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Username Post: 08 Malibu brake vibration keeps returning        (Topic#356166)
mhamilton 
Senior Member
Posts: 183
mhamilton
Loc: North Carolina
Reg: 10-15-04
04-26-19 05:27 AM - Post#2765061    

Hi,

I have a 2008 Malibu (classic) that I use as my commuter car. Owned this car since around 2010 and had no issues with brakes until recently. Here's what's happened so far:

1. October 2017 at 107k miles it developed a really bad vibration when braking, the whole front end would shake violently. At that mileage I figured it was due for new brakes so I replaced the OEM rotors and pads with Raybestos. Brakes were nice and smooth for a few months.

2. October 2018 the brake vibration had gotten just as bad again. I checked everything up front: found I had a loose outer tie rod, replaced that and had an alignment, same vibration. Found that one of my caliper pins was sticking so thought "ah ha" that must be it. Cleaned pins well, replaced all the brake hardware, rubber pieces on pins, lubed with Sylgard. Installed new coated rotors from NAPA, kept same pads. Also flushed the brake fluid. Nice smooth brakes until now.

3. 5 months later the vibration is returning.

I can't believe that 3 rotors and 2 sets of pads all develop the same issue on this car. There must be something I've missed. Struts and mounts are new. Rotating tires have no effect. Car tracks well and I don't feel anything loose in the front end. I must be overlooking something obvious on a simple brake job



Edited by Michael Hamilton on 04-26-19 05:36 AM. Reason for edit: No reason given.

 




Shepherd 
Frequent Contributor
Posts: 1756

Loc: Lake George, NY
Reg: 11-11-15
04-26-19 06:44 PM - Post#2765121    
    In response to mhamilton

Have you confirmed the rotors have excessive runout? Did you thoroughly clean the rotor mounting surface on the hubs? No excess play in the wheel bearings?



Edited by Shepherd on 04-26-19 06:45 PM. Reason for edit: No reason given.

 
mhamilton 
Senior Member
Posts: 183
mhamilton
Loc: North Carolina
Reg: 10-15-04
04-30-19 07:28 AM - Post#2765374    
    In response to Shepherd

I've checked the bearings for any play, nothing is loose. I did clean the hubs thoroughly, although there was very little rust.

I did try to check the runout with a dial indicator on the last set of rotors. I didn't measure anything appreciable, but I was having issues with the mount staying steady.

Are you thinking pad deposits are the culprit?





 
Shepherd 
Frequent Contributor
Posts: 1756

Loc: Lake George, NY
Reg: 11-11-15
04-30-19 12:29 PM - Post#2765393    
    In response to mhamilton

Could be, but to really diagnose this you need to confirm .003 or less runout.



 
junkman104 
Frequent Contributor
Posts: 1364
junkman104
Age: 60
Loc: Murphy N.C.
Reg: 01-25-14
04-30-19 05:49 PM - Post#2765419    
    In response to Shepherd

Caliper slides not lubed and moving freely and brake hoses failing internally are another thing to check. Pads that have excessive drag cause high heat temps.



 
mhamilton 
Senior Member
Posts: 183
mhamilton
Loc: North Carolina
Reg: 10-15-04
06-24-19 01:18 PM - Post#2769165    
    In response to Shepherd

Sorry for the delay posting back... I finally ordered a new dial indicator holder, one of the flexible type with the visegrip to clamp on. I'm hoping to confirm the runout in the next week or so. The brake vibration has only gotten worse since I last posted.

Found some interesting info. I watched this video on YouTube, apparently the pulsation from rotor runout only occurs once brake material has accumulated unevenly. https://www.youtube.com/watch?v=t_IZzyQcBPA
I probably have had runout all along (say in the wheel hub) but every time I put new rotors it would be fine for 4-5 months until the friction material built up enough to cause the pedal pulse again. This explains my symptoms...

How much runout is acceptable at the hub flange?



 
Shepherd 
Frequent Contributor
Posts: 1756

Loc: Lake George, NY
Reg: 11-11-15
06-26-19 05:16 AM - Post#2769276    
    In response to mhamilton

.003.



 
mhamilton 
Senior Member
Posts: 183
mhamilton
Loc: North Carolina
Reg: 10-15-04
07-04-19 05:59 AM - Post#2769906    
    In response to Shepherd

I measured the total runout. 0.0015" LF, 0.002" RF. These are repeatable measurements, made 1/2" in from the outside edge.

The caliper pins all move freely and smoothly. Pads slide easily in the bracket. I re-checked the suspension--other than a very minor play in the RF inner tie rod, there's nothing I can find wrong there. Lower control arms and ball joints are tight.

I've attached pics of the front rotors. These have only been on the car for 5,000 miles. What are your thoughts on the grooving? I can run my finger nail over and it doesn't catch, but they're visibly apparent. No signs of overheating in the pads.

At this point the only thing I can think to do is have the rotors cut and try a different brand of pads. (the current rotors and pads are Napa/Raybestos).








Edited by mhamilton on 07-04-19 06:02 AM. Reason for edit: No reason given.

 




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