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Very intuitive. My layman’s version: Break the lug bolts loose, jack the car up and remove the wheel. First thing I did was pulled the two, small plastic brake pad level sensor connector out – not from where they ‘mount’ to the pad, or are inserted in the pad, but to where they connect to the caliper (and thus, are wired into the car’s electrical harness). Gently wiggle back and forth- they will come out. I then opened the master cylinder – be sure you don’t have a full master cylinder reservoir, or fluid will spill out when you compress the caliper pistons. Keep an eye on this. Next thing I did, with the master cylinder cap open, is put a screwdriver between the brake pad and caliper – and pried against the brake pad – on all four corners, pushing the four caliper pistons flush. You’ll need them as flush as possible to fit the new pads against the new rotors. Clearance will be tight, but will fit. Remove the pad mounting pins (two per wheel) with a narrow, long punch and hammer – the pads will drop out of the bottom of the caliper. I also, I think before the above steps, loosened the two caliper-to-spindle bolts. There are four large bolts here, you only have to remove the two that hold the caliper in place. It’s intuitive – so look, and you’ll see. Very straightforward here. My only warning is to use a 3/8� ratchet and SHORT six point socket and extension on the top bolt head, as the ½� combinatation, or 3/8� deepwell combination, will not allow you to get a straight-on bite to the bolt. Or – use a sturdy, tight fitting wrench. I definitely recommend a breaker bar as well. You’ll need it. Just be careful here, that you don’t round off the corners of this top bolt. I almost did. When removed, I simply propped my caliper up on the outer tie rod end linkage where it was out of the way – and be careful – and don’t let it drop. Only held in place by fragile fluid lines. The rotor came off very easily, with a 5mm hex wrench/socket (remove the bolt). I cleaned the mating surface (hub) with a drill/wire brush and put antisieze on the hub before installing the new rotor. After the new rotor was in place, I used loctite on the caliper mounting bolts and bolted it back on (81-5 ft lbs torque, I believe). It also helps to have your key in the ignition so you can turn your wheels (at the wheelwell) where you want during this process. Also, it’s a good time to pry off your wheel bearing cap (outside of the hub). Mine was packed full of fresh MB green wheel bearing grease- which is a good sign in my book. This design is very ford-like, so I had to problem getting the cap on/off. Just a large, flathead screwdriver to pry all around the cap until off. And the hammer to gently tap back in place. Next, I spent a lot of time on the pad preparation. Which included removing the original sensors from the pads – they are PLASTIC and press in. I ended up using a small amount of WD-40 on the area, to help the sensor slide out. I used a ‘pick’, like a finely pointed dental instrument, to slowly eeek the sensor out of it’s hole in the old brake pad. And finally, as it was near the top, wiggled out with pliers. Installation is very straightforward. Same way out, same way in. Just go slow and be careful. They are cheap to order, it’s just something you may want to do on your next order if you will be taking on this job. Order a couple of spares. Next – my only dilemma was what to use from brake pad paste (anti-squeal). The original coating looked kinda yellow/green, but was definitely dirty. So I wiped dry the little steel plate that presses next to the backside of the brake pad, and put it aside. I then coated the backside of my new brake pads with an antisieze I got from oreilley’s (like autozone – in texas). Two small tubes of red material. Basically, put it on very liberally on the back of the new brake pads AND on the side of the steel plate (that pushes against the brake pad) that the caliper pistions press. In other words: Back of pad (anti-seize) < steel backing plate < other side of steel backing plate (anti-seize) < caliper piston. Hope that made sense. All metal-to-metal areas had anitisieze on it. Oh yeah, my dilemma….I would’ve liked to use the Mercedes benz paste, but didn’t want to make the trip to the dealer. Next time, I’ll plan ahead better. (so it was a short dilemma…we’ll see if the brakes are squeaking next month!) One last thing – I let the pieces with anti-seize sit in the sun for awhile – so it would dry faster and cure. Didn’t want to install wet, as I didn’t want the paste to be ‘pushed away’ during assembly/brake use. Also, you might find you’ll need to push your caliper pistons back in place, with your new rotor on. Just use the old pads – and use a screwdriver between the old pad/pistion, and compress them. Being an old ford/Volvo guy, I had my “C� clamp out – in preparation to compress the pistons. NEVER needed it. Reassembly was straightforward. I used a few drops of oil on the wheel bolts – and loctite on the rotor-to hub bolt (5mm). I think that’s it. And this is the way I did it – a first time MB DIYer. Very simple. Brakes work great – no squeal. And total cost was around $150.

