Push on the brakes and have a helper look at soft lines running from each wheel position. Make sure none of the lines are swelling. I had this issue with the SD and it drove me crazy until we caught it.

My rear brakes are SL600's, fronts are E420.

I did manage to tear into that rear passenger rotor today and found that my spring clip was rubbing up against the rotor so I think that was the source of my noise..but I did take the pads out and put some anti-squeal paste on them and drove around town.

The pedal seems better but still not quite as firm as I would like but I think the pads are still bedding-in.

I just managed to beat the rain with working on those pads. I didn't want to challenge the gods of rain any further by attempting to bleed the whole system.

Maybe I should move back to SS lines.. I miss that ultra firm pedal.

Either you bedded in the brakes or you didn't, they can't "still" be bedding in, it's a big problem with brake jobs. You even described how to bed in brakes in your first post, I was impressed. The normal result in brakes that aren't bedded in are squealing brakes.

Did you or do you intend to flush & replace the fluid?

Akebono brake pads are the worst ones I have ever installed. Get rid of them and get some Textars. May fix 50% of your problem because they won't stop your car (and I know what a mushy brake pedal feels like)! If you do your flush and still have the same issue...I guarantee it's your pads. I have a 300E 3.0 and put in new rotors (not even cross cut like yours!) and Akebonos...felt like I was leg pressing 3000 lbs when I tried to stop and pedal felt mushy (because there was no bite). Ordered some Textars, threw them in, drove about 20 miles and bam! Barely have to step on the brakes to stop the car now. Have never bled my brake lines.

???

Exactly what I was trying to tell you. What was the logic in switching to swelly rubber hoses in the first place is what I would ask. If you had a firm pedal before, why did you go changing it? SS lines don't go bad in the same way as rubber hoses, and if they're Goodridge they have a lifetime guarantee. So you really shouldn't have messed with them.

You also have upgraded calipers on both ends, did you also upsize the master cylinder/booster? This could be a factor. The bore of your original master was designed for your original calipers, not the huge calipers from the SL600/E420.

I don't remember the logic! It was a good number of years ago. The brake system has gone through many things.

When I bought the car in 06, the calipers were already on the car with a 190E master and 190E booster.

The master went so I replaced it with a 500E master.

Later I swapped in a 500E master/booster because I felt that was more appropriate than the 190E booster.

I forget when/why I went to the rubber hoses. I was agreeably dumb, I did keep the steel lines so when I flush the brake fluid sometime here I can easily put them back on.

I've no idea who made the SS lines, they were on the car when I bought it in 06...

Thats sad to here. Here I always thought Akebono's were generally well regarded. I kept my Axxis ULT pads and I believe I have a set of Textars (slightly used) in a box here somewhere. I keep too much stuff....

And to rebe, yes, eventually I will flush the brakes out. Probably this coming Friday or that weekend.

I've got the new W124 to deal with as well. Its brakes are nice and smooth though, no issues there.

Well I had planned on doing one last thing before doing anything with pads.

I wanted to swap the ABS block with one from a known good braking car (my friends parts 560SEL to be precise).

I was almost done but the one fitting on the ABS to the FL caliper rounded. >:O

The EPC actually calls the abs block the "brake pressure regulator" interesting.

I would be ecstatic if that solved my issue. But I'll have to have that stupid fitting replaced first. That or a new line, whichever is cheaper.