Inboard front brake pads worn out
07-04-2013, 07:50 PM
#1
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Join Date: 11-19-2008
Location: oregon
Posts: 123
Inboard front brake pads worn out
2007 HHR.
Inboard brake pad on both sides wears tremendously compared to outboard.
Was on trip, coming to a stop, noticed grinding sound driver side front. Inboard brake pad was down to backing plate. No warning - i.e., no screechers.
Milage: 82k - mostly rural driving. Car has been driven many times down steep grades using brakes rather than lower gear - no, it wasn't me driving.
After another 300 miles, similar situation with passenger side.
Replaced pads. Caliper action seems fine, no evidence of stuck pistons.
Curious as to whether this is a common problem.
************************************************** *********************************
"Problem" solved.
Conclusion is that there was no problem with brakes.
Problem was lack of screechers. More specifically, on driver side inboard backing plate there was a mark indicating presence at one time of a screecher clip. On passenger side inboard backing plate, there was a screecher clip, but the finger that contacts the rotor was broken off; there was a corresponding annular score around inboard rotor surface.
Without screechers, and assuming slide bushings and piston in good order, by definition inboard pad will wear down to backing plate long before outboard pad. Now, suppose ouboard pad wears 50% as fast as inboard. Then when we see 100% wear on inboard pad, outboard is only 50% worn, and there is a tendancy to worry.
But wait! When the inboard pad was 50% worn, and the outboard was only 25% worn, the situation for remaining wear would have been: 50% inboard and 75% outboard - not likely worrying.
And when inboard pad was 25% worn, outboard would have been 12.5% worn, and the situation would have been 75% inboard and 87.5% outboard remaining thickness - not at all worrying.
And if new pads were inspected at 100 miles, there would be no sensible difference in wear.
So the real issue was the lack of screechers. As I said, on a trip, suddenly grinding and crunching noises as the last of the driver side inboard pad disintegrated and the backing plate became the friction surface. About 300 miles farther on, the same happened to the inboard pad on the passenger side.
Obviously, a cursory check of pad wear is easier for outboard pads, which can be misleading if pads are sufficiantly worn, because when there are several thousand miles "worth" of pad on outboards, the inboards may have 0 miles left.
The fact that 100% wear on inboard pads happened at essentially the same mileage on both driver and passenger sides suggested that brake mechanisms were fine. Actual examination confirmed suggestion. Slider bushings are essentially lubricated for life, and in any case were obviously well lubricated. Pushing back pistons showed that they were obviously moving freely on both driver and passenger sides. (Note: Bleeder screws were open to avoid damaging ABS upstream.)
Inboard brake pad on both sides wears tremendously compared to outboard.
Was on trip, coming to a stop, noticed grinding sound driver side front. Inboard brake pad was down to backing plate. No warning - i.e., no screechers.
Milage: 82k - mostly rural driving. Car has been driven many times down steep grades using brakes rather than lower gear - no, it wasn't me driving.
After another 300 miles, similar situation with passenger side.
Replaced pads. Caliper action seems fine, no evidence of stuck pistons.
Curious as to whether this is a common problem.
************************************************** *********************************
"Problem" solved.
Conclusion is that there was no problem with brakes.
Problem was lack of screechers. More specifically, on driver side inboard backing plate there was a mark indicating presence at one time of a screecher clip. On passenger side inboard backing plate, there was a screecher clip, but the finger that contacts the rotor was broken off; there was a corresponding annular score around inboard rotor surface.
Without screechers, and assuming slide bushings and piston in good order, by definition inboard pad will wear down to backing plate long before outboard pad. Now, suppose ouboard pad wears 50% as fast as inboard. Then when we see 100% wear on inboard pad, outboard is only 50% worn, and there is a tendancy to worry.
But wait! When the inboard pad was 50% worn, and the outboard was only 25% worn, the situation for remaining wear would have been: 50% inboard and 75% outboard - not likely worrying.
And when inboard pad was 25% worn, outboard would have been 12.5% worn, and the situation would have been 75% inboard and 87.5% outboard remaining thickness - not at all worrying.
And if new pads were inspected at 100 miles, there would be no sensible difference in wear.
