Chronic brake rotor warping - 2001 Outback Legacy

I agree about having what I call "calibrated arms" - probably pretty consistent torque once you develop a feel in early life.

Might I suggest using anti-seize instead of oil? I say that because I suspect that torque with anti-seize is much closer to dry torque than torque with oil is. I've never seen any numbers on that, but I believe it to be true (due to metal particles in the anti-seize). It would prevent the corrosion at least as well as the oil (i.e., no down sides that I can think of).

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

I know what you're talking about: When my elbows make a cracking sound, it's tight enough.....

Hi, Go to a your neighborhood tire shop and ask. It's not a legend. Only time you need oil is when trying to free up the rust frozen lugs. Tony

Hi, And when you get older, your forearm will fall off, LOL. Tony

FYI -- Porsche is now using ceramic rotors on some of their very expensive models. Do those warp or just explode?

Al

Hi, It is possible to make a ceramic engine block, so I guess it is strong. Tony

I was referring to the link to the expert on warped rotors -- he never mentioned torquing wheels more than once in the entire article. By far he was much more concerned with peoples braking habits, than mis-torqued wheels.

Father Guido ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ I plan on living forever... so far, so good

It may not be a matter of rotor warping. Floating disks may shake because of rust at the surface where the rotor contacts the hub. They may also shake because the bearing is not properly seated in the hub. You laugh? Both of my Legacys show the symptom, on both front wheels. My in-law's laughable Plymouth Acclaim had its rotors perfectly straight.

The shop manuals say that the runoff should not exceed 7 mils. This is the thickness of a sheet of paper. Take the wheel off, put the bolts back on the rotor, run the engine and get the wheel rolling, then look at the caliper. If you see it moving laterally on its pins, there's the problem. There's much more than seven mils of runoff. When the caliper puts the pressure, the movement is transmitted to the whole suspension. I've seen this with new and reshaved rotors. It may be rust, it may be the hub, it may be the bearing.

Reinstalling the rotor one or two bolt holes further may diminish the movement.

Finally Felix came with a true approach:

Measure the disc runout. You may find that they are within specs. If only one disc warps, there might be a problem with the caliper.

Did any> It may not be a matter of rotor warping. Floating disks may shake

I had that problem when the brakes were hot from stopping.

I replaced the pads with semi-metalic... problem gone

I read somewhere that some auto shop did a big investigation of "warped rotors" and they came up with the pad going bad. I had a Chrysler 300M that had brake vibration problems every 20K. I cut them, replaced pads, replaced pads with $80 ceramic pads and new rotors. Still sold the car at 70K with "braking vibration" the replacement pads are on for 800 miles and no more "breaking vibration"

snipped-for-privacy@spame.me

I'm interested in feedback, but isn't it fairly typical with any brand of car that disks need shaving at 30K and 60K, with disk replacement at about 90K? At least that's always been my experience, and not only with Subarus.

Regards, LK '99 OBW

It must depend on how you drive. My Soobie, with over 160,000km has never had more than the pads changed.

-- Dominic Richens | snipped-for-privacy@alumni.uottawa.ca "If you're not *outraged*, you're not paying attention!"