Brake Pads Always Touches Brake Disc

[Eric Cheung]

The brake pads of my 97 ES300 appears to be always touching the braking discs. Is this how it should be or my brake pads are poorly placed? I would have thought there should be a small gap between the pad and the disc, and they touch only when the brake is applied. Driving and fuel economy is not affected, though.

My concerns are:

1. If the brake pads always touche the brake discs, will this cause the pads to wear excessively?

2. The are too much brake dusts resulting from the friction between the pads and the discs if they are in contact all the time.

Thanks!

[Thienn]

Jack the car up; check to see if the wheels freely spin (put gear in neutral for the drive wheels)! If it is free to spin then you have nothing to worry about. Good Luck.

[jragosta]

I seem to recall that this is normal, but your suggestion to jack it up and spin the wheels is a good one.

I read a book on improving fuel economy several years ago which discussed this. There's not much friction between the brake pads and the rotor under these conditions, but there's still some. They suggest jiggling the wheel from left to right a bit after you reach highway speed. Apparently, that helps the pads to retract just a bit more. I don't know if it's true or not.

[lbinh]

I had my front pads replaced at Pep Boys ($99 PG Plus Brake Service, squeeked from the begining) two years and 40K miles ago. Recently I had to replace them again because of the brake indicator squeeking noise.

Took it to small independant shop to inspect and the left front pad was completely worn and the right front pad still had 75% left. Well, naturally I didn't trust Pep Boys to install again so I got the small shop to do it for $30 labor plus $50 composite front pad set. These new Raybetos composite pads are smooth, low dusting, and better yet no squeeking at all.

I asked the shop mechanic why the left front pad would wear only. He replied that it could be the caliper.

Anyone know if a caliper(maybe front right caliper, left front caliper over compensating and causing extreme wear) can go bad and what you can do to fix it? Does it have to do with air in the brake lines and maybe a bleed would help? I don't think the caliper is sticking.

Thanks...

[amf1932]

When moisture(water) gets into the braking system it can rust the calipers pistons. This will sometimes restrict the free movement of this piston to release. This is known as a "frozen caliper". This is why it's important to change your brake fluid after a predetermined time, especially if the car is equipped with ABS. As said before, when the car is up on a lift, spin the wheels to check if they turn freely.

[SKperformance]

if one side wears more than the other either it is

air in the lines

sliders have not been lubed at each pad replacment

piston not lubed either

[Eric Cheung]

Jack the car up; check to see if the wheels freely spin (put gear in neutral for the drive wheels)!  If it is free to spin then you have nothing to worry about.  Good Luck.

←

I jacked up the car and spinned the four wheels hard individually, here is the observation:

front left: spinned 1 revolution only, intermittent friction sound was heard

front left: same

rear left: spinned 2 to 3 revolutions, intermittent friction sound was heard

rear righ: same

It seems that the brake pads are stopping the wheely from free spin. Can this be corrected and how?

Thanks!

[jragosta]

Jack the car up; check to see if the wheels freely spin (put gear in neutral for the drive wheels)!  If it is free to spin then you have nothing to worry about.  Good Luck.

←

I jacked up the car and spinned the four wheels hard individually, here is the observation:

front left: spinned 1 revolution only, intermittent friction sound was heard

front left: same

rear left: spinned 2 to 3 revolutions, intermittent friction sound was heard

rear righ: same

It seems that the brake pads are stopping the wheely from free spin. Can this be corrected and how?

Thanks!

←

Best guess would be that the calipers need to be rebuilt or replaced.

[amf1932]

Don't be surprised if after the calipers were rebuilt or replaced you still hear the brake pads brushing the rotors lightly. Disc brakes don't have return springs as do drum brakes.

This slight sound you're hearing is completely normal. The fact that when you spin the wheels and they all stop turning at different times is no indication of a problem.

A better way to check this is have somebody sit in the car when it's up on a lift. Have them apply the brakes as you try to turn the wheel. Then release the brakes and see if you can then spin the wheel by hand. If at this point the wheel doesn't release immediately you probably have a sluggish caliper(slightly frozen).

[Thienn]

I would say you either have problems with the calipers sticking (no retract when the pressure release) or your rotors are unevenly wears (maybe even warped); the friction sound you heard. Wheels should spin a lot more than couple revolutions if brake system function properly.

[steviej]

front left: spinned 1 revolution only, intermittent friction sound was heard

front left: same

rear left: spinned 2 to 3 revolutions, intermittent friction sound was heard

rear righ: same

1.

-Don't forget that the rear wheels are just wheels on spindles.

They will move freely than the front wheels.

-The front wheels are attached to half shafts that rotate in the tranny. When the front are spinning you have wheels shafts and gears moving. This will cause increased drag so the overall rotation duration will be shorter.

2.

