A Tale of Three Calipers, Tell me about different RIBE hardware Options

[zoomCat]

I'm putting together a pair of rear calipers for a six, which the previous owner had replaced with 911 rears to get the vented disks. He didn't keep the originals, it was back in the 80's and nobody cared.
Here's what I've got so far:



On the left is a rebuilt stock 914/6 left rear. The plan is to add a spacer for vented disks.
In the middle is a 914/6 right rear, which I got years ago that already has a spacer. It will be rebuilt.
On the right is what I think is a right rear Ferrari 308 caliper, because the bleeder is in the wrong place. It can be a donor if absolutely needed. The rears the previous owner had installed are the first candidate for donors.

My question today is about the RIBE hardware.



On the left is the rebuilt stock, on the right is /6 caliper that had a spacer added. The fasteners on the left have sloped shoulders, while the other has more square shoulders, which I see on the front A and M calipers I've got.

What was original, either for the stock calipers or the GT calipers?
Is there any functional difference? Esthetically I'd like to get it all matching and correct before I send it all off to PMB, but that depends on availability.

[gandalf_025]

Then again, you could always make your own
hardware and spacers …. These worked well for
quite some time..

[Eric_Shea]

Then again, you could always make your own
hardware and spacers …. These worked well for
quite some time..

This is a perfect example of what “NOT” to do (IMG:style_emoticons/default/biggrin.gif)

If I recall, we fixed this. (If I’m not wrong, they’re probably now the correct GT calipers pictured above in post #12)

Wrong size spacers and wrong size aftermarket fasteners that had no strength and no right to be on a brake caliper. (IMG:style_emoticons/default/wink.gif)

[PatMc]

Then again, you could always make your own
hardware and spacers …. These worked well for
quite some time..

This is a perfect example of what “NOT” to do (IMG:style_emoticons/default/biggrin.gif)

If I recall, we fixed this. (If I’m not wrong, they’re probably now the correct GT calipers pictured above in post #12)

Wrong size spacers and wrong size aftermarket fasteners that had no strength and no right to be on a brake caliper. (IMG:style_emoticons/default/wink.gif)

Might not be anything wrong with the fasteners (aside from the fact that they're too long and look like hell).

170,000psi fasteners are readily available in 1/4-28 thread. A 1/4-28 bolt of this spec will have a tensile strength of 8,340 lbs. We have 4 of those bolts in the caliper...so 16,500 lbs or so combined.

With a 38mm piston at 1200psi, caliper is trying to spread (or clamp) with a 2,100lbs of force.

Looking at the OEM M7 fasteners, 12.9 strength...they should also be 170,000psi. But the unthreaded shank is necked down smaller than the threads, and only about .020" larger in diameter than the shank of a properly made high grade 1/4-28 bolt.

Ate also used the same M7 fastener (differenent lengths) in the 42mm 84-89 911 rear, which at the same 1,200 psi would exert almost 2,600lbs of force.

Based on these figures, I'd say a 170,000psi 1/4" fastener would be more than suitable to hold a caliper together properly with 33 or 38mm pistons, and 42mm pistons too.