Clutch Bolt Strength

[moodoo]

Guys,

 

Long story short...have built a 2.2 to replace the 1.9 in My A-series....

 

Bolts for clutch to flywheel:

 

On the 1.9 they are 8.8 grade hex bolts, but the clutch kit I have for the 2.2 will only accept socket head screws (SHCS), there isn't enough rom for hex bolts.

 

The only SHCS I can get are 12.9 grade, but I wonder will they be too hard for the job - ie, they are very strong, but relatively more brittle than 8.8 or 10.9 grade.

I could use a Stainless Steel SHCS, which would have about the same strength as the 8.8 bolts, and would not be brittle, but I'm figuring that the larger clutch

for the 2.2 will likely need a stronger bolt than was used on the 1.9.

 

Am I thinking too much about it...will the 12.9s be OK to use?

 

Thanks,

Fin

 

 

[MicsManta]

i don't know weather they would be too brittle,they should not be as long as the clutch springs should releve pressure of shock on the bolts as well as the dowls should take the strain. but the old way of solving power/torque transfer is by adding more dowls in the flywheel and as long as they are balanced then it should be ok.

 

but hopefully someone will have already either found out by doing it or working it out.

[tony g]

12.9's will be fine. I wouldnt use stainless though as they can work harden and become brittle. Stainless bolt are not recommended for steering and suspension areas.

 

Tony

[moodoo]

Ok, thanks for the reassurance Tony! Yeh, I would be reluctant to use stainless in that type of application too, but was just a bit cautious about 12.9s as well!

[lamchop77]

Fin

 

The 12.9 is the tensile strength of the bolt, I would always use the highest strength bolt available. As Tony g has said never use stainless for any high stress areas.

 

Cheers

 

Chris