Chronic brake rotor warping - 2001 Outback Legacy

Once you cut rotors, they're thinner, and more prone to warping again.

Sounds like time for fresh rotors, and taking stock of your wheel torque. A not-uncommon cause of rotor warpage are clue-impaired techs using air-driven wrenches to tighten lugnuts to the improper torque. A hand torque wrench is a wise investment.

-- Todd H.

2001 Legacy Outback Wagon, 2.5L H-4 Chicago, Illinois USA

First cutting at 30K on factory new rotors, all dealer servicing. I would think they would know what torque to use. They also did tire rotation and new tires. Second cutting at 60K front/rear.

New rotors fr>

On Tue, 21 Oct 2003 21:22:06 GMT, "Jerry C Shaw" wrote in news:2shlb.198920$%h1.192739@sccrnsc02:

You would think a mechanic could avoid over-tightening wheel nut/bolts but it happens quite often as they're too lazy to torque them properly and it's quicker to simply use the air wrench.

This topic comes up quite often. It is more likely either the rotors were not broken in properly or the wheel nut/bolts were over-torqued.

I haven't had a warped rotor since I started torquing my own wheels. They used to be common when I took my car to a dealer for servicing and didn't check and correct the torque.

2001 Outback with former braking vibration. Replaced pads with best aftermarkt $43 pads (semi-metalic) Nothing else. Vibration gone. 51K on former pads. Nothing done to rotors. Vibration on stopping was worse when brakes were hot. Had a Chrysler 300M that had rotors go every 25K ...oh that's right Chrysler...never mind.

Interesting article, wonder why he didn't mention wheel torque?

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

My 2k Outback had warped rotors due to overtightening wheel lug nuts. Had the rotors turned myself at 50K and put the best pads on I could find....I used my own torque wrench this time around....I will never let a shop tighten them again!...BUY A TORQUE WRENCH!!!

On Wed, 22 Oct 2003 03:20:23 GMT, Father Guido wrote in news: snipped-for-privacy@4ax.com:

He does. Paragraph 3: "...to the recommended torque specification..."

There are lots of other articles which talk about the importance of using a torque wrench. Here's one:

Read it again and pay attention to the third paragraph! Looks like he made his point there about wheel nut torquing.

According to Dave Null Sr. :

What would you consider a reasonable torque to apply to the nuts? My owners manual doesn't contain anything about this.

Cheers Steffen.

I would agree with you if since the last installation of new rotors and pads

10K ago, the wheels had been touched.

Now here's what leads to the mystery:

1) Had a third party do the brake job, who told me about the overtorquing, so he knows. 2) He used organic pads and third party top quality rotors (there are 3 grades). I had been told that metallic pads may overheat. My organics stop fine, it's just now that I'm getting rapid vibration during 60 mph braking.. 3) I seldom use the emergency brake so "no clamping on hot rotors after hard braking", so driving habits are not the issue. 4) How do you "break in rotors properly", as one respondent replied. Use of organic pads should not require "breaking in". In addition, the warping only started showing up about 2K ago. You would think if "breaking in" was an issue, it would result in vibration earlier. 5) I've had several new cars since they came out with disc brakes and this has never been a problem

Why should consumers be saddled with buying a torque wrench for Subaru cars, and, if so, why aren't the specs in the owner's manual?

I'm back to bad engineering design.Click and Clack mentioned the industry use in recent years of too-thin rotors (and maybe poor quality steel) in a recent program so if overtorquing is the issue, it may prevail with other brands, too.

Oh well!

Jerry

On Wed, 22 Oct 2003 12:40:12 GMT, "Jerry C Shaw" wrote in news:MUulb.517992$ snipped-for-privacy@rwcrnsc52.ops.asp.att.net:

I guess you didn't follow any break-in routine if you didn't know one existed. Read the article under "Prevention." Pad material bonds to the rotors unevenly and creates a high spot. This gets worse over time, but starts probably day one.

Which is correct. It is a problem with many cars today. Manufacturers should be trying to educate mechanics on why not to use an air wrench, and consumers on how to break-in their pads and rotors properly.

On Wed, 22 Oct 2003 07:50:16 GMT, Steffen Kluge wrote in news:YEqlb.161052$ snipped-for-privacy@news-server.bigpond.net.au:

Like most nut and bolt torque specifications, it is in the shop manual.

The spec is quite wide for the torque, but an air wrench is often well beyond the spec.

I appreciate all the good information about not overtorquing lug nuts. But I beg to differ with the view that a torque wrench is necessary. I've rotated my own wheels since I got the car and have had no brake problems. I use a T lug wrench and tighten the nuts in a crisscross pattern and with

3 stages of tightning.

I also make sure the nuts and studs are clean and have a light coat of oil on them. I've never re- torqued them and I've never had them loosen up.

If you've worked around equipment most of your life, you develop a pretty good biological torque wrench.

Hi, OIL? That's big no, no. You ask any experts. Oiling tire lugs are not a good thing. Good turque wrench is not that expensive and it's useful for many things. I have one with micro meter control which cost less than 50.00. I do tire work at home using air tools(which can cause over torquing) Having a good air compressor is very handy. Tony

Can you cite a reference? Sound like a legend to me.

I wasn't aware of a special coating either, but maybe so. But Ed's definitely right that the torque values take into account dry surfaces, and that if you lube them, all bets are off.

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