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Neglected rear brakes - What to replace?


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15 replies to this topic

#1 Red92

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Posted 15 December 2011 - 11:22 PM

So I was doing a test fit of some different wheels on my '94 Legacy GT today, and was somewhat surprised at what I found when I pulled the rears:

Right:
http://www.ultimates...&pictureid=3432

Left:
http://www.ultimates...&pictureid=3433


Judging by the condition of the rotors (rusty, pitted, and not shiny on the braking surface), it looks as though the right rear isn't doing anything, and the left rear just the smallest bit of braking. I had to use the flash to make any of the rotor wear show. :-\


Has anyone seen them get this bad before, to give me any tips on what I'm up against? I didn't think to check the condition of the pads, it was getting dark and I wanted to get out of the street.

Is this most likely the result of the calipers binding up, or just extremely excessive wear on the pads? I'll need to replace the rotors and pads for sure, but will I need to replace the calipers as well?

The joys of used cars. :-\

#2 jarl

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Posted 15 December 2011 - 11:39 PM

Those look nice... trust me :)

The first thing you need is new pads, but before I would check whether the sliding surfaces on the caliper are badly rusted. The tolerances on between the pads and the guides (covered with the stainless steel shims) are very tight, and any rust underneath the shims can prevent the pads from moving freely. I would use Evaporust on my calipers but I don't think they will come out without a fight.

Then you want to make sure that the pins are moving freely, and that the rubber boots on the pin and the piston are in good shape. If you need to overhaul too much, it may be cheaper to buy some rebuilt calipers.

As for the disks... well. The easiest thing to do is just replace them. I didn't do it with my car, though. I just wore them down with the brakes :) I'll replace the rotors when my bank balance recovers a little bit from all the stuff I have thrown at this car.

Edit: forgot to mention: start soaking all the bolts with a good penetrating oil!

Edited by jarl, 15 December 2011 - 11:41 PM.


#3 1982gl4

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Posted 15 December 2011 - 11:48 PM

Ahh the joy of rust. I see them this bad on a day to day basis. Usually the slides on the calipers freeze so they can't travel. Or the pads rust into the calier bracket alloying them not to move. This leads to the rear disc rusting due to them not being used. When this happens on a customers car (I work at a small auto repair shop) We replace both rotors and pads. Check the calipers by making sure the piston slides back easily and the slides move freely, and check the dust boot for any rips. Also while you have the rear discs off check your e-brake shoes/hardware mine fell off on my 92 and started making some pretty strange noises :D. The caliper bracket will also need a good cleaning around where the pads sit along with the anti rattle clips (the little clips around the end of the pads), I use air tools, but a file will do just fine, it will just take a bit longer.

A warning. Sometimes (pretty often where I live) the caliper bracket bolts will rust and need heating to be removed. Otherwise they snap off, and getting them out of the bracket is no fun....

#4 bstone

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Posted 16 December 2011 - 01:27 AM

When you replace them make sure to use anti-seize goop on the threads. You'll thank yourself in the future.

#5 MilesFox

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Posted 16 December 2011 - 11:28 AM

i would say the uneven wear is caused by rusty slide pins. take the time to clean them u with steel wook and a penetrating oil, then lube them up with sil-glyde or other similar caliper lube.

the rotors could be turned if they have not been before, it would cost you 10 bucks at a chain retailer. it would cost more to turn the drum portion, but it probably wont be necessary.

also check that the piston is not corroded, as it can become seized.

i like to use the caliper grease on the face of the boot where it meets the piston to protect if from corrosion.

if you are lucky sourching parts, you can retrofit to the larger rotor size from a 2000 outback, turbo legacy 1st gen, or anything else that has a 2 piston caliper up front. you will need the caliper brackets to fit the larger rotor. I swapped them on my 94.

the only downside is that you wil have to go with 15 inch wheels, as 14's wont clear the 2 piston calipers.

i have the complete pull-off set of brakes form my 94 if you have trouble finding parts. My rotors and pads were worn, and i just swapped to the larger brakes because i had them, but my pull-off parts are still useable with new pads and rubber.

#6 Red92

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Posted 16 December 2011 - 02:22 PM

Thanks everyone. Posted Image


So what would be the recommended process to fix this, given that at the moment, I would have to do it on the curb side or a borrowed driveway?

I'm looking at the '92 FSM, and it appears as though the caliper can swing out for pad replacement without removing it or the caliper bracket? It also looks like you only have to remove the caliper bracket to remove the discs, correct?

