Brake Caliper Noise????

[Cloudsurfer]

Originally Posted by vath2001

What about adding Lock-tight, or thread locker instead of buying new bolts?
You discuss the fact the bolts are "stretched" when applied to the torque spec, but are we exceeding the tensile strength of the bolt design... or even reaching the yeild strength?

Don't get me wrong, caliper bolts are a safety item and critical to the operation of the braking system. But I don't always have extras available.

Not the same thing. Once a stretch bolt stretches, it is stretched. Using your idea, you are relying on the loctite to pickup where the tension between the threads left off, as the bolt you are re-using is already stretched.

For a few added bucks during a brake job, is it really a big deal to just do it the right way?

[sd_boxster]

Just got done replacing mine. I ordered them a couple of months back when I picked up my new rotors, but I didn't have the bit I needed. The OEM bolts (at least on an '03 non-S) require a hex bit, while the Suncoast replacement bolts require a star driver bit... so I got to spend my $20 AutoZone reward on a new bit and a 1/2" drive 19mm socket for the impact wrench.

[vath2001]

Originally Posted by Cloudsurfer

Not the same thing. Once a stretch bolt stretches, it is stretched. Using your idea, you are relying on the loctite to pickup where the tension between the threads left off, as the bolt you are re-using is already stretched.

For a few added bucks during a brake job, is it really a big deal to just do it the right way?

But we aren't stretching the bolts beyond the tensile or up to the yeild strength? By the same arguement, I would need to replace my lug nuts and studs everytime I take a tire off.

Is the requred torque (I thing its 63 ft-lbs for the M12 x 1.5) exceeding the tensile strength of the bolt? If it is, I would step up to a Grade 8 bolt or higher. And should we be worried about bracket failure? If the bolt is stretching, then the bracket is also deforming and the threads in the bracket under tension. And the caliper itself is under a compression load. All potential failure conditions.

[sd_boxster]

My layman's understanding - with a Google assist - is that the reusable bolts undergo elastic deformation - they deform under load but return to the original shape when the load is removed. A bolt formulated to undergo plastic deformation when torqued to spec preloads the joint to ensure that the bolt doesn't work loose due to vibration, but it makes the bolt non-reusable.

[vath2001]

This is the not the forum for the discussion of the design of the mechanical elements of the Boxster brake system.

I will agree that it is good practice to replace the caliper bolts, along with the retaining spring and pin... per the Porsche Technical manual. Then again, the Porsche owner's manual allows oil changes up to 15,000 miles.

I will choose to be selective about the maintenance of my car.

[sd_boxster]

"Technical Chat" seems like a pretty good choice of forum...

Originally Posted by vath2001

This is the not the forum for the discussion of the design of the mechanical elements of the Boxster brake system.