Can anyone tell me what the minimum rotor thickness is for a 1969 to 1970 Olds 98 front rotor mine are 1.244 I think its 1.250 but I need to be sure before I turn them!

 

The minimum allowable thickness should be cast right into the hub of the rotor.

 

If I were in your shoes I might not have the rotors turned unless you have plenty of metal there to remove. It would be better to live with warped rotors and have to replace the brake pads more often than having to track down a new set of rotors for your car. The reason being, it is impossible to find new rotors for the early B/C bodies.

Either that or take the rotors to a small mom and pop shop that don't care about minimum rotor thickness. Of course, then you are dealing with the devil. It depends mostly on what you use the car for and why you are doing a brake job.

 

I saw a photo recently of a rear rotor from a nineties era Mercury that had worn through! There was nothing left but the outer ring of the rotor. Did anyone else see that? I can't remember where I saw it ROP or here......not sure???

 

I saw it too. It was a solid (non finned) rotor.

I had something similar happen to me when I was 17. The left front rotor on the 75 cutlass burned through the rear down to the fins. Lost the front brakes when I Was 40+ miles from home and had been up for 36+ hours. I drove it home....yeah yeah I know...to be dumb and 17 again.
To my defence the brakes were VERY solid before it went and were not making any noise because the previous owner had replaced the pads without doing the rotors. Hence no squeal.

 

Unfortunately there is no minimum thickness cast in to the rotor. This is not uncommon as I have seen it many times when I was working as a mechanic! The rotors are not warped just need resurfaced. I was just hoping to get .008 too .010 taken off but its hard to find someone competent enough to do so my engine lathe does not have the capacity do do it with out major modification. and its an antique so I don't want to ruin it.