Exhaust manifold thread pitch??

[Off Road SHO]

Does anyone know what the bolt (stud actually) diameter and thread count is? I think it's a metric 10mm with a 1.5 thread pitch, but it doesn't line up with any of my thread pitch guages or taps and dies. It almost looks like a ******* size in between two sizes.

I've got a broken off stud on an exhaust manifold that I'm going to have to drill out and re-thread. Thanks in advance.

Tom

 

[yamahaSHO]

Tom,

I don't know the size, but if you are in need of another stud, I have some. But I'm sure you have a bunch too.

 

[Off Road SHO]

Jason,

I do have some new studs already and that is what's got me baffled. The new stud doesn't match any metric or SAE taps or dies that I have. I want to "clean" out the existing holes with a thread chaser or a tap. Thanks for the offer though.

Tom

 

[Ishodu]

Yes the studs are indeed m10* 1.5mm.

 

[Off Road SHO]

Thanks Marcel, I'll try that again. I'm wonderin if maybe the stud or the hole for it in the manifold has been swedged or something to cause it to self lock in place. I noticed the brand new studs from NAPA have a "+" stamped in the manifold end of the stud. Hmmmm....

Tom

 

[Ishodu]

3/8's are also very close to m10. I wonder if they the ones you have are 3/8ths. I do know for sure that the studs are m10*1.5 though, I have made some.

 

[Off Road SHO]

Marcel,

You were right, they are 10 x1.5. Cleaned out the manifold with a tap and cutting oil and cheased the remaining un-bent studs with a die. Thanks again.

Tom