Rebuilding Caliper Instructions?
 

Can anybody tell me, or tell me where to find, step by step instructions for rebuilding the front calipers on my 1994 E420? Do I need any special tools (i.e. air tools)?

You should be able to find detailed instructions in most any service manual.

There is not much to it though. Remove the calipers, use compressed air to blow out the pistons and DON'T get your fingers where the piston can be hit. Once the pistons are out, carefully clean bores, pistons and grooves without abrasives or scratching. Put your new seals in place in the bores, coat them, the bores and pistons with brake fluid and push the piston in carefully without folding the seals. There will als be some outer dust seals to install.

Reinstall calipers and bleed.

Good luck,

ARe they fixed or floating?

From reference material, I have not done this procedure.

Fixed caliper;
1.press off dust cap from housing with screwdriver
2. Insert metal segment (1.1 inches thick) into fixed caliper, then carefully force pistons out against stop with compressed air. If piston is siezed due to rust, replace complete cylinder housing.
3.remove deposits on pistons with soft brass wire brush or rough cloth only. If there is noticable damage to chrome plating, replace piston.
4.Remove piston seal from groove in cylinder bore.
5. Check cylinder bores in fixed caliper for signs of wear. If bore is scored or rusty, replace complete floating caliper.
6.Lightly coat new piston seal with ATE brake cylinder paste and insert into groove in cylinder bore.
7.insert piston into bore in fixed caliper.
8. Replace dust cap by installing on piston and positioning at collar of fixed caliper, then press onto collar with pliers.

Floating Caliper:
1. Remove self locking bolts
2. Remove heat shield
3. Force out piston with compressed air and using piston turning tongs. If piston is seized due to rust, replace complete cylinder housing.
4. Remove deposits on piston with soft brass wire brush or rough cloth only. If there is noticable damage to chrome plating, replace piston.
5. Remove piston seal from groove in cylinder bore.
6.Check cylinder bore of floating caliper for wear. If bore is scored or rusty, replace complete floating caliper.
7. Lightly coat new piston seal with ATE brake cylinder paste and insert into groove in cylinder bore.
8. Replace dust cap, ensuring that cap is seated properly.
9. Install heat sheild. Retaining lugs must engage in upper piston groove.
10. Replace dust boots, ensurinig that boots are seated properly.
11. remove and clean sliding pins and guides. Coat with special grease included in sliding pin repair kit, then assemble and ensure sliding pins move easily.

It is interesting that these instructions, that I copied word for word, seem to have forgotten to replace self locking bolts, heat shield, etc, I have done many brakes and I when I read though this I had to stop and think, " OK, I guess step 11 is the end , now installation is the oposite of disassembly" If I had never done brakes before, I would have been scatching my head.

Hope this helps.

Thanks guys, you are the best!

Actaully, one more question, what exactly are floating calipers? I have a '94 E420. I am just confused as to the difference between the two types (floating vs fixed). How can I tell?

E420 has fixed calipers. That means the caliper is bolted, and does not move. The pads follow the rotor.

The floating calipers are bolted, but they can moved back and forth to follow imperfections in the rotor.

However floating calipers dont stop very fast, they are found on early model 300Es.

If you prefer to have those brakes, I can trade you. :D

Floating calipers
 

The following definition of floating calipers is not correct.

<<The floating calipers are bolted, but they can moved back and forth to follow imperfections in the rotor.
However floating calipers dont stop very fast, they are found on early model 300Es.>>

Floating caliper have the piston on one side only, pressing on the pad on the piston side and then drawing the moving portion of the caliper containing the other pad toward the disc. So, the caliper moves a bit when the brakes are applied. The main reason floating calipers are used is cost since they are a bit cheaper to manufacture. There is no particular disadvantage in them in everyday use but it's true, I think, that true high performance cars use fixed calipers with one or more pistons per side. Or, old and slow ones when things cost less. Disc imperfections don't come in to it.

My C280 used fixed on one end and floating on the other. My C320 uses floating on both ends. As does my Porsche. It's all about cost.

RLE/seattle

Pads are almost always in contact with the rotor even when the opporator is not pressing on the petal.

Fixed calipers are more expensive to make, there is a lot more metal involved with the casting of the calipers.