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High Temp Thread locker - No, not Bill

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29 minutes ago, Slugworks Paul said:

 

your brakes would give out before the bolt would vibrate loose. 

Solve the big problems (cause) before the little ones (secondary side effect) and you might do better :)

I guess i should have used green font when I wrote that my calipers have been that hot.... :D

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6 minutes ago, wvumtnbkr said:

I guess i should have used green font when I wrote that my calipers have been that hot.... :D

The only thing left after Gingerman were the caliper bolts...

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3 minutes ago, tommytipover said:

The only thing left after Gingerman were the caliper bolts...

Pretty much.  There was some rubbery stuff that oozed out onto the wheels too!

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No, Im not.  I was trying to make fun of myself with my first post....:D

Edited by wvumtnbkr

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23 hours ago, enginerd said:

- Turn the wrench harder next time. No amount of Loctite will save you from an undertightened bolt. As a general rule of thumb, there is no downside to putting more torque on a bolt... if you don't break it during assembly, it won't break in use. And if you do break it assembling, then you know how much is too much for next time! I (almost) always tighten things well beyond the recommended torque in the manual, flywheel bolts are one exception.

- If the "nut member" material is aluminium, be careful of thread stripping (when over-torquing) as this can be much harder to detect than a broken off bolt head.

- The design goal with bolts is not "tighten it so it doesn't unscrew", it is "tighten it so that there is a very high normal force between the two mating components. Friction will then prevent them from moving relative to each other. More normal force leads to more friction. If the two surfaces (caliper and caliper bracket) shift because there isn't enough friction in the joint, the bolt will start to loosen and unscrew on successive 'shifts'.

Dunno if I agree to #1; 

 

Bolt torques are an indirect method of getting to the desired tensile strength. It's indirect in the sense there are a bunch of variables that are assumed, EG coefficient of friction, yield strength, etc. 

If you keep going 'ugga dugga' on them, you weaken the bolt. Brake bolts are hardened; once you go past the yield strength, the pretty much flatline in tension as you start inducing micro cracks into the material; you're really just stretching the bolt (ultimately WEAKENING it) w/o adding much more clamping force - you're just pushing it closer to the failure criterion w/o any benefit. 

 

Then adding to it, the heat from operating near the brakes will further weaken the bolt. 

 

I'd go to some sort of positive locking method like safety wire + blue loctite. You could also see about getting a higher class/grade bolt (12.9 vs 10.9) which WOULD allow you to run a higher clamping force but that would also require you to re-calc the new torque specs. 



 

Edited by RandomTask

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9 minutes ago, RandomTask said:

Dunno if I agree to #1; 

 

Bolt torques are an indirect method of getting to the desired tensile strength. It's indirect in the sense there are a bunch of variables that are assumed, EG coefficient of friction, yield strength, etc. 

If you keep going 'ugga dugga' on them, you weaken the bolt. Brake bolts are hardened; once you go past the yield strength, the pretty much flatline in tension as you start inducing micro cracks into the material; you're really just stretching the bolt (ultimately WEAKENING it) w/o adding much more clamping force - you're just pushing it closer to the failure criterion w/o any benefit. 

 

Then adding to it, the heat from operating near the brakes will further weaken the bolt. 

 

I'd go to some sort of positive locking method like safety wire + blue loctite. You could also see about getting a higher class/grade bolt (12.9 vs 10.9) which WOULD allow you to run a higher clamping force but that would also require you to re-calc the new torque specs. 



 

 

You are somewhat correct, however, torque values are specified based on (correct me here nate) something like 80% of yield. You can torque a bolt something like 15% tighter without yielding or weakening it. I believe that's what nate is recommending. By doing this you are creating a greater clamping force, it won't fall off until you actually yield it. 

I actually use this approach, I torque bolts to very close to their yield point and I replace often because they can only handle so many cycles of being torqued right up to the yield point, and i'm sure I end up going a bit over occasionally.

Edited by Slugworks Paul

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36 minutes ago, Team Infiniti said:

Never had issue, split washer, hit with 1/2 impact, this all sounds like under torque.

 

So you're saying use a NASCAR impact gun?

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