I am another that has never heard of this, I have titanium 65mm always copper slipped mine, never had one come loose, never overtighten and don't use torque wrench, I am an engineer so you get a feel for how tight things should be, I remove them and service them every year.
I've never changed mine, you're more likely to strip the threads by over torqueing than snap the bolt. The caliper is sat on location points as well so rotational force is not all against the bolt. A bit of white marker on the heads would tell you if they were coming loose with a quick check round But it's up to you if want to change them, I'm just a tight bugger
Thanks for reminding me of the 'Bit of white marker on the heads' it's a top tip, old school sensible stuff
Probably just another service expense from Honda, like Mark said the calipers are in compression during breaking so as an engineer I don't see an issue unless you are on the track maybe
This is a interesting read: https://barringtondieselclub.co.za/technical/stretch-bolt-theory.html Essentially stretch bolts allow a greater clamping force. But.. every time they are tightened, they will elongate and reduce diameter on the shank. For me.. is you use the OEM bolts, then I'd follow the manufacturers guidance. If you swap to a non-stretch bolt, then you can re-use them as you wish. Just my 2 pence here.
My previous CBR having ABS had the callipers off every other month! Over 70k and several track days never changed the bolts. Only maintenance was a full clean, corrosion stopper on thread and torqued to 45Nm
Just a thought, are Hondas classed as stretch bolts, Mine are aftermarket titanium, but still never had any issue with brake bolts,
Yes they stretch, I measured mine. They are specced at 60mm on the parts fiche, vernier said 62 and a bit.
Stretch bolts are for things like conrod big ends where the bolt is in tension and is tightened to its elastic limit to prevent movement under load. Caliper bolts are in shear, not compression as stated above somewhere. Probolt are expensive, try Titan classics.
I thought I must do a test so I have used my old ones,taken off at 700 miles 2014 std bolts, I made a test jig that I can measure total bolt length, pic 1 is standard bolt M10 x 1.25 with drilled centre hole 5.1mm up to threaded area then 4.1mm after, pic 2 shows after 50 tightens at 45nm and still tightened at 45 nm, pic 3 shows torqued to 70nm,to me the bolt has not changed, I could get the micrometers out but I think it would not change the results, the verniers are on the end of the bolt not the alloy
IIRC they are 60mm when new. You shouldn’t torque until they stretch but just to what they are specified according to the service manual.
I have been an engineer for 45 years and to me these have never been 60mm, the threads are still exact form under the microscope, and the length has not changed even going to 70nm, stretch bolts are torqued to yield point after this they take a permanent elongation, these do not, they have not changed in size even at 70 nm, I would like to measure an off the shelf bolt but I very much doubt many dealers will have any, even those that change tyres and remove calipers
Can you imagine the effect on the thread profile if the bolt stretched 2 mill over that relatively short length? If you reused the bolt you’d bugger the thread. As other knowledgeable people have said, they aren’t stretch.
just looking at a feature on youtube about stretch bolts for con rods, they torque to length not a specific torque value, you have a DTI on a jig and the bolts have dimples at each end you then tighten until you get some strange measurement 6 to 10 tenths of thou, or in real money about .015mm to .025mm, so many things make a difference to torque settings lube etc
If anyone is still worried about this, the reason for replacement is fatigue cracking. They are not stretch bolts. If you want to inspect the bolts before reuse, the most common points for failure are just under the head, the first thread after the shank, and the first thread of engagement in the nut or in this case, the bracket. These points are all stress risers as they are locally the thinnest part. If you ride in winter then fatigue can be accelerated by stress-corrosion cracking, as currently blighting the french nuclear industry. If there is rust on the above mentioned places, it would be best to replace them. Titanium can corrode even at low temperatures but in a typical motorcycling environment it will not be an issue so they are a good replacement option.
