V7 final drive

[bobdog6861]

My 2013 V7 stone started to make funny noises in the rear drive when I hit a bump or sudden movement.  It felt like something was loose in the rear casing that would occasionally bump up and interfere with the drive gear.  I drained the rear fluid and found it was silver with aluminium bits suspended in the oil.  I took the final drive apart and found that two of the 8mm hex bolts that bolt the bevel gear to the hub had sheared off and the heads had been bouncing around inside the casing grinding the crap out of the aluminium shell. The other 4 were loose.  What a disaster.  The bike is 3 years old and has 25,000 km on it.  It is fixable with a good cleaning and new bolts and gaskets but wow.

Dave

[jacksonracingcomau]

My 2013 V7 stone started to make funny noises in the rear drive when I hit a bump or sudden movement.  It felt like something was loose in the rear casing that would occasionally bump up and interfere with the drive gear.  I drained the rear fluid and found it was silver with aluminium bits suspended in the oil.  I took the final drive apart and found that two of the 8mm hex bolts that bolt the bevel gear to the hub had sheared off and the heads had been bouncing around inside the casing grinding the crap out of the aluminium shell. The other 4 were loose.  What a disaster.  The bike is 3 years old and has 25,000 km on it.  It is fixable with a good cleaning and new bolts and gaskets but wow.

Dave

Wow indeed, you dodged a bullet, if bolthead caught twixt drive gears bets are off what would have happened, OR actually another few mins and hole could've appeared draining oil on tyre !!
Stuff like this should not happen but glad you survived. Others might not feel/hear the warning

[ITSec]

I don't recall having heard anyone else with that problem. I'd guess either those bolts were improperly torqued on assembly, or Chinese counterfeits are in the supply chain somewhere (gee, what a surprise - not). It doesn't seem like a place you'd use a thread lock compound...

[johnk]

You are very lucky. I had one where the bolts punched a hole in the case and the rear end locked up while commuting across the (San Francisco) Bay Bridge. Lucky for me it was during rush hour and I wasn't splitting so I was only going about 15MPH.
This is the first I've heard of the newer small blocks doing this. The one's from the eighties did this all the time. I thought Guzzi would have figured out by now how to fix it.
Good you caught it when you did. 
johnk

[sib]

This is the sole instance of this that I've ever encountered on a small block MG.  My first guess is that the assembler's tool had the torque setting mis-dialed and the bolts were severely over-torqued, leading to their failure in use.  But, that wouldn't explain why the other 4 bolts were loose.  I don't know what MG's policy is about post-warranty-period coverage, but if you can convincingly show that your bevel box wasn't previously serviced, you might be able to make a claim.

UPDATE:  Uh Oh!  Now I have to start being concerned (see second report by aiken, below).  Not a good development.

[OlDogface]

Bobdog,

Possible you could put up some photos of the disassembled unit?

[aiken]

My 2014 V7 Stone is in the shop right now for the same problem; only one M8 SHCS head grinding up in my final drive...

[Chuck in Indiana]

This is the sole instance of this that I've ever encountered on a small block MG.  My first guess is that the assembler's tool had the torque setting mis-dialed and the bolts were severely over-torqued, leading to their failure in use.  But, that wouldn't explain why the other 4 bolts were loose.  I don't know what MG's policy is about post-warranty-period coverage, but if you can convincingly show that your bevel box wasn't previously serviced, you might be able to make a claim.

UPDATE:  Uh Oh!  Now I have to start being concerned (see second report by aiken, below).  Not a good development.

Maybe under torqued?
As mentioned above, crown wheel bolts coming loose were a common occurrence with the early small blocks, and is one of the two things that *need* to be addressed with them. The OP was lucky, indeed.
This is the first time I've heard of the problem on the new small block rear drive. Maybe it is just an assembly problem on a few units?