The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

Rotor Life, Brake Vibrations - GT350 - New to the Track Life

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

7
0
Exp. Type
HPDE
Exp. Level
Under 3 Years
Virginia
I have a lot of feeback/vibration in the steering wheel when braking and I have a couple of questions regarding rotor life, pad changes, and if you can re-bed the rotors. I was hoping someone could share some knowledge with me. I have tracked my GT350 about 12 or so days now and have a total of about 5,000 miles ont eh rotors and car (but it is three and half years old and sits outside). Last year I was soloed with FAAT (Summit Point) and run my car hard and I am heavy on the brakes as the end of Summit Point Main as I am generally going from 140s down to about 50 in a short distance and run decent lap times. Almost all of my track time is at Summit Point Main, two days on the Shenandoah Circuit (also at Summit Point), and two two days at VIR, one on the full course and one on the grand course. I figured this may help with the questions below.

At the end of first set of OEM pads I was starting to get some serious feedback in the steering wheel under light to moderate braking but were fine under full load. Eventually the brakes were worn out and I was getting the vibration under heavy braking and I swapped out the pads for another set of OEMs. After bedding in the new pads, everything was back to normal for about two track days. Then I took everything off and did a brake clean and flushed all fluids and everything was good for about 3 more sessions (not even a full track day). Now I have about 30-40% pad life left and the vibration are back with a fury.

Sorry for the long story so here are the questions:

1. Should I try to rebed the brakes to see if it scrubs them clean so I can finish out the brake pads or is this not even possible?
2. Should I replace the rotors (I have a fresh set of OEM rotors) and use old brake pads?
3. Should I replace the rotors and install the new Carobtech (XP20) pads I have waiting?
4. Should I replace the pads and use the new Carbotech pads on the old rotors? I am not sure if this will scrub them clean but I don't want to mess up the new pads (if this is possible).

I just want to make sure I don't mess up the new rotors or the new brakes pad by doing something stupid. I was also curious roughly how many track days people are generally getting out of OEM rotors. I appreicate everyone helping a newbie.
 
1,246
1,243
In the V6L
I have a lot of feeback/vibration in the steering wheel when braking and I have a couple of questions regarding rotor life, pad changes, and if you can re-bed the rotors. I was hoping someone could share some knowledge with me. I have tracked my GT350 about 12 or so days now and have a total of about 5,000 miles ont eh rotors and car (but it is three and half years old and sits outside). Last year I was soloed with FAAT (Summit Point) and run my car hard and I am heavy on the brakes as the end of Summit Point Main as I am generally going from 140s down to about 50 in a short distance and run decent lap times. Almost all of my track time is at Summit Point Main, two days on the Shenandoah Circuit (also at Summit Point), and two two days at VIR, one on the full course and one on the grand course. I figured this may help with the questions below.

At the end of first set of OEM pads I was starting to get some serious feedback in the steering wheel under light to moderate braking but were fine under full load. Eventually the brakes were worn out and I was getting the vibration under heavy braking and I swapped out the pads for another set of OEMs. After bedding in the new pads, everything was back to normal for about two track days. Then I took everything off and did a brake clean and flushed all fluids and everything was good for about 3 more sessions (not even a full track day). Now I have about 30-40% pad life left and the vibration are back with a fury.

Sorry for the long story so here are the questions:

1. Should I try to rebed the brakes to see if it scrubs them clean so I can finish out the brake pads or is this not even possible?
2. Should I replace the rotors (I have a fresh set of OEM rotors) and use old brake pads?
3. Should I replace the rotors and install the new Carobtech (XP20) pads I have waiting?
4. Should I replace the pads and use the new Carbotech pads on the old rotors? I am not sure if this will scrub them clean but I don't want to mess up the new pads (if this is possible).

I just want to make sure I don't mess up the new rotors or the new brakes pad by doing something stupid. I was also curious roughly how many track days people are generally getting out of OEM rotors. I appreicate everyone helping a newbie.
It's odd that this is happening - I have a few questions that might help us help you:

What range of coaching have you had? Have you been trained in techniques like trail braking?

Have you had to come to a full stop as you're coming off the track, where you might have sat waiting for something with your foot on the brake?

Do you do a cool-down lap?

Sorry if your skills are way past all this, but the pulsing brake sounds like a pad deposit problem, and that's usually more about technique than it is about the equipment.
 
