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I've been coming home from work (~25 mins, highway) with a on/off hot rim on the rear drivers side. Car is a 2009 VW Rabbit. It has that signature burnt smell and the rim is very hot to the touch.

Related issues/maintenance:

  • Bad bearing, replaced 2 years ago (October) w/ MOOG bearing ass.
  • New pads, rotors last year

Related information

  • Wub wub wub sound similar to a bad bearing at generally all speeds, but is the worst at about 55 mph. This however does not get better or worse by shifting weight to one side or the other.
  • Some high pitched squeeking at low speed, but only occasionally, making it very difficult to diagnose and poinpoint. Assuming it's coming from that wheel though.
  • Rotated tires a few times since then, sound and heat are still present
  • Appears to pull to the left slightly. Possibly an alignment issue?
  • Wheel bearing appears to move freely and smoothly, no play in the bearing, no crunchiness.
  • E-brake lever (on the caliper) can be squeezed and retracts on its own
  • Pads don't appear to be significantly worn, nor is there any wearing on the inside vs the outside.
  • Pins run smooth and are easily contracted/retracted.

Thinking it's the pads sticking, judging by the difficulty of putting them in and out, I filed the rust out of the mounting brackets today, not all the way to bare metal, but enough to get the original dimension back. Hoping that this fixes the issue, but not sure what to do after this.

So my question: Am I heading down the right path and what should I do next if this doesn't work? My thought is that the caliper may be bad and not retracting. I'm not sure how to diagnose this though. The Rabbit has the turn and push type plungers, so it's difficult to tell the resistance. I will say that doing the brakes on my wife's Prius, the Rabbit's plungers go in much easier.

Thanks ahead of time!

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3 Answers 3

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Sounds like your pads sticking to me. The pad should slide in smoothly ideally they should be so annoyingly smooth so that they fall out if your are not careful.

I have had stuck pin and stuck piston before, both resulted in extreme pad wear on one side of the pad, or the back pad in the caliper. I have also had stuck pad, mild uneven wear, noise.

In my instance i had the original pads around and when i checked the size, the new pads were slightly larger as if they were poorly made. Though not recommended I ground the lips of the pads to match the size of the original, polished the edge and they slide in great and I have had no problems since. Perhaps the cleanup you have already done will fix the problem.

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Likely a sticking caliper, if you're ok doing your own maintenance and comfortable with brakes.. Firstly just check your brake fluid level is ok and not too low (NO need to top it up!) we just don't want it to get too low during the next proceedure. If its at least half full that's fine for now.

Pull one pad out from troublesome caliper and pump the brake a few times so that the piston comes out about half way or so, leaving one pad in will help prevent the piston coming out too far. Screw the piston all the way back in, then press the pedal a few times again to bring the piston back out. Doing this a few times should help free the caliper up. Unless its really old or too far gone, in which case a replacement may be necessary.

EDIT FROM COMMENT: The reason we don't automatically top the fluid level up to max for this procedure is that we are going to be winding a brake piston right back in. So we purposely leave some space in the reservoir to accommodate the extra fluid that will be returning from the calipers fluid chamber. If we started off by topping up the reservoir and the pads were say half worn, We'd likely have excess brake fluid either overflowing or literally squirting out of the breather in the reservoirs filler cap all over the engine bay, and possibly paintwork too. Topping up on job completion is fine.

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As well as the items mentioned in @Orb and @Chris answers, it's also worth checking the flexi hose to the brake for any signs of swelling - sometimes the rubber can perish and swell, causing the hose to behave like a one-way valve - as you press the pedal, there's enough pressure to force the fluid through to apply the brake, but when you release, the fluid doesn't flow back, causing that brake to stick on.

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  • Thank you all! I'm still getting the low level wub wub wubs, but the heat has stopped. I believe it was the brake binding in place. The rust removal, cleaning, and regreasing seemed to do the trick. It is possible that the heat generation damaged my fairly new bearing?
    – GravyBagel
    Commented Nov 27, 2019 at 3:22
  • It's possible, yes. Jack the car up, support on stands, and spin the wheel by hand (also try rocking it back and forth both at 12/6 o'clock and 3/9), see if there's any noises or roughness
    – Nick C ♦
    Commented Nov 27, 2019 at 9:11
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    It can cook the grease in the bearing is what I have read. If the grease is gone or reduced or turned into something else then wear happens. So if it is not bad right now, it may have a reduced life that's all. Mine from the seized piston was fine and that thing was nasty and hot, been a year so far and no bearing issue yet... so could be just down luck, but expecting the next bearing to go to be the front right
    – Chris
    Commented Nov 28, 2019 at 5:44

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