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Determine Minimum Rotor Thickness?

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Hello everyone,

 

This is my first time checking the brakes on my 1998 Legacy I purchased last year.  I want to check the thickness on the rear rotors but I don't know the minimum thickness.  I believe that it was embossed on the edge of the rotor but the lettering has rusted off.  It's not on the inside either, and I don't know the brand either.  Is there a standard measurement or does it vary significantly by manufacturer?

If they shake, throw them out. If they don't, don't worry about it.. The manufacture of vehicle lists it usually, but its not normally a concern unless you want to machine them.

Edited by matt167

The rears never need replaced. 260,000 miles on mine, but I've never measured them.

 

Fronts commonly cause vibration when braking, not the rears.

when they start to look like these - that is when replacement is due. :blink:

 

those are off my 1995 Legacy with well over 200K and living in Northern Wisconsin (salt!)

post-80-0-20663100-1464694770_thumb.jpg

post-80-0-49926300-1464694807_thumb.jpg

I would not be concerned about the thickness of rear rotors. They never seem to wear out. I have 235K miles on my 99 OBW, and the rotors still look good. Most of the braking action of the car is at the front wheels, so rear brakes last a long long time. If the rotors look good, don't worry about it,  just drive on.

Heartless those are some sweet looking rotors. Hang those on theXmas tree.

 

That's low miles for the year, did it ever sit for a period of time? Or have seized caliper pins- those are nearly guaranteed in the crust rust belt?

 

I wouldn't expect rotors to typically get like that with average daily driving, never sitting for extended periods or having extended caliper issues.

I agree with the above. Only when they get extremely rusty do I replace rear rotors. They don't warp.

 

 

 

But, since I have the service manual handy, it says minimum service limit is 8.5 mm (0.335 in).

When the caliper locks up and you just keep ridin.

 

Might be a little thin...

post-23241-0-34029700-1464720457_thumb.jpg

Fairtax - that picture is priceless! :D I love how the ring just floats in mid air, held in place by the caliper... 

 

as for how mine got in the condition they were in - they were like that when I got the car. I suspect it did sit for a while at some point... it was not being driven when I bought it (cheaply) due to tranny issues (no reverse) how long did it sit? hard to say, and the last driver was a teenager...

 

The front rotors were not nearly as bad, but they were getting grooves worn in them, so I replaced those as well.

 

surprisingly enough, the caliper pins were not that bad.  a bit of cleaning and re-lubing, new rotors and pads all the way around, and she was good to go. I did have to replace one front caliper due to a seized piston...

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