Thanks to all who advised me on this. Please feel free to comment/correct me where necessary. I hope this helps. Best regards, 71Rcode
 

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About the antisieze... the MB brake is identical to the antisieze paste commercially available at nearly every auto supply house. I know, because I reverse-engineered the MB paste in our lab. No need to use the MB stuff.

Plus antisieze doesn't "dry" or "cure" as does antisqueal paste... at least not immediately, so you didn't have to wait for pad installation. It takes a long time for it to dry out.
 

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Keep in mind that if you have a 93 400E make sure you check that you have either the older 22.4 mm thick or upgraded 25mm rotors.

In 11/92 (when my car was made) they started the change.
Unfortunately, both suppliers I tried were unaware of this fact and now I have to reorder the rotors again (for the 3rd time).

Though I still don't understand why they sent me 92 rotors when I told them I had a 93.
And another fact. Both the 94-95 E320/E420 take the same rotors as the 93 400E.
 

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Luckily I've never had the rotor thickness problem, though on other parts I've been given the wrong version a time or two. When ordering online it can get to be tricky.
 

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Fortunately, I found a local German Car shop that I can order a pair of Zimmerman replacements for $55 each and I'll have them the next day :thumbsup:

That's better than the $70+ per Napa Auto Parts was charging for their cheapo generic brand.

The eBay place I got the first set from wasn't aware of the difference so I told them to pull their 94-95 E320/E420 rotors from auction because they have them referenced with the same part number as the 92 400E thinner rotors

Also the first set that Napa got me, one was milled wrong and the hole for the set screw didn't line up

Lesson learned, I'll go with the local shop next time
 

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Youtube videos

Here are three youtube videos that shows how to replace w124 break pads and/or rotor (disc):




Hope someone can post some tutorial with pictures as well about how to DIY with changing the break discs + pads
 

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'90 300E brake job

Great video (1987 300E) is exactly what I was looking for since the other youtube videos I have seen were for 93 - 94 300 E's. Thanks for posting!!
 