So the real issue was the lack of screechers. As I said, on a trip, suddenly grinding and crunching noises as the last of the driver side inboard pad disintegrated and the backing plate became the friction surface. About 300 miles farther on, the same happened to the inboard pad on the passenger side.
Obviously, a cursory check of pad wear is easier for outboard pads, which can be misleading if pads are sufficiantly worn, because when there are several thousand miles "worth" of pad on outboards, the inboards may have 0 miles left.
The fact that 100% wear on inboard pads happened at essentially the same mileage on both driver and passenger sides suggested that brake mechanisms were fine. Actual examination confirmed suggestion. Slider bushings are essentially lubricated for life, and in any case were obviously well lubricated. Pushing back pistons showed that they were obviously moving freely on both driver and passenger sides. (Note: Bleeder screws were open to avoid damaging ABS upstream.)
Last edited by blacky; 07-07-2013 at 08:33 PM. Reason: Answering own question
07-04-2013, 08:13 PM
#2
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Join Date: 04-09-2006
Location: Vancouver, BC, Canada
Posts: 7,037
Nope, not a common problem to that extent. It does point to insufficient lube on the sliding parts of the calipers however. It's not likely a stuck piston, but more than likely a stuck or sticky caliper.
Hopefully when you encountered the problem with the first one, you replaced all the 4 bake pads (sounds like you replaced just the ones on the one side)? When replacing any of the pads on the front, you really need to replace all four - to do otherwise can lead to unbalanced braking.
The lube needed is a high-temp silicone lube that is available at any auto parts store. The tube is usually marked "suitable for brakes" or words to that effect.
And you do need to keep the rear brakes properly adjusted, to make sure they do their fair share of the work, else the fronts will do most of the work, leading to excessive pad wear, and overheated rotors. The rear adjustment can be quickly checked by seeing how many clicks the emergency brake need before the rears start to engage. The rule of thumbmost here go by is 3-5 clicks - any more, and the rears need adjustment. It does make a major difference and is very important to make sure the adjustment is done.
Hopefully when you encountered the problem with the first one, you replaced all the 4 bake pads (sounds like you replaced just the ones on the one side)? When replacing any of the pads on the front, you really need to replace all four - to do otherwise can lead to unbalanced braking.
The lube needed is a high-temp silicone lube that is available at any auto parts store. The tube is usually marked "suitable for brakes" or words to that effect.
And you do need to keep the rear brakes properly adjusted, to make sure they do their fair share of the work, else the fronts will do most of the work, leading to excessive pad wear, and overheated rotors. The rear adjustment can be quickly checked by seeing how many clicks the emergency brake need before the rears start to engage. The rule of thumbmost here go by is 3-5 clicks - any more, and the rears need adjustment. It does make a major difference and is very important to make sure the adjustment is done.
07-04-2013, 10:48 PM
#3
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Join Date: 09-19-2011
Location: myrtle beach, sc
Posts: 333
Nope, not a common problem to that extent. It does point to insufficient lube on the sliding parts of the calipers however. It's not likely a stuck piston, but more than likely a stuck or sticky caliper.
Hopefully when you encountered the problem with the first one, you replaced all the 4 bake pads (sounds like you replaced just the ones on the one side)? When replacing any of the pads on the front, you really need to replace all four - to do otherwise can lead to unbalanced braking.
The lube needed is a high-temp silicone lube that is available at any auto parts store. The tube is usually marked "suitable for brakes" or words to that effect.
And you do need to keep the rear brakes properly adjusted, to make sure they do their fair share of the work, else the fronts will do most of the work, leading to excessive pad wear, and overheated rotors. The rear adjustment can be quickly checked by seeing how many clicks the emergency brake need before the rears start to engage. The rule of thumbmost here go by is 3-5 clicks - any more, and the rears need adjustment. It does make a major difference and is very important to make sure the adjustment is done.
Hopefully when you encountered the problem with the first one, you replaced all the 4 bake pads (sounds like you replaced just the ones on the one side)? When replacing any of the pads on the front, you really need to replace all four - to do otherwise can lead to unbalanced braking.
The lube needed is a high-temp silicone lube that is available at any auto parts store. The tube is usually marked "suitable for brakes" or words to that effect.
