2008 Chevy Malibu "incurable" brake vibration

billr

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#16
OK, that is what I use for pads. Still, trying something else may be useful. In the pictures it looks like the left one is scored pretty bad. Is that true? What do the back sides look like? If you have calipers that read down to .001", measure the thickness in several places.
 
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#17
The back is about the same as the front. If I run my finger nail across the rotor I don't catch on any score lines, but if I run my finger tip I can feel the surface is uneven. I can actually feel small divets from the center to outer edge. The rear brakes do not have this, and are perfectly smooth. As are the rotors on my other vehicle.

I think I'll order new pads, get these rotors turned, and start over. I'll measure the hub faces when I get those off. If the hub is not out of spec, and the rotors are still at 1.5 and 2.0 thou, do you think I should just give them a go with new pads and see? Or get some of those shims to get the runout closer to zero?
 

billr

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#18
My opinion? That small bit of run-out of the rotor isn't the problem. I certainly wouldn't shim between the hub and rotor. If you do replace/re-surface the rotors, do some careful measurements of run-out and thickness; then compare to what you have when it starts acting up.

Another "Hail Mary" play: replace both brake hoses, in case they are acting as check-valves and trapping fluid pressure and making the brakes drag all the time
 
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#19
Good point. Caliper sticking was one of the thoughts I had after the 2nd set of brakes went bad. That's when I got out the IR gun and started checking temps.

There is anything else I can check to verify calipers aren't sticking? I'm not seeing any chalking of the pads. When I took the calipers off immediately after driving I didn't find the rotors dragging (the calipers slid right off without having to pry them).
 
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#20
As always when the gang here searches the collective brain cells and no consensuses I look at TSB;s - getting real detailed (anal) did you check the rotor lateral runout - seeing the spec had me say wtf thats a tight tolerance .002.
 

billr

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#21
Did I read correctly, at one point you replaced the rotors but left the old pads in and that cured it for a while? That seems to accuse only the rotors.

As tedious as it sounds, I would try getting repeatable results; putting on new/good rotors to confirm it is fixed, then putting back on the "bad" rotors and confirming the problem instantly returned. Do this several times. Worse yet, I would do this on one side at a time...
 
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#22
As always when the gang here searches the collective brain cells and no consensuses I look at TSB;s - getting real detailed (anal) did you check the rotor lateral runout - seeing the spec had me say wtf thats a tight tolerance .002.
The spec is 0.002" on Total runout? I was going by a spec of 0.003", measured max 0.002"

Did I read correctly, at one point you replaced the rotors but left the old pads in and that cured it for a while? That seems to accuse only the rotors.
Vibration started with OE pads/rotors. Replaced pads and rotors, 4-5 months the vibration came back. The 2nd time I replaced the rotors only. I used the "best" rotors the store sold. The vibration went away for 4-5 months. This is where I'm at now.
 
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#23
Wanted to post an update. This weekend finally had time to get the rotors turned, and put on brand new pads. This time went with PowerStop so I could avoid any variety of Raybestos pads.

Not sure what to make of the rotors when I took them off. They were slightly blue tinged. Would be interested in thoughts on the "before" pictures. These have a total of 8k miles on them.

Shop turned them no problem. Caliper pins are still free and smooth. Measured total runout on the rotors after machining, I have 0 on the left side, and only 1.5 thou on the right side. That's down from the measurements made previously by at least 1 thou. Also found my RH inner tie rod is loose, so going to replace that. I replaced both outer tie rods in Oct 2018 when I started down this rabbit hole, the inner was not bad at that time. Not sure if that just failed from old age or if the excessive vibration killed it.

I did the recommended break-in procedure from the pad manuf, so only time will tell if the vibration returns. May trade the car in before then...

before1.jpg

before.jpg

after.jpg
 

nickb2

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#25
Ok, late to game, but an inner tie rod will accentuate.

The above pic shows before and after rotor. From first pic, they are blue. Metal only goes that color when it cooks.
 

nickb2

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#26
Also, on this car, turning rotors at this point is a waste of time, they will warp in no time.

Had a cop car in the the other day, front end would go nut. AWD ford interceptor. Brakes were done a few months ago, heavy bastard brakes, it was a 15-04 number, so the car has been in service since 2015.

Once dial gauge on rotors, not more than than the measurement you got. But under heavy load, with a faulty inner tie rod loose, front end was always going nuts no matter what the cop said.


So I went and test drive the car with a co worker. Cold, car was fine, hot, all hell goes. Sometimes, rotors warp under high stress, come back to natural state. Obviously, from the blue pics, those rotors cooked. :eek: My avice, stop turning the rotors, buy new ones, replace inner tie rod, should go back to normal.

That was my $.02
 

billr

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#28
Those rotors don't look all that "blued" to me. Do I see a difference in the before/after pix? Sure, but I see the same color difference on the center (bolt-circle) part of the rotors that did not get resurfaced.
 
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#29
These were coated rotors, so the bolt-hole portion has a powder coat on it giving it the gray appearance. I was mostly concerned about the center of the pad area, which looked slightly blue, but that may just be dark and not blue. And I know, normally I wouldn't waste my time turning rotors, but I just paid >$100 for these two fronts and I wasn't ready to toss them if the problem was going to come right back.

Have the new inner tie rod on order.

The rear brakes were also replaced recently, so those should be good to go.

Having driven a few miles on the new front pads/rotors, there's a difference I can feel. The brakes definitely work but they are not nearly as grabby as the previous setup. I'm thinking the Raybestos pads were way too aggressive. So far I have a nice wear pattern, not the horrible scoring like the old rotors showed.
 
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