Vibration Under Braking

Morning Everyone,

Looking for some guidance here. I have a 2010 LGT with 110k.

About 6 months ago I replaced the pads and rotors on all four corners. StopTech pads and Raybestos rotors. Installation went fine, bedded the pads, no issues.

A few days later I started to notice a vibration in the steering wheel under light braking at freeway speeds. Pulled all the wheels and reinstalled (just to be sure). No improvement, so I ordered new front rotors. Installed them, took it for a drive, seemed much better. So I called it good

2-3 weeks later the issue is back, vibration under light braking at highway speeds. I regreased the front caliper pins, and checked to make sure the front rotors felt seated. Even pulled and cleaned one that was a little rocky to be sure.

No improvement.

I don't really want to redo the pads and rotors if it isn't going to fix the problem, so I wanted to check with everyone to see if I am missing something. I haven't been looking at the rears much because the vibration is shown most in the steering wheel. Could it still be the rears?

Other causes? Or should I just replace everything again?

Thanks for the help!

I cleaned the hub with a wire brush and brake cleaner prior to installation. Should I have done something more in depth?

For bed in - I followed the procedure recommended by StopTech

I am having the tires rotated and balanced today, so we will see what happens.

How do I check for bearing play? I had to replace a caliper bracket during the rotorr change due to a stripped thread

How are your tires and wheel/tire balance?

I was going to suggest this... if your tires are badly worn (like mine were just a few weeks ago) and/or your alignment is out you may get vibration under braking (as I did). I don't think it's a wheel balance issue, as that would appear at all times, not just under braking. Once I got new tires and a proper alignment, my braking shaking went away.

when I do brakes I replace all rubber parts on the caliper pins... and I have never had an issue.

I also use anti seize on the hub so I don't have to beat the crap out of my car to get the old rotors off.

Tire balancing did not correct the problem. Did not see abnormal wear when I replaced the old pads.

I will check to bearings when I get back on Monday. If that feels good, the plan is to replace the front rotors, pads, and guide pins

Have you checked your lower control arm bushings and inner and outer tie rods? I had car that would shake like a warped rotor and it turned out to be bad tensions struts. Now we don't have those but the physics would still apply. I wouldn't throw parts at it, If you have a magnetic base and dial indicator you can check the run out of the rotor. You will need to torque the rotor in place to simulate a wheel being bolted to it.

If your pads are ceramic, I have read where they can add material (copper) to the rotor surface and can simulate a warp rotor scenario . A repeated bedding process can sometimes remove said build up, or an on the car disc lathe, which would also true the rotor(s) to your car.

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I also use anti seize on the hub so I don't have to beat the crap out of my car to get the old rotors off.

If the anti seize doesn't do the trick get a pair of M8-1.25 X 25 bolts, they will remove your rotors very nicely when installed into those extra two holes in the rotor.

Morning everyone. Thanks for the helpful tips. I have access to a dial indicator and a magnetic base, so I will measure the rotors to see if they are warped. I assume that I need to use the lug nuts to tighten up the rotors, and then mount the magnetic base on the caliper and measure.

Let me know if there is a better way.

Morning everyone. Thanks for the helpful tips. I have access to a dial indicator and a magnetic base, so I will measure the rotors to see if they are warped. I assume that I need to use the lug nuts to tighten up the rotors, and then mount the magnetic base on the caliper and measure.

 

Let me know if there is a better way.

This is the way I have done it. Lug nuts may not be long enough so either use a stack of washers or get regular nuts and washers (I like a washer between the nut and rotor.) Pre-load the dial indicator and check a few spots on the rotor. As you turn the rotor you can hear and feel the wheel bearings too. While its in the air, check it all out. Pull the pads and look for shinny wear spots on the metal, this would mean the pad in moving and may be "chattering".

If you do find a warped rotor you could find a shop and have it trued to your cars with an on car brake lathe.

An update from tonight: borrowed a dial indicator and a magnetic base to check the rotor run out. Jacked up the car, used two nuts to clamp the rotors down, and checked each rotor in the middle and towards each side. Took a little while to get a good zeroing technique, but in the end all rotors were within +/-0.002". No some occasional black lines on the rotors that looked like caliper pad. Also felt the wheels for bearing wear, no evidence at any corner.

Super confused now... Any thoughts?

Tire wear is good. They checked all four during the rotation/balancing.

I pulled on the tie rods, no play

Control arm bushings? Subframe bushings? Toe link?

Did you check for play in all of these areas? You may need to jack up the rear and support it on jack stands to get the load off so you can see if any of them are showing wear.

Control arm bushings? Subframe bushings? Toe link?

 

 

Did you check for play in all of these areas? You may need to jack up the rear and support it on jack stands to get the load off so you can see if any of them are showing wear.

I will try this on Saturday, thanks.