sonofbuster Posted May 29, 2015 Share Posted May 29, 2015 as the weather warmed up, my 2001 OBW started vibrating under braking. like i imagine a warped rotor would feel. in the last couple weeks, however, it's bad enough that i can feel it in the steering wheel and it causes the brake pedal to pulse. so i finally had a peek at it today. i pulled the driver side caliper and rotor and found that the rotor is clean on the outside, but pitted and rusty on the inside. the caliper slides nice and smooth but the pistons are tough to move in. i'm using one of those quick grip type clamps to push the pistons in. they will push out when i press the pedal so they're not completely frozen. the brake pads look the same as far as condition/wear. it doesn't make sense that on a caliper like this, the inside pad would NOT be causing some wear on the inside face of the rotor judging by the smoothness on the outside face. doesn't the inside have to contact in order for the outside to contact? background: had same/similar vibrating issue in winter of '14 after car had been sitting unused for a couple months. turns out rear brakes were completely non-functioning and i assumed all the braking load on the front was causing vibration. braking was very weak too. after replacing pads and rotors and cleaning caliper in the rear, issue was gone. issue returned this year with the warm weather with no other changes to the car as far as other problems. braking otherwise feels fine this time. car does need new axles in the front but no noise, grinding, etc. from that issue aside from play in axle. that doesn't seem to have gotten worse either. not sure if that has anything to do with things. my questions are: should i clean up this caliper and rebuild it, or simply replace it? my instinct is to lube the pistons. i don't want my instincts to get me killed, though. also, are the pistons supposed to move in and out fairly easily or does it require some force? thanks in advance for the help! Quote Link to comment Share on other sites More sharing options...
gbhrps Posted May 29, 2015 Share Posted May 29, 2015 (edited) sonofbuster, The caliper can be refurbished, if it and the piston haven't been allowed to go too far in the corrosion game. The only way to know for sure is to pop the piston out of the caliper and clean it up and inspect it. To be really certain, you need to do this to all four calipers. The brake fluid is supposed to be flushed out and refreshed every 4 years at most, as water will invade and rust the pistons in their bores, and rot the brake lines from the inside. Then the pistons stick and won't release pressure evenly. Then brake issues arise. You can remove the caliper from its mount, slowly press the brake pedal repeatedly until the piston pops out (messy), or remove the caliper from the car and pop the piston out with compressed air (YouTube videos on this). Then inspect the seals to see if they are ripped/worn. If good, then clean the piston with 0000 (four aught) steel wool. Inspect closely to see if it has any rust pitting. If it has ... replace the caliper. If not, clean the caliper bore the same way and flush liberally with fresh brake fluid. Spread the dust seal over the piston and press it back into the caliper, sealing the dust cap in its groove on the piston. There is a YouTube video on using the air compressor to flap open the dust seal over the piston to allow you to push the piston back into the caliper. Trying to do it with your fingers can be a bit**, but it is possible. Replace that one rotor, or any others that look like it. I've done a hundred of these over the years. Its not rocket science, and I've never had one fail to work or even leak. Good Luck! If you do this to each caliper in turn, and clean/ lube the slide pins, and clean/lube the chrome clips that the pads slide in, you should be good to go after sucking out all of the old brake fluid from the MC, filling with new DOT 3 and rebleeding each wheel in order. Edited May 29, 2015 by gbhrps Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted May 29, 2015 Share Posted May 29, 2015 For my time and money, I would buy a rebuilt caliper from Advance Auto Parts. The do it yourself of trying to repair an old caliper just never seems worth the effort. If you go on line to Advance and look for coupons, you can usually find a coupon good for $25-$30 off the selling price. If in stock at a local store, I pay for the part on line, and pick it up at the store. You will also need a new rotor, but I bet you already know that. Quote Link to comment Share on other sites More sharing options...
