qwertymess

Bumping this back up.

After 2 track weekends
Road America
Autobahn Country Club South Course
20 Heat Cycles Total
BBK: Essex Endurance Front kit
Tires: Hoosier R6
Pads: Carbotech XP24

This is only happening on both fronts. More on the inboard side then the outboard pad.

Pictures incoming

qwertymess

Is this normal:

Olitho

I have come to the conclusion the taper is from the spindle flexing.

I have gone the newer C6 ZR1 spindles and this problem is gone.

qwertymess

Makes sense. I still have the stock spindles with SFK hubs

qwertymess

Did you do the rears as well or just the front?
Im running the stock C5 Z06 Front calipers in the rear.

lbk16

Oli, do you have part numbers for the ZR1 spindles? (front)

Bluefire

I did a track day yesterday. This was my first time out on my new AP Racing Endurance Kit (CP5060 caliper). They are tremendously better than stock. These 6-piston calipers also have varying sized pistons in them. They gradually get bigger in diameter with respect to direction of rotor rotation. This is supposed to minimize pad taper. I haven't had time to look at them yet. I'm now curious on how much the taper was reduced.

Adam@Amp'dAutosport.com

Try flipping your inner and outer pads for more even wear.

Olitho

I did not change thre rears as I have not had the problem on that end of the car.

Olitho

We can thank RX-Ben for identifying the part numbers in this post:

Part number is 88965637 and 88965638.
$160ish per new.

https://www.corvetteforum.com/forums...post1586457759

JeremyGSU

I have the old Hardbar AP T1 kit with SKF hubs, LG spindle ducts, ducting, on the stock C5 knuckles with stock rear calipers running XP20/XP10 pads.

My pads also taper just like that. I have since upgraded to the C6 knuckles but have not done a track day since to see if they still taper.

I just switch the pads around inbetween track events and they typically wear pretty evenly.

Bill Dearborn

The Wilwood SL6 calipers I had on my C5Z would taper the pads as well. They had different sized pistons that got larger in the direction of rotation but still tapered the pads.

One thing I did notice is even though the pads tapered I did not get the long pedal that happened when pads tapered in the stock floating caliper.

To reduce the tapering and to decrease wear I would flip the pads from side to side and I would use pad shims as they wore down. This worked well.

The W6A/W4A calipers I have on my C6Z taper the pads somewhat but they seem to cause more wear on the inboard pad than the outboard pad. Others have told me that is common on most opposed piston calipers but I didn't notice it on the SL6s.

Bill

redtopz

+1.

naschmitz

Another thing the makes my pads taper in the CP8350s -- Hawk brake pads! There is so much paint on the backing plate of a Hawk pad that it cooks off and builds up on the pistons. My upper pistons were much harder to move in and out of the bores than the lower pistons and this caused considerable taper.

Once I cleaned the pistons and replaced the seals, the taper got a lot better.

flink

Stupid paint. It makes a mess and interferes with taking thickness measurements. When prepping new pads I remove all the paint with paint stripper. I also scuff the mold release off the faces with an orbital sander so the pads start working sooner.

troyguitar

So has anyone tried running just the stronger spindles with stock C5/C6 calipers? If that is all it takes to eliminate the taper issue I'd like to do that first, then maybe eventually get better calipers.

UstaB-GS549

Isn't this part of the fact that the leading edge of the pad sees less heat than the trailing edge?

I get a little taper on my pads but just wrote it off to temperature differential.

Olitho

It depends upon how the pads are tapering. I don't remember how stock pads taper at this point. As I vaguely recall there was equal taper on each side with the trailing edge the thinnest. This is due to the increased heat I presume and stock calipers are not built like race calipers to account for the heat/pressure differentials.

Race pads when run with high grip tires on high speed high grip tracks produce a sort of parallelogram style taper from the whole caliper torqueing under the load.

At first I was not sure if this was caused by a hub flex, spindle flex or caliper mount or some other cause. It all went away with stiffer spindles so draw your own conclusion.

CP Thunder

Jim.....just reread this thread and that is the funniest stuff I have read in here in a long time....!!!

Olitho

Hah! I just saw that post by Tway. I don't read his posts when he can't race. He just gets plain ornery...