I have a flywheel that doesn't have the bolts to hold the pressure plate on. I found the correct size at "Home Depot", but they only had grade 5. I *thought* I read somewhere that the bolts for the pressure plate should be grade 8, but I can't remember for sure or find where I saw that.

So, are the grade 5 bolts adequate, or should I get a higher grade? If the grade 5 bolts I have aren't right and could shear off, I'd obviously prefer to wait and get what I need.

Thanks,
Steve

 

Given the kind of stress those bolts see, I wouldn't personally use anything short of either OEM or grade 8.

-=Russ=-

 

A grade 5 would be the term for an SAE bolt. Most flywheels including aftermarket flywheels for Mazda use metric 8mm x 1.0 pitch bolts. You should use a 10.9 grade which is similar to grade 8 SAE. Don't confuse a 5/16 x 24 bolt for the proper metric bolt. I have never seen a Home Depot with anything that will help you. The fine pitch 8mm is uncommon and difficult to find at hardware stores.

 

The bolts I need are 8mm, 1.25 thread, 20mm long, and Home Depot does have them. I'm not really sure what grade they are though, since they're marked with W.T. and 8.8.

 

Metric grade 8.8 is the same as grade 5. Bah!

 

Metric grade 8.8 is the same as SAE grade 5. Bah!