And you do need to keep the rear brakes properly adjusted, to make sure they do their fair share of the work, else the fronts will do most of the work, leading to excessive pad wear, and overheated rotors. The rear adjustment can be quickly checked by seeing how many clicks the emergency brake need before the rears start to engage. The rule of thumbmost here go by is 3-5 clicks - any more, and the rears need adjustment. It does make a major difference and is very important to make sure the adjustment is done.
07-05-2013, 11:31 AM
#4
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Join Date: 10-13-2011
Location: Welland,Ont Canada
Posts: 37,620
every oil change I rotate the tires, pop off the rear drums clean the shoes and adjust them, clean a lube the slider pins on the front calipers only takes a few minutes and saves this uneven pad wear from happening, 135,000 miles, just on third set of pads and rotors second set of rear shoes
07-07-2013, 03:54 PM
#6
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Join Date: 11-19-2008
Location: oregon
Posts: 123
"Problem" solved.
Conclusion is that there was no problem with brakes.
Problem was lack of screechers. More specifically, on driver side inboard backing plate there was a mark indicating presence at one time of a screecher clip. On passenger side inboard backing plate, there was a screecher clip, but the finger that contacts the rotor was broken off; there was a corresponding annular score around inboard rotor surface.
Without screechers, and assuming slide bushings and piston in good order, by definition inboard pad will wear down to backing plate long before outboard pad. Now, suppose ouboard pad wears 50% as fast as inboard. Then when we see 100% wear on inboard pad, outboard is only 50% worn, and there is a tendancy to worry.
But wait! When the inboard pad was 50% worn, and the outboard was only 25% worn, the situation for remaining wear would have been: 50% inboard and 75% outboard - not likely worrying.
And when inboard pad was 25% worn, outboard would have been 12.5% worn, and the situation would have been 75% inboard and 87.5% outboard remaining thickness - not at all worrying.
And if new pads were inspected at 100 miles, there would be no sensible difference in wear.
So the real issue was the lack of screechers. As I said, on a trip, suddenly grinding and crunching noises as the last of the driver side inboard pad disintegrated and the backing plate became the friction surface. About 300 miles farther on, the same happened to the inboard pad on the passenger side.
Obviously, a cursory check of pad wear is easier for outboard pads, which can be misleading if pads are sufficiantly worn, because when there are several thousand miles "worth" of pad on outboards, the inboards may have 0 miles left.
The fact that 100% wear on inboard pads happened at essentially the same mileage on both driver and passenger sides suggested that brake mechanisms were fine. Actual examination confirmed suggestion. Slider bushings are essentially lubricated for life, and in any case were obviously well lubricated. Pushing back pistons showed that they were obviously moving freely on both driver and passenger sides. (Note: Bleeder screws were open to avoid damaging ABS upstream.)
Conclusion is that there was no problem with brakes.
Problem was lack of screechers. More specifically, on driver side inboard backing plate there was a mark indicating presence at one time of a screecher clip. On passenger side inboard backing plate, there was a screecher clip, but the finger that contacts the rotor was broken off; there was a corresponding annular score around inboard rotor surface.
Without screechers, and assuming slide bushings and piston in good order, by definition inboard pad will wear down to backing plate long before outboard pad. Now, suppose ouboard pad wears 50% as fast as inboard. Then when we see 100% wear on inboard pad, outboard is only 50% worn, and there is a tendancy to worry.
But wait! When the inboard pad was 50% worn, and the outboard was only 25% worn, the situation for remaining wear would have been: 50% inboard and 75% outboard - not likely worrying.
And when inboard pad was 25% worn, outboard would have been 12.5% worn, and the situation would have been 75% inboard and 87.5% outboard remaining thickness - not at all worrying.
And if new pads were inspected at 100 miles, there would be no sensible difference in wear.
So the real issue was the lack of screechers. As I said, on a trip, suddenly grinding and crunching noises as the last of the driver side inboard pad disintegrated and the backing plate became the friction surface. About 300 miles farther on, the same happened to the inboard pad on the passenger side.
