The inner portion of the caliper is also the part bolted to the knuckle assembly, which acts as a brace on that side making it much more rigid than the outside which is solely supported by whatever material is bridging the span over the rotor. Under pressure the caliper is going to act like a C clamp that is overtorqued and try to spread. Since the inside is essentially fixed due to the mounting bolts and extra bracing from them, it leaves the outside free(er) to deflect. The most deflection will occur at the point of highest leverage (inner portion of the rotor). As you move across the face of the caliper towards the outside edge of the rotor, it becomes a much more rigid structure, and deflects less.

Hope this makes sense, might get on Cad and do a free body diagram.

 

makes sense, but I'm leaning toward the flex being in the rotor and the hub, I've seen wear uneven from front to rear of the pad, explain that one.

 

That is why there are staggered pistons sizes in calipers. Also, the pad tries to "dig in" more upfront as you basically have a center of stiffness that the pad tries to rotate around.

 

...the open side of the C-Clamp is toward the inner part of the rotor.

 

Thus the reason there is less pressure on the inside area and the pad tapers towards the top. The top of the pad is the thinnest as it gets the most load applied to it.

Here is a crappy MSPaint diagram...



The inside pad stay flat as there is much less flex on this side (hub and bearing flex would lead to inside pad taper). The outside pad gets tapered due to the bridge flexing and putting the pistons on an angle to the rotor.

 

That's a good MS cross section

Thing is though, caliper connects back at front and rear (large section too).

Jim,

Can you measure both top and bottom (as picture is) for base to top of pad material.

Question might be is the caliper flexing or rotor/hub under load.

 

I know I posted up earlier that I've seen this on my Evo...

But had more of it this weekend at Road America. Didn't know how hard this track was on brakes, including T5 which for me was 147mph down to 45mph and downhill! I ran 2 sets of pads that were < 50% to begin with so that's an issue there.

I think both fronts had the outside pad wear a little more at the top vs the bottom. Not a crazy amount more, but a little. I last replaced all the seals at the beginning of the track season and do it yearly (I've used more than 1 set over the course of the car's life btw). My .02

 

Sorry, not exactly sure what you are saying here?


Something worth possibly looking at too is pad taper front to rear. If this is caliper flex, I'd also expect to see additional wear ant the lead and trailing edges as the bridge will provide more support on the edges. This would leave the center of the pad front to rear as the thickest part of the pad. Although, if you are getting leading edge wear (pretty typical on many calipers) it may make it difficult to see any such wear pattern.

 

Thinking on how the caliper deforms under stresses. They are connected front and rear. For that flex to happen; it would have to also stretch the thickest parts of the caliper.

 

Do you go full lock on the racetrack?

 

Maybe we are thinking differently here, but the front to rear connection at the hub has nothing to do with the pad taper we are talking about?

Caliper flex that we are interested in would be the bridge flexing. It is definitely NOT the thickest part of the caliper?

 

and for sure getting around in the pits and on the way to the track.

 

While it's not ideal to have reduced turning radius, the fact is you still have 60-70% of full lock running the duct along the fender liner. This is with 9.5" wide wheels. I know if I removed the fender liner and made some small tweaks, I could get that to 90% or more. There's always tradeoffs, and a in this case (at least for me) a slight inconvenience in the paddock and streets is worth the increased cooling from the bigger ducts.

 

Sorry if this is dumb, but has anybody thought of cutting a 2" (or whatever size ducting you're using) in the fender well and running it through to the bumper? I don't know anything about track regulations but you could use something similar to this on the bumper to route a new inlet instead of stealing from the oil cooler. This would be the most "direct" route and more efficient.

Just a thought, they never hurt.

 

Has anyone ever put brake air inlets in their hood? Obviously not for the faint of heart..