Replacing Rear Brake Pads

[denver123]

I have ATE calipers with the Mercedes star on them so they are possibly original to the car, a 1985 300 TD Wagon. I ordered pads, retaining pins, and anti-rattle clips for both sides. Problem is, I have never in my life changed a set of brake pads. Any one of you patient, intelligent people willing to give me a step-by-step? I have the Service Manual but it really seems like they wrote it for people who have at least changed pads once in their life - or perhaps seen someone do it. For example, it doesn't really say how to get the old parts out except by using their special tools, which I don't have.

Does peril await me?

Thanks in advance.

[johnathan1]

I need to know this info too... And I don't have a service manual.

[Don350SDL]

On one level, I greatly applaud your willingness to go after this.
On the other hand, we ARE talking about brakes, which is definitely a safety-related item.

It's difficult to decide if we can take the liability for advising you as to what to do - we aren't there to spot problems and mistakes - or just refer you to someone with experience. I hope that i am conveying the gravity of this dilemma.

Replacing the rear brake pads isn't a difficult job - basically, you remove the springs, then punch out the pins. Retract the pistons back into the calipers, remove the old pads, clean everything, put in the new pads, put in the pins & springs, and pump the pedal a few times before moving.

But it doesn't get inbto the brake pad paste that needs to go on the back of the pads. How to protect yourself against that dust - it's not healthy to breathe it. Inspecting the rest of the system, especially all the rubber. Proper torque if you remove the caliper bolts. And a zillion other little things. You really don't need any special tools.

The best advice I can offer is to find someone who has done brakes before and let them either show you, or watch while you do it. Maybe someone else can chime in, and eventually get you enough info to do it.

Don

[stricht8]

On one level, I greatly applaud your willingness to go after this.
On the other hand, we ARE talking about brakes, which is definitely a safety-related item.

It's difficult to decide if we can take the liability for advising you as to what to do - we aren't there to spot problems and mistakes - or just refer you to someone with experience. I hope that i am conveying the gravity of this dilemma.

Replacing the rear brake pads isn't a difficult job - basically, you remove the springs, then punch out the pins. Retract the pistons back into the calipers, remove the old pads, clean everything, put in the new pads, put in the pins & springs, and pump the pedal a few times before moving.

But it doesn't get inbto the brake pad paste that needs to go on the back of the pads. How to protect yourself against that dust - it's not healthy to breathe it. Inspecting the rest of the system, especially all the rubber. Proper torque if you remove the caliper bolts. And a zillion other little things. You really don't need any special tools.

The best advice I can offer is to find someone who has done brakes before and let them either show you, or watch while you do it. Maybe someone else can chime in, and eventually get you enough info to do it.

Don


I just wanted to add that you should remove only one pad at a time before retracting the piston into the caliper. If you remove both pads and push one piston back then the other one will push out too far as it has no pad to hold it in place. This can cause damage to the seal or allow the piston to pop out completely. Not good. When pushing the piston back it is recommended to use a special tool to uniformly disperse the force thus not cocking the piston which again can cause damage to ,I think, the seals. I don't have this tool and I'd be surprised if many people did including professional mechanics. I usually just use a large pry bar or screwdriver to force it back in with the screwdriver blade aimed toward the rotor surface. Once the piston is retracted a bit I then slide in the old usually thin pad to use as a prying surface (pry against the old pad) in order to more uniformly distribute the force. I have seen mechanics use large Channelock pliers with lower profile jaws for this purpose. Also the anti-squeal gel is available at your dealership cheap.
Dimitri

[technor]

Ditto with watching someone first....say the left side then have them watch you do the right side.
Disk brakes are very universal..... So you surly know someone who has done this type of repair work before.

As one of my engineering Profs said...It's all easy ....once you know how.

[denver123]

Thank you all for your advice and guidance. I did the replacement today and it went very smoothly. I attached a 2 1/2 foot plastic hose to the bleeder valve and filled it with brake fluid until there was about 9" of fluid in it (measured vertically when holding the tube in a vertical orientation,) wired it to something above the wheel assembly and put the other end in a jar. This way, when I crack the bleeder no air enters the system. I cracked the bleeder and gently squeezed the pad against the caliper with a pair of pliers so it would create some room, closed the bleeder and pulled the pad out. Once out, I slipped a couple of steel foundation shims (1 1/2" by 2 1/2" x 1/16' thick) into the pad area, stuck a big screwdriver between the shims, cracked the bleeder, pushed the piston out, and closed the bleeder. Worked nice, the shims distributed the force evenly on the piston and protected the rotor. The whole thing took like 1/2 hour and they work great. Did one pad at a time - good advice. When all were in, I started the engine, "energetically" (M-B manual term, not mine) hit the brake pedal a bunch of times, and then checked the fluid level. It was still just above max. Indie mechanic must have overfilled it last time. Drove the car, "bedded" the brakes by using them semi-hard about 8 times in a row, rested them for 1/2 hour, bedded them again, and done. All in all, very rewarding. Thanks again.

