Does anyone know who does upgraded high tensile strength flywheel bolts for a 2 litre 16 valve (1991) Ianb
Ians flywheel came loose at Mallory. Some flywheel bolts broke. He was revving to well over 7500revs and I think he's a bit worried about safety. I was sat in the passenger seat on one session too
Right, ere we go, I'll try and explain......... Mild steel bolts have a 4.6 rating. High-tensile bolts have an 8.8 rating or above. The strength ratings most often used are 8.8 and 12.9. The number before the point is the ultimate tensile strength in N/mm2 (or MPa) divided by 100. This is the stress at which the bolt will fail, i.e. break in half. The number after the point is the yield strength as a percentage of the ultimate tensile strength, divided by 10. Yield strength is the stress at which the bolt will receive a permanent set (an elongation from which it will not recover when the force is removed) of 0.2%. (Copied that out of a book btw, I ain't quite that sad!)
Would a higher tensile require a higher torque or lower torque when applied ? And surely a higher tensile would be more likely to snap than one that is of lesser tensile which would give slightly.
You could torque it higher, its the shear factor of the bolt. If ya dont drive it like a c*nt, then ya should be alright with standard VAG bolts !
So is there such thing as uprated flywheel bolts anyone?? Thought ARP or someone like that would stock them. Bill apparently they used to fail regularly on the 16 valve race cars running 8500 RPM. Just looking for safer options Ian
It's a simple enough question... ARP make them Ian. They are most likely re-useable aswell. Remember to put the flywheel back on in exactly the same place, otherwise the bottom end won't be balanced again ! The ARP bolts feel so much nicer to thread in, i'm sure they roll the threads on them..
how much you reckon they are? 1.50 ea from the stealers, arp being re-useable aswell reckon will be alot more!
well its a place called SBD, but thats no help to you as they are a vauxhall specialist. my input to this thread was merely to point out that ARP do make uprated flywheel bolts and that they are available for popular engines.
Are we talking about the bolts that hold the pressure plate to the crank? Or the pissy little 9mm headed bolts that hold the flywheel to the pressure plate? (oddball,VW clutches are a*se about face,the pressure plate goes on first,then the disc, then the flywheel is on the outside ) Edited by: G_V_K
