geolab

I agree....
To me, it depends what usage you have of the vehicle, and how you perceive things.
What I mean is that, the way I drive the highway phobic in the avatar, I prefer to change parts to new and FORGET IT.
If I was to mend, adapt or alternate... I would be thinking of the part whilst driving ALL THE TIME.
And I do very long journeys, thus I cannot imagine myself going for example to Greece (2000 miles), and thinking Caliper..Caliper..Caliper..

Peter R.

Normally no one takes notice of my mumblings, and rightfully so. This time, however, I suggest you do, and heed this advice :

"DON'T F*CK WITH YOUR BRAKE SYSTEM"

Replace the damaged part.

Peter R.

Garth S

Were it my car, I would install a timecert ( or keycert) with confidence: the repair is generally stronger than the original, and the timecert is swaged in. That cold rolled 'cert' joint is kept to form by the caliper bolt, if there is any doubt.
Use of blue loctite is another precaution against the bolt loosening from the insert, if vibration was a concern ( or cross drilling the two heads for a loop of safety wire).

In Johns case, it is the lower bolt of a front mounted caliper that is in question .... so in the very worst case of failure of that fastner under braking, would not the caliper rotate on the upper bolt as a pivot .... pulling the caliper inward to the hub as braking continued?
Mind you, that doesn't work in reverse, so ... Jonh, watch your back up speeds please

Peter R.

I would be careful about taking advice from a bloke that drives a 'nougat brown' 928 as well

Peter R.

John D.

Hmmmm...... Nice thing about being on Rennlist for so long, is that I make a lot of neat contacts with folks involved with Porsche racing and race team mechanics... When I read Chris' post (the Chris with the scary avatar ) and many others of you - it got me to thinking and talking to a few folks.. Here is what was explained to me - so, I'll open it up for conversation (DISCLAIMER - I AM NOT AN ENGINEER, so I understood about 25% of what was being said.. )

The 993 front caliper attachment design was the first commercial production Porsche to use the front attachment system. It was based on the same mechanical theory that the bolts needed to be sheer resistant rather than "hold" the caliper from moving on it's rotational axis. And, these are seated so the bolt won't loosen (that's why Porsche recommends new bolts that are "unstretched" from a previous application) The bolts job is to simply seat (and then he went on into some rotational mass, caliper stuff) - the caliper - NOT to take the effect of the braking. It's designed that way..

OK - I sort of get it so far..!

Next on the question of the inserts, replacements and other ideas...

Obviously - he was a advocate of replacing the parts to factory form. When asked about inserts - he brought up two issues - which I'll throw out... First, the piece is cast metal, and softer than the bolt (8.8). With the heat of the braking - you have now a third metal ( 1) bolt, 2) cast metal in the upright; and 3) the insert..) which all have various expansion characteristics.. Hmmm - good point..? Whether they would "hold" under constant expansion/contraction (heat related) would be an unknown - and *could* (maybe/might??) allow the bolt to loosen.. Second is the "contact" area of the length of the threads - as an "insert" is shorter than the tapped threads in the cast upright (but the cast piece is "softer", so the thread count is important (or something??)..

So - we got off into other areas.. We discussed other applications. I learned that the CGT has the SAME design of the 993 - BUT - uses a M12x1.5 high alloy NUT as the bolt "lock"?? He chuckled and asked me why I didn't upgrade into CGT brakes.. I chucked back and told him I'd play the lottery and let him know...

So - I'm guessing in order of options....

First choice - replace the upright.. Second choice, look at and understand the CGT mount system (uses a M12x1.5 bolt/nut) and see if it could be applied to the 993? Third - inserts.....

Just my rambles for the day....

John D.

Alfie

Hi John....... I think you should simplify all this engineering mumbo jumbo, with a solution less expensive than CGT brakes. Just get Big Reds, and call it a day.

Happy to help

John D.

I'm thinking a 964 Turbo - with Big Reds already installed... Got one available at IRA Porsche???



(I'm only half kidding - guess which half??

Best to you Alfie!!!



John

cobalt

I have a set of big reds with adapters if your so inclined. Although I would go with the 964 turbo myself.

Alfie

See, problem solved. You can thank me later


HAHAHAHAHAHAHAHAHAHA you're all done...

grmnxtc

Your "friends" are all offering the wrong advice......

You need to Freeze that bolt back in place...

All the best.

Bill Verburg

I'm sure that you and John are just kidding around here, but just in case.

Big Reds bolt on to the same failed upright as the stock caliper, a slightly bigger caliper solves nothing.

Just as I'm sure that Cobalt realizes that 993s don't employ caliper adaptors

But i'm often at a loss as to when folks are kidding

cobalt

Me too and sometimes my sense of humor is missed as well. I figured you would pick up on that one, However I figured the big evil grin was a dead giveaway.

Garth S

Good point ! In anticipation of this seal of disapproval, that car was sold to make room for a blue 993 .... , although I may be guilty as charged for other reasons.

Back to the calipers, I find a certain inconsistency between being bent out of shape regarding the integrity of a thread repair .... and the view that bolting on adapters that both offset caliper centering and ear mount centers (to add larger calipers) is OK.

John D.

You found me a 964 Turbo?? EXCELLENT!!! THANK YOU!!

BTW - what will you give me for a trade-in on my 993?? Being that it's been "slightly enhanced" from when I purchased it for $14,000 (in other words - it actually "runs".. Stopping?? Well - stopping isn't to great right now - but, don't let that sway your opinion of the turn in value... )

Also - Clive.... Remember - I invented "Frozen Rotors" (they were rusted in place when I bought my 993 - hence - "frozen"..).. To freeze the caliper back into place should be easy as well - I just need to figure out how to reverse the process??? (OH - Alfie - don't let this effect my trade-in value, OK??? )

And Bill - about being serious... Last time I was serious is when I got married to Jen. I was seriously sure that she had a great sense of humor (so married me.. ). I learned my sense of humor from her... It was either "fall in line" or "fall out"...

Thanks to all of you for your somewhat "helpful" advice...

As for me?? I've got sawzall in hand - and about to cut through the drivers floorboard - with a pair of steel-heeled boots on order... I'll show you guys what "man braking" is all about....



John D.

Alfie

Last time I went out to dinner with John and Jen, we talked seriously about Haiti, seriously about rennlist for about 1 minute, and joked about the service at dinner for the rest of the night. We may have also joked about dogs, tires, and the fact that life doesn't get cheaper when they hang out with me. With that in mind, and in the way in which I "helped" him buy his 993, my suggesting he buy a new set of unnecessary brakes that won't fix his problem is absolute sarcasm. (Or is it???????????)