Bahnzii

UPS decided to delay my 2-day shipment from LG (Cobalt XR2 pads!!) to tomorrow, so now I am stuck with my stock pads.

The front left has more wear on the inside than the outside, the front right has less wear.

I was going to swap side to side and inside to outside, but I also wondered if I could swap in some of my rear pads, there is very little wear on them.

All the pads wear unevenly, they taper from top to bottom (thin to think). Is that normal??

These are OEM pads, so I assume the friction material and padlet shape is the exact same front and rear (for cost savings).

My track day is early tomorrow morning, so I have the calipers off right now and am waiting for any tips everyone can give me

rustyguns

SWAP EM! I DO ALL THE TIME! JUST MAKE SURE U BED THEM IN REAL GOOD

HAVE FUN


FYI REARS AND FRONTS ARE NOT THE SAME BUT YOU CAN SWAP SIDE TO SIDE, INSIDE AND OUT ETC ON THE SAME AXLE

wtknght1

Switch to Carbotechs!!!!!!!!

NewFoundPower

I do that too, seems to be pretty common practice.

JDIllon

????? I used to swap fronts and rears all of the time, I think??? Before going to BBK. What is the difference???? JD

Adam@Amp'dAutosport.com

BEZ06

I believe Bahnzii has a C6 Z06, and the padlets are exactly the same size front and rear (unless you get the one piece aftermarket pads) and the OE padlets are the same compound front and rear.

So....he can swap them around all he wants.

Bahnzii, you don't need to be overly concerned about your pads. From what I saw in the pictures, you've got plenty of pad to have a great day at the track tomorrow. If you've flushed with Motul I think you've taken care of what I would consider to be the main concern. If you're on OE tires the stock pads will work well for you.

Bob

rustyguns

thought it was a c5

Bahnzii

Thanks everyone for the replies.

I did some quick research and checked part numbers and determined the padlets were the same all around and just swapped them so I had the thickest on the front left, then front right and then the rest on the rear.

The day was pretty good at Thunderhill, except by my fourth session I had warped a rotor and abs was starting to kick in even when I was on comp mode

So I called it a day, so I would have something to drive home and not tow home

I think I am harder on the brakes than I think, so my decision to by a 4 wheel BBK earlier this week, seems even more justified now.

That and I need to get my quantum ducting mounted up before my next event, didn't have time before yesterday's event.

BEZ06

I doubt you have a warped rotor. If you have a pulsating brake pedal, it's most likely due to uneven buildup of pad material or pad imprinting. Take a look at this Stoptech bulletin:

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

When ABS starts activating it's because you're pushing the brake pedal too hard - you need to modulate brake pressure to keep max braking just below the point where ABS activates.

AH doesn't do anything to change when ABS activates. ABS is set to release the brakes as the wheel speed sensors detect that the brakes are just locking up and the tires are losing traction and beginning to skid. The mode of AH doesn't do anything to change when ABS activates, so it doesn't matter if you're in Comp mode, AH completely off, or AH full on - ABS will activate at the same time.

Cooling to your front rotors is a very good idea. I just used allanlaw's method that you can see in his picture below:




You can get spindle ducts that will direct the air onto the rotor better, but Allan's method works very well for me as a weekend track guy that only does HPDEs and not w2w racing.

Also, I find the stock C6 Z06 brake calipers to be an outstanding caliper for my needs. When running on Hoosier R6 tires with Hawk DTC-70 or Carbotech XP12 pads on DBA 4000 rotors, the stock brake calipers bring me down from very high speeds with great confidence.

Bob

Poor-sha

Yup, get some scotch-brite pads and brakekleen. Hose down the rotors and scrub with the scotch-brite pads. This is a bit easier to get both sides of the rotor if you pull the rotors off the car. Then make sure you re-bed your pads in.

I had a similar issue earlier this year and that fixed it right up (thanks to LG for the tip).

