Which washer would you pick to go between the 10mm bolt head and the cam gear, to prevent slipping?

My Toda intake cam gear is slipping for the first time after 4 years. Appears that the intake cam gear is slipping when i set it to +2.5 degrees, probably due to +2 and +3 being used so much in the past. So the 6M X 1.25 Hex bolts i am using as a replacement of my Toda bolts, are not holding the intake gear either. It's slipping about a half a degree, but only in the +2.5 area.

Go to Fastening and Sealing Section here:
http://www.mcmaster.com/

TIA
I.

 

I believe Toda use a socket headed cap screw, allen key adjustment. You may be limited in fastener type since the screw hole is located so close to the edge of the flange. I'd suggest using some stock type hex bolts, with the washer built in. Not sure if you'll have enought space. Go to the dealer and see if they have any bulk bolts to match up to.

 

I currently am using 10.9 grade automotive Hex bolts (M6 X 1.25) which i bought at Pepboys or AAParts, can't remember, but i had to cut them down and have been using them without a washer.

i'm just gonna try a 10.9 M6 flat washer and see how that works out.