Pressure Plate Fasteners Question, What size & grade? Options

[frank_c]

I just had my flywheel lightened, and I'm having it and the pressure plate balanced next. I want to include a new set of the six bolts and washers that clamp the pressure plate to the flywheel before giving the parts to the machine shop. I thought this would be easy (IMG:style_emoticons/default/sad.gif), but here's what I found:

• PET states that the bolts (900-075-104-01) are M8x15 (NLA)
• Searches show both 8x16 & 8x20 are recommended, with 8x20 being more common (the 8x20 bolt does capture all the threads in the flywheel, the 8x16 does not)
• Some results say Grade 8.8 is fine, other say 10.9 or even 12.9 is necessary
• Regarding the washer, PET indicates a split-type locking washer, while most search results say to use a wavy lock washer

I know we are only talking a few grams here, but if 8x16 is fine, then I'll go with that instead of 8x20. But what about the hardness? I suppose there is no harm in getting 10.9, but is 12.9 really needed for this application?

And split or wavy on the lock washers?

Btw, the old bolts I removed were 8x20 Grade 8.8 with a wavy washer, but of course that does not mean they were correct.

And one more - Blue Loctite, yes or no? (for final assembly)

Thanks for any help.

[bdstone914]

Original bolts were 20mm long grade 10.9.
I use internal star washers as they have more locking power than wave or split lock washers

[frank_c]

Original bolts were 20mm long grade 10.9.
I use internal star washers as they have more locking power than wave or split lock washers

Thanks Bruce - I'll go with 10.9 20mm.

Out of curiosity, this morning I looked up the bolts spec'd in PET for a 912E (which should be basically the same engine/transmission as my '76 914 2.0), and it states M8x18 (again with a split washer).

I found it strange that PET would state 8x15 for the 914, and 8x18 for the 912E, so I went back to check the 914 again in PET, and saw that the bolt is 8x15 for the 1.7/1.8, but 8x18 for the 2.0. So, my mistake on that (I have a 2.0).