I have a 98 Expedition (56,000 mile)that is going through rotors every 5000-6000 miles. SUV drives straight and true until brakes are applied and them I get the shimmy in the steering wheel. I have taken it to 2 seperate ASE mechanics to have them look at the entire system. This last time everything was OK except for rotor warpage. The rotors were new so I had them turn the rotors/new bearings/pads ect.... The time before last was new rotors/and bearings (pads OK). SUV drives great until about 3000 miles after rotors have been turned and the shimmy keeps coming back. All parst use are Ford Motorcraft Parts. Both times I asked the mechanic to look close at the calipers and see if they were sticking..... everything (including calipers) OK by both mechanics. SUV makes NO noises(braking) and has been a great vehicle. I was going to give this vehicle to my son next year, but would like to get the brakes squared away. Any help would be great.

 

Assuming their is nothing wrong with your calipers................ my experience dictates that most warped rotors are caused by improperly torqued lug nuts.
Lug nuts should be torqued in a cross pattern a lttle at a time. 30, 50, 70, 90ft-lbs, etc. Many garages use air guns to tighten the lug nuts and never are they tightened to the proper torque. Some garages use what they call torque sticks on their guns which brake away (clutch mechanism) at a specified torque, but still never tighten the lug nuts in a cross pattern, this puts uneven stress on the rotor and when they get hot from braking, warp. In all my years as a mechanic I see more warped rotors due to improper torqueing. Never, never let anyone use an air gun on your front wheel lug nuts, specify hand torqueing and watch them to make sure it's done by hand! If your rotors warp after new tires are installed or after brake work is done, bring it back and demand they repair it at no cost to you. 1990 Toyota 4-runner, 150,000 miles, 6 sets of brake pads installed myself, no-one touches my lugs! Rotors never warped. 1999 Ford Expedition, rotors turned at 65,000 miles after I ran the pads to thin. Still the stock rotors. Never, ever had warped rotors.
On the other hand, my sister with her Dodge sedan and my brother with his Ford Ranger have had their rotors replaced twice........ right after they had tires replaced! Interesting!

Cheers!

 

Yeah I thought of that, but I watched them torque down the lug nuts with a torque wrench and not an impact wrench when I had the tires rotated at the last rotor turning evolution. I didn't however verify the torque setting..... I hoped he had it set correctly.

 

If they get to hot even once they can warp. Are your rear brakes working OK or are your fronts doing all the work?

 

I'm assuming they are working OK..... Both mechanics said they were fine.