sonofbuster Posted May 29, 2015 Author Share Posted May 29, 2015 (edited) thanks for the replies. i'll have to decide what i have time and money for although rotors seem pretty cut & dry to replace. i forgot to mention the pads and rotors were new as of Feb 2014 (the rear sets are Summer '14). i think letting them sit (maybe before they bedded in??) for so long didn't do them any favors. my wife works at a school so maybe i can time the work to her time off b/c i sure as hell know i will be making multiple trips to the parts store for this and my axles. that's how it goes! Edited May 29, 2015 by sonofbuster Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted May 29, 2015 Share Posted May 29, 2015 thanks for the replies. i'll have to decide what i have time and money for although rotors seem pretty cut & dry to replace. i forgot to mention the pads and rotors were new as of Feb 2014 (the rear sets are Summer '14). i think letting them sit (maybe before they bedded in??) for so long didn't do them any favors. my wife works at a school so maybe i can time the work to her time off b/c i sure as hell know i will be making multiple trips to the parts store for this and my axles. that's how it goes! Pads and rotors should not wear out in less then a year and a half. Was the inside brake pad that rubs against the inside of the rotor worn out to permit metal on metal contact to wear the rotor so badly?? If so, the caliper continues to put pressure on the rotor, even though your foot is not on the brake pedal. Chances are, if you pull of the rotor, then compress the piston back, you will see a bad rubber seal, and rust build up on the walls of the caliper. It is that rust that keeps the piston from retracting as it should, when your foot is off the brake. Quote Link to comment Share on other sites More sharing options...
sonofbuster Posted May 30, 2015 Author Share Posted May 30, 2015 Pads and rotors should not wear out in less then a year and a half. Was the inside brake pad that rubs against the inside of the rotor worn out to permit metal on metal contact to wear the rotor so badly?? If so, the caliper continues to put pressure on the rotor, even though your foot is not on the brake pedal. Chances are, if you pull of the rotor, then compress the piston back, you will see a bad rubber seal, and rust build up on the walls of the caliper. It is that rust that keeps the piston from retracting as it should, when your foot is off the brake. still plenty of meat on the pads as far as i can tell. the rotor looks like it was wearing at some point, then it just never got touched again so the forces of nature chipped away (literally) at it to make it what it is now. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted May 30, 2015 Share Posted May 30, 2015 (edited) still plenty of meat on the pads as far as i can tell. the rotor looks like it was wearing at some point, then it just never got touched again so the forces of nature chipped away (literally) at it to make it what it is now. Well with plenty of meat left on the pads, you may get lucky, and not need to address a caliper repair or replacement. Put on a new rotor, and drive on. Old rotor may have been made with bad steel. Probably a good idea to keep an eye on that rotor replacement. If you feel any braking with foot off the brake pedal, or smell a hot brake pad, then you can get suspicious that the caliper is a problem. It would be nice to check the temperature of the rotor, after driving for a while, with a heat gun (with digital read out), to see if there is any high temperatures at any of your rotors. Edited May 30, 2015 by Rooster2 Quote Link to comment Share on other sites More sharing options...
sonofbuster Posted May 31, 2015 Author Share Posted May 31, 2015 (edited) gonna try a couple rotors for now and keep an eye on things. i suspect i'm gonna need more work in the way of calipers -- either rebuild or replace -- and a complete bleed and flush of the old fluid. i assume i'll need to bed in these rotors after install. any tips? Edited May 31, 2015 by sonofbuster Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted May 31, 2015 Share Posted May 31, 2015 Unaware that Subie rotors need "to be bed in." I just install mine, and drive car as usual. No special treatment needed. Quote Link to comment Share on other sites More sharing options...
