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Caliper bolts torque setting??
Posted: Fri Jul 13, 2007 4:51 pm
by plivez
Hi all. Great forum, spent countless hours reading the archives.
I am changing my brake caliper bolts for stainless, does anyone know what the torques should be?
Posted: Fri Jul 13, 2007 5:51 pm
by Blackal
For caliper to fork mount - 40Nm
I would put a dab of molykote or copaslip on though.
Al
Posted: Fri Jul 13, 2007 6:16 pm
by plivez
Thanks,
What about the 4 bolts in the caliper itself?
Posted: Fri Jul 13, 2007 6:24 pm
by Blackal
plivez wrote:Thanks,
What about the 4 bolts in the caliper itself?
The manual doesn't say, but I'd be looking at about 20Nm and use nutlock on clean threads.
Al
Posted: Fri Jul 13, 2007 8:12 pm
by r550s
before I stripped my brembos I marked a couple of the bolt heads & used a torque wrench to re-tighten them back to the same place (because as blackal says, the manual doesn't tell you). It was about 30 nm, but that was with crusty threads, so 25 nm with a clean/lubed bolt is how I rebuilt them. Unless you keep a really close eye on things, then go for threadlocking compound too. Bear in mind too that the stainless replacements won't have the tensile strength and quality of the originals - another reason to keep a close eye on them. In theory, stainless isn't a good choice for something as important as this. On the other hand, FWIW, I've used stainless bolts all over bikes, and the only known failure was when the head fell off a disc rotor bolt on a K (the remaining three held things together!)
Posted: Fri Jul 13, 2007 8:22 pm
by JoeC
According to Mr Haynes ...
Non EVO brakes - 40Nm
EVO brakes - 30Nm
Blackal wrote:For caliper to fork mount - 40Nm
I would put a dab of molykote or copaslip on though.
Al
Posted: Fri Jul 13, 2007 9:41 pm
by plivez
Many thanks guys..
Posted: Sat Jul 14, 2007 7:38 am
by throttlemeister
Blackal wrote:For caliper to fork mount - 40Nm
I would put a dab of molykote or copaslip on though.
Al
Never use copaslip for anything unless it is specifically needed for the application. Which is almost nothing and only things that get really hot. Copaslip has a nasty habit of seizing over time when it dries out.
Rule of thumb: if you can use moly, don't use copa.
Lubricating bolts...copaslip et al
Posted: Sun Jul 15, 2007 9:35 am
by Basil the Labrador
For my sins I have a bit to do with bolted fixings...and just a word of caution.
Be careful with tightening torques and lubricated threads. A change to the mu (coeff of friction..scuse me if I am patronising you all here) will radically effect both the clamping load of the bolt generated by a certain torque.
On the face of it that sounds good but what happens is that the bolt is actually seeing higher tensile load...potentially approaching it's Yield strength or worse.
Lubricated threads can also suffer from a tendency to undwind back down the thread, dependant on pitch, thread geometry and loading cycle.
IME, the manufacturer will spec torques with dry bolts (they may well be coated or have encapsulated thread loc for some non-serviceable applications) but they will have calculated the clamp load they want and not taken account of lubrication on their calc.
That could mean you taking your bolt to yield when you tighten with a lubricant later...do this a few times..wheel bolts are a classic and they can snap..or crack and fatigue later.
I know why people use copaslip etc...just swapped tyres on my R and it was covered in the bloody stuff, but unless you throw away your fixings after each use (and for wheels of course you don't) then I tend to wipe it off....
In reality I guess for a bike you get away with it the loads are lower...but trust me, on cars and trucks and other things lubricated bolts come undone and snap...so spare a thought perhaps.
Cheers
Basil