Dood

98 Imprezza Outback Sport, the brakes squeal. I've had two shops look at it, they both say the pads are fine, one shop sanded everything, which stopped the squeal for about 4 miles, then it came back. Both places say that this is a common problem with Subarus and there isn't much you can do. I'm wondering if there are different pads that are known not to squeal? Any help out there?

dbasteve

Non asbestos pads tend to squeal fairly easily. If your pads don't have steel shims behind them they will be worse. There are all sorts of goos you can buy to stop squeal and some actually work. Next time you are up for pads try the Hawk HPS or Axxis Ultimates. These pads are a little more agressive and less likely to squeal.

Dood

I don't understand how metal shims behind the pads, or goop behind the pads, would stop squealing. I assumed the squeal was coming from the interface between rotor and pad. Is it actually a vibration issue, or is it amplified by vibration, and therefore can be lessened by shims or goop behind the pad?

dbasteve

The shims or goop absorb the vibration between the piston and pad backing plate which reduces noise.

Dood

Gotcha!

X1_SRT

having heard many people complain about this at the shop, we still couldn't make it go away. stock pads just do it sometimes. its usually only on light braking when the pad vibrates just a bit. step a little harder and it usually goes away. we've put silicone, brake quiet, shims, sometimes those things work. but like you said it usually comes back.

-PJ

dbasteve

It's a pain in the bum!

A slight missalignment in the caliper body can cause this too.

Zahnster

Ever since I changed the rear pads to Axxis Ultimates, I've gotten rear squeal. At first I had forgotten to install the steel shims behind the pads. I went back and did this and it had pretty much no effect. I've got some goop, but haven't put it on yet.

Perhaps I should have the rear rotors trued?

bigdog

Brake noise What is Normal????
What is Normal??? This is the first deep topic a psyche 101 student ponders. One of the most common concerns that any vehicle owner perceives as a problem is brake noise when stopping the vehicle.Industry wide the question pops up "What is considered to be an "acceptable" level of brake noise??
The disc brake sysyems used on vehicles today are designed and develpoed to meet many different, but very strict requirements. This must be accomplished while providing an optimum level of performance under a wide range of vehicles and environmental operating conditions.
Tha brake pads used by a manufacturer is ultimately a balanced choice. There is a fine line between a quiet brake pad and one which will provide optimum performance under extreme braking conditions.Consequently, when a change is made in the pads formulation(whether it is meant to provide for longer pad life,shorter stopping distances,noise reduction,or a change in pedal effort)a trade-off must be made in one area or another. An example od pad formulation change would be the industry's switch from asbestos to semi-metallic brake linings due to environmental concerns.
Brake friction materials generate noise and heat in order to dissipate energy, a necessary physical reaction.When this occurs,brake dust and vibration of the brake pad within the caliper is generated.These factors can be changed by other environmental and road conditions such as ambient temperture,moisture,road salt,mud,dirt,etc.
It is important to remember that all brale make noise.The frequency at which the noise becomes audible to us will vary. Any effort to eliminate an intermittent brake noise,which is considered normal, is usually temporary at best. This is not to say,however,that all brake noise should arbitarily be considered normal.All brakle noise should be diagnosed as outlined in the appropriate model year service manual.
That preyy much sums it up.
Sorry for the long boring speech
Hope this will explain some brake noise issues
Or try some anti squeel on the pads and tapper a 45 degree 1/4 suface on the face to change the surface of the pads
it is like a chalkboard..when you run it at 90 degrees it will make the hair on your neck stand up---but change the degree of the chalk and the noise goes away

hope this helps--good luck
bigdog

Dood

I stopped at the local NAPA store and asked them what they suggested, they said Ceramic pads, at 68 bucks a pair. Is this what the Axxis and Hawks are, or is this something different, and should it really cost this much? I'd hate to get them and still have the squeal.

X1_SRT

as far as i know, even the high end pads from napa, are still organic materials. things like hawk and axxis metal masters are a semi metallic pad. basically bits of metal embedded in the pad material to give a stronger bite into the rotor surface. semi-met.'s tend to squeal a tad more than organics, and may cause some more dust than stock.
that price does not sound too bad to me. they wanted $98 for a set of rear pads for my talon. i went with Axxis Metal masters from and back. got them both 70 total. i think he under charged me though... o well. don't have the fronts on yet, only the rear, as they gave me the wrong set. but lemme tell you, with powerslots on the back, and brembo cross drilled up front, it sure does stop a whole lot better.

-PJ

Zahnster

Well, I switched back to stock pads for now and most of the squeal has gone away.

I'm not sure how much to trust this info since it sounds like BS, but then again it's not like he's on commision. The Subaru Parts counter guy was saying that racing type pads are not designed for the material the stock rotors are made with. The stock pads are.

So I was thinking, would getting some DBAs or Stoptech stock size rear rotors be a good way to go if I was going to switch back to the Axxis Ultimates.

NJDrew

I have always found that stock pads sqeel less than after market or performance. Given the stopping power is usaly less. Its a choice, Stock pads = less to no sqeel, Aftermarket or Performance more stopping power. Whats more inportant to you is the question. Just a thought, Drew