Information for where to get the O-rings is here

ATE Caliper half, O ring source




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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Edit: I now see this is old. But still. If it ain't broke don't fix it. Unless you are stretch. In which case take it completely apart down to the smallest level. And share how it works. 😜


Whoa whoa whoa. First things first, why do you need to split it?

I never do. I will never do it. I'm not sure when you need to. But if you do, don't mix up the bolts. Cut a cardboard pattern and stick the bolts through.

The rebuild kit I got from the auto stop had the small O-rings. I was surprised.

If it's frozen, and the brakes or air won't get it out, put a bolt in the hole for the brake line. Open the blender and start pumping I grease with a grease gun. You can soak in penetrator before hand. But the grease will do it.

Never touch the piston or bore with anything under 1000 grit sand paper. Microscopic scratches will effect performance.

If it's corroded bad, you need new pistons. Most rebuilds are new pistons.

If it's corroded on piston or bore beyond the square sealing edge. You need new calipers. Good rebuilds are bored out and re-chromed.

Feel free to enlighten me on the reason to split them.

(Grumble grumble - now now now!!!!!)

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Haha. I ment it in a good way. I learn a lot through your posts. I like to know what's in there. But not that advanced yet.

Pressure testing. That's probably the key point.

I through them in the blasting cabinet with the bores covered up. Maybe that's not good.

I did too!

I think the key reason for not splitting them and then using mechanical methods to remove rust is the likelihood that you'll damage the machined mating surfaces between the two halves. The chances that they'll sit right is not so great if they've met a wire brush on an angle grinder!

The other thing is that people might then start to look at halves as individuals (or wholes) and then think it will be OK to match OK with kind of OK - you then get (the chance again) of mismatching problems.

I've always regretted media blasting / sand blasting hydraulic components - the dust gets everywhere and clogs up path ways. In these cases I reckon I spend more time trying to remove the grit than I would have done whazzing it with a wire brush. Same trouble with the professional water and media jet machines too.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I split mine to remove the rust from the whole outer part of the casing - this is difficult to do with the two halves in place - particularly on the inner parts of the lip where the outer seal fits.

I'm not going so far as to recommend splitting the callipers though especially if you are not going to pressure test them afterwards.

@everyone - sorry I really should have mulit-quoted that little lot!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Few people who have been around this forum will be surprised if I side with the FSM warning about not splitting the halves...

They say in no uncertain terms....

I do not know WHY they say it....

the cost of professionally rebuilt ones is relatively cheap... given that many people appreciate having the vehicle STOP when they press on the correct pedal...

For most any other item... except STEERING.... I say have fun and learn all you can..
on BRAKES I say do not take any chances that we do not know something MERCEDES DOES know about why we should not split them ourselves...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

By the book? Really? However I just got my buddy a Haynes manual for Christmas. He always annoys me with his crazy ideas. So I see where it comes from.

Is this what getting older feels like? Da** kids.

Before sandblasting I cover the bores with old brake pads and small c-clamps. I put a bolt in the hole for the line. And tape off the bleeder.

Then clean with brake cleaner. Then flush with water. Then dry with the compressor.

Paint. Install Pistons. Done.

Ive always split the caliper because the whole assembly was rusted to hell and the pistons frozen. Makes it a lot easier to extract the pistons. Its not rocket science, its 4 bolts and some O rings.

All the fussing on here over a short sentence in the FSM. If you want to do it, go ahead. If you dont, thats an option too.

Ive been so unimpressed by rebuilds ive purchased, that im happy to do my own rebuild.

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This post brought to you by Carl's Jr.

X2.
When Disc Brakes started to be common on Cars I don't recall any warning about not splitting the Calipers on those Calipers that it could be done on. I had been doing it for years before I had a Mercedes.

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84 300D, 82 Volvo 244Gl Diesel

Case in point:



Lol. Couldn't help it.

How do they seal? Like is there a big gasket around the whole case?

Still not gonna do it. But curious.

For petes sake. The caliper has a couple fluid ports from one half to the other. These are sealed by small O-rings. The secret is find and replace the O-rings with something that fits which will work with brake fluid.
I found o rings that worked at a hydraulics store. (Parker). You slam the thing back together with original brittle O rings, of course it will leak.

The 4 bolts hold the thing together otherwise. The FSM tells you how to completely rebuild a motor, but undoing 4 bolts and replacing a couple O-rings is beyond that job in skill level required?

Nonsense.

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This post brought to you by Carl's Jr.

Why don't YOU offer some theory as to why , given exactly what you have said, they said DO NOT split them... and that is not just MB... but industry wide... clearly it is not that that one item is where they plan on making lots of money... given the instructions for fixing all the way more expensive stuff....

Sometimes in life... given the importance of brakes and steering... and how cheap new calipers are.... and how important... it might be smart to just follow the warnings and put new or rebuilt ones on the car.... and focus on something else.

Calipers CHEAP.
LIFE NOT REPLACEABLE .
It is one of those things in life you would not want to be remembered posthumously for exercising your God given right to show HUBRIS. Just not worth it.

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Right. Because all the other brake system components you are allowed to work on that depend on a sealed clean system for your safety are also too dangerous to service.

I guess i should stop bench bleeding my master cylinder, god forbid i replace any brake lines or fittings.

Demonstrate the "industry wide" comment. Last i checked most every auto manufacturer sells rebuild kits. Plenty of data out there to do it correctly. Nothing special about the benz split caliper design, BMW and others use it too, yet you are allowed to rebuild them.

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This post brought to you by Carl's Jr.

I understand your opinion on the subject but the rebuilder splits the Calipers reguardless of what the Manual tells you.
So you can split the Calipers yourself or you can let the Rebuilder do it for you.

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84 300D, 82 Volvo 244Gl Diesel