Brake pads dragging after change
 

I replaced my brake pads on Monday (the old ones looked awful, wow), and I've noticed that they drag now. It's not enough that I'm getting a noticeable drop in fuel economy, although I can see it boost harder off the line and coasts to a stop a little faster than usual ... basically drives normal though and the wheels don't get any hotter than they did before. When I lift the wheel off the ground you can really feel the resistance when turning it by hand (and hear it scraping). What did I do? I used MB brake pads from the dealer, MB brake paste, and everything looks fine. I bedded them in after installing them. Brake fluid level looks fine (I used MB fluid to refill since I bled some out to get the caliper piston in). Brake pedal feels normal and it stops on a dime. Where should I start?

Did you happen to look at the rubber dust boots in the caliper? If they were torn, the pistons may have been contaminated/rusted, so that when you pushed them in to make room for the new pads, they are not quite as free as they should be.

Were the pistons difficult to retract?

With the tire off the ground, kick it hard on the outboard side at the 3 and 9 o'clock positions. Then spin the wheel and see if it still drags.

Boots looked good. Both pistons were difficult to retract at first but after they went in a little they went the rest of the way fairly easy. I'm not sure how difficult they should be to push in so it was hard to guage. I used channel locks and didn't have a lot of trouble ... opened the bleed valve and lots of fluid came out as i pushed them in.

I'll try the kicking. That sounds like fun.

The purpose of the kick is to knock the pads away from the rotor. If that reduces the drag considerably, you probably don't have a problem. New pads are a bit rough until they break in, anyway. So, normal contact between the pad and rotor will be a bit more evident until the pads break in more completely.

disc brake dragging
 

My car has done this since I bought it in 2006, only the front wheels do get warm. I have replaced all 4 calipers, RF twice, all 3 rubber hoses to the wheels, all metal brake lines, and the master cylinder. I replaced the discs when I did the calipers, only now the heat has warped them. I have bled and bled and bled- it gets better for one 40 mile trip then reoccures. 80 240D with Bendix front and Abel rear calipers. I'm so frustrated about this that I'm considering pulling the power pack and putting it in my Ford Pickup with drum brakes, and scrapping the car.

Tango - you might be right but I have never experienced his problem and have been changing the pads since '84. Will be interested to see the final resolution; interesting problem.

Did you have to force the pads into the caliper..........or did they slip right in?

Did you happen to clean the caliper with a wire brush where the backing plates ride?

They slipped right in. The only thing I noticed was that I kind of had to smoosh the metal clips on the edge of the pads down to get the caliper to close all the way .. it didn't really want to go down all the way, even though it had clearance at the piston.

I did clean the areas of the caliper where the back and sides of the pads touch with a wire brush and brushed the excess dust off with a shop rag. I didn't use brake cleaner or anything and they didn't look shiny clean when done, but I got a lot of dust off.

Also, FWIW, all four pads that came out were evenly worn.

"Running In" new Pads/Rotors
 

Any body ever go to the trouble of breaking in new brake gear?

'Like 5 runs from 30MPH to 2MPH
'Then 5 runs from 60MPH to 10Mph

You don't want to let them completely STOP rolling during this process.
You're just trying to "Bed" the pads into the new rotors.

in the OP she says she bedded them in. I have been doing this recently- I never even knew it was SOP until this year- isn't the www grand....I did just put in some pads which claimed they were specially "cured" and did not require bedding in.... I still did it.


back on track.-

any chance you disturbed the dust shield on the back of the rotor- and that is now rubbing on the rotor, causing the noise's?

[QUOTE] The only thing I noticed was that I kind of had to smoosh the metal clips on the edge of the pads down to get the caliper to close all the way .. it didn't really want to go down all the way, even though it had clearance at the piston.
/QUOTE]

I dont quite follow this- but maybe the clips are dragging now?? if you remove the wheel, you should be able to see if they are all shiny looking from being ground down.

Interesting thought ... I'll take a look at them. I had a tough time getting the wheels back on (To a 110-pound girl those wheels are heavy) so maybe I knocked something off kilter in the process.

The clips I speak of are the butterfly clips on the outer edge of each pad ... they only make contact with the outer part of the caliper, not something that moves, but I wonder if maybe the back of the caliper pushes on those clips and moves the pads out of sorts. I don't think so, but just an idea.

A bent dust shield will make plenty of noise, but it's not going affect the way the vehicle performs.

The retaining clip? Those do create some pressure and the pads do have to over come that to retract a bit when the piston retracts as bit.

Some drag is normal based on the design. Warped rotors push the pads and piston back further than unwarped ones.

Some drag is normal with disc brakes. If you were getting enough friction to be noticeable when driving the brakes would be getting hot. It is likely there is no problem at all.