I was in the garage doing some maintenance on one of my bikes this afternoon, so in a quiet few minutes I took the bevel drive apart to see what the problem was. As predicted, it was the bearing nearest the wheel that had started to go. You can clearly hear how bad it has become in this video.
Next steps are to get the shaft pressed out of the assembly, remove the failed bearing, refill it with oil and reassemble it as a back up.
The bearing in the bevel drive has failed on my Mandello after 13000 miles. Luckily I caught them early on, so they didn’t have the chance to do any damage to the bevel gears, but to get the dealer to change them was going to cost £1600 at On Yer Bike in Aylesbury. When I dropped the oil from the bevel box it was clear that there was a lot of metallic debris in it, but it was fine dust, not flaking bearing races or bevel gear detritus.
I looked into changing the bearings myself, as I’m pretty good with a spanner, but I needed to buy a hydraulic press and a 65mm bearing puller with a suitable slide hammer, which would have cost £300 before I even started with the bearings and seals.
The alternative was to buy a second hand swing arm and bevel box from Motomine Parts for £337.50 that had been saved from a bike that had done under 1500 miles. The parts came with a 30 day money back guarantee, so it was worth a spin.
I swapped the bevel box from one swing arm to the other in less than 90 minutes and hey presto, we’re back in business. I’ll probably still strip the damaged bevel box to try work out why it failed and possibly get the bearings swapped at some point. Unlike some reports I have read, the splines on the shaft were clean and well greased, but I still cleaned the old grease off and replaced it.