Well, for some reason, the new front brake pads I purchased for my replacement project will NOT for the life of me slip into place. I've pushed the pistons in as much as I can, and they seem flush with their caliper holes that they're in, but I just can't get the new thick pads in!?

Does anybody have some helpful suggestions here? This was very aggravating because it seemed like if I only had fractions of a millimmeter more of clearance they would have gone in? I had to abandon the project for the night and I can't drive now. What's going on here?

Were the new pads I bought bogus or something, and too thick? Perhaps the rotor was deformed somehow at the outer edge so that it is thicker than it came from the factory originally? Anybody have some ideas here? I'm really frustrated.

Any help PLEASE!?

are you certain you bought the right pads for your caliper manufacturer?

is there a ridge of rust along either the outer or inner perimeter of the rotor outside of the contact surface?

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you need to use a vice to push the pistons all the way in

Yes... I suppose there is some rust where the pads did not wear away the rotor and it was left at it's original thickness.

Would it hurt to try filing away some of the rust on these edges to see if I can get clearance? It's just that outer edge/rim that I need to get past, as once I'm past that, there's the groove where the old pads wore into the rotor, but just a millimeter or two i think down....

I was using a c-clamp to push in the pistons, and I think I got them pretty far in.... seemed like they were flush with the rest of the interior calipers...?

Was this not enough?

Thanks all for the suggestions... keep them coming...

I had that problem with Mintex Pads...they were just too thick. Using the Autozone pads helps a lot, they are about 10% less thick.....or the PBR Ceramics....they are about 10-15% less thick as well, really makes it easier getting them in. I ended up trashing the Mintex.....they would probably work with brand new rotors/calipers, but if they are old and don't like going in all the way, there will be problems.

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Put your old pads back in and use a large screwdriver to pry the pistons back by prying between the rotor and pads. The rotors are tough. You won't hurt them.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

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I could be that the pads are not correct for your year model. Earlier W123 versions used a thinner pad.

i had this problem before and it is easily fixed....do this.... you have to loosen the whole caliper from its mount. there are two big bolts that hold it to the car. you need to loosen them enough to give you enough clearance. the pads will easily go in. once in place, just tighten the bolts and you are done!

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Ben
1987 190d 2.5Turbo

Some brake pads do not come with the circular chamfer for the ridge close to lug holes.You can wear a dust mask and grind with a small grinder outside.

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Did you remove BOTH brake pads on the same caliper and THEN push back the pistons? If so, what can happen is that one of the pistons gets pushed out too far allowing the seal to fold.

The correct method is to remove one pad, push the piston back into its bore and install that pad. THEN pull the other pad and push THAT piston back into its bore and install the new pad. This prevents the pressure from the pressing of one piston from pushing the other piston out too far.

Are the pistons oriented correctly so that the heatshields go flush to, or have a slight recess with, the caliper? FSM says the piston should be 0.1 mm past the heatshield. Do you have a "crescent" of the piston making contact with the back of the pad, or the metal heatshield itself?

At some point in my car's past the calipers were not correctly rebuilt and the heatshields wouldn't fit. The PO just forced the heatshields onto the pistons. There would be no way to fit new pads onto that combo with a good rotor.

New pads and a new-ish rotor make for a very tight fit. The pistons had to be ALL the way in on mine. I used a C-clamp and the old pads - but the calipers were off the car since I was doing a caliper rebuild (trashed dust boots and heatshields).

Regarding pushing the pistons in, I was advised that I should open up the bleeder screw so I am not pushing brake fluid / dirt / air back up the line while forcing the pistons in. Theoretically there should not be dirt or air in the line at the piston anyway, but I tried this and is was sooo much easier to push the piston in with the bleeder valve open. I did not need a clamp at all. Of course, I had a clear hose connected to the valve and going into a bottle, and was planning on bleeding the brakes anyway. The clear vinyl hose allows you to see any air bubbles and also which way the fluid is running.

With the pistons all the way in, I knew if there was resistance somewhere, it was not the piston sticking out too far. I did have to scrape some dirt or rust away from the sides where the edge (width) of the pad fits in, and that was my problem. But without the piston being all the way in, I would not have known that.

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