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The rotors on my 2014 Impreza Premium are getting pretty well warped and at 42K miles it will probably need pads soon, so I'd like to replace pads all around and front rotors (possibly rears if there is still pedal vibration after doing the fronts).

 

I've never done brakes on any Subaru newer than our old 2005 Impreza- is there anything about these later models that's different, or anything to watch out for? Everything regarding pads and rotors was quite straightforward on the 2005 as well as my 1997/ 1998 Legacy's- just checking to see if anything had changed by 2014 that I should watch out for.

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Only thing i can think of.

On the rear calipers. See if the parking brake is built in to the caliper, or it still has the traditional drum in hat style.

 

If it's for the brake in the caliper, you need to turn the piston while pushing it back.

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rear rotors last the life of the vehicle, they are pointless to replace. Unless that car was in some weird incident, it’s not the rear rotors.

 

if you can identify which front is bad, you can have it turned or just replace one rotor. There’s good reasons for a shop/mechanic working with largely unfamiliar customers to do it, but for DIY there’s no need to confine yourself to one-size-fits-all approaches. Though I get that you’re unlikely to do that...

 

So - why are rotors bad at 40k? I’d check points that frequently compromise pads and rotors:

 

Make sure all pad clips are straight, no bends or waves, no build up or corrosion (seems doubtful so new). I usually replace these clips at least once by 150k because they’re cheap and actually prevent issues due to points I mentioned and have seen happen.

 

Check slide pin bushing for proper operation. If it’s swollen or tight replace it, I throw them away as they’re pointless and cause failures.

 

Clean and grease slide pins with SilGjyde or other high quality lube, generic brake grease sucks here and is actually detrimental to the pin bushings.

 

Since I’ve been doing these three things consistently I’ve never had to replace a rotor. Before that I was replacing one every year or two.

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I've seen other cars warp by 40K miles and I never ride the brakes, or use them excessively (I use them to come to a stop and that's about it).

 

I agree it's most likely the front ones only since they do the majority of the work and build up more heat. I'll definitely check the slide pins for free movement and check everything else over.

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If there's more than about 3mm left on the front pads and there's no sticking parts - I'd try left foot dragging the brakes for a coupla blocks while maintaining 30-40 mph. Then, drive 1/2 mile or more WITHOUT STOPPING to cool-down the brakes.  If it helps, try it again or maybe investigate a more aggressive bedding-in procedure. If it gets worse, you may need a new rotor.

 

'warped' rotors are almost never 'potato-chipped' or non-parallel. They can develop uneven pad deposits which create a pulsing feeling. But, if the rotor's metal has been severely overheated in one spot, the alloy may not be cut-down enough to prevent the problem from coming back quickly.

 

good info about it here; http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

 

http://www.stoptech.com/technical-support/technical-white-papers/bed-in-theory-definitions-and-procedures/brake-pad-bed-in

Edited by 1 Lucky Texan

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So LT you’ve seen riding the brakes help with vibrations? That’s nifty and I’ll try it next time I see it though mine don’t seem to ever do it any more.

 

In general brakes are same but electronic parking brake equipped vehicles have some differences so take note of those if you have that.

 

Otherwise most people would just install new pads and rotors and be done with it. If you do that I’d still check the things I mentioned.

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hate to see folks jump to dumping good rotors if not needed. Of course, the brake system is fiddly enough that it's always good to inspect it. Things must be able to move evenly and center themselves under hydraulic force, but also release and float when not used.

I have cured brake pulsing in 3 cars by left-foot dragging. Daughter's car took a second, more aggressive attempt. I did the wife's 03 once. Worked fine. If I'm not hard-driving on my WRX often enough, it will get a little uneven feeling and the technique brings it back to smooth for me. Could be the StopTech pads are different enough that they need aggressive use more regularly. That seems to be everyone's theory about them and my limited experience confirms it. (man, after I do the technique on my WRX, it really bites and modulates smoothly!)

It's easy to try and safe - IF you select your road carefully, and make sure to do the cool-down run with no stops. You don't want to clamp hot pads onto a hot rotor. That's how 90% of the uneven pad material transfer issues start. An emergency-type stop followed by sitting at a light or RR crossing w'ever with hot pads in one spot on the rotor.   If you MUST stop of course, do w'ever you need to to be safe. If possible, use the hand brake to hold the car at a light. (works on Subarus with the little drum/hat parking brake shoes - won't work if the p-brake use the regular pads)

 

On my daughter's Impala, I could SEE the outline of a pad on the rotor through the wheels!

I have a low-use highway service road near where I live that I can easily cruise down on a weekend morning to check for activity/cops. Then come back through and do any brake bedding-in or other runs I might need to do. Again, doesn't really take long and, if there's no sign of improvement or the problem gets worse, you probably need new rotors. I have read that under extreme condistions of overheating, the rotor alloy under the pad can alter to 'cementite' and the change goes far enough under the surface that even a lathe may not remove all of it. Modern brake rotors may only have a millimeter you can take off each side. I'd replace it instead of cutting it deeper than the minimum thickness - or maybe even getting 'close'.

Edited by 1 Lucky Texan
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stevo - did you get rotors?

Yes I did buy new rotors and pads- but thinking of trying the left foot dragging procedure before I pull the old ones off- I guess it couldn't hurt at this point

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