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New Routers and brake pads

Very intuitive. My layman’s version: Break the lug bolts loose, jack the car up and remove the wheel. First thing I did was pulled the two, small plastic brake pad level sensor connector out – not from where they ‘mount’ to the pad, or are inserted in the pad, but to where they connect to the caliper (and thus, are wired into the car’s electrical harness). Gently wiggle back and forth- they will come out. I then opened the master cylinder – be sure you don’t have a full master cylinder reservoir, or fluid will spill out when you compress the caliper pistons. Keep an eye on this. Next thing I did, with the master cylinder cap open, is put a screwdriver between the brake pad and caliper – and pried against the brake pad – on all four corners, pushing the four caliper pistons flush. You’ll need them as flush as possible to fit the new pads against the new rotors. Clearance will be tight, but will fit. Remove the pad mounting pins (two per wheel) with a narrow, long punch and hammer – the pads will drop out of the bottom of the caliper. I also, I think before the above steps, loosened the two caliper-to-spindle bolts. There are four large bolts here, you only have to remove the two that hold the caliper in place. It’s intuitive – so look, and you’ll see. Very straightforward here. My only warning is to use a 3/8� ratchet and SHORT six point socket and extension on the top bolt head, as the ½� combinatation, or 3/8� deepwell combination, will not allow you to get a straight-on bite to the bolt. Or – use a sturdy, tight fitting wrench. I definitely recommend a breaker bar as well. You’ll need it. Just be careful here, that you don’t round off the corners of this top bolt. I almost did. When removed, I simply propped my caliper up on the outer tie rod end linkage where it was out of the way – and be careful – and don’t let it drop. Only held in place by fragile fluid lines. The rotor came off very easily, with a 5mm hex wrench/socket (remove the bolt). I cleaned the mating surface (hub) with a drill/wire brush and put antisieze on the hub before installing the new rotor. After the new rotor was in place, I used loctite on the caliper mounting bolts and bolted it back on (81-5 ft lbs torque, I believe). It also helps to have your key in the ignition so you can turn your wheels (at the wheelwell) where you want during this process. Also, it’s a good time to pry off your wheel bearing cap (outside of the hub). Mine was packed full of fresh MB green wheel bearing grease- which is a good sign in my book. This design is very ford-like, so I had to problem getting the cap on/off. Just a large, flathead screwdriver to pry all around the cap until off. And the hammer to gently tap back in place. Next, I spent a lot of time on the pad preparation. Which included removing the original sensors from the pads – they are PLASTIC and press in. I ended up using a small amount of WD-40 on the area, to help the sensor slide out. I used a ‘pick’, like a finely pointed dental instrument, to slowly eeek the sensor out of it’s hole in the old brake pad. And finally, as it was near the top, wiggled out with pliers. Installation is very straightforward. Same way out, same way in. Just go slow and be careful. They are cheap to order, it’s just something you may want to do on your next order if you will be taking on this job. Order a couple of spares. Next – my only dilemma was what to use from brake pad paste (anti-squeal). The original coating looked kinda yellow/green, but was definitely dirty. So I wiped dry the little steel plate that presses next to the backside of the brake pad, and put it aside. I then coated the backside of my new brake pads with an antisieze I got from oreilley’s (like autozone – in texas). Two small tubes of red material. Basically, put it on very liberally on the back of the new brake pads AND on the side of the steel plate (that pushes against the brake pad) that the caliper pistions press. In other words: Back of pad (anti-seize) < steel backing plate < other side of steel backing plate (anti-seize) < caliper piston. Hope that made sense. All metal-to-metal areas had anitisieze on it. Oh yeah, my dilemma….I would’ve liked to use the Mercedes benz paste, but didn’t want to make the trip to the dealer. Next time, I’ll plan ahead better. (so it was a short dilemma…we’ll see if the brakes are squeaking next month!) One last thing – I let the pieces with anti-seize sit in the sun for awhile – so it would dry faster and cure. Didn’t want to install wet, as I didn’t want the paste to be ‘pushed away’ during assembly/brake use. Also, you might find you’ll need to push your caliper pistons back in place, with your new rotor on. Just use the old pads – and use a screwdriver between the old pad/pistion, and compress them. Being an old ford/Volvo guy, I had my “C� clamp out – in preparation to compress the pistons. NEVER needed it. Reassembly was straightforward. I used a few drops of oil on the wheel bolts – and loctite on the rotor-to hub bolt (5mm). I think that’s it. And this is the way I did it – a first time MB DIYer. Very simple. Brakes work great – no squeal. And total cost was around $150.

Thanks to all who advised me on this. Please feel free to comment/correct me where necessary. I hope this helps. Best regards, 71Rcode
A friend of mine changed new routers and pads today, the problem is the brake pedal goes all the way down and the mechanic told him it will take a while before it goes back to normal position!! I don't know if the mechanic done his job well. I need your opinion about this
 

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A friend of mine changed new routers and pads today, the problem is the brake pedal goes all the way down and the mechanic told him it will take a while before it goes back to normal position!! I don't know if the mechanic done his job well. I need your opinion about this
No he has not, you need new mechanic.
 

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A friend of mine changed new routers and pads today, the problem is the brake pedal goes all the way down and the mechanic told him it will take a while before it goes back to normal position!! I don't know if the mechanic done his job well. I need your opinion about this
No he has not, you need new mechanic.
So what do you think happened? Is it possible that air get into the system
 

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They damaged the master cylinder seals by pushing
the pedal to the floor after replacing the pads.

You have to pump the pedal to bring the caliper pistons back out.
But you should short stroke the pumps, otherwise the piston in
the master cylinder goes past the normal end of travel to where
fluid sits in the bore.

This damages the seal(s) as they pass corrosion in that area.

Just as corrosion builds in the calipers, due to lack of brake fluid replacement.

This should be done every 2 years.

.
 

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Unless he didn't know how to back out the caliper pistons with pressure rather than releasing the bleed valve.
That would introduce air in the system.
 
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