Brake Caliper overhaul

[knirk]

For years I have reconditioned brake calipers by splitting them in two. I have honed out any sign of rust and deposits in the cylinders, used fine emery paper on the pistons, and replaced the seals. I have accepted cylinder walls with some small craters. I have never had a new leak, and the brakes have worked perfectly.

Then I read the Brakes chapter in the BBB and discover that:
1.   The callipers should never be split!
2.   The cylinders may only be cleaned with polishing gloss, and the pistons only with a soft brass wire brush or a coarse rag! The reason is that the chromed surface would be damaged.

Why can’t the halves be split, and do any of you really change the caliper if you need more than polishing gloss or brass wire brush/coarse rag to clean it?


Per G. Birkeland
69 280 sl aut 834
Norway

[rwmastel]

Per,

Hello.  I rebuilt mine even though there were small (in my opinion) craters in the cylinder walls.  Here is another member's pictures of my type of calipers, and I mention in that post what I replaced:
http://index.php?topic=439

I don't know why they say not to split the caliper.  I guess another question would be, why would you want to?

Regarding the cylinder wall cleaning, I sanded with very fine sand paper that was wet with brake fluid.  I moved the sand paper around the cylinder, not in and out.  I got new pistons made in stainless steel as new MB ones are so expensive.  Seals are readily available.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[knirk]

Rodd

The reason I split them is just for it to be easier to hone the cylinders. But I will stop doing this and just sand them like you mentioned, if there is a good reason for not splitting them.


Per G. Birkeland
69 280 sl aut 834
Norway

[George Davis]

Per and Rodd,
My understanding is that it may be impossible to get the caliper to completely seal up again after it is split apart.  I suspect with skill and luck they can be resealed, but IMO it's not worth the trouble or risk.  I use a method similar to Rodd's for caliper rebuilding, fine sandpaper soaked with light oil, and lots of cleaning.

George Davis
'69 280 SL Euro manual

[merrill]

Rodd,
so, overall do you consider rebuilding the calipers a good way to go?
I talked to K and K Mfg to order the seals and they told me that they do not recommend rebuilding the calipers because the typically leak.

they of course suggested buying new calipers only AFTER replacing the pads and rotor if needed.

any feedback?
Matt

[rwmastel]

Matt,

Mine don't leak.  The brake pressure is not equal (pulls to one side a little), but that's more likely a brake fluid issue, not a caliper or pad issue.

What the heck, give it a try!  The seals can be frustrating, for a novice.  If you've done calipers, pistons, seals before then you should have no problems.  Sorry I don't have pics of my pitted cylinders in the calipers.  It would be nice to show the severity.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[bpossel]

Look at this source for brake calipers...

http://www.classicgarage.com/rearbrakcalf6.html

Bob


bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[mbzse]

quote:Originally posted by Per G. Birkeland (knirk)

../..Why can’t the halves be split?

For sure the halves can be split. But, the required torque for joining the halves together again has not been told by M-B, and there is a little O-ring seal between the two halves which is non-available (you have to get the best replacement you can obtain). So, when you decide to split the halves, you are kind of on your own. As George D mentions, they are hard to seal well after a split.

Remember and think about, brakes are a primary safety device for yourself, your passengers and other people on the road...[:0]
Rinse parts and channels with an Isopropyl alcohol rinse. Things must be scrupulously clean. Make sure all parts are absolutely dry before assembly (a hair blower dryer or similar is useful), ensure the complete removal of any moisture or alcohol.


/Hans in Sodertalje

[merrill]

Rodd,
thanks for the reply,  I asked gernold at sl tech and he did not recommend the rebuild , he recommended just replacing the calipers.

since my 66 is 40 years old it probably would not hurt to just go ahead and install new ones with new rotors and pads etc...

thanks
matt

[rwmastel]

Is your '66 running Gerling 3-piston or ATE 2-piston calipers?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Cees Klumper]

SLS list the brake calipers at 200 euros each for the ATE, and they also seem to have replacement sets for the Girling (522 euros for a set of two). They list new pistons at 104 euros for the Girlings, and 27 euros for the front ATE, and 40 euros for the rear ATE brake pistons. Also seal sets. In short, they appear to have all the necessary replacement/rebuild parts at not-too-outrageous prices.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[mdsalemi]

My car has the ATE.  When being restored in 1999-2001, I had taken the calipers to a local foreign auto parts store (it was one filthy, dirty, grimy collection of ATE castings--all seized and looking every bit of their 30 years old life)and asked if they can send them out for rebuild, as they offer this service for all kinds of foreign cars.  The answer was yes.  For $45 each, I received back what looked like factory-new calipers from a professional rebuilder, and they have functioned without leaks or other issues since then.  I suspect that a professional rebuilder knows how to re-assemble; has the right tools; and knows how to re-seal them as well.

Note there's about 8,000 miles since the rebuild, and about 6 years.  Brake fluid is changed annually.

Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[Naj ✝︎]

Article of interest :?:

http://www.dianasmercedes.com/TechnicalArticles/CaliperRebuild.htm

naj

68 280SL