And also, when I do brakes, I ALWAYS (and have for 20 some years), put a dial indicator on the new rotors to make sure they're running 'true'. Otherwise you could end up putting a lot of time into brakes and end up with a crappy job ...when, with just a little more effort you could end up with a first-class job. I just got tired of 'guessing' and trusting the new rotors to be 'true', when many times they just aren't. I would never just throw on a set of rotors and go.
Reasons why new rotors might not run 'true'?
1) Rust on the hub face you didn't get removed, or a flake of rust fell in as you were installing the new rotor
2) New Rotor came pre-warped! Yeah it happens a lot. I've taken several rotors back to Napa and OReilly's. There was a time years ago where I bet 60% of the rotors I got from the local napa store were pre-warped. Even my buddy there admitted they had a crappy supplier and eventually had to stop selling theirs. That was quite a while ago, and the china quality has gotten a lot better. But I still get an out-of-spec rotor from time to time.
3) Un-true hub. Can hubs really be out of spec? Sure. I bought a hub/bearing assembly 2 years ago at ORelly's (not their cheap version either) and the hub face brand new out of the box was .005 out of spec. A guy would never get a rotor to run true on that hub and the wheel would wobble. But if a guy had a used truck and the previous owner hammered on the hub, he could put deformaties on the hub ...which maybe could be filed smooth (or replace the hub).
4) Hub/rotor manufacturing tolerance differences. A lot of times if a rotor measures out-of-spec initially, you can rotate it on the hub and get it to run 'perfectly'.
Get some
over-sized nuts (for bolts), which will fit OVER your truck's wheel studs. Put them on the studs and tighten the lug nuts. Just get them snug, not full tightness. A wheel distributes the clamping pressure across the entire rotor, the over-sized nuts don't distribute pressure as much. You don't want to distort the rotor and get an errant reading. So, just tighten to 30 lbs or so.
A good spec to get your new rotors at would be .000" run-out. I wouldn't settle for anything more than .002" In fact my vehicles, the most I would settle for is .001. And
make sure your caliper sliding surfaces are filed clean, esp if your truck has stainless steel sliders (rust can build up under stainless sliders, preventing the pads from releasing away from the rotor). . Watch the 2nd half of this video. Look up a dial indicator and base at Harbor Freight.
Video tutorial on how to check a rotor for warpage. Rotor warpage is usually caused by extreme heat from either hard braking, riding the brakes, or having a ...
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