Topic: Snapped A Cylinder Stud: Do I need to replace gasket?

[campbmic]

I have a 1975 CB550 and I was in the process of replacing the bottom gasket and head gasket. I put the new gaskets in, put the cylinder and head on, and hand tightened the cylinder studs. A few days later I bought a torque wrench and in the process of torquing them to 16ft/lb snapped a cylinder stud.

I had tried to replace the studs when I was replacing the gasket, but couldn't get them out. At this point my plan is to loosen all the flange nuts, remove the head, remove the cylinders, then try to remove/replace the broken stud. When I replace the stud I've read to use the two nut method and torque it to the case at 8ft/lb. Since I was in the process of torquing everything down, do I need to replace the new gaskets? I'm hoping not, but want to make sure.

Also, please let me know if there's anything wrong with my plan. Thanks!

[DaveBarbier]

Your gaskets will be fine to reuse. No heat cycles and wasn’t fully torqued.

8ft/lbs sounds about right, I know it’s something fairly low. You definitely don’t want to go too tight as it can break out the bottom of the hole into the case. Just make sure to clean out the hole before threading in the new stud.

[campbmic]

I know its been a few days since I posted this. When I separated the head some of the gasket material was stuck to the surface of the cylinders. Do you still think I can reuse the gasket? Not sure if its the metal portion of the gasket or the paper that does most of the work.

Also, turns out this all happened because I borrowed a defective torque wrench from Autozone's "loan a tool" program. It was one of those click torque wrenches and after this happened I tested it on a stationary nut and it didn't "break away" or click even on the lowest setting. I will definitely be getting one of the lever torque wrenches in the future!

[bryanj]

If the paper has split off it will leak oil, sorry but you need a new one

[PeWe]

I have snapped one cyl stud too.
I replaced all studs which is the way to go.

It was a heavy duty stud which is harder with less flex as all bolts of higher grade which cannot be overtightened.

I had borrowed a torque wrench from my job, expensive model but not used in production. It must have been wrongly calibrated.

I bought a new set of studs and replaced the broken one only.
I also ordered new torque wrenches.
1/2" socket 10-60Nm
1/4" socket 2.5-25Nm

I tightened head 28Nm (20.65 ft lbs) as always.
I tested how much I need to continue tighten the nuts to move, 36Nm!!
28Nm should have  been enough, gasket must have compressed a little more and not need much extra to start the movement.

Shortly after I read a post on this forum where one guy had done same thing. Another of the overtightened studs snapped while riding, the upper part with nut fell into the engine which failed completely.

This made me to cut frame and install Franks frame kit. Lifted head and replaced all studs with new.

I could later purchase one single stud for the extra set I had. Now used in another build.

If you have snapped one heavy duty stud by too high torque, replace them all.

APE or Kibblewhite same type of studs that are made to not flex keeping the gasket intact.
Max specified torque is 22.5 ft lbs.
Respect to the used tool tolerance must be taken too.
4% is common (here 1 ft lbs.)
2% is very expensive.
This when new, the tool can become more wrong.
20 ft lbs is enough anyway for stock and big bore CR 10.5.

[DaveBarbier]

I’m with Bryan. It will weep oil probably. Although it is only the cam chain tunnel that is in that area. Only crank case pressure and dripping oil going back from the cam. Won’t leak a lot but if it was me I’d replace it and chalk it up to bad luck.

[DaveBarbier]

And as far as the torque wrench, those rental tools from advance or autozone get beat on badly and they don’t ever send them out for calibration. They’re essentially only as good as a breaker bar. Don’t rent tools that require calibration or precision from them. I’d recommend buying a name brand torque wrench. Good tool to have. Range of 10-80ft/lbs is good for the bike.

[PeWe]

A bad tool can cost.
My new and own torque wrench did not cost more than a new stud set and new head gasket.