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.

[BillJ]

Waiting on all 4 of my -6 calipers to arrive from PMB in a couple.days myself. You should ask Eric he will know right away. His expertise on the hardware for these is outstanding.

[gandalf_025]

This is a factory 6 rear that was rebuilt by PMB
and as far as I know they reused the original
hardware..

[gandalf_025]

This is a 914-6 gt rear caliper
rebuilt by PMB also. They supplied
the hardware for these.

[gandalf_025]

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

[914Sixer]

You normally used the hardware that came out of the donor
911 caliper to install spacers

[mepstein]

You normally used the hardware that came out of the donor
911 caliper to install spacers

(IMG:style_emoticons/default/agree.gif)
I sent PMB some 914-6 calipers and rear M calipers and they sent me back 914-6GT calipers.
The non vented M calipers can be used on the back of a 912.

[BillJ]

You normally used the hardware that came out of the donor
911 caliper to install spacers

(IMG:style_emoticons/default/agree.gif)
I sent PMB some 914-6 calipers and rear M calipers and they sent me back 914-6GT calipers.
The non vented M calipers can be used on the back of a 912.

If you want to send those over to me since it was an error that would be fine (IMG:style_emoticons/default/drunk.gif)

[Eric_Shea]

Factory 914 six calipers had no spacers and used the “button” head M7x50 and 55 Ribe fasteners. (Caliper on the left)

Factory 914-6/GT “prototype” calipers used both the spacers and the fasteners from the new long wheelbase 911 S with vented rotors on the rear. Those fasteners were M7x60 and 65 “cap” head Ribe. (Caliper in the middle) This early spacer was machined not cast and they have rounded edges with machining marks on them. Remember, this was all new for ATE. Everything was solid rotors up to this point. They didn’t have a 60 or 65mm fastener on all previous calipers. These one off (41 off) prototypes used the 911 stuff all around. These cap head fasteners do not look like A-Caliper fasteners. They look like M7 versions of “M-Caliper” fasteners. M-Calipers used a “cap” head M8 fastener. A-Caliper fasteners are actually M9 versions of our 914-6 M7 button head fastener. M7 fasteners have Ribe R5 bit heads. A-Calipers, again, use an M9 version of our “button” head with a Ribe R6 bit head. Probably one of the more delicate fasteners to get apart because of the smaller bit head and larger M9x1 thread engagement. In contrast, the M8 M-Caliper fasteners use the M8 cap head with a much more robust Ribe R8 bit head. Much easier to remove without damaging.

The last caliper is a Ferrari 308 caliper. (Bleeder positioned under the handbrake arm). (Caliper on the right) These came from the factory with spacers installed. These would be a cast, more form fit spacer as identified by the casting line running around the spacers. By this time ATE spec’d the proper M7 x60 and 65 button head Ribe fasteners to use on these calipers as this was a production unit.

Hope that helps.

[Eric_Shea]

The non vented M calipers can be used on the back of a 912.

And the 69 solid rotor 911’s and a 76 912E.

[Eric_Shea]

This is a factory 6 rear that was rebuilt by PMB
and as far as I know they reused the original
hardware..

This is a perfect example of a factory 6 caliper with the M7 button (crowned) head fasteners.

[Eric_Shea]

This is a 914-6 gt rear caliper
rebuilt by PMB also. They supplied
the hardware for these.

This is a perfect example of a factory GT caliper. Low casting number. Shouldered “cap” head vintage 911 fasteners were used. If you know what you’re looking for you can see the rounded edges on the spacers as they come to the pad cavity.

[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)

[Eric_Shea]

Perfect example of early 911 rounded spacers vs later Ferrari form fit spacers.

[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.

[BillJ]

I told you Eric would know. Just chuckling in amazement at the depth of knowledge and understanding. Good stuff.

[gandalf_025]

You recall correctly Eric..
I bought these a few years ago at the Hershey Swap Meet
just as shown, they were sitting in a box with other calipers..
They were sent to you immediately and made
into the set above..


[/quote]

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)
[/quote]

[Superhawk996]

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

Setting aside the question of fastener tensile strength and suitability for application.

If they didn't have the tools and/or couldn't be bothered to trim the fasteners to the proper length, I have to wonder what else they couldn't be bothered to do properly when working on brakes. (IMG:style_emoticons/default/sheeplove.gif)

I would never trust my life to workmanship like that. (IMG:style_emoticons/default/slap.gif)

[Eric_Shea]

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

Setting aside the question of fastener tensile strength and suitability for application.

If they didn't have the tools and/or couldn't be bothered to trim the fasteners to the proper length, I have to wonder what else they couldn't be bothered to do properly when working on brakes. (IMG:style_emoticons/default/sheeplove.gif)

I would never trust my life to workmanship like that. (IMG:style_emoticons/default/slap.gif)

Those were a hot mess. Duly noted though that Home Depot fasteners are OK to use on brake calipers. (IMG:style_emoticons/default/biggrin.gif)

[zoomCat]

Thanks for all the feedback, Eric in particular for the encyclopedic knowledge of the particulars. It looks like the 60 and 65mm button head fasteners on the Ferrari were never used on the 914/6 GTs, so I don't need to chase down a set of those.
I wouldn't hold up the build for that non-functional distinction, but it's amazing how you can become invested in some of the smallest details when you disassemble a car to every nut and bolt.
Now I just have to get the very rusty bleeders out of my donor M calipers. I suspect that the piston bores are not salvageable anyway.