It is normal for brake pads to slightly touch the discs. There is only about a half of a thousandths of an inch space. (not much wiggle room there). The caliper retration is cause by the reshaping of a "square O-ring" after the pressure is released on the caliper plunger. Not alot of return force here, so the plunger doesn't come back very far.

3.

It sounds as if your brakes are normal so far. Remove each wheel and see if you can't measure the thickness of each pad and compare to each other to see if you have abnormal wear.

4.

A possible problem could be that if the pads where ever replaced, the shop may have clamped off the brake lines with a pair of vise grips. This can crush the rubber is such a way that that fluid flow to the caliper was uneffected but return flow of the fluid was impeeded. This impeeded flow would result in poor caliper return travel, thus leaving a pad in hard contact with the rotor.

(This was common practice in many shops in the 90's, especially Goodyear shops. This practice has since been abandoned.)

5. Excessive brake dust can be from inferior pads, especially metalic pads. Metallic pads will also create a more noticable noise.

steviej

[Eric Cheung]

front left: spinned 1 revolution only, intermittent friction sound was heard

front left: same

rear left: spinned 2 to 3 revolutions, intermittent friction sound was heard

rear righ: same

1.

-Don't forget that the rear wheels are just wheels on spindles.

They will move freely than the front wheels.

-The front wheels are attached to half shafts that rotate in the tranny. When the front are spinning you have wheels shafts and gears moving. This will cause increased drag so the overall rotation duration will be shorter.

2.

It is normal for brake pads to slightly touch the discs. There is only about a half of a thousandths of an inch space. (not much wiggle room there). The caliper retration is cause by the reshaping of a "square O-ring" after the pressure is released on the caliper plunger. Not alot of return force here, so the plunger doesn't come back very far.

3.

It sounds as if your brakes are normal so far. Remove each wheel and see if you can't measure the thickness of each pad and compare to each other to see if you have abnormal wear.

4.

A possible problem could be that if the pads where ever replaced, the shop may have clamped off the brake lines with a pair of vise grips. This can crush the rubber is such a way that that fluid flow to the caliper was uneffected but return flow of the fluid was impeeded. This impeeded flow would result in poor caliper return travel, thus leaving a pad in hard contact with the rotor.

(This was common practice in many shops in the 90's, especially Goodyear shops. This practice has since been abandoned.)

5. Excessive brake dust can be from inferior pads, especially metalic pads. Metallic pads will also create a more noticable noise.

steviej

←

Stevie,

Thanks a lot for the detailed analysis and explanation. I really appreciate that . The brake dust really bothers me, as it make the sidewalls of the front tires and wheels look brown. I'm thinking of changing the brake pads to some non-metallic ones, hopefully to avoid future brown stains.

[steviej]

use Toyota/Lexus OEM. not dust on my wheels. :whistles:

steviej

[Eric Cheung]

use Toyota/Lexus OEM.  not dust on my wheels.    :whistles:

steviej

←

Cheers Stevie. :)

[amf1932]

use Toyota/Lexus OEM.  not dust on my wheels.    :whistles:

steviej

←

There will be some dust after some constant city driving where you use your brakes a lot. Stevie probably doesn't notice it because he takes better care of his car than I do. heehee :)

[Eric Cheung]

use Toyota/Lexus OEM.  not dust on my wheels.   :whistles:

steviej

←

There will be some dust after some constant city driving where you use your brakes a lot. Stevie probably doesn't notice it because he takes better care of his car than I do. heehee :)

←

amf, most of the time I drive on highways (50-60mph) and so don't use the brake very often. A mechanic I spoke with today said something about the brake dust like "it blows outwards for the front wheels and inwards for the rear wheels". I was thinking he talked about the way the brake discs are cooled down (just guess), and thus the brake dust is blown out from the front wheels and so is visible.

He also mentioned that fiber brake pads produce less dust but the braking is not as effective as what I'm using now. What do you guys think?

[steviej]

use Toyota/Lexus OEM.  not dust on my wheels.   :whistles:

steviej

←

There will be some dust after some constant city driving where you use your brakes a lot. Stevie probably doesn't notice it because he takes better care of his car than I do. heehee :)

←

nah, I just never take it into the city. It's all out twisty country roads and rural highways for my Lex. :P B)

sj

[steviej]

more brake dust is produced in the front because 70-80% of the braking is done with the front brakes.

steviej

[Eric Cheung]

more brake dust is produced in the front because 70-80% of the braking is done with the front brakes.

steviej

←

I'll give the Toyota/Lexus OEM pads a shot. I'm gathering information to make myself confident in change the pads myself. Cheers :D

[amf1932]

more brake dust is produced in the front because 70-80% of the braking is done with the front brakes.

steviej

←

I'll give the Toyota/Lexus OEM pads a shot. I'm gathering information to make myself confident in change the pads myself. Cheers :D

←

Good luck, I'm sure you'll do an excellent job.