sonofbuster Posted June 9, 2015 Author Share Posted June 9, 2015 picked up a couple of new rotors and layed them against the old ones and couldn't really tell what was warped. maybe the part that contacts the hub? anyhow, issue is fixed for now but i'm gonna keep an eye on things and plan on servicing the brake system soon. 1 Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted June 9, 2015 Share Posted June 9, 2015 Not a caliper issue. The inner side of the rotor got too rusty and the pads aren't making even contact with the surface. The heavily rusted areas are where the pads can't make contact at all. Usually that starts as a small area only 1/8-1/4" wide on one edge and spreads from there. All of that is probably from when the car sat for so long. That will lead to vibration as the other surface of the rotor creates more heat during braking. The amount of warp or thickness variation necessary to create a vibration is not visible to the naked eye. .003" is usually the limit for rotor warp. .006" will cause the steering wheel to shake bad. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 9, 2015 Share Posted June 9, 2015 that's a terrible rotor - did that car drive through salt slush and then get parked in grass during the time it sat? i routinely see rotors completely rusted over from sitting, then drive them for awhile as the pads wear the rust away, never seen that happen. i'd just replace the rotor, caliper is probably fine. caliper rebuilds are simple on Subarus, its just one seal. push out pistons, clean up, install seal around piston, reassemble with new dust boot. but calipers are cheap enough that it's rather simple to just get a caliper too. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 9, 2015 Share Posted June 9, 2015 you could check to see if a local place will turn your rotors as well, they can turn that back down to flat if it's new it should still have enough material available for that. feel free to replace one rotor at a time, replacing in pairs is in no ways beneficial, i routinely replace only the bad rotor. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted June 9, 2015 Share Posted June 9, 2015 (edited) most of us do fine with non-performance parts and normal driving without a bed-in. Is it a good idea? probably - might help if you engage in 'spirited driving' right out of the gate - but plenty of people would have no problems after the first 2-3 gentle stops. You could do a 30-30-30 . Do a normal stop from 30mph, Drive for 30 seconds, stop again. Dot that 30 times. But really, modern pads work well against decent rotors without much chance fro drama. make sure to clean any protective grease off the rotors. good opportunity to wire-brush off the front of the hub and I like to hit the studs with some gentle wire-brushing - just to knock off any corrosion. maybe put some light grease or something on the front of the hub to help keep corrosion down? some silicone spray or ??? Edited June 9, 2015 by 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 9, 2015 Share Posted June 9, 2015 i've never done a bed in procedure...not intentionally anyway. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted June 9, 2015 Share Posted June 9, 2015 i've never done a bed in procedure...not intentionally anyway. Well, I have done a "bed in procedure," but it had nothing to do with a Subaru. 1 Quote Link to comment Share on other sites More sharing options...
sonofbuster Posted June 10, 2015 Author Share Posted June 10, 2015 Not a caliper issue. The inner side of the rotor got too rusty and the pads aren't making even contact with the surface. The heavily rusted areas are where the pads can't make contact at all. Usually that starts as a small area only 1/8-1/4" wide on one edge and spreads from there. All of that is probably from when the car sat for so long. That will lead to vibration as the other surface of the rotor creates more heat during braking. The amount of warp or thickness variation necessary to create a vibration is not visible to the naked eye. .003" is usually the limit for rotor warp. .006" will cause the steering wheel to shake bad. great information. that's wild that such a small deviation could cause what felt like the car was going to fall apart. that's a terrible rotor - did that car drive through salt slush and then get parked in grass during the time it sat? i routinely see rotors completely rusted over from sitting, then drive them for awhile as the pads wear the rust away, never seen that happen. had both front rotors replaced sometime in the winter then parked it in the driveway for a couple months. you could check to see if a local place will turn your rotors as well, they can turn that back down to flat if it's new it should still have enough material available for that. feel free to replace one rotor at a time, replacing in pairs is in no ways beneficial, i routinely replace only the bad rotor. both rotors looked identical. i'm keeping the old rotors for just that posibility. Quote Link to comment Share on other sites More sharing options...
sonofbuster Posted June 10, 2015 Author Share Posted June 10, 2015 make sure to clean any protective grease off the rotors. good opportunity to wire-brush off the front of the hub and I like to hit the studs with some gentle wire-brushing - just to knock off any corrosion. maybe put some light grease or something on the front of the hub to help keep corrosion down? some silicone spray or ??? i use T-9 on some parts of the car, but it's not long lasting. i feel like the grease that spews out of busted axle boots would be great to spread across the entire underside of the car but for the horrible smell that would emit. gonna do the axles soon using a tutorial from this site (i think?). will try to clean everything up then. wish me the best... haha Quote Link to comment Share on other sites More sharing options...
fishy Posted June 10, 2015 Share Posted June 10, 2015 most of us do fine with non-performance parts and normal driving without a bed-in. Is it a good idea? probably - might help if you engage in 'spirited driving' right out of the gate - but plenty of people would have no problems after the first 2-3 gentle stops. You could do a 30-30-30 . Do a normal stop from 30mph, Drive for 30 seconds, stop again. Dot that 30 times. But really, modern pads work well against decent rotors without much chance fro drama. make sure to clean any protective grease off the rotors. good opportunity to wire-brush off the front of the hub and I like to hit the studs with some gentle wire-brushing - just to knock off any corrosion. maybe put some light grease or something on the front of the hub to help keep corrosion down? some silicone spray or ??? I just drive a normal Outback in mostly normal capacity but I always do some shorter version of the 30-30-30 break-in procedure on new brakes. Probably just to make myself feel clever for doing it. I have no way to measure if it really helps in any way. *shrug* Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.