Rebuilt Mercedes brake calipers

I attempted to attend the MBCNSW May night drive with two separate cars.   Coincidently, I had the same brake issue with both cars.   On both cases I experienced a soft brake pedal, and on further investigation a very hot drivers side rear wheel.    The rear caliper was not releasing properly causing it to drag and boil the brake fluid.

I knew the hoses were only a year old on the 560SEL, so the issue was likely to be with the caliper.   The hoses were probably due for a change on the 250SE, so could have been either issue there.   Based on this, I checked the caliper types and ordered the appropriate rebuild kits.   I also ordered a set of hoses for the 250SE.   I had to double check the electronic parts catalogue, as the rear hoses are not the same for each side on my car.

The 250SE went first, and while the hoses were due for replacement, all four calipers were pretty bad.   The difference in feel in the brakes is immense.  The first few times I drove the car, the pedal was so easy to push it was almost like there was something wrong.   In addition, I had some more work done on the ongoing stuttering issues I am having with the car.   My mechanic was able to tune it up as best he could but he thinks I’m close to needing a rebuild for the mechanical fuel injection pump.   Not only is it causing these odd fuel delivery issues, but it has an oil leak out of the back.     He also suggests I keep my eye out for a good used thermal time switch (part 001 545 92 24).  Cold starts are very slow.

Next was the 560SEL.   In this case, the fronts were fine, but the rears were pretty locked up.   While he was there, I also had the front shocks replaced.   Fixing both has made a big impact to how the car drives.   Again, the pedal feel is much better even with just the rears done.   And the ride over bad surfaces is significantly improved from the shocks.   Those Pedders shocks were really low quality and were already knocking despite not being that old.   They really ripped off the previous owner of the car.

I figured after having three pairs of brake calipers rebuilt, I was done for a while.   Turns out, I wasn’t.   Around the same time, the brake pad wear indicator lit up on my 560SEC.   Assuming this was a routine brake pad change, I got to work.   I don’t normally detail routine maintenance on this site, so wasn’t planning to feature anything about this.   However, when I had the first pad out, and it had most of the wear materials left, I started looking more closely.   Turns out only one piston has been working and that side is mostly down to the backing.

While I was there, I also measured the thickness of the rotors to see if they need replacement.   They look pretty old and crusty, so its quite possible they do.   Instead of swapping the pads, I put the old one back in.  I will book in this car to have the calipers checked.   I’m pretty confident I’m going to need another set of rebuilt Mercedes brake calipers on this car.    Luckily, I have a set of Bendix rebuild kits of hand that I purchased but didn’t need for the 560SEL.

Based on this experience, I expect that a vast majority of classic cars are driving around with brake calipers that are not functioning as they should.   They still stop the car, but performance is not as good as it should be.   This is going to be particularly prevalent in cars that are not driven regularly.   As much as having the calipers rebuilt is not a cheap exercise, good performing brakes are not something I am willing to compromise on.

Finally, while I was under the 560SEC, I swapped and adjusted the SLS control rod.   The rear ride height was too low, so I used the same technique as I did previously with the 300SE.    The height is better, but I think I need another couple of cm of height to have it back to factory.   The old control rod was starting to fail, so I used the one I had on hand for the 280SE and will order another one for that car.

In all this, I’ve found that when having a bunch of cars, I have the same issues on multiple cars at roughly the same time.   Part of it might be that having an issue on a car makes you more aware of it on others, but in the case of needing the rebuilt Mercedes brake calipers, I’m not so sure.