TKOGTO

I have been getting what I think is a very large amount of pad taper with Wilwood W6A calipers and was wondering what the experience of others has been. The taper occurs in both directions but less so radially (~3mm). However the taper is about twice as much top to bottom on the inner pads (~7mm difference) after a day and half at Watkins Glen. I can swap the inner left pad with the inner right as the taper top to bottom is opposite.

I never saw taper of this amount with OEM calipers. Any thoughts would be appreciated.

Bad Karma

I have seen pad taper on mine; definitely axial wear, I didn't notice any radial wear (however, I did not mic the pads). This is from when I was trying to have a dual duty pad, running BP20s. I have since switched to full race pads - H Race compound and the wear looks even. I was definitely overworking the BP20 pads and putting them above their temperature range, with the H pads I have more brake than tire and the wear looks even.

brkntrxn

What pads are you running?

I have two race seasons on my W6 and W4 combo with no issues and no complaints. NASA ST2/3 car. I have been running Carbotech RP2 and XP20s as well as Wilwood As (only one set).

0Todd TCE

A number of factor here could contribute.

1. Calipers mounted on the wrong side. The upper piston must be the larger of the sets.
2. Poor pad selection leading to premature wear relative to temps.
3. Bad wheel bearings.

Heard of more than one bearing issue here so I might look there if the others are all in order.

truth.b

Why would a bad wheel bearing cause a pad to tapper?

ZedO6

The excess bearing lateral movement inherent in a failing wheel bearing would change the center alignment of the rotor within the caliper. The normally perpendicular contact between the brake pads and friction surface of the rotor would not be in this situation. This would probably result in top to bottom brake pad taper

Think of the rotor as having negative camber while the caliper is set at zero.

0Todd TCE

Thanks. Better to be heard from another owner in a way. Not an uncommon complaint/issue from what I read. I confess I'm not a Corvette owner so I can't speak first hand.

TKOGTO

Wilwood H pads

1. Can this be determined w/o removing the caliper, i.e., position of the external pipes or Wilwood logo (read top to bottom or vice versa)?
2. H pads
3. SKF's - checked when diagnosing warped rotor. They are good.

moespeeds

I ran Wilwood H pads on SL6 calipers for 3 seasons, and got bad pad taper. New SKF hubs and poly all around, and I went to sphericals the 3rd season with no improvement. I ran every rotor under the sun from NAPA stuff to Cryo and 2 piece Spec 37 Wilwoods. I'm a nut about maintenance so I'm sure everything was tight. I would simply flip the pads after every weekend, and I used spacers.

Bill Dearborn

I get a little pad taper. To combat it I just keep track of which caliper the pads were used in and put them in the caliper on the opposite side of the car for the next event. That pretty much evens out the taper and also counteracts the tendency for the inside pad to wear more than the outside pad. I don't really worry about it since it doesn't affect brake pedal travel like similar taper would do in the C5 floating calipers.

Bill

moespeeds

I thought I read somewhere that a spindle upgrade solves the taper issue. Was it ZR1 spindles? I can't remember.

ErnieN85

all late model replacement uprights are stronger (thicker)

TKOGTO

One with a lot, one with a little: a case of "your mileage my vary" I guess.

Flipping the pads after each day is not a problem as I usually swap to street pads in between events. The minor concern is something is not right (easy fix, just need to identify it). The bigger concern is if it is the inherent flex of the caliper, I should have paid up and went with StopTech or AP Racing. I don't like upgrades that perform worse (albeit in one aspect only) than the OEMs they replace.

Bad Karma

I should also note the street pads I over heated were also on factory bearings before the switch to SKFs.

brkntrxn

I can only attest to my satisfactory experience with the Wilwoods. Sprint races, endurance races, and national championship races. All with podium results, so I am not exactly a slow driver. A couple of lap records when the fast guys stayed away. ABS at most every corner, braking hard enough to push fluid out of the master cylinder, etc.

But, like you are seeing, some people have no issues and others have lots of issues. I think it comes down to braking style. When we all raced PTA on stock OEM C5 Z06 calipers, a LOT of my fellow racers experienced some to a lot of pad taper. I experienced little to some. Again, I think it comes down to braking style. If a driver is a habitual "stomp the pedal and throw out the anchor at the last minute" driver, then the initial hit of the coldish pad/rotor could "scrub" off material before heating up to slow the car through proper friction. I am not saying this is you, but saying what I have seen. One good friend of mine ALWAYS had braking issues versus me even though our cars were virtually identical in PTA and later in ST2/3 and we had very similar lap times. The data and video showed he was a harder "braker" than me. I have seen him have radial and lateral pad taper on OEM calipers and StopTechs.

ZedO6

Oli may check in with his story, but in short he broke the caliper mounts off one of the original 2002 C5Z knuckles (also called spindles) during a race last year. It was surmised this failure was due to the original part flexing, which was never intended to deal with the side loads of a fixed caliper. As noted by others, the later parts, especially the ZR1 knuckles are significantly beefed up to reduce this flexing from the side loads presented by a fixed caliper.

FWIW, I just started running the Wilwood 14.25 Aero 6 calipers and have seen no pad taper issues (Wilwood H). Like Kevin notes, some of this can be due to differences in brake application.

TKOGTO

Thanks Kevin. It does feel a bit better to hear of taper with the StopTechs - a little schadenfreude goes a long way. More importantly, I will test different initial brake applications over the next couple of events to see how much of an impact dropping the anchor vs. not has on the taper. I have taken a good chunk out of my lap times over the past year braking later, harder and getting back to power earlier so if that costs more than normal taper - so be it - I see that as a small price to pay.

Bill Dearborn

Caliper flex probably wouldn't cause the type of taper you are describing. Caliper flex usually causes radial tapering where the inside of the pad wears more than the outside of the pad wears. I haven't noticed any of that with my W6As but if you notice Wilwood as changed the caliper over to the Aerotech design which has a strong non removable reinforcing bridge across the top. They may have done that to reduce an inherent tendency toward radial taper in the open top caliper.

The other thing I know from many years of using Wilwood calipers is it is best to keep the pistons from pushing far out of their bores. They tend to **** sideways in the bores and not move as freely when extended way out which could lead to pad tapering across the pad length. I use spacers to keep them inside the bores. The spacers also reduce heat transfer into the brake fluid as the pads wear.

Bill

0Todd TCE

Caliper flex under high pressure on the FSL6 I can see, but far more limited on the W6A and new Aero6 parts. Everybody screamed they waned a bridge...now the Aero6 has one and its huge. And as pointed out the flex leads more to simple radial taper - front to back if you will across the pad.

Very interesting thoughts on the brake application btw.

brkntrxn

Explain?