Replacing Rotors and Caliper Mounting Bolts

[andrewc4]

94 Polo Green Coupe - 102450 miles, daily driver.

Do I have to remove the caliper mounting brackets to get the front rotors off? The service manual says yes, and also says to replace the caliper mounting bolts.

The bolts require about four million pounds of torque, actually 165 and I weigh 150, so I could hang from an extension bar and still not be able to loosen the bolts. :ugh

Do I really have to remove the caliper mounting bracket or is it possible to twist the rotor past the bracket? Any tricks for loosening the bolts? Do you actually replace the bolts as the service manual suggests? Do you replace them because they're similiar to head bolts and stretch as they are torqued?

I've been doing brakes since the my first car, Toyotas, Chevys, Fords, Mopars and Buicks, but this is my first rotor replacement on my C4.

 

[Dougs91]

andrewc4- don't think my 91 is any different from your 94,and I did have to remove the mounting bracket to remove the rotors. I used a 2 ft. breaker bar with a 13/16" 12PT. socket. You can buy new bolts from GM(they have the threadlock already on them)or just reuse the old bolts and put some "locktite" on them.Make sure to hang your calipers up with wire ,or something,don't let them just hang off the brake lines. C4 brakes are easy!! Good Luck Doug

 

[Hib Halverson]

You must remove the caliper brackets to get the rotors off.

As for the replacing or reusing the bolts, there's a lot of opinions on this.

Some say the reason GM specifies bolt replacement is that the bolts are torque-to-yield fasteners, which, of course, cannot be reused.

Others believe that the reason GM wants them replaced is that the stock bolts, as discussed previously, have a threadlocker applied to them during manufacturing and GM wants that particular thread locker used so it specifies new bolts.

My personal opinion is that they are probably not torque-to-yield bolts and can be reused as long as 1) the bolts and bolt holes in the knuckle are in good condition, 2) all threads on the bolt and in the holes are clean 3) a thread locker (ie: Locktite) is used on the bolts during installation and 4) they are tightened to the specs in the service manual.

Lastly, note that the torque specification for the rear caliper bolts was misprinted in several model years of service manuals. In those books the front spec. (which is for a larger bolt) is listed as the rear spec.

 

[andrewc4]

Very good guys, thanks for the reply. I'll go with new bolts from GM. Again, thanks.