Interesting Article on Preventing Warped Rotors

[rsiwicki]

don't know how much truth is in this as I have never heard anything like this to prevent warping but maybe Q45tech and provide us with his thoughts....

A few years ago I read a study by the Society of Automotive Engineers that investigated the causes of rotor warpage. Bottom line was that a very high percentage of warpage (something like 87%) was caused by improper torqueing of the wheels.

Always using the following procedure should prevent warping.

1. Only remove the wheels when the brakes are cool.2. Loosen the lug nuts in the same "star" pattern that is used totighten them.3. Ensure all threads on studs and nuts are clean and rust free. I will use WD40 and a fiber or brass bristle detail brush, not steel, to clean the threads of any dirt, grease, rust, etc. Although WD40 aerosol does a good job of cleaning, make sure that the threads are dry before installation. This is important for proper torque readings.4. Install all lug nuts by hand, turning each one a few turns by hand, insuring it is not "cross-threaded."5. Torque the wheels, in the next step, off the ground. That is, with no weight on the wheel. Use either the car brakes or a wedge between the tire and the ground to keep the wheel from turning. 5. Progressively tighten the nuts -- ALWAYS USING A "STAR" PATTERN. That is, do not tighten the nuts to the recommended tourque the first time around. I run each nut down (IN A STAR PATTERN), using a "four-way" lug wrench, to about "hand snug", not tight. Next I use a calibrated torque wrench to tighten each nut to about 45 lbs, then around again to about 60 lbs, finally around again (ALWAYS IN A STAR PATTERN) to a couple of pounds over the minimum recommended torque.6. After 50 to 100 miles, with cold wheels and brakes, loosen (never use your torque wrench for this), about a half turn, and re-torque, individually, again in a Star pattern, each lug nut.

This really isn't as difficult, nor does it take as much time, as it seems at first. Once you have done it a few times it goes rather quickly. I have two deep six point sockets (available at Sears - Craftsman - with lifetime guarantee) that I use with a 6 inch extension on my torque wrench with the other one on either a breaker bar or speeder handle, depending on what I'm doing. This way one doesn't even loose the time of switching the socket to the different tools.

IMPORTANT: All torque values are given for clean, dry (not lubricated) threads, unless otherwise noted. Lubricants dramatically reduce the amount of torque to be applied to a nut or bolt -- something on the order of 35 to 55%, depending on the type of lubricant. For instance, on a 5/16-18 thread/inch bolt, 20 weight oil would reduce the torque rating 38%, white grease 45%, and graphite and oil 55%. I would not recommend lubricating lug nuts.

NEVER, EVER, USE AN AIR WRENCH (IMPACT WRENCH) ON YOUR LUG NUTS. PERIOD. END OF DISCUSSSION. (Unless, of course, you want to ruin the studs, nuts, etc. I have even seen people that "only" use such weapons to remove nuts screw up and accidently have the gun on "tighten" and consequently over-torque a nut, stretching, and ruining, the stud. Somehow I don't think they replaced the then weakened stud.

I have never had a warped rotor on a car that has only had the above procedure always, religiously, followed on it. I have had many warped rotors on other cars that were not treated as well.

My XKR Coupe has the crossed-drilled Brembo brakes on it. I believe the cross-drilling allows centrifugal force (think squirrel cage fans) to draw considerable amounts of cooling air between the rotor faces and substantially cool the rotors.

One last point, if I think the brakes are at all hot, I do not allow the car to sit still. Rather, I let it slowly creep a little, even at stop lights, in order that the calipers do not sit over just one area of the rotors for any period of time. Only use the brakes lightly, not hard, before allowing the car to sit for an extended period.

http://forums1.roadfly.org/jag....html

[Jesda]

I avoid the problem with low-end pads. OEM pads always gave me warpage. Ryan told me about some high-end pads he used that completely chewed up his rotors.

[Jeff Williams]

Those are great instructions, but I think there is more....