Bahnzii

Hmmmm, so I really thought at the start of the day it might be brake pad build up, but by session 3 the vibration was so bad the steering wheel was shaking as I reached half pedal, I could also see the side mirrors vibrate, not a little but a lot

I have read the Stoptech article before (its a good read) , but would I really get that much vibration from just brake pad deposits?

I was having a hard time modulating the brakes, as even when I backed down to about 75% I was still getting crazy vibrations and I had reach deep into the pedal to get some friction which I am sure is where the abs kicked in.

How well does the plastic venting work with the heat from the calipers??
It looks like a damn good cheap way for venting!!

Back to the rotors, I would really like to mic the rotors and see what the runout is like to see if they really are warped.

Do places like Kragen's rent anything like that??
Keep in mind, I have never mic'd a rotor but it can't be that hard to do (I like to do all my own work if I can )

Sidney004

Be sure to inspect the rotors for cracks, severe vibration can easily result from a crack extending to the edge. Pad build up due to glazed and overheated stock pads is extremely thin yet can lead to intense vibration. Visual inspection of the surface of the pads and rotors could give you a big clue. I have never seen a warped rotor either.

BEZ06

with Sidney004

Take a look and see if there are some cracks, maybe on the back side where you can't see them easily without removing the rotors.

Below is a picture of a cracked rotor. I went out on the track with it, but quickly came back in after getting a "thump-thump-thump" when braking. I didn't get a vibration like you, but yours sounds like it was a pretty heavy vibration and could be from a crack.




A crack like that can be dangerous - parts of the pad could come chunking off and pieces might get jammed. If a wheel were to lock up at speed it wouldn't be pretty!

Good luck finding the problem.

Bob

rustyguns

yeah with stock pads u can get alot of build up. did you make sure you did a long cool down lap after every session and not hit the brakes during the cool down lap?

if you came in and parked with hot calipers the stock pads can melt to the calipers leaving a big patch on the caliper, giving a horrid vibration

did you set the parking brake?



but i have cracked a bunch of rotors too

FYI almost impossible to warp a rotor

Bahnzii

I have made it a habit from my first track day to do a cool down lap depending on what turn they show the checkered flag. Then I always do a few laps from one end to the other of the parking lot with no braking and then I park the car in gear and never set the parking brake

I tend to believe that warping rotors would be very difficult unless someone over-torqued the lug nuts, but I check my torque ratings (100 lb/ft) after every session.

Taking everything off tonight to see what I can determine to be the problem. I will post pics of the rotors once I get them off.

Bahnzii

Well all four rotors are off and there are no cracks.

I don't have a run out tool (yet) so I will check for run out later this week just for fun but I now believe everyone that warping one of these rotors, especially the fronts!! These things are think, especially the hats.

Now for a pic, it seems to my untrained eye that I have some brake pad smear along the outer edge of the front rotors and some bigger smears on the inside of the front left rotor. So I assume at this point, what I felt was indeed pad buildup and possibly cementite.

Now the question, short of turning the rotors, is there anything I can do to get them clean again?

Should I just call it a day with these rotors and get some DBA's??

Brakecleaner and a scotchbrite pad??



It might be hard to see in the photo but this is the inside of the left front rotor that has 2 definite dark areas that imho have to be pad buildup.

Any and all thoughts welcome

flink

Using race pads on the street is usually a good way to scrape the faces clean.

Stoptech recommend using Hawk blues as rotor cleaners and I know of a couple of
guys who have used them for that with success.

But I've found that the Hawk DTC pads do a pretty good job also, and I expect your new
XR2's will do the same thing. So you could pop them on and go for a putter around the
suburbs, see how the rotors look after that.

otoh, as you already have the rotors off the car, giving them a whizz with a flap wheel might
be easier.

rustyguns

whatsa flap wheel?

Bahnzii

I might try the flap wheel idea...

What grit would you use? I don't want to take off a lot of material just enough to remove the pad smears