72' 280se 4.5 brake pad replace

[tjohnson]

putting on a new set of front pads today. here is where I am at: removed pad cover from caliper, knocked out retainer pins, opened bleeder and removed old pads. with bleeder open depressed caliper pistons on both sides. the new pad fits the outer side fine...the inside doesn't have near enough room to even begin to slide in the new pad. what am i doing wrong?! thanks for any help....i can see the inner piston is depressed

[Mike D]

A couple of possibilities. You might have a ridge on the outer rim of the rotor or the inner piston is not depressed all the way. Both of those circumstances are quite common on the inner caliper half. Any gunk in the system tends to build up in the inner caliper housing.

I usually dont open the bleeder screw to compress the pistons. I do open the bleeder after the pads have been changed and gravity bleed until clean fluid appears.

[tjohnson]

I was wrong! it is the inner piston, not depressed....the dust excluder in full view was throwing me off. the sucker is stuck too, doesn't want to budge

[Mike D]

You've got torn dust boots on the caliper. Look very closely at the rubber and look for cracking. I've temporarily resusicated calipers by spraying some rust buster into the split under the rubber, applying pedal pressure to expand the caliper and working it back.

Put the old pad back into place before applying brake pressure. Usually 4 or 5 times of the alternating routine will get the piston freed up. Use brake cleaner and compressed air to remove the rust buster fluid be fore installing the new pads.

Time for a rebuild. It's easier to get rebuilt calipers (always replace in pairs) than to mess about with rebuilding the set you have.

[tjohnson]

thanks again Mike. Yep, time for new calipers.