5.1 Break-in pads and rotors easily. It is better to find an empty road for this. accelerate to 60 MPG, lightly apply pressure to brakes, to slow the car to 5 MPH, do not stop.5.2 Accelerate to 60, press a little harder to slow the car to 5 MPH, do not stop.5.3 Accelerate to 60, then apply more pressure to slow the car to 5 MPH, accelerate to 60, then press firmly to 5 MPH, do not stop.5.4 Accelerate to 60 MPH, then press as hard as you can, to 5 MPH, do not stop.5.5 Accelerate to 60, then stomp on the pedal, to activate the ABS, to 5 MPH, do not stop. There should be smoke pouring out of your front wheelwells, and your car will be stinking. The rotors should be nice and colorfull. The pads will be worn about 10 to 15%. This usually gets bystanders thinking you are completely crazy, especially if you use a small strip of road, and keep making u-turns. 5.6 Now, drive about 20 minutes, to cool the brakes without stopping.

This "Sets" the pads, and burns off all the crap, and tempers the rotors. I have never had a rotor warp, after I did this. I get about 20,000 miles from the rest of the pads.

I got this off of a thread Dennis did, about a year or two ago. It was a link to a web site. There is a great article on it, if you find it. I kinda put it in my own words.

Also, if you ahve the dealership or a tire store rotate your tires, ask them to use "torquesticks" on the air wrenches, and to manually torque the lugs. They do it for Corvettes and Ferraris, why not your Infiniti.

[elwesso]

Good post Jeff... Ill remember that.....

[Falkdesigns]

Those are basically Brembo's instructions up there, and also how I bed new pads / rotors.

As far as torquing, I always follow the star and start bolts by hand. My mechanic has a set of Matco torque sticks that prevent an impact wrench from over tightening and I use that for the final torque if I'm at the shop, or I use my torque wrench at home. I've never had a problem with warped rotors, and I have no idea how old my rotors are (I know pads were done last year), but they aren't warped. Even under hard braking there is no vibration, and I've always felt I could work in the NVH department somewhere since I'm so hyper sensitive to sounds and vibrations in cars.

[elwesso]

Usually warpage if first apparent with a slight vibration or shimmy of the steering wheel at 60MPH.. or when you just feather the brakes you can feel a little pulsing.....

[Falkdesigns]

Trust me, I've never met anyone more sensitive to sounds and vibrations in a car than myself. There are no vibrations at any speed or brake pressure in my car.

[maxnix]

One last point, if I think the brakes are at all hot, I do not allow the car to sit still. Rather, I let it slowly creep a little, even at stop lights, in order that the calipers do not sit over just one area of the rotors for any period of time. Only use the brakes lightly, not hard, before allowing the car to sit for an extended period.

I do this all the time after a brisk deceleration. Kind of stop behind by 10 feet and every few seconds move forward a foot or two. Will shift to Neutral to allow release of brake pads on level ground.

[squeefoo]

Trust me, I've never met anyone more sensitive to sounds and vibrations in a car than myself.

You have now.Does everyone you drive with think you're nuts too ??I can't believe they can't feel/hear some of that.

Four clicks down from the top on my rattle gun, gives me ~ 85 ft/lb.FSM says 72 - 87 ft/lb (pg. MA 26) Guess I'm just lucky

Keeping the hubs and rotor hats clean makes a big difference too. Looking into brake ducting for the next DIY project. All the 300ZX kits look like they'll work (someday I'll have a camera).

[Falkdesigns]

You may be as sensitive to the sounds and vibrations in a car as I am, but I seriously doubt you are more so. I am VERY in tune with the machines I drive.

Can't feel or hear what? My car doesn't make any noise.

My wife's Accord wagon has some annoying little sounds in the doors and dash, but she can't hear it unless I turn the radio off and really describe it well. Her brakes used to be warped, I replaced them with Brembo OE replacements and QS pads a year and a half ago, still perfect.

[Jesda]

Mechanical vibrations? Thank goodness for loud hip hop.

[elwesso]

You know i can feel things, but id assume be immune to them... If people dont like it, too bad.....

But alas, i tend to notice a lot of things, but I generally learn to ignore them or cant afford to fix them (usually both)

[squeefoo]

Can't feel or hear what? My car doesn't make any noise.

When I drive or ride shotgun in other people's cars.My Q is mint (see below) too, lots of work and $ over the last 6 years.

Slight wiggle in the FR rotor now , therefore brake ducting after I put the dial indicator on it and weigh it, then re-index to the hub in tension. Might have to have it turned if the re-index won't do it.

[Falkdesigns]

I see what you meant. No, they don't think I'm nuts, they just know that I'm a car freak. I'm also the person that most of my friends / family turn to when looking for a new car or having problems with thiers.