Author Topic: New Pads, New Discs, NEW VIBRATION!! (Read 3831 times)

dude8383 · « **on:** April 21, 2007, 02:03:35 AM »

This makes no sense...

I installed brand new rotors and pads today.

Brembo Blanks, and Axxis Ultimates.

So after breaking in the pads (3 hard stops from 80-5mph) the car developed a vibration. Its possible the vibration was there before the breaking in period.

My friend broke em in for me.

Anyways, This vibration comes from the front left wheel, whenever I brake, it feels like something is wobbling loose.

Oh to add, when I brake the car doesn't brake smoothly...kinda like the caliper squeezing and letting go of the disc every 2 seconds...a pulsating feel.

It is possible to warp rotors during the break in period? Is it possible that there might be some air in the system after pushing the caliper pistons back in to their housings?

I've torqued down everything on the left...

What do you guys think?

Hope that wasn't too confusing!

bmwman91 · « **Reply #1 on:** April 21, 2007, 03:32:18 AM »

Odd.

Brembo's are not known for warping, especially blank ones. Does the wobble only happen under braking? Have you double checked the caliper bolts and lug nuts? Do a good visual inspection of everything when you have a chance. Perhaps something is not seated properly? Let us know!

dude8383 · « **Reply #2 on:** April 21, 2007, 09:02:01 AM »

Quote from: bmwman91;24179

Odd.

Brembo's are not known for warping, especially blank ones. Does the wobble only happen under braking? Have you double checked the caliper bolts and lug nuts? Do a good visual inspection of everything when you have a chance. Perhaps something is not seated properly? Let us know!

This only happens under braking!

I've checked the left side, and will check again today just to be absolutely sure nothing is out of place.

I'll keep you guys posted.

nomad · « **Reply #3 on:** April 21, 2007, 09:43:39 AM »

How old are control arms, bushings and tierods?
I know that using an impact wrench on the wheel lugs is a problem on other marques. Did you torque wrench the wheel lugs in the star pattern?

christophbmw · « **Reply #4 on:** April 21, 2007, 12:50:45 PM »

three hard stops from 80mph on new pads:eek: , i dont know the break in period for brembo stuff, but on normal pads that will creat hot (or hard) spots and will create a vibration. sounds to me like you toasted your pads.

asubimmer · « **Reply #5 on:** April 21, 2007, 01:22:22 PM »

even if he glazed the pads he could sand em a tad to bring them back

Febi Guibo · « **Reply #6 on:** April 21, 2007, 02:04:21 PM »

my vote: installer error!

D. Clay · « **Reply #7 on:** April 21, 2007, 02:46:04 PM »

Have someone push on the pedal just enough to engage the pads and rotate the wheel. A warped rotor will drag and then spin free as it's rotated. We used that method to set the front/rear brake balance on racing cars with a pedal system that had a bias adjustment. Push just enough to lock up the front and the rears to just slightly drag.

nickmpower · « **Reply #8 on:** April 21, 2007, 03:03:59 PM »

Quote from: D. Clay;24194

Have someone push on the pedal just enough to engage the pads and rotate the wheel. A warped rotor will drag and then spin free as it's rotated. We used that method to set the front/rear brake balance on racing cars with a pedal system that had a bias adjustment. Push just enough to lock up the front and the rears to just slightly drag.

thats dumb as the fronts will have much more weight pushing the tires into the ground

Febi Guibo · « **Reply #9 on:** April 21, 2007, 04:31:34 PM »

Quote from: nickmpower;24195

thats dumb as the fronts will have much more weight pushing the tires into the ground

uh, threshold braking...

D. Clay · « **Reply #10 on:** April 21, 2007, 08:29:45 PM »

By "pushing the tires into the ground" I assume you are talking about weight transfer. The brake system is designed to be in some sort of relationship to this effect by using different size rotors, tires and wheels, calipers, master cylinders, and the bias adjustment in the pedal system itself. All I can say is that I've done it for years and have seen it done that way by lots of other people.
It will also reveal a warped rotor if you put just enough pressure on the pedal to make the pads drag.

dude8383 · « **Reply #11 on:** April 21, 2007, 10:26:21 PM »

You know, I actually noticed that.

Today:

I noticed that the outer control arm ball joints were absolutely shot.

Going to replace those tomorrow, and see what happens.

I will check on the brake disc as well.

Thanks guys!

Quote from: D. Clay;24194

Have someone push on the pedal just enough to engage the pads and rotate the wheel. A warped rotor will drag and then spin free as it's rotated. We used that method to set the front/rear brake balance on racing cars with a pedal system that had a bias adjustment. Push just enough to lock up the front and the rears to just slightly drag.

nomad · « **Reply #12 on:** April 22, 2007, 04:03:53 PM »

Quote from: D. Clay;24194

Have someone push on the pedal just enough to engage the pads and rotate the wheel. A warped rotor will drag and then spin free as it's rotated. We used that method to set the front/rear brake balance on racing cars with a pedal system that had a bias adjustment. Push just enough to lock up the front and the rears to just slightly drag.

This is true. It may not work 100% of the time but a warped rotor is either warped or has high/low spots on it. If it is a good enough warp you may feel it when very slowly braking at real low speed. the brakes will feel on, then off.

I used to turn the rotors at an autoshop I worked at in high school. You can see clearly when you throw it up on the lathe if it is warped.

dude8383 · « **Reply #13 on:** April 22, 2007, 08:10:09 PM »

Quote from: nomad;24236

This is true. It may not work 100% of the time but a warped rotor is either warped or has high/low spots on it. If it is a good enough warp you may feel it when very slowly braking at real low speed. the brakes will feel on, then off.

I used to turn the rotors at an autoshop I worked at in high school. You can see clearly when you throw it up on the lathe if it is warped.

Yeh I'm going to have the disc checked!

Thanks