Horrible screeching from right front wheel

[Alec300SD]

83 W126 300SD, "Rena 2.0" developed a horrible grinding screech at the right front wheel.
The front wheel bearings were okay on both front hubs.

You guessed it, the brake lining on the outer front right pad was AWOL and metal on metal braking ensued.

My independent mechanic let me order OP front rotors and OP semi-metallic front brake pad at his cost.
Last weekend I replaced the front rotors and the DS brake pads.
The outer piston on the PS caliper had siezed.
"Rena 2.0" had to spend the week perched on jackstands in the driveway.

Friday I received the rebuilt PS ATE caliper from my independent mechanic (also at cost...yes!!).
The caliper was complete with new bleeder, bleeder cap, brake pad pins, retaining spring and heatshield for the piston dustshields.

Today I finished the front axle brake job.
The front brake sensor harnesses were replaced with used Pick-n-Pull units from a 91 W126.
The old ones had frayed and had been poorly repaired with crimp connectors by the PO.
Of course, I cracked the PS plastic clip that holds the PS brake sensor harness to the top bracket that also secures the flexible brake line.

I planned to replace the flexible rubber brake lines with new ones I had on hand.
Unfortunately, they did not fit the bracket, the female end of the hose needs to have the 17mm hex fitting.
The new ones I had on hand had 14mm hex fittings at both ends.
I will be ordering a set of front and rear stainless steel brake lines from Deerfield Precision and install them when I do the brakes on the rear axle.

Gravity bled the brakes and switched over to DOT 5 brake fluid (Motor Medic brand from Walmart...it has a purple tint).
Bedded in the new brakes, brake pedal is nice and solid.
"Rena 2.0" is back on the road.

[optimusprime]

Sound like you made a good job of the brake caliper .
You say gravity bleed the system .
Can you tell me how you went about doing this please ?.

[Alec300SD]

This guide explains the process pretty well.
How To Gravity Bleed Brakes

I used a six point 9mm socket to crack open open the bleeders (no vise grip pliers).
With the vinyl tubing on the bleeder valve, I used a 9mm thin ingnition open end wrench to open and close the bleeder valve.

The main things are to keep the reservoir full, and have a long length of hose on the bleeder valve,
and keep the end of the hose above the level of brake reservoir (so you don't siphon out all the fluid).

The fluid will seek its own level, in doing so the air bubbles will be removed.

[Mike D]

DOT 5 is completely WRONG for your car. Please flush the system completely and replace with either DOT 3 or DOT 4.

DOT 5 can be used if you COMPLETELY flush and remove all traces of the old fluid. Good luck with that! Ain't gonna happen.

Long read but it might answer any questions you have:
Silicone Brake Fluid

[Alec300SD]

Originally Posted by Mike D

DOT 5 is completely WRONG for your car. Please flush the system completely and replace with either DOT 3 or DOT 4.

DOT 5 can be used if you COMPLETELY flush and remove all traces of the old fluid. Good luck with that! Ain't gonna happen.

Long read but it might answer any questions you have:
Silicone Brake Fluid

I respect your opinions and I realize there is controversy regarding switching over to DOT 5.
I have had good experience with DOT 5 in "Desert Rose" since acquiring her in January 2014.
My 78 W116 300SD was was converted to DOT 5 in May 2013 by the former owner Doktor Bert.
See Post # 31. DOT 5 Fluids:

I'll be keeping a close watch on "Rena 2.0" and will advise if any issues develop.

[Mike D]

Best of luck and please keep us informed. This "old dog" is never adverse to learning new tricks.

I am overly cautious regarding braking systems as I consider them to be the most important aspect of a moving vehicle.