friend has car with ASR, does he need special brake calipers?
 

friend has a 1990 merc with ASR (also known as Acceleration Skid Control). He wants to know if the car requires special brake calipers?

No

Actually, it would appear that the rear calipers do differ. They have an extra lug for mounting the socket for the wear indicators.
If rear pad wear reaches the contacts is the ASR then disabled? Or do the rears have indicators simply because there is the possibility of increased rear pad wear with ASR actuation?

good questions. Don't know for sure, however I would think your first question might be correct. Mercedes was beginning to bring more automation into the picture around that time frame.

OK, found more information on what exactly, ASC does for the car. It appears the brakes may play a more active role when the car over-accelerates causing possible fish tailing. I don't believe this car has the kind of power to worry about fish tailing, but then I'm not a mercedes engineer, either.

https://www.mercedes-benz-bus.com/en_GB/models/tourismo-rhd/safety/safe-driving.html

Same calipers listed for my 300CE-24
 

As said, only 1 listed for each side of mine and it has ASR. I would expect the EPC to list the options but no.

RayH

The definitive answer to the question will be found by inspection.
Remove a rear wheel and examine the caliper for the presence (or absence) of wear sensors in the brake pads. If there are sensors, then the caliper will have a mounting lug for the sensor socket.

It is possible that in her wisdom Mother Benz specified rear wear sensors in some models, and not in others. The OP has told us the year - 1990 - but not the model, so inspection is in order.

It is possible that one side has a wear sensor and not the other. My '97 has a wear sensor on the passenger side (right) and none on the drivers side.

He has a 1990 560SEL, I guess I'll tell him to inspect the rear brake pads for sensors.

we found what appears to be a mysterious hose (not the brake fluid hose) going to the rear brake caliper (photos attached). Would this indicate that this is an ASC car? We haven't pulled the brake pads out yet.

Please note; fluid seen on brake caliper bolts is kroil oil we put on the brake caliper bolts so we can loosen them.

If I understand you correctly, that's not the caliper. It's the carrier and that would be the parking brake cable.

OK, that makes sense.