are warped rotors visible?

I've been reading a bit about warped rotors, overtorqued lug nuts, turning versus sanding rotors, and measuring the specs of the rotors'
thickness, etc.
OK, so I can put a tool on the rotors and check the size, but can I use this tool to see if the rotor is warped?
I have a shimmy in the steering wheel when I brake. I also know that the front bushings on the car are pretty well shot.
So, not knowing if my shim is from rotors or bushings, I'd like to try and determine this. I have all of the replacement bushings, so I want to replace these. Would it be practical to replace the bushings, then clean/sand the rotors and replace the pads with OEM pads, clean everything, and if it still shimmies, then just replace the rotors?
Any problems with trying new pads on the old rotors and just replace them last if needed?
Thanks.
PS: forgot to add I should re-pack the wheel bearings.
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In an earlier contribution to this discussion,

In order to check whether the discs (rotors) are running out (warped) you need a dial indicator like http://tinyurl.com/lpy4r with a magnetic base to attach it to a fixed part of the hub. The little plunger has to press against the side of the disc. You then rotate the disc and, if there is any lateral motion, the plunger moves in and out - causing the pointer to move. You then need to compare the run-out with the maximum permitted amount, and get the discs machined or repplaced if not within tolerance.
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Roger
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Ingenious! There is a tool for everything - it seems. Unfortunately we're expected to exchange currency for them.
;-(
Jamie
Roger Mills wrote:

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Or, just remove the tire and wheel, turn the rotor by hand and eyeball it.
If it's warped, you'll see it.
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snipped-for-privacy@comcast.net wrote:

yep... and you can rig up any old thing to get a pointer (pencil on top of a jackstand, or whatever) up next to the rotor. Spin it 'til it touches only at the highpoint, then rotate until the gaps the biggest and slide a feeler gauge (or yardstick, depending on amount of warpage) in there to measure the runout.
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On Mon, 05 Jun 2006 12:24:25 -0700, zencraps wrote:

Nah. Consider the runout spec for the 700/900 series Volvos (I don't have it off hand, but I'm pretty sure it's in the FAQ). Runout of a few microns (warped rotor or just not mated properly to the hub) will cause noticeable pedal vibration. Try eyeballing *that*.
--
alex

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In an earlier contribution to this discussion,

I think you might just find something similar on sale in your part of the world! <g>
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Roger
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