Rotor thickness?

[ABfish]

The most recent improvement to my Mark III Sprite was the installation of rebuilt shocks from Pete C at World Wide. As mentioned numerous times on this forum, World Wide provides a good product, reasonable prices, and fast service.

While installing the shocks, I noticed that one of the front brake rotors is markedly thinner than the other. The left side is about 1/4", while the right side is about 3/8". (I've got a digital caliper, but did not check with it).

What's the minimum acceptable thickness for these rotors? The car stops well, but if the thin one is way out of spec, I'll replace it as soon as possible.

 

[Sarastro]

Are the rotors for these cars all the same? If not, you might have an incorrect rotor intended for an earlier or later car. If one has been turned down, an eighth of an inch seems like the limit, or comfortably beyond it.

Sorry, I don't know if they are all the same; I drive a bugeye and don't know about these newfangled-disk-brakey thingies. But in any case, something is definitely amiss, and you really should make sure you have correct rotors.

I'm sure someone will follow up with the straight dope.

 

[ABfish]

My shop manual indicates a minimum acceptable disc thickness (actually it says "width") of 0.29 inches for a Mk IV Sprite, but does not list a thickness for the Mk III.

I just measured my "thinner" disc - it's only 3/32 in. or about 0.09 in. I've never seen a rotor that thin, but then I've never owned a 1600 lbs. car, either.

 

[jlaird]

.09 is too thin in my opinion. Check a new one. Don't want to screw up a disc.

 

[aeronca65t]

8 mm (about 0.31") is standard thickness.

They can be cut down to 7 mm.

 

[ABfish]

8 mm (about 0.31") is standard thickness.

They can be cut down to 7 mm.

I guess I need to add a new disc to the project list. At least they're fairly cheap.

 

[Sarastro]

I'm stunned that anyone would turn down a disk that much. Disks for bicycle disk brakes aren't much thinner than that.

Sure you didn't mean 3/16"? Even that's awfully thin, though.

 

[ABfish]

I'm stunned that anyone would turn down a disk that much. Disks for bicycle disk brakes aren't much thinner than that.

Sure you didn't mean 3/16"? Even that's awfully thin, though.

I couldn't believe it was that thin, either. It looks like something from a 5hp go-cart. I assumed it was normal until I removed the other front wheel and realized how much thicker that disc was. I'll get an exact reading of both with a digital caliper tonight.