Brake Pulling == Ti Shields?

[widebody911]

I'm right smack dab in the middle of rebuilding my front 930 calipers. I just got the left side done and a new rotor installed, and while my lovely assistant was helping bleed the brakes, I noticed something: the pads were not able to move side-to-side! I was having a dragging problem, and assumed it was the calipers, and although the problem came on suddenly, the dragging problem with my old stock calipers had started fairly suddenly, and a rebuild fixed those. So why weren't the pads able to slide side-to-side? Because the inside slot of the Ti shield, where the pad retainer spring goes, is just a wee bit higher than the pad, and catches on the spring. trapping it in place. The force of the piston is enough to push it one way, but then the spring won't let it go back.

I haven't tested this yet, as I'm in the middle of the brake job, but with the limited testing I did by hand, my hypothesis seems valid. When my lovely assistant pushes the brakes and the Ti shields are on, I cannot move the pads back by hand, and the rotor drags. When she applies the brakes without the shields, I can move them back by hand, and even when I don't, the brakes only drag an infintessimal amount.

Comments? Challenges? Suggestions? I tried mangling the spring slightly, but no luck yet in finding a config that doesn't rub on the shield.

[island911]

It is beyond me why the "shield" is the full size of the pad.
If I were to design those, the shape would be just enough to cover the piston contact area. the rest of it just adds weight and cost.
. . . and potential for interference

[Jim Sims]

Originally posted by island911
It is beyond me why the "shield" is the full size of the pad.
If I were to design those, the shape would be just enough to cover the piston contact area. the rest of it just adds weight and cost.
. . . and potential for interference

Besides conduction there is radiative heat transport too. Perhaps the increased area of the shield (beyond the piston contact area) acts as a shroud to keep the pads from "seeing any of the caliper" and radiating heat to it. I agree of course that the Ti shield shouldn't interfere with the piston/pad movement.

Cheers, Jim

[widebody911]

Well, the Ti shields are off the hook - almost. The pulling is still there, although the dragging is gone. I like the idea of the TI shields, so I'm going to figure out some way to deepen that channel and then re-install them.

[island911]

Originally posted by Jim Sims
Besides conduction there is radiative heat transport too. Perhaps the increased area of the shield (beyond the piston contact area) acts as a shroud to keep the pads from "seeing any of the caliper" and radiating heat to it. I agree of course that the Ti shield shouldn't interfere with the piston/pad movement.

Could be. But do you really believe there is any testing of this product to support the need for the extra "shielding"?¹
Some race-engineers have been working on ceramic "buttons" (as they're called) with the same intent of insulating the caliper pistons.
That these are "buttons", leads me to believe radiant heat off the back of the pad, into that large finned block of aluminum (caliper) is not going to cause problems in the fluid.

1)Speaking of testing; Thom. .. What do you think your doing testing all these products? First the eRam, now this.
Don't you know, you're to buy & install with blind faith? . .. and tell all yur friends "Ya, cool huh. . .wurks real good too"
Kidding, of course. Nothing gets improved if no one is paying attention. Your product testing Rocks!

[Efrain68912]

Thom used the phrase "lovely assistant". What's up with that?