I was driving next to a Lexus IS 300 yesterday on the highway. It had some road racing spoke rims on it so it was fairly easy to see the brakes. On the right rear, I could clearly see rust spots on the rotor and it didn't look like the rotor was spinning.

I swung around to the left side and the rotor was cast iron gray and looked "normal".

Is this a design I've never seen before that makes it possible for the wheel to turn but not the brake?

The rotor wasn't just rusty orange, but I'd swear that I could see spots, like if water got splashed on it and was left for several days.

...not unless something is broken. Maybe a 2-piece rotor that somehow got separated from the hat.

maybe an optical delusion,(I know I said delusion) like when a wheel appears to be spinning backwards as it slows down.

Maybe, but the brake definately wasn't working.

just a thought.

maybe an optical delusion,(I know I said delusion) like when a wheel appears to be spinning backwards as it slows down.

Maybe, but the brake definately wasn't working.

This is exactly what I was thinking also. The illusion of the wheel going slower then it actually is because of the speed makes it look like the rotor is actually not turning.

And the fact that it really is rusty brown tells you that the caliper is most likely, siezed up and hasnt been working for a while and the rotor has started to rust.

...not unless something is broken. Maybe a 2-piece rotor that somehow got separated from the hat.


I've seen rotors broken right at the base of the hat before. People just keep driving, wonder what that noise is. I've also seen vented discs worn so far down, the outside braking surface was the actual vents themselves. :clonk:

:mr hand: "Are you on dope?" :mr hand: :beers:

I've also seen vented discs worn so far down, the outside braking surface was the actual vents themselves. :clonk:

I've seen the rear surface worn down that far! I was pretty sure I was the only person to ever have seen that.

My dorko cousin drove his car metal to metal so long that when he decided the change his brakes his rotors with actually thinner than sheet metal. I was able to snap them off like crackers. That was one of craziest things I'd seen.

I've seen the rear surface worn down that far! I was pretty sure I was the only person to ever have seen that.

A lady comes into the shop.
"My brakes are making some noise."
"Ok, we'll check it out for you."
We pull the front wheel and sure enough, the rotor is worn halfway through the vents. Then we go back to the lady.
"Exactly how long have the brakes been making noise, ma'am?
"Only a day or two."
"RRIIIIGGHHT":noway:

I've seen rotors broken right at the base of the hat before. People just keep driving, wonder what that noise is.

The noise will eventually go away, so why worry? ;) :D I have seen rotors like that too, seemed like they rusted off all the way around the perimeter of the hub. This could be the case with that Lexus, a separated rotor that was only held in place by the caliper. Must have made a terrible racket though... at least for a while. :D

I actually found a rotor like that at a redlight once, it had separated from the hub, split in half and fallen off the car. I'm sure that was an interesting experience to the driver. :)

BTW: At what time of the day did you see this? The illusion that the wheel is turning backwards or not turning at all can only be seen in artificial light, not in daylight.

The illusion that the wheel is turning backwards or not turning at all can only be seen in artificial light, not in daylight.
Right. The illusion is caused by the street/highway lights. AC powered lights, operating at the US standard of 60 Hz, actually cycle off/on 60 time a second. Can't see it for the most part but the cycling causes a strobe effect. When the rotation speed of the wheel matchs that of the lights cycle - bingo, they can look like they aren't even turning. Turning just a little faster or slower will make them look like they are turning backward, or forward. The degree to which one can see it also depends on how much light the particular wheel design reflects.

BTW: At what time of the day did you see this? The illusion that the wheel is turning backwards or not turning at all can only be seen in artificial light, not in daylight.

Can't recall precisely but it was about 3 or 4 in the afternoon. Partly cloudy but still plenty of daylight.

I've heard of (and seen) the effect you guys are talking about when something is spinning at just the right speed something looks stationary or moving backwards.

which effect causes one to see rust spots?