywheel, and do my best at dressing up the crankshaft.
The bolts were installed with these washers;
(https://i.ibb.co/bMymRXMC/PXL-20260627-134324628.jpg) (https://ibb.co/bMymRXMC)
Is it usual practice to use locking tabs?
Those are correct. Maybe someone reused the bolts and washers. That is not the place to go cheap. Always use new fasteners there and of course torque them properly.