Identifying W126 Brake calipers

I recently attempted to take my 560SEL on a Mercedes Club night drive.   On the way there, I experienced a soft brake pedal and a very hot drivers side rear wheel.    I had an issue with a soft brake pedal on a mountain road back in 2020.   At the time I thought I had solved it as I removed the aftermarket brake dust shields and had all the hoses replaced.   It’s pretty clear that I have a sticking rear caliper (or two) that is the root of the issue.   It also explains why I always felt the 560SEC had better brakes than the SEL.

There are a few parts on Mercedes of this era where multiple suppliers were used for the same part.   W126 Brake calipers are one of them.   Another example is window regulators and motors.   In the case of brake calipers, the different suppliers are interchangeable, but the rebuild kits are different.   Calipers are supposed to be the same brand on each axle, but front and rear can be different.    The window regulators are a similar story.  You can replace the whole regulator and motor combination, but if you’re only changing one, it has to be in the same brand.

The two suppliers of W126 brake calipers were ATE and Bendix.   Other than the series 1 SEC, you could get either ATE or Bendix calipers on your front or rear axle.   To order the rebuild kits, I needed to know the brand.

The easiest way is to remove the wheels and check.   The ATE and Bendix calipers have a different arrangement for securing the brake pads.     In my case, this was a bit harder.   I had just had an operation where I wasn’t supposed to lift more than 5kg for the next two weeks.   Luckily, my little boroscope was good enough to get in and look at the caliper.   It wasn’t possible to see the pads, but I could see the brand stamped on the outside.

Looking at the caliper alone is not immediately apparent, but if you check the company logos, its obvious what you’re looking for.    In this case, I had Bendix calipers on the front axle of my W126.    The fronts are harder to examine than the rears, as the calipers are much larger.   Getting the boroscope down to see the rear caliper logos was much simpler.

In my case, ATE calipers on the rear.    I’m not sure if I will need to have the front calipers rebuilt, but I want to have the rebuild kits available just in case.   Kits are available for both types, bu the ATE kits are much more accessible, and available from different brands.   The Bendix kits were much harder to to find, and 4x more expensive.

Next time I have the wheels off the other cars, I am going to note down the caliper brands.   Even if you don’t source your own parts, it’s worth telling your mechanic what you have, so they order in the right rebuild kits before you arrive.