Whilst changing discs I ordered a set of s/s disc bolts from this bunch. Went to fit them this morning, and it turns out they’re made of cheese: brand new hex bit, torquing to 30Nm, and they just round off. I’ve got 9/10 back out but #10 I’m probably going to have to slot with an angle grinder. Absolute pathetic shit.
Angle grinder and impact driver did the trick: OEM bolts back in. But the angle grinder went through the bolt head like it wasn't there…
I did, and their response was that their M8 bolts should not be torqued beyond 20Nm. Which is interesting, given that they sell these bolts explicitly as brake disc bolts for the 1200s, for which - like most modern Ducatis I’ve seen, spec 30Nm. My older Ducatis are all in the 25Nm+ range, so it does as though they shouldn’t be selling these bolts for securing brake discs.
Stainless steel bolts are not very strong. Not unless they're made from very special and expensive stainless. Most have a rating of 5.5 which is way below your average 8.8 spec bolt. Same with titanium. Not good replacement materials where strength is required.
So I’ve discovered. To sell bolts suitable for the requisite torque, they should have been (IIRC) [Edit to reference S/S rather than carbon steel standards - we'd want at least A2-80/A4/80 -, not Gruyère. I’m afraid that I assumed that would have been the case. They’re a bit hacked off that I keep using the phrase, “not fit for the purpose supplied” but QED on that.
Racebolt should be careful if they ignore your 'not fit for purpose' message. By the way, the really strong stainless for bolts, etc used in industry is 17-4 PH, but I've never seen any bike suppliers using that alloy unfortunately.
Raceboltuk.com | Ducati Forum I've learned far more about bolt materials and strengths in the last 72 hours than I could ever have imagined wanting to know!
Sadly many sellers aren’t aware of material properties. Whilst cost is an issue, there is a reason why OE isn’t stainless. Even when you find specs strong enough, they can be more brittle, not suitable for repeated removal/ refitting etc etc. I still see places seller aluminium bolts in lovely bright colours but pics of them in load bearing locations. Most if not all trading standards departments are underfunded and many sellers are overseas to pretty much immune. Buyer beware as the old saying goes.
Ironically, I specifically chose a UK supplier of UK-made bolts, for just the reasons you describe. I’ve had a constructive response from the MD of Racebolts & will summarise here when time permits. I’ve now reverted to the OEM carbon steel T40 bolts - they (as you’d expect) torqued up beautifully
Your example is even more frustrating than normal, you did everything you could and still fell foul of a seller not understanding the materials. I am desperately trying to remember the name of the supplier we used when I did contract work for Lola Racing. They didn’t advertise to the public but would happily supply small volumes, and were brilliant with advice. They were just North of Watford. Not cheap as you would expect but not as crazy as you might think. They made most TI stuff in house. They also did high end machining of various sorts. They made us a fair few parts for the prototypes and the precision was always beyond spec in a good way. Just wish I could remember the bloody name……
