Overtorqued head stud

[Lammif]

I stupidly overtorqued the head stud and managed to snap the top bit off, anyone know how I should go about getting it out?

I also managed to chip the little bit off the top around where I have circled, will I need a new head or will it seal fine it I place the bit back on and tighten bolt.

 

[butre]

the head is fine, but you'll need a new stud. best to just upgrade the whole lot while you're at it, the stock head studs have a similar shear strength to cheddar

 

[crassius]

I'd try the head, but be prepared for a crack to show up at some point. Head is cheap tho. With head off, you should have plenty of room to remove broken stud.

 

[Lammif]

the head is fine, but you'll need a new stud. best to just upgrade the whole lot while you're at it, the stock head studs have a similar shear strength to cheddar

Where could I find better studs?

 

[butre]

fastenal if you're willing to do your own hacksawing, or just about any motorized bicycle performance parts website will have them for a bit more money

 

[Lammif]

fastenal if you're willing to do your own hacksawing, or just about any motorized bicycle performance parts website will have them for a bit more money

I think I might just go with bike berry, any foolproof way of working out what stud size I have?

 

[Steve Best]

Pull the cylinder off and remove the stud. Take it with you to an automotive (not hardware) store.
Ask them which size nut fits the stud, 6mm or 8mm. Buy a box of both. You will use both.
Automotive grade nuts are the proper 8.8 strength that you need. Hardware store is often 4.2 or less.
But a small 1/4" pointer type torque wrench while you are there.

You are lucky you had the weak studs. If you had good ones you would have stripped the case threads. Bad.
Use the torque spec for aluminum when yo look it up. The nut and stud are steel, but the case is aluminum.
Use a flat washer under the nut. I don't use lockwashers at all. Useless, seriously. Torque it properly.

While at the store, buy a sheet of 150 (or there abouts) emery paper.
With a sheet of glass or your wife's good granite counter top (a reliably flat surface) sand the head sealing surface.
Imagine sandpaper under this head:

Sand it in a circular motion for a few seconds, then have a look a it:

Look for 100% contact. Do it on the cylinder as well. When you have it you are good to go. Wash them both well.

Steve

 

[crassius]

also, be aware that some studs have 1.0 thread on one end and 1.25 thread on other end

 

[Lammif]

also, be aware that some studs have 1.0 thread on one end and 1.25 thread on other end

That's what I have unfortunately. And 1.0 thread is crankcase side so im not sure if it was upside down or if the crankcase thread is 1.0

Anyone know anywhere I could purchase 8mm studs with 1.0 and 1.25 threads?

 

[Lammif]

Pull the cylinder off and remove the stud. Take it with you to an automotive (not hardware) store.
Ask them which size nut fits the stud, 6mm or 8mm. Buy a box of both. You will use both.
Automotive grade nuts are the proper 8.8 strength that you need. Hardware store is often 4.2 or less.
But a small 1/4" pointer type torque wrench while you are there.

You are lucky you had the weak studs. If you had good ones you would have stripped the case threads. Bad.
Use the torque spec for aluminum when yo look it up. The nut and stud are steel, but the case is aluminum.
Use a flat washer under the nut. I don't use lockwashers at all. Useless, seriously. Torque it properly.

While at the store, buy a sheet of 150 (or there abouts) emery paper.
With a sheet of glass or your wife's good granite counter top (a reliably flat surface) sand the head sealing surface.
Imagine sandpaper under this head:

Sand it in a circular motion for a few seconds, then have a look a it:

Look for 100% contact. Do it on the cylinder as well. When you have it you are good to go. Wash them both well.

Steve

Yeah will do