Obviously, a cursory check of pad wear is easier for outboard pads, which can be misleading if pads are sufficiantly worn, because when there are several thousand miles "worth" of pad on outboards, the inboards may have 0 miles left.
The fact that 100% wear on inboard pads happened at essentially the same mileage on both driver and passenger sides suggested that brake mechanisms were fine. Actual examination confirmed suggestion. Slider bushings are essentially lubricated for life, and in any case were obviously well lubricated. Pushing back pistons showed that they were obviously moving freely on both driver and passenger sides. (Note: Bleeder screws were open to avoid damaging ABS upstream.)
Last edited by blacky; 07-07-2013 at 08:33 PM. Reason: update answer
07-07-2013, 04:26 PM
#7
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Join Date: 04-09-2006
Location: Vancouver, BC, Canada
Posts: 7,037
I'd put the cause down to not frequent enough brake inspections, screechers or not. Tire rotations, and swapping summer/winters gives a great opportinity to eye-ball the brakes really well, and make note of how they are wearing, and forecasting when the next set of pads/shoes are going to be needed.
07-07-2013, 05:31 PM
#8
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Join Date: 01-23-2009
Location: Fredericksburg,VA
Posts: 25,326
There is a inspection hole on the caliper so you can see the inner pad with the wheel off. You can see the outer easily enough when the wheel is off. If you cannot see the slot in the pad, then replace very soon. The other indicator is the brake fluid level, never top it off.
" (Note: Bleeder screws were open to avoid damaging ABS upstream.)" Not a worry, you never need to open the bleeder unless you need to bleed (duh). There is no one way valving to damage, it's just an inline pump.
That is why the brake fluid reservoir is an indicator; full=new pads, low=replace pads. You should NEVER need to add to the reservoir except to flush the system or replace calipers or cylinders. In case you want to argue "old school" read your Owner Manual.
" (Note: Bleeder screws were open to avoid damaging ABS upstream.)" Not a worry, you never need to open the bleeder unless you need to bleed (duh). There is no one way valving to damage, it's just an inline pump.
That is why the brake fluid reservoir is an indicator; full=new pads, low=replace pads. You should NEVER need to add to the reservoir except to flush the system or replace calipers or cylinders. In case you want to argue "old school" read your Owner Manual.
07-07-2013, 08:38 PM
#9
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Thread Starter
Join Date: 11-19-2008
Location: oregon
Posts: 123
Nope, not a common problem to that extent. It does point to insufficient lube on the sliding parts of the calipers however. It's not likely a stuck piston, but more than likely a stuck or sticky caliper.
Hopefully when you encountered the problem with the first one, you replaced all the 4 bake pads (sounds like you replaced just the ones on the one side)? When replacing any of the pads on the front, you really need to replace all four - to do otherwise can lead to unbalanced braking.
The lube needed is a high-temp silicone lube that is available at any auto parts store. The tube is usually marked "suitable for brakes" or words to that effect.
And you do need to keep the rear brakes properly adjusted, to make sure they do their fair share of the work, else the fronts will do most of the work, leading to excessive pad wear, and overheated rotors. The rear adjustment can be quickly checked by seeing how many clicks the emergency brake need before the rears start to engage. The rule of thumbmost here go by is 3-5 clicks - any more, and the rears need adjustment. It does make a major difference and is very important to make sure the adjustment is done.
Hopefully when you encountered the problem with the first one, you replaced all the 4 bake pads (sounds like you replaced just the ones on the one side)? When replacing any of the pads on the front, you really need to replace all four - to do otherwise can lead to unbalanced braking.
The lube needed is a high-temp silicone lube that is available at any auto parts store. The tube is usually marked "suitable for brakes" or words to that effect.
And you do need to keep the rear brakes properly adjusted, to make sure they do their fair share of the work, else the fronts will do most of the work, leading to excessive pad wear, and overheated rotors. The rear adjustment can be quickly checked by seeing how many clicks the emergency brake need before the rears start to engage. The rule of thumbmost here go by is 3-5 clicks - any more, and the rears need adjustment. It does make a major difference and is very important to make sure the adjustment is done.
07-07-2013, 09:12 PM
#10
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Join Date: 12-06-2009
Location: Alabama
Posts: 11,368