[Gromit Dog]

It's cool when people take an active interest in their cars. but as a joourneyman technician I cringe at folks doing their own brakes.

Yes, they are easy if you pop in new pads, but that is not the right way. When you replace brakes on a car you need to check every component for proper function and condition. This means removing the caliper (not hard) and checking not only haw easy the pistons move but their condition as well. if there is ANY rust on the pistons, either rebuild or replace the caliper or it will be leaking befor you know it.

Ever notice a minimum machine spec on your royors? it is there because to eliminate pulsation, brake fade or pad damage the rotors need to be machined at pad replacement time. Sometimes we can get away with scuffing the surface if the rotors are in excellent shape with no runout (rare) but machining is required for waranty and ultimate effectiveness.

Pins and assorted hardware needs to be clean and lubed or treated properly. it is a question of not only even wear and increased pad life, but heat transference for best brake performance.

doing all this also gives you the oportunity to inspect the inner drums, shoes and axle seals etc.

To be honest, when a guy comes into my shop and says " I just did my brakes and...." it always ends up costing a lot more than he "saved" doing it himself the quick way.

That said, yes I have just slid pads in. but it is never a completely satisfactory job, and I usually do it over the right way when I have a slow day in the shop.

I say get it done by someone with the right equipment. then twice a year or so, you can clean and service them yourself and they will last longer and save you bucks in the end.

oh yeah...NO USED BRAKE PADS!!!!!!!

[Maxbumpo]

Ever notice a minimum machine spec on your royors? it is there because to eliminate pulsation, brake fade or pad damage the rotors need to be machined at pad replacement time. Sometimes we can get away with scuffing the surface if the rotors are in excellent shape with no runout (rare) but machining is required for waranty and ultimate effectiveness.

Excellent post but one minor nit-pick; MB does not recommend machining the rotors ever but replacing when wear exceeds the service limit.

[Gromit Dog]

Excellent post but one minor nit-pick; MB does not recommend machining the rotors ever but replacing when wear exceeds the service limit.

I was unaware, however, I can tell you as someone doing brakes on a daily basis skimming (light machine) is required on 99% of all rotors, especialy aftermarket even when new out of the box. I have put new rotors on vehicles (from dealer) and had brake pulsation imediately.

Anyway, As I probably said, if you don't machine, at least hit them with some 60 grit paper to scuff them. it allows the pad to surface better.

[Maxbumpo]

'Skimming' is probably fine, MB has special temporary scrubbing pads that are installed vice the brake pads, and then the tech. is supposed to carefully drive around applying the brakes to roughen up the surface of the discs. Personally I think that skimming is much safer and probably quicker, given the right tools.

[Sokoloff]

Someone will correct me if I'm wrong, but it is my understanding that factory Mercedes brake rotors are Blanchard ground, producing absolutely true, parallel surfaces and the only thing turning those rotors will do is ruin that perfection. Aftermarket may be different, but that's probably why Mercedes says "Nein" to turning their rotors.

[dropnosky]

something may leave the factory in perfect condition, like a mercedes rotor, but in the process of transit and storage, damage can certainly happen. Checking them for runout and damage seems like the better part of valor.

Ever seen a shipping company load a truck? especially automotive parts, they automatically assume the metal is tough. Might as well be sure

[Gromit Dog]

It reminds me of something ...well... the onlything I remember from the movie "Armagedon" (hey it was on a free pass) "Soviet Parts...American Parts... All made in china"

It is one of those things, sometimes you can get away with it, sometimes not. I stay on the side of caution. whichever you do, get good quality pads (should be available from most any store, I get them from NAPA without having to order in) and scuff the rotor so the pads will seat.

[Highway Star]

It reminds me of something ...well... the onlything I remember from the movie "Armagedon" (hey it was on a free pass) "Soviet Parts...American Parts... All made in china"
.

Actually it was, quote: "American components, Russian components... all made in Taiwan!"

Also the only I remember about that movie, too.

[Highway Star]

stuck a big screwdriver between the shims, cracked the bleeder, pushed the piston out, and closed the bleeder.

I don't remember how many times my instructor yelled at the other students for skipping that part of the procedure. A lot of the fluid that's in the caliper doesn't get pulled back to the reservoir, so it gets pretty nasty and can even start to boil under long constant braking. And plain old bleeding just won't get it out. Kudos for doing that right the first time.