That explains a lot - I guess I was really lucky to get one bolt out cleanly with my standard Torx bit. Strange that the OEM replacement bolts are Allen head, not Torx. Maybe Piaggio had complaints about users damaging the heads of the TorxPlus type.
This is a bit of a basic question, but is there any way of looking at a bolt and being able to determine if it’s high tensile steel or not? Are there any markings that all high tensile steel bolts carry? My replacement caliper bolts are a dull light grey colour rather than zinc plated - is that a clue that they are high tensile steel?
Thanks. Must admit I hadn’t heard of High tensile stainless before just A2 and A4. Didn’t realise it was not what it seemed with no engineering background.
Wensleydale, lad. Wensleydale.
tjwood have a look at THIS
Thanks Speedy23. That’s a really useful link
Yes, numbers embossed on the head, usually, at least on hex boilts.
Just to mention, I do not have an ‘issue’ with stainless fasteners in terms of are they strong enough or not for the purpose of doing whatever. I like stainless screws and bolts and nuts (a lot) and have used them often, and have bought ‘stainless fastener kits’, precisely because they’re shiny and rustproof, and at least once, the vehicle came so equipped from the factory.
All I said was, and just supposing you are are a stickler for doing things up to the correct reccomended torque according to the manual, but you have replaced original with stainless, just be aware, the maximum torque that can be applied to that fastener may be different to what the manual says. I now keep torque tables handy so I can double-check.
I might be wrong but I got the impression that they are Allen on the Stone, but Torx Plus on the Special. Go figure (if that’s the case).
Thanks Mike. Like you I am a real fan of stainless fasteners. I rebuild 60s and 70s classic bikes as a hobby and I always use stainless where possible, even for non-bolt applications such as rear brake rods, mudguards etc, although I often paint those mudguards to get a more original look. I can hear the purists screaming at me but I’d rather have a rust-free restoration than a truly original one with rusty bits.