Chewed up my brake piston when rebuilding Caliper 83 240D - PeachParts Mercedes-Benz Forum

Carrameow · #1 03-18-2003, 10:25 AM

I am rebuilding my Brakes on an 83 240D from a pair of ATE's I found in a junkyard. One of the calipers was stuck so bad, I had to use a huge pair of vise grips to extract it.
Unfortunately, I chewed up and marred the top 3/16" of the machined piston area (no to be confused with the non-machined ridged area that sits on the top of the piston).
I still think I can still use this piston because the top 3/16" of the brake piston's machined area sits above the line where the caliper's internal seal seals the piston.
Does anyone know if I can?

Finally does anyone know what comes in an ATE rebuild kit?
I was curious and took one pair of the two calipers and unbolted the two halves apart to see what the cross section looked like. There are two internal orifices that will now need O rings when I rebolt the two halves. Does the ATE kit have these parts?

Wasuchi · #2 03-18-2003, 12:26 PM

How chewed up is the piston? If it isn't very bad try some very fine sandpaper to smooth it off..... worked well on my slightly pitted Bendix piston, 400 I think was the # on the paper. If it's bad I would try to locate another piston just to be safe unless you are totally sure that it will work. Sorry, don't know what's in the ATE kit, the Bendix had the o-rings for the pistons, rubber boots for pistons, and the metal thing that the pad sits on. You might be able to find the right size o-rings if you look at some used for ac systems.

Capt Kirk · #3 03-18-2003, 12:56 PM

the ATE set came with a metal lock ring and a seal. This was from a year ago, so there might have been a second rubber piece, not quite sure.

samiam4 · #4 03-18-2003, 11:32 PM

Sounds like you need another caliper...

Instructions are pretty clear never to take them apart at the joint. Realignment of the two halves to be perfect +sealing is suggested as a rebuilder only job.

Find another caliper...

Michael

P.E.Haiges · #5 03-19-2003, 12:46 AM

Samiam4,

Where are the instructions to never take calipers apart at the joint? How can you rebuild the calipers without taking the 2 halfs apart? I have taken calipers apart replaced the parts and reassembled them with no problems.

P E H

samiam4 · #6 03-19-2003, 12:36 PM

Every manual I've ever looked at...

Try looking it up in the MB cd's. Rebuilding without breaking them apart is possible. Never said you would have problems-just that it is suppose to be done.

Personally, I use to get calipers pretty cheap- so it was a no-brainer to replace them. Until recently, the 123 calipers were in the $50-60 range.

Michael

psfred · #7 03-19-2003, 07:08 PM

Low pressure (15 psi) air will push the pistons out -- you can use a C-clamp to hold one side in while pushing the other out. The only parts I ever replace are the dust boot, heat shield, and piston seal, which is what comes in the kit.

I've always felt that since I could easily do the work without taking the halves apart, there is not need to do so, so I don't.

If a piston is so stuck you have to take huge visegrips to get it out, both piston and caliper are shot, don't bother, get another one.

Scratches, gouges, dents, and rough spots will cause the piston to either stick or refuse to seal, so if not perfect below the seal, ditch it. Not worth the cost of loosing brakes at a deeply incovienent moment.....

Peter