Basically, I'm wondering if I can check the "easier" stuff first - pad wear, slide pins, and possibly caliper pistons, without fully disassembling everything or disconnecting the brake lines. All of my previous brake rebuilding experience is with drum brakes. :rolleyes:


Thanks for the parts offer, Miles. I do have a set of Outback 15's that will be going on the car for the winter, but I'll probably keep the LGT 14's for the summer tires. If I end up needing parts, I'll definitely let you know. Posted Image

#7 grossgary

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Posted 16 December 2011 - 03:19 PM

the pads are hanging and not clamping on the rotor. caused byon e of two things:

1. seized slide pins
2. pads rusted into the clips

if more than one of the four (two on each side) surfaces look like this then it's likely the slide pins just aren't moving and allowing the pads to clamp.

if you're lucky you just pull them out and regrease them. if they're really bad they might not come out and need a torch to replace or just replace the entire bracket with one that has good pins in it.

on your existing (if possible) or the new/used bracket and pins - removing them, clean them up good, and regrease them with brake caliper lube.

about the only for sure way to get this job done in limited space/time is to get a set of used or new brackets with pins already in them in case yours are seized. they're really not worth much so if you can find someone that has them buy them just in case.

or you can simply go in, remove the caliper and see if the pins will all come out before trying to tackle the job or if you'll need torch/new pins and bracket.

i just ran into this this week on a friends 2004 buick - front caliper pins was seized. hammering wouldn't even budge it - it was rust welded into place. had to order in a new bracket, put the car back together, and wait a day...box didn't have bracket...had to wait another day...and finished the job today.

pretty common around here to see seized pins.

have the rotors turned, cheaper and probably higher quality metal than a parts store replacement.

#8 jarl

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Posted 17 December 2011 - 03:49 PM

In my case the pins were *mostly* fine, but the sides of the caliper bracket were rusted so badly the pads were 100% frozen. One of the pads was bent :)

I had to remove a lot of material (i.e. rust) from the brackets to allow the new pads to move easily.

#9 uniberp

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Posted 18 December 2011 - 10:42 AM

The excessive rusting of rear discs is so common that I now understand why they use drums on some. The problem seems to be that the pads rust to the bracket, rather than sliding pin problems. I make it a practice to occasionally brake hard in the Legato to actually crack them loose and use the rear brakes occasionally.

#10 nipper

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Posted 18 December 2011 - 12:53 PM

Don't forget to inspect the parking brake.

#11 Towel Rail

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Posted 19 December 2011 - 02:11 AM

Oh snap! Good thing you didn't crash into anything, David. ;)

#12 Red92

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Posted 20 December 2011 - 05:59 PM

the pads are hanging and not clamping on the rotor. caused byon e of two things:

1. seized slide pins
2. pads rusted into the clips

if more than one of the four (two on each side) surfaces look like this then it's likely the slide pins just aren't moving and allowing the pads to clamp.


So I had a few minutes this afternoon, and pulled the right rear wheel. The right side brake was the one that looked the worst initially, with the outer surface of the rotor having little to no sings of any contact with the pad.

I didn't pull the caliper off, but looking at the backside of the rotor I could see that it was a little bit shiny - not as evenly as I would like, but substantially more than the outside. So it would appear as though I did have *some* rear braking after all. I also looked through the inspection hole in the caliper body, and I can see that the inner pad is almost entirely gone, while the outer pad is quite a bit thicker, and still has a bit to go before it hits the wear indicating notch.

So based on the pad and rotor wear, I'm assuming that my root problem is stuck slide pins, preventing the caliper body from centering itself? Since the inner side of the rotor has some wear, I can safely assume that the caliper piston isn't seized, correct?


By the way, can someone clarify the difference between "slide pins", "guide pins", and "lock pins" for me? The FSM seems to show one "guide pin" and one "lock pin", and it looks like the lock pin has to be removed first (like a bolt), then the caliper body swiveled up, then the caliper just slips off the end of the guide pin and then that pin can be removed? And is it correct that the lock pin has two boots, but the guide pin only one?

Thanks again for the help. :)

#13 nipper

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Posted 20 December 2011 - 06:31 PM

Some people call them slider, sliders, or guides or caliper pins. Based on what you are saying i would go out get a set of replacment rotors (just easier). When a caliper freezes it can not apply a squeeze to the rotors which stops the car. The rears were just there for decoration.

Also flush the brake fluid.

#14 bheinen74

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Posted 20 December 2011 - 09:13 PM

and lube the slide ears for the brake bracket holders, after you wire wheel the rust off the bracket. It shouldn't take a pry bar to remove your brake pads, but in this case, it looks as if that will be needed......they are all sorts of messed up.

#15 jarl

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Posted 21 December 2011 - 01:45 AM

I didn't pull the caliper off, but looking at the backside of the rotor I could see that it was a little bit shiny - not as evenly as I would like, but substantially more than the outside. So it would appear as though I did have *some* rear braking after all. I also looked through the inspection hole in the caliper body, and I can see that the inner pad is almost entirely gone, while the outer pad is quite a bit thicker, and still has a bit to go before it hits the wear indicating notch.


Hey! When did you look at my car??? :D
As mentioned before, the problem in my car were NOT the pins, but the rusted calipers. There's an Endwrench (?) article about this as well -and of course I can't find it now-. Tolerances are just too tight.

If I remember correctly, the recommendation from the Endwrench article is to file the grooves on the pads where the stainless steel shims are supposed to slide. I decided to file the caliper instead.

#16 Red92

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Posted 04 January 2012 - 09:43 AM

An update-

I took one more shot at it last week, but couldn't get the right caliper to budge. With that, and with the weather we've had (daytime high temperatures in the teens), I decided to just take it to the shop. :-\

I got a call from the shop the next day, and even with a torch, things were so rusted that they couldn't get the caliper off either! So now I have the car back, with two new discs, new pads, and... a replacement caliper. ;) It cost more than I wanted to spend, but brakes are too important not to fix properly. Posted Image




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