[eggman65]

Does anyone know the torque spec for exhaust flange mounting bolts (connection to the cylinder head)? My bike is a 2010 C5 Classic.

[ScooterBob]

"Torquing" them, per se, is useless ..... they are going to allow a leak. If you've had the pipe off, tighten the nuts 'til they make contact, start the bike and tighten them EQUALLY until no leakage is heard - without the bending the flange. The torque specs are in the catalogue, BTW .....

[Arizoni]

The nfieldgear catalog says the correct torque is 4 ft/lbs (48 in/lbs).
The torque values I found for that size thread gives 8 ft/lbs for a steel to steel interface.  This might be a bit high but because it is a steel stud in an aluminum head it could serve as a guide to a maximum limit.

About the last thing anyone wants is to twist off the stud by overtightening it.

[olhogrider]

You will bend the flange long before you pull the stud out. I tightened them enough to just begin to bend the flange. I still lost the nuts. Now they have jam nuts.

[ScooterBob]

You will bend the flange long before you pull the stud out. I tightened them enough to just begin to bend the flange. I still lost the nuts. Now they have jam nuts.

Yup - This is the truth .... most of the factory ones that I took apart had the flange bent to where hell itself wouldn't have them in an attempt to stop the leakage. I used a BIG Crescent wrench to slightly over-bend the flange the other way, two gaskets and the "tighten 'til the noise quit" routine and had good luck. You'll not pull the studs out of the head - and MOST of them are in there just finger tight anyway ..... Jam nuts are an EXCELLENT idea - so are mil-spec lock nuts. The little electrical "scratchy washers" go a long way here as well .....