1,289
1,113
Exp. Type
HPDE
Exp. Level
5-10 Years
Philly Metro Area
For track use, these are done. I run past 50% and then change the pads.
This is not only good advice since you don't want to run out of pad before the end of your day, but also because the thinner pad will allow more transfer of heat to your calipers. This will degrade your dust boots and seals. More importantly, it will increase the probability that you will boil your brake fluid.
 
7
0
Exp. Type
HPDE
Exp. Level
Under 3 Years
Virginia
It's odd that this is happening - I have a few questions that might help us help you:

What range of coaching have you had? Have you been trained in techniques like trail braking?

Have you had to come to a full stop as you're coming off the track, where you might have sat waiting for something with your foot on the brake?

Do you do a cool-down lap?

Sorry if your skills are way past all this, but the pulsing brake sounds like a pad deposit problem, and that's usually more about technique than it is about the equipment.
Sorry for the delayed response I was super busy at work and wanted to swap the parts out before reporting back.

The only coaching I have had is instructors with typical HPDE groups in our area. I would say my level of formal instruction is fairly low in my opinion if though the check rides I do with various groups always bump me to solo. I do trail brake in different parts of my home track (where appropriate).

I always do the cool down lap a speed where I never have to touch the brakes, I never use the ebrake or brakes in the paddock. It is ingrained in my brain to never touch the brake even on the grid.

I pulled the rotors and installed the new brakes but have not attempted to bed them in since the weather this weekend has been terrible in VA. I have added some pics and as you see the back side of the old rotors and the pads and you will see some massive deposits that were probably causing the vibrations. I measured the thickness with a digital caliber and there is plenty of life left based on the read out but not sure if the rotors should just be tossed. My car does sit outside so you see the massive rust deposits from the last few weeks since the car has moved.

Any insight on how to avoid this or what do is welcomed (even if it is a personal attack on me as to what not to do).

IMG_5015.JPEG

IMG_5016.JPEG

IMG_5017.JPEG

IMG_5018.JPEG

IMG_5019.JPEG

IMG_5020.JPEG

IMG_5021.JPEG
 
7
0
Exp. Type
HPDE
Exp. Level
Under 3 Years
Virginia
If you have the 20’s and new rotors, put them on. Bed IAW the manufacturer. See what happens.
You could clean the old rotors and try again with the old pads, but why?
I have another set of the nondrilled rotors but figured I would use these up first. Unfortunately the nondrilled rotors were not a thing when I purchased these.
 
7
0
Exp. Type
HPDE
Exp. Level
Under 3 Years
Virginia
I was cleaning up my shed this morning and was breaking down the rotor boxes and noticed that the front rotors had different part numbers for right versus left. :rolleyes:

I definitely didn’t look at that when installing. I assumed they were the same. I can’t tell from the old rotors if the part numbers are stamped on the rotor. I am now wondering if they were installed on the proper sides and if it makes a difference.

I guess I have a 50/50 chance. Is there any easy way to tell?

This is the drivers side.

9425BA34-57A4-4C2D-BFC3-C13C7FCCE18A.jpeg
 

TMSBOSS

Spending my pension on car parts and track fees.
7,530
5,247
Exp. Type
HPDE
Exp. Level
10-20 Years
Illinois
I believe you will find the umbers of the center hub. Wheel will need to be removed. There is a very good chance the rotors are directional in that the venting internal to the disc it self works open one direction only. Think of it as a fan made to spin one direction to pull the heat out of the rotor. Put it on the other side and the purpose is defeated. That may be your problem.
Pull a wheel and have a look see.
 
7
0
Exp. Type
HPDE
Exp. Level
Under 3 Years
Virginia
For anyone reading this it does make a difference which side the rotors go on. I couldn’t find any markings on the rotor itself but I did find a reference of how the vanes should look between the front and back of the rotors when the rotor is mounted.

The good news is I am learning new stuff everyday and I have gotten really efficient at changing the pads out. The bad news I installed them on the wrong side.
 

TMSBOSS

Spending my pension on car parts and track fees.
7,530
5,247
Exp. Type
HPDE
Exp. Level
10-20 Years
Illinois
Nope, your glass is half full.

You figured out the problem!!

So, everyone who works on their own car and has never made a mistake, speak up.....so we know you ain’t telling the truth.

Good job in running this to ground. It was easier for me when I changed front rotors. I bought a set but they came in separately marked boxes. I took a marker and wrote “Right” on the wear surface of the right and “Left” on the wear surface of the left rotor. Even I would have had a hard time messing the that up. Lol.

Now switch the rotors and get on track and have some fun.
 

TMO Supporting Vendors

Top