What is the correct hex socket/wrench size to undue the caliper mounting bolt for a 1986 Firebird TA stock oem caliper. I bought a 10mm hex socket but it does not fit, a little too big.

 

3/8"

Just like every other GM car of the era.

 

That's what I am saying, 3/8" is 10 mm. I tried an 8 mm, which was a little too small, so must be 9 mm. I used a ruler on the caliper bolt opening. Measures 9 mm not 3/8" or 10 mm. My 3/8" or 10 mm hex socket is a little too big.

 

3/8" is close to 10mm but not the same thing. So if you wanted to try a 3/8" then you might be able to get the calipers off.

EDIT: Seemed like I said that kind of dck-ish. But I'm meaning to give a light-hearted spin to this. Doesn't seem to be working.

 

you are correct. I went to an auto parts store before your post and tried one of their 3/8" hex socket in one of their caliper bolts. fit perfectly. tried my 10mm, did not fit. The reason I got the 10mm in the first place is because on the brake board there is a post on how to redo you brakes and the fellow mentions getting a 10mm hex wrench for the caliper. Maybe one of the moderators should change it to 3/8" so people won't waste money on the wrong socket ie. metric . Anyway thanks for your help. now I can do my brakes.

 

10mm is .393 inches, 3/8 is .375 inches in decimal form.

 

Thank you Google.