Excessive Rear Brake Pad Wear & Squeaking Pads for Impreza & Forester

[SVX_commuter]

What is up with rear brake pads in the Impreza and Forester????

I have a 93 LS Impreza that seems to eat rear brake pads. I just changed both the rear caliper assembly and waiting to see if that fixes the problem.

The best pads from Advanced Auto were only lasting about 10,000 miles and Suby pads maybe about 20,000.

Two years ago I did the rear pads in my sister 2001 Forester. Does the Forester have the same pads as the Impreza?

Last night on this Forester I was cleaning and re-lubing the contact points last night on all four wheels. The brakes were squeaking.

I am surprised at how much the rear pads have worn in 36,000 miles. The pads are also not wearing uniformly across the thickness. The side of the pad that gets jammed into the bracket when braking has more wear.

I am thinking that the metal backing on the pads doesn’t have enough support to the bracket when the pads get about 60% wear on them. The metal backing plate for the pad has moved off the bracket but I am not sure.

Has anybody else noticed this excessive wear on the rear pads for the Impreza and Forester?

The front pads on this Forester were squeaking which I know is due to lack of pad lubrication on the contact points to the bracket and shims. So I popped off the stainless shim and there was no lube on either shim. The carbon steel shim was held in with RTV to the back of the pad. These pads were dealer installed last year. Is this RTV always used? There is no lube between the pad and slotted carbon steel shim so this isn’t great for squeaking brakes BUT It will hold the shim in place after it starts to rust away.

The front brake pads look brand new with no wear at all after 18k miles. They will way out last the rear pads and I think the carbon steel shim will rust away before the front pads wear to the point of replacement. A nice slotted Stainless Shim would be great.

Any thoughts on this?

[porcupine73]

It sounds like it is overbraking the rears/underbraking the fronts. Not sure what would cause that?

[avk]

Try another factory pad kit, which comes with all new hardware, and make sure the caliper guide pin/bushing and the sleeve (inside the boot) are lubricated. No silicone is required, according to FSM. Also grease the area where the pad edges are sliding. That's where the braking force is transferred. Tapered wear could mean the pin is worn, so check for that. The bushing shouldn't be worn since the caliper is new. FWIW, rear disk brakes on Impreza and Forester are the same as on the Legacy model, although some have ventilated disks.

[SVX_commuter]

It sounds like it is overbraking the rears/underbraking the fronts. Not sure what would cause that?

 

Yeah I agree with that and it was my first thought too.

 

The piston in the Impreza were a little stiff to push back in. I couldn't do it with the usual leverage of flat bladed screw driver. I had to use a C-clamp. That is one of the reasons I replaced them re-maned

[nipper]

SHck your front brakes. Uneven pad wear is a sticking caliper. THere is also the possability of a bad master cylinder, but thats rare. Before you remove anything compare the drag on the rear wheels with the front. If there is more in the rear then the front its possible that a checkvalve (if there is one) is sticking. SInce this is a diagnal break system check both the wheels on the same side.

 

Use OE pads whenever youhave unusual pad wear, this way you can rule out cheap pads.

 

Inspect the rotors.

 

FLush lines with new fluid.

 

How is your gas mileage?

 

 

nipper

[SVX_commuter]

Try another factory pad kit, which comes with all new hardware, and make sure the caliper guide pin/bushing and the sleeve (inside the boot) are lubricated. No silicone is required, according to FSM. Also grease the area where the pad edges are sliding. That's where the braking force is transferred. Tapered wear could mean the pin is worn, so check for that. The bushing shouldn't be worn since the caliper is new. FWIW, rear disk brakes on Impreza and Forester are the same as on the Legacy model, although some have ventilated disks.

 

Yup I lube all those pad sliding edges with copper anti-seize. I have used that silicon grease on the pins in the past but no more. I find it bakes or something and gets stiff and sticky. Now I just use the copper anit-seize on the pins and guides too. It's the best anti-seize I have found.

 

So maybe this Forester with 61k miles has worn out the guide pins for the calipher because there is no lube from the factory? Huh, I almost think the clearnce between the pin and guides was too big from the factory. There does seem to be a lot of slop in these parts and the claipher does not seem to be guided well.

 

So what is the clearance between the pin and guide supposed to be?

 

It is easy to measure and check the actual with a dial indicator. Take out the pads and install the calipher with no pads. Set up the indicator to measure the travel and move the calipher back and forth. Just from the feel I think it is about .040 inches or so.

[avk]

FSM does not specify that clearance, just says to inspect. I agree it's possible that some calipers didn't have enough grease from the factory. Found it to be the case on one side on the front.

I should add that my Dodge minivan, and the Ford it has replaced, have very simple Kelsey-Hayes calipers with two sleeves/rubber bushings and no pins, which wear squarely and evently even with lack of lubricant on the outside.

[Petersubaru]

when I purchased my 01 outback last nov. I took the car to our subaru dealer in town here for an inspection..although the brakes were completely new (Rotor and Pads on all 4) the mechanic remarked to me that all was fine in his opinion except the new brakes..he said with most aftermarket installations and also some subaru places are not aware of the proper way to install the pads, to keep them from binding up,when the caliper has been released,...when rotateing the tires he felt that there was to much drag, and although borderline in his opinion, we left the situation as a "wait and see"...2000mi later for another inspection on all 4 wheels, now the inside of the disc was showing abnormal wear, in otherwords the disc was not remaining clean and becoming somewhat rusty in places..the cure for this was to remove 1-1.5mm from the length of the pad so that the pad moves more freely "within" the anti-rattle clips...I should have known better myself because it was a common problem for my 85 vw and 93 pontiac..several thousand miles later all is fine now..don't forget to use the synthetic grease between the shim and pad and on top of the pad and of course the anti-rattle/slider area

[porcupine73]

There was a note in endwrench about that.

[SVX_commuter]

when I purchased my 01 outback last nov. ....................the cure for this was to remove 1-1.5mm from the length of the pad so that the pad moves more freely "within" the anti-rattle clips...

 

This is what I have been thinking. The pads fit too tight in the calipher springs and cannot slide properly. The AA pads have been real bad in this regard. Even the Suby pads are hanging up pretty good. They will require belt sander to get them to move better.

 

Why is the "size quality" so poor on these pads? This kind of metal removal should not be required. The pads should drop right in there and move freely.

 

Thanks

[Petersubaru]

There was a note in endwrench about that.

"That'ill teach ya for takeing the car somewhere else"... or in otherwords..this must be subarus' way of punishing those who take there car for brake service to a non-dealer/ un-informed dealer/ mechanic or the DIY

[SVX_commuter]

I replaced the caliphers with rebuilt Subaru and made sure the pads were free to move. They have been working fine for the longest time ever

[porcupine73]

Sounds good and glad it's working.

 

All vehicle makes and models have various TSB's and technical notes issued. A saavy independent shop will be aware of these for the vehicle makes they service and the type of work they do.