Broken Jota Sprocket Carrier

[Laverdalothar]

while waiting, how about filling the warranty claim form and send it to Laverda - errr - Aprillia - errr... Piaggio??  :

 

[Paul Marx]

Come on, I didn't imply that wire wheeled machines didn't blow sprocket carrier bearings 
All bearings are built to blow up sometime.
I did say that cast wheeled bikes do it regularly which in my experience, they do. Carrier bearings becoming maintenance items along with rear tyres.
Paul

 

[jotajoe]

At the tyre depot I use, ( Tyre Link Tamworth ), I remove the wheels , They fit the tyres and balance. I make the tea and then check  and clean the calipers and check bearings all round. It is a ritual.

Until we get the bike back it's hard to do a post mortem on it as there could be a wild card at play. I just don't know yet. The bike did spend a day on the roads of Connemara and they aren't known for being kind to vehicles. Toyota used to test their cars suspension systems out there. The road floats on the peat bog...

Joe

 

[Davo]

Did you align the rear wheel correctly when you fitted it?

 

[jotajoe]

Did you align the rear wheel correctly when you fitted it?

Good point David. Yes I did take great care and exercise due diligence at that juncture 

joe

 

[jotajoe]

The all important spacer between the two bearings was missing. I didnt build this particular cush drive.
I have a feeling it came with the bearings already fitted without the spacer as it happens.
I feel a bit shaken by this . In future anything in a rolling chassis which has bearings in it is going to have its bearings removed and replaced so I can inspect it properly.

I fitted the bearings and spacer myself this time.

joe

 

[Simonr501]

This seems to be a common issue, luckily I caught mine before I took it out on the road.
I suppose some people cannot visualise what is happening to the bearings without the spacer.

Glad there was no cat-arse-trophy and that the damage was minimal.

 

[jotajoe]

Onwards and forwards....Moral of the tale ..assume nothing ..

joe

 

[jotajoe]

The damaged carrier..

and the bearings as they came out of the carrier...The Monkey is not impressed 

 

[jotajoe]

and here is the replacement carrier on the bike yesterday...Lot of thanks to Clem, Kevin ( Troutbishop ) , Malcolm Cox, and Herman the Gorilla ....!

Joe...

 

[sfcpiet]

Seen rather a lot of drum brake cush hubs with the air scoops smashed off and swing arms with lumps out of them so they are not immune. Nothing to do with wheel flex, normal cause of the problem is poor assembly or lack of maintenance.

  Keith

(bigthumb)

Or even over-enthusiastic maintenance.  I find a lot of chains adjusted too tight.  It's a bit foolish to think a chain might stretch... it won't, and it will stress the bearings at either end of the drive train every time it tightens up, ie, every time the suspension moves when transversing a road bump.  One could consider himself lucky if only the sprocket carrier bearings fail, could just as well be the gearbox output bearing, or engine casing, meaning even more cost and hassle!

Wire-wheel carriers tend to last longer because they are fitted with larger bearings that can take a bit more strain before finally blowing.   End effect is much the same as with the cast wheels.

Chain should be checked with the bike laden so the wheel axle is in line with both the swingarm pivot and the drive sprocket, ie, the wheel axle is at the furthermost point in its arc around the drive shaft.  About 10-15mm slop in the middle of the chain run at this point will be enough to ensure all bearings can keep up.  Many riders would be surprised how much slop then results when the bike rests on the centre stand.

A #630 chain is far less-forgiving than a #520 or #530, an over-tightened #630 will wreck the bearings a lot quicker if not adjusted correctly.

piet