Hi all,

I am rebuilding the calipers on my 1968 280s, and was wondering what is the proper bit to use on the heads of the 4 bolts that hold each of the calipers together.

I was able to get at them with a T45, but it definitely wasn't the correct bit for it. If I wasn't leaning into it with all of my body weight, I probably would have caused some damage to the heads. My next Torx size up (T47 if I remember correctly) was too large.

Is it some kind of propriety Mercedes bit, and if so, where do I buy it? I checked the Snap On truck today and they had nothing and cannot get it.

I can post pictures if needed.

Thanks in advance for any replies!

Bryan

__________________
1984 240D Euro 5 Speed 201,000 miles
1984 300D Euro 4 Speed (runs great but ugly)
1984 300TD 185,000 miles
1985 300TD, 240,000 miles
1972 220D, 240,000 miles w/ a stuck odometer
1984 300D, 214,000 miles
1984 300TD, 255,000 miles rustbucket parts car

Hi,
What are you using to replace the flat O-rings between the caliper halves?

__________________
Tony H
W111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux Pickup Truck-Dad bought new
'73 Toyota Celica GT

I am reusing the old ones. Not ideal, but they are in good shape.

Reason I am asking is they are not included in the rebuild kit since the halves were not intended to be separated. I think 914 kits have the flat O-rings-I am tempted to buy one just to see if they are the correct 0-rings

__________________
Tony H
W111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux Pickup Truck-Dad bought new
'73 Toyota Celica GT

Huh, I didn't realize the halves were not meant to be separated. Seems that it'd be a pain removing the pistons, and especially cleaning the bores without the caliper being separated.

For what it's worth, I have rebuilt several dozen 123 calipers (separating all of them and reusing the O-rings) without issue (for now, the oldest caliper rebuilds I've done are around 5 years old, and the highest mileage ones have around 80k on them).

I'm sure I could find an O-ring from the nearby Cat dealer that'd work, but it'd probably cost more than the initial purchase price of this car.

Bryan

__________________
1984 240D Euro 5 Speed 201,000 miles
1984 300D Euro 4 Speed (runs great but ugly)
1984 300TD 185,000 miles
1985 300TD, 240,000 miles
1972 220D, 240,000 miles w/ a stuck odometer
1984 300D, 214,000 miles
1984 300TD, 255,000 miles rustbucket parts car

Hi,
the rings are available in Germany. ATE 13.8101-5703.1
Dichtring/Kanalring für ATE-2-Kolben-Bremssattel Opel Manta Kadett Rekord | eBay

Shipping costs by Priority Mail are below 5.-$.


But you have to know the following:

The OEM forbids separating the halves.

- the bolts and nuts are very special, extremely hardened ones They are very expensive - about 9.-$ ONE bolt with nut
https://www.wallothnesch.com/bremse/bmw-1502-2002-turbo/katalogbild-34-03.html?dir=asc&order=name

- there is a special remounting instruction, you have to draw the bolts in stages up to quite high torque depending on the diameter of the bolts.
example: 2-3-1-4, 18 Nm, then 2-3-1-4, 34 Nm, than 2-3-1-4, 60Nm,
at last only 2-3, 70 Nm (inner bolts with higher torque!)
This is just a sample - values depend on the diameter!

The calipers are then tested by ATE at 200 bar = same pressure as fully fillled oxygene bottles.
None of us can do this very dangerous test!

It is absolutely not necessary to separate the halves when they are not leaking in between.

Regards
Norbert

Thank you for the great info!

Bryan

__________________
1984 240D Euro 5 Speed 201,000 miles
1984 300D Euro 4 Speed (runs great but ugly)
1984 300TD 185,000 miles
1985 300TD, 240,000 miles
1972 220D, 240,000 miles w/ a stuck odometer
1984 300D, 214,000 miles
1984 300TD, 255,000 miles rustbucket parts car