Do you think .030 of rotor runout, measured on the OD would cause problems?

 

Do you feel any vibration when applying the brakes?

 

No I feel vibration all the time, with a peak at 65 MPH.

 

Don't think you have a rotor problem, sounds more like a tire problem.

 

That's what I thought, had the Pirelli's load forced balanced - No Change, rotated - No Change, indexed the drive shaft - No Change, replaced the tires - No Change. What to buy a set of low mileage Pirelli Scorpion tires 275/55 R20? Called up Bear Brakes and told them how far they were out, they are sending me two new ones. They said run out should be no more than .003 not .030. Can't wait till they get here. I sure hope this fixes my steering wheel nibble; nothing else has made a dent.

 

Is that .030" or .003" ? Almost can't believe you could drive something with thirty thou of runout and still hang onto the steering wheel. I turned my rotors this week for a measly 5 thou, any pulsation drives me nuts. By the way, Ontario, Canada specs say that 3 thou runout is the limit, more must be turned or replaced. (as per the G.M. dealership I was working at the time.) Ford specs, don't know. So in my opinion, yes, .030" runout is too much, and yes, it's the source of your steering shake.

 

I'm not sure for the F150 (still don't have my F150 tech docs yet), but the service installed spec (calipers removed) for our F350's and Excursion is 0.0015 and I believe it's the same for our Rangers. I'd imagine the F150 would be the same. The average cheapo gauge that only measures in 0.001 increments is not good enough for accurately checking runout. To do this right, you need a gauge that accurately measures in at least 0.0001 increments. At 0.003, you'll be way out of spec on the runout (installed runout) and that much difference definitely will cause pulsation, but there are other reasons why pulsation can occur such as from worn slide pins, or off brake rotor wear, or from carbides (rapid heating / cooling causing hard spots), or from one or more pads hanging up in the tension clips.

Make sure to torque the lug nuts evenly because a differential of 20 lbs can distort a rotor beyond spec depending on the stiffness of the wheel. Also, tightening each sequential nut in a circular pattern can add stress and distortion into a rotor, so make sure they're properly torqued.