'97 Legacy GT Rear brake problem

[Shik]

Hey guys,

 

My '97 GT's left rear brake is confusing me. I noticed last month that the outside of the rotor was full of rust. Not just the little surface rust rotors get when the car sits for a few days, but really rusty. The inside of the rotor is clean and shiny. The car has 225,000 miles on it and figured for $39.00, I'd throw a reman caliper on it and clean everything up and lubricate the sliders, etc. while I was there.

 

Did that and not much has changed. None of the rust on the outside of the rotor was cleaned up.

 

What I do know is :

• The brakes were bled with no problems

• There are no leaks anywhere

• There was never any noticeable difference in pedal feel

• Watching the brake closely while someone pressed the pedal, I can see the caliper squeeze AND release fine, which tells me the hose is not collapsed internally since it releases fine.

• The brake in question never gets abnormally hot as would a brake/rotor/wheel would when a caliper is sticking.

• The inside pad is worn 50% more than the outside pad, both pads are worn evenly. I would think this shows that the brake IS working correctly?

• No odd sounds or vibrations from the brakes at all

 

 

What am I totally missing? Why would the outside of the rotor look a mess but the inside looks normal. I do not know how old the rear rotors are, but I know I never replaced them in the last 85,000 miles. Is it possible the rotor is just beat that bad? I've had some pretty creepy looking rotors on my older Subies before but they were always clean where the pad would come into contact w/ the rotor. Never came across this before.

 

It's getting inspected next month(last inspection it will have, as I'm retiring it next year ), and I'd rather have it figured out before it goes in.

 

Thanks in advance!

 

-Matt

[spooln30]

So the rotor was pretty rusted and you expected the brake pad to remove the rust? Not gonna happen, you need to either buy new rotors or have those old ones cut. I would just buy new ones and replace the pads at the same time. If the pads are like New then take some 80 grit sand paper laid on a flat surface and take the pads and sand them in a back and forth pattern. In the direction the rotor would spin. Do this all the time without issues. The caliper slides will be the cause of this happening more so than the calipers piston. So buying a new caliper wasn't needed unless the piston was seized or leaking. Make sure to use high temp caliper grease on the slides or this will happen all over again.

[Shik]

spooln, thanks for the input. Yes, I do believe the rotor is just too nasty at this point. No use in cleaning them up for the price of some new ones. I'm not sure why I just assumed the pad would clean things up on the rotor

 

I did have a front caliper seize around 200k miles, so I figured for the price it was worth a shot on the rear.

 

I'll throw some new rotors on it and go from there. I'm also going to periodically clean the brake calipers/clips/slides from here on out(w/the caliper grease) as that is something I never got in a habit of doing unfortunately. Thanks again.

 

-Matt

[spooln30]

I found over the 15 yrs of being an auto mechanic I found that the Synthetic caliper grease from Napa does the best and most importantly it lasts the longest. It comes in a white plastic container with the brush attached to the cap and it is a Blue color. I've used other grease and have had them re seize after a year or so. If the slides were pretty stuck in the bracket it's best to wire wheel the slides as well as sand the inside of the caliper bracket where they slide. If you don't clean everything up no grease will last long. The last thing would be to make sure those rubber boots don't have holes because that will allow water and crap to enter and make them not move quicker. GL.