Short story long....
Not to challenge GM's use of TTY technology, can anyone explain
WHY these fasteners are so important--beyond "GM said so"? Many TTY fasteners are used today (LS engines, for example), and aftermarket sources, such as ARP, offer replacement fasteners that are not TTY--ie. they are re-useable. No BS flag, just would like to see this aired and given proper explanation beyond the "don't re-use" directive. If it truly is critical, can someone offer further elaboration?
Another part of brake service that has not been mentioned (so far) in this thread: properly bedded pads/rotors create a transfer film of friction material onto the rotor surface...I'm not talking about a "glaze", in this case. This film often is not compatible with a new set of pads.
The replacement of pads, alone, is only doing half the job, and, in the case of replacing one pad compound/source with a different compound or source, the proper way to do this includes refinishing the rotor (there are several ways to do this) to remove the transfer film of the pads being removed.
Granted, we are discussing "new" cars, many with very few miles, so the normal wear that might be experienced through a pad's life, which will vary with driving style, may be less of an issue than otherwise when doing a "normal" service at, say, 30,000 miles. Still, rotor runout needs to be checked, as well as RTV (
rotor thickness variation)--those things that most often are attributed to WARPED rotors, when in fact it is uneven rotor wear, possibly as a result of rotor runout (a hub out of spec, for example), or an uneven buildup of friction material that has transferred from the pads onto the rotors, especially when the brakes are hot--the automatic transmission only contributes to this, because often it is driving situations where hot brakes and sitting stopped holding the car from moving (still in gear) combine to promote the concentration of heat that can cause excess friction material to transfer onto the rotors. This, in turn, can promote brake shudder/judder as the high spots on the rotors pass through the pads.
In the case of the Brembo front brake system on the SS, I do not know if any of the cars using it (such as CTS-V, Camaro SS, etc) have such a tendency, but it is not uncommon. The Brembo combination may mitigate this by the rotor mass and specific friction compound used, probably more stable at higher temps than typical GM and other OE pads.
The various fixes to provide a fresh surface for new brake pads include:
1. replace rotors
2. turn rotors
3. re-finish rotors - 3M sanding discs, sandpaper & wood block, and my preferred solution,
using a Flex Hone, which, properly used, will provide a non-directional finish to improve new pad bedding-in.
Even if rotors are turned, they need to be sanded or honed to knock down the sharp edges of the cut rotor--a phonographic surface is not conducive to good pad break-in. In addition, rotors need to be cleaned thoroughly after turning, sanding or honing, to remove as much of the residual metal particles from the refinishing process as possible. Oil/scent-free detergent (granular) in warm water to make a sudsy lather, and a clean nylon-bristle scrub brush, will dislodge and float away these metallic contaminants. Follow this with a thorough flush of fresh water, then air-dry the rotors (not with compressed air), is the ideal approach--spray brake cleaner really does not do a good job of removing these metal particles, and if they remain, they can tend to gum-up and clump as the new pads are being bedded on the rotors
While these processes (2 & 3) can be performed on-car, the results will be much better with the rotor(s) removed and mounted on a brake lathe. In all cases, this means removing those pesky TTY caliper mounting bolts, so I understand the DIY approach to just ignore this whole process I'm talking about.
Added perspective: on the 2011 PPV, which has VERY dirty front pads, but great stopping power (using a single piston front caliper, same as V6 Camaro) clamping a 345mm rotor, I found that in 15000 miles, the rotors were worn to half of minimum thickness (total allowed wear before discard)--assuming the wear rate continued at that pace, if the pads lasted to 30K, the rotors would be at or beyond discard thickness. I changed to Camaro-spec OE pads, and the dusting was reduced significantly, but brake feel is noticeably "softer" at initial application compared to the cop-car pads--which also tended to be noisy (squeal).
I have other plans as far as the next brake servicing for this car, but the OE police package pads are obviously quite aggressive--dirty, with high rotor wear rate--and stop like crazy, but I expect the rotors to be able to last beyond 30K if I wait that long, considering the Camaro-spec pads are much more friendly, quiet and produce far less dust. As my wife is primary driver of the car for now, really aggressive pads or gonzo brakes aren't "necessary".
Still, to re-iterate, I went through the entire process addressed above, removing the rotors, honing them, etc, and that also meant removing the TTY bolts (the calipers are floating, not like SS) to get the caliper bracket out of the way to remove the rotors. While I do have the new bolts, I admit, like others have acknowledged, that I did not use them--my recollection at the time was that I did not have a torque wrench with a high-enough setting to install them properly, and I don't have a TTY gauge--TTY specs typically will specify a number PLUS an additional rotation, ie. 140 lb/ft +90 degrees. I'll talk to my favorite dealer tech to get some further insight on this--is it truly critical, is it to sell parts, or is it a protection instituted by (in this case) GM legal beagles, to insulate the company in a court of law?
