Broken Chaincase Cover Bolt - Common?

[TheNatural]

I serviced the chain case in my 2016 Viper MTX today. First time I've done it myself. Just cleaned it out and inspected, all good until reassembly. It had a slow leak so I put the newer updated gasket in (not really related).

Torquing the 11 bolts back down, I used a torque wrench set to the 12 ft lbs in my manual. Slowly tightening one it got to about 11 ft lbs and the bolt broke. Another one got to about 10.5 before it got easier... I stopped before it broke too.

What gives? Hass anyone else had trouble with these not holding up to the torque spec?

I guess I'll stop at 10 ft lbs next time - when I can get a new bolt.

 

[GR8BBQ]

Yes, this is quite common. Less torque (measure in in lbs with smaller wrench) and/or stronger bolts. Many opt for hex head bolts as the torx bolts can be difficult to get to also.

 

[cannondale27]

I seat the cover by hand with a driver like this. You can feel it seat. All of them. Then use a 1/4in drive with swivel for some for final torque with less in mind. Once its seated it wont leak so use Loctite on bolts and treat it like Grandmas fine China. Two fingers lots of Loctite Blue.

 

[GR8BBQ]

Another suggestion... If you are reusing bolts, make sure you clean off the old loctite. Some people even go so far as to gently run a tap in the chain case to remove old loctite there as well.

 

[TheNatural]

Thanks guys. I ordered a new set of replacement bolts. I was surprised that the bolt broke before the hole stripped, but on the chance that it was designed that way on purpose (to keep me from stripping the holes in the Chaincase) I'd like to retain that "feature" rather than use stronger bolts.

I'll use a hex head off the shelf to get the sled back in action for today, back off on the torque and use plenty of locktite as suggested.

 

[DennyTuna]

We have broken many bolts over the years. I have often wondered about the use of Loctite in this application. When removing them for service one has to use some force to loosen, and I just wonder if the weakening of the bolt starts then. Now we go to torque one down at even 10 ft lbs and snap. You can just feel when its going break, somethings not right....snap!

 

[cannondale27]

We have broken many bolts over the years. I have often wondered about the use of Loctite in this application. When removing them for service one has to use some force to loosen, and I just wonder if the weakening of the bolt starts then. Now we go to torque one down at even 10 ft lbs and snap. You can just feel when its going break, somethings not right....snap!

I still am using all my Original bolts. Screw the Torque wrench. Torque is wrong. Like I said once its seated it wont leak unless the bolts back off. The Loctite prevents that and really the driver is all thats needed. you can feel when it seats. Cleanliness too is really important.

 

[74Nitro]

12lbs seems a tad high on a bolt of this size. I think Yamaha(non Cat models) has usually spec'd 9-10lbs on this size bolt in most applications.