So per my recent thread it seems that one of my pistons is getting stuck so I want to give my hand at rebuilding it.

I haven't done a caliper rebuild before but I found a video on YouTube for an sl500 4pot fixed caliper and I figure it would be the same process but with my 2 piston.

As far as brands go...the genuine MB is 45 a side while thr ATE kit is 10. Is there a big difference or is the ATE kit ok?

Any other general tips? My piston isn't frozen as I was able to push it back to get the new pads in...but it's just sticky and wearing one pad down faster than the other.

I'll do both calipers in the rear to maintain same braking power.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

You're just a glutton for punishment aren't you?

I have a boat-load of experience rebuilding calipers and my advice is to buy a set of rebuilts. Seriously. The amount of money you might save is not worth the risk.

f you do decide to rebuild them then CLEANLINESS is the key. Don't split the calipers (if they are two piece type) because getting the proper seal gaskets are a royal PITA to find.

ANY rust or marks in the surface of the pistons make them junk. It's normal for there to be wear lines on the pistons from the rubber seals. If they don't disappear with the use of brake cleaner and a light scrub of 0000 steel wool or a "scrubbie" pad then they should be discarded.


When reassembling the calipers, do NOT force anything! The pistons should slide into place using hand pressure. Make sure the seals are properly seated and don't nick them with the pistons or whatever tool you use to install them.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

I have a set of 400E calipers that I rebuilt and getting the boots on were a PITA! I ripped 2 and had to buy them again.used silicone and it still took hours just for the boots. Finally got it done and put them on the w201 and the stock rims wouldn't even clear them. Lol. Now I have them sitting until I get some stock 400E rims. I would probably go with the rebuilt option. That way you won't spend time trying to clean everything up and buy all the parts and if it's defective you can return it as a whole unit.

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1990 190E 3.0L

Buy off the shelf rebuilds. ( And I can / have fixed or rebuilt _everything_ on a car from engine to rebuilding window motors to rekeying locks. )

When the pistons start to stick, it is from rust build up between the piston and caliper top lip. Any marks on the piston won't seal. Rebuilders grind then re hard chrome the pistons.

The dust boots are difficult to install without a press and a tool to hold then square. The dust boots have a steel ring inside the rubber that will tear out if you hammer on them.