95jersey

Here is a little background...

I just got a new set of Wilwood W6A's for my C6Z. I installed them last month and they have been working great. I put on spindal ducts recently as well, and as a result had to shim the caliper mount to compensate for the width of the material the spinda duct created where the rotor lays on the hub (the Wilwoods have very little room and fit very snug with the rotor, compared to OEM). I went to home depot and could only find a grade 8 washer that provide about 1.5mm of offset (1mm is what I really needed, but it is what it is). It was enough to clear the rotor and free up movement.

Next Steps...

I have a track event coming up this weekend and the other day installed my H pads and proceeded to bed them in by doing the usual brake 5 times then let them cool down and so on. They worked fine, no problems. I did notice in the right front caliper, with the pistons fully compressed, the pad barely fit into the caliper and needed some help with some light taps of a hammer. Apparently the 1.5mm offset made the pad fitment tight on one side (inner side)...meaning without any brake pedal pressure, the pad fits tight against the rotor (I didn't have this problem with the street pads as they wore down slightly before I installed the spindal ducts that it wasn't a problem). I figure it won't take but a few passes before I wear off the 1/2mm to losen them back up again.

The issue...

I went and bed the pad in according to Wilwood specs, and they worked fine. Then last night (2 days later), I went to go break in my new Hoosiers and give them a heat cycle. I didn't really use the brakes during this whole procedure, but when I did get on the brakes to give them a feel, they would grab real hard and "stick". Meaning after I left off the brake, it would continue to apply pressure and brake the car (so much that applying throttle barely moved the car forward. They within 2 seconds it would release. It did this a few times which concerned me.

I then let the car rest for a hour and went back out and tried it again. This time it did not do it at all no matter how hard I stopped or how many times I tried.

Very weird...I tried to provide as much background as possible whether it be relavant or not. I am worried I am going to travel 300 miles for my next track event to have this problem and turn around and come home...

Any ideas??

mousecatcher

Two things.

1) the stick/release sounds about right. Because your pads were always in contact with the rotor (with pressure), you cannot possibly bed the pads correctly. Bedding requires a heating and cooling cycle. Without a proper pad release, proper cooling cannot occur. If it's ok now, I wouldn't worry about it.

2) What spindle ducts did you use? The LGM requires removal of the factory shim/bracket as (obviously) if you leave it in place you are now offsetting the rotor. I may not understand the problem correctly though, since my belief is that a washer/shim at the caliper mount will offset the caliper in the wrong direction. Leaving the factory wiring bracket/shim in place with the LGM spindle duct will offset the rotor towards the outside, whereas adding a washer/shim to the caliper mount will offset the caliper to the inside -- ie making the problem worse. I might misremember how that stuff goes together, or maybe the Wilwoods don't have a radial mount as I would expect.

0Vector Vette

I would say that your washer is too large and the pad is wedged between the caliper and rotor. In essence, acting like a brake. Once you ran the car, you have most likely worn down a little pad material and now have a little clearance. I would suggest not using the washer but get an arbor spacer. They are ground flat and can be bought in differant thickness. We use a 1.0" OD x .047" thick with a 5/8" hole for the same application. Differant caliper but is used to space out the caliper adapter plate. You can get them at McMaster Carr or if you have trouble finding them, give me a call and I can send you some.

Robert Finlayson
Performance AFX Motorsports
815-254-2631

95jersey

I bought them from ECS, so I have no idea what brand they are. They also installed them while I had the car there getting other work done.

95jersey

Let me be clear, I am less worried about the problem of the clearence at the moment, I can fix that later and get by with what I have for now.

I am more concerned with the brakes applying force and stopping the car without me pushing them in...how is this possible? When I released the pedal, it continued to push the brakes and bring the car to a stop even though my foot was off the pedal. The engine could barely push the car while this was happening. This would be an issue if I am applying the brakes at 120mph.

DOUG @ ECS

Matt, do you know which pad is rubbing the rotor? Inner or outter? Give the shop a call and we can discuss it in length.

95jersey

Inner right side only.

DOUG @ ECS

Mike offered to drop off the correct size spacers for you tonight since he lives close to you. Give the shop a call so he can get directions to your house.

mousecatcher

post a picture

mousecatcher

Well, initially you had to use some force to even get the pad in, and you know there is/was a rotor-to-caliper clearance problem, so it should be clear that the piston is bottomed out with new pads.

Then when you tried to bed the pads what you actually did was leave a bad spot or 2 on the rotor due to the pad not releasing. This caused your subsequent sticking of the brakes.

Just a theory of course.

John Shiels

Dragging they over heat and won't release.

95jersey

This is my thought as well. That maybe they were too tight on the rotor and heated up when I was driving around the clover and
wouldn't release off the rotor. It also pulled to the right, so that confirms where the problem is...

I figured taking a quick spin and hitting the brakes would take off the 1/2mm I need to provide the clearance. But here is the strange part, when I bed them in the day before (AGGRESSIVELY hitting the pads to the point of smelling burning brakes) it did not stick. They worked great. It was after I drove around the clover for 20 minutes (without braking), that it happened.

DOUG @ ECS

As the caliper heats up, they expand. It needs the proper spacer and the problem will be solved permanently.

We have them here ready to go, Mike will come down and install them for you, just give him some directions! (he called earlier and left a message)

96CollectorSport

Here's my theory, the reason that the car didn't pull or drag when you bedded in the pads was because you didn't have a transfer layer on the rotors. The transfer layer is needed between the pad and rotor to work effectively, that's why you need to bed in pads and rotors. So without the transfer layer you wouldn't have the kind of bite you would have after the layer is there.
When you took the car out for the second trip the transfer layer was there and then that pad was dragging. After it wore away a little more material the problem went away.
BTW you may have not wore away as much material as you thought while bedding in, it was just tranfered to the rotor face.
Again that's just my theory.
Joel

mashinter

There is a small hole in the master cylinder between the piston bore and the reservoir called a compensating port. It is uncovered with the piston fully retracted and gets covered when the piton moves into the bore. If this is plugged, when the fluid gets hot and expands (with your foot off the brake), the fluid applies the brakes instead of flowing back into the reservoir. Of course, as the brakes heat the fluid, the brakes apply harder.

95jersey

I spoke to Mike last night and appreciate you guys going out of you way to help!!

DOUG @ ECS

Anytime Matt,
I am going to send the spacers to you regardless so you do not have any issue's at Mid Ohio. Have fun out there, I'm jealous!