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Silver big brake calipers, are they real/original? & what to service?
Hi, I have recently purchased a set of silver big brake calipers.
I knew they were somewhat tired, as in the offered pictures they already appeared 'hurt' by brake fluid or something like that.
After receiving them and giving them an initial "quick-clean" I noticed that on multiple areas the paint came off quite easily.
That triggered me into studying more closely and I noticed that on certain areas the fit of the 2x pieces of the calipers was not aligned (by quite a bit).
Anybody that has experience with these, such that you would think these are original or not?
Secondly, if they would be original, what kind of service would be recommended? Why do people change pistons on these?
Thanks, Pete
OP, they don't look tired to me. Dust boots on the pistons look virtually brand new. Someone repainted these silver at some point. Paint color and condition do not affect braking performance.
"BIg Silvers" They look identical to my big reds. They are the real deal.
I remember these being available somewhere in silver. I just forget when and why.
993 Turbo brakes were available in red, silver and yellow from the factory. The rears look like all pistons are the same size from the photos, 28mm, so they are turbo rears
993 Turbo brakes were available in red, silver and yellow from the factory. The rears look like all pistons are the same size from the photos, 28mm, so they are turbo rears
Thanks, indeed I also believe the rear pistons have the same diameter, but will check when back at the garage :-)
The square profile o-ring has distorted or lost its elasticity resulting in it no longer performing the function of retracting the caliper pistons once one take their foot off the brakes
Corrosion or other physical problems are interfering with the pistons moving smoothly during the braking cycle
At one time most every mechanic serviced calipers. The move to dedicated rebuilders was driven by servicing entity economics.
Although a rebuilder will use abrasives to clean the exterior of a caliper, in some cases paint it or apply a dichromate finish none of these cosmetic services influences performance. If the piston and the internal cavities are within good dimensional tolerances, the bleeder screw & hose port threads are in good shape and the internal cavities are carefully inspected and cleaned adding new O-rings and seals and pressing thing together is all that is needed. This is not a complex process.
The square profile o-ring has distorted or lost its elasticity resulting in it no longer performing the function of retracting the caliper pistons once one take their foot off the brakes
Corrosion or other physical problems are interfering with the pistons moving smoothly during the braking cycle
At one time most every mechanic serviced calipers. The move to dedicated rebuilders was driven by servicing entity economics.
Although a rebuilder will use abrasives to clean the exterior of a caliper, in some cases paint it or apply a dichromate finish none of these cosmetic services influences performance. If the piston and the internal cavities are within good dimensional tolerances, the bleeder screw & hose port threads are in good shape and the internal cavities are carefully inspected and cleaned adding new O-rings and seals and pressing thing together is all that is needed. This is not a complex process.
Thanks,I fully agree, was just not sure about the piston, since I understand that the "official" Porsche Service Kit comes with a piston?
It is indeed my intention to clean them, and change the seals. The pistons I have checked, and move freely, but nicely firm (with effort, can press them in by hand) It would make more sense to me to first do the seals and then repaint, or is there a good reason to first paint and then do the seals?
Thanks,I fully agree, was just not sure about the piston, since I understand that the "official" Porsche Service Kit comes with a piston?
It is indeed my intention to clean them, and change the seals. The pistons I have checked, and move freely, but nicely firm (with effort, can press them in by hand) It would make more sense to me to first do the seals and then repaint, or is there a good reason to first paint and then do the seals?
cheers, Pete
If things are masked off properly before or after shouldn't matter.
03-20-2018, 02:18 PM
Silver big brake calipers, are they real/original? & what to service?
