Brakes..
 

Im going to do front brakes on my uncles 84 300D tommorow.. Belive it or not i've never done brakes before... Can someone give me a breif rundown for a retard like myself :)

Pretty straight forward. Look at the "outside" of the brake caliper - perpendicular to the axle looking down "into" the caliper. You will see two "pins" that keep the brake pads in place. At the ends of these "pins" you will see a little clip that goes through the hole in the pins (similar to a cotter pin). Remove the clips and drive the pins out then pull the pads straight out. You can use a big screwdriver to force the pads back into the calipers. Check the wear on the rotor by looking at the outer edge. If it has a pretty pronounced edge replace them. Better yet, if you have the tools get a measurement and see if they are within specs. If the rotors need replacing you will need remove the caliper (two big bolts on the back - memory seems to say 17 mm), remove the hub and separate the hub from the rotor by removing the allen bolts that hold the rotor on. While you have the hubs removed is a good time to do the wheel bearing maintenence. Search the threads for "tightening" wheel bearings on one of these. Also, take a good look at the condition of the ball joint rubber pieces and bushings to determine if they need replacing or not. If you see grease on the outside of the ball joint rubber or cracks that go all the way through you will want to replace them eventually. You will also find the "sensor" that activate the brake pad wear light on the dash. These just pull out. You will want to replace them while doing this job because usually they will break when you remove them - especially if they are old.

This is for the 124 MBZ, which is very similar tp your car.

http://www.peachparts.com/Wikka/W124BrakePads

I hope this helps.

Jim gives some good instructions, but I would like to add a few comments and warnings.

First of all remove and replace the pads ONE AT A TIME! Remove one pad, leaving the other in place. Use whatever tool you want to use to push the piston back into its bore (I use a giant pair of channel locks), then put in that pad, got to the other pad in the same caliper and repeat. DO NOT REMOVE BOTH PADS AND THEN PUSH THE PISTONS INTO THEIR BORES! If you do, you risk forcing one piston beyond the seal making it impossible to put back in the bore without removing and replacing the seal.

Also, before you push the pistons back in their bores, it wouldn't be a bad idea to suck some fluid out of the master cylinder reservoir. This is because when you push the piston back in the bore, it will displace fluid back into the reservoir.

Also, you usually will not have to replace the rotors, but as Jim says, you certainly want to inspect/measure them.

Once the pads are replaced, it would be a good time to flush the fluid. It is important to flush the fluid periodically. Brake fluid is hygroscopic, and the moisture it absorbs can and will eventually corrode the hydraulic portions of your brake system. When I look at a used car, I always look to see how clean the brake fluid is. This is a good indicator of how well the car has been maintained.

Good luck,

so in regard to brakes...what's the skinny on MB rotors.?...two dealers in two states have told me not to turn MB rotors...the only time I had some turned was years ago with an 85 300SD and they were warped within a 1000 miles of the turning...I ended up having to replace rotors anyway.....my current vehicle has 40K on the front pads.I am not sure of the mileage on the rotors but I somehow feel that its will soon be braketime for my car.The last time I had the brakes done by the way was with MB pads,front and rear, about 40K ago

I also noticed the prices of the non MB brake parts...they are so much cheaper that it would not really be a big deal to do the rotors...my dealer dealer wants $525.00 for front pads and rotor replacement.....anyone have any input here to what is tried and true?

Warren
1992 300SD 130K
Columbus Ohio
[img]http://images.prosperpoint.com/images/1628/82440-3.jpg[/img]

Don`t turn the rotors. MB rotors don`t leave a lot meat, so don`t turn them.

Take the measurement and if in spec you could use them again, I wouldn`t. Ate Power disc`s for my SEC were $51 each from Fastlane.For peace of mind and safety, replace them.

John

rotor question
 

Engatwork, can you give pointers on replacing the rotors. Someone here suggested an impact wrenc to loosen the allen bolts but how do I torque the bolts when reinstalling the new rotor to the hub? Thanks in advance.

There is a German word for not machining MB rotors, It is "SHEIZEN" which translated into "BS". I have had MB rotors machined many times (not the same ones) with good results. They are cast iron just like any other make rotor, not some miracle allow because they come on a MB.



If the rotors look worn, have them measured and if they are at least .020" (0.5 cm) above the minimum at the thinnest spot and are not warped, they can be resurfaced for 1/10 the cost of new ones. The minimum thickness can be found in the repair manual. Any shop that doesn't measure the thickness of the rotors before machining them is incompetent. Places that do "fast" brake jobs like Midas and Pep Boys usually will machine rotors and some parts shops will do it for you.

$500 from the dealer? You can probably DIY for $50 or less like I do and its not rocket science. Just follow the instructions in the replies above. Then you can buy your wife or girlfriend a nice Xmas present with the $450 you saved. Who do you want to get screwed by, the dealer or your wife /girlfriend with her nice new $450 Xmas present?

P E H

As a follow up to engatwork's advice; I have a question. You mentioned that if the ball joint rubber pieces look torn or are leaking that you should replace them. Having just completed a brake job I have noticed some grease escaping the ball joint seal directly below the hub. How the heck do you replace these? I've tried many ways to no avail, (actually destroying a $75 separator tool). Obviously I removed the locknut, but is there something else that I'm missing? Is there any trick to their removal? There are no instruction to this in Haynes or Chilton's. I bought the replacement boots from my dealer for $4 each side. Please help!!! I'd like to do these soon (before snow and SALT) so I don't have to have the entire balljoint pressed out and replaced.

TIA
Sincerely
Adam

Hey Guys,

If you would consider changing the rotors for the peace of mind it gives you and because they are only $51 apiece, why would you ever force the old used brake fluid from behind the extended pistons back into the brake hydraulic system? Just flush it out when you are changing the pads! Attach a fuel line hose to the bleed nipple on the caliper and direct the other end where the fluidwill come out to the botom of a pint or so jar. I like using a clear glass jar so I can see the fluid that comes out. Crack open the bleed fitting when you are pushing the pads back into the caliper and there is next to no real resistance, and you will purge the air in the hose, or most of it, and cover the end so no air will get back in later. AFter changing each pad, separately as noted by Larry, you can complete the flushing by adding brake fluid to the reservoir (take care to keep it topped off when you are changing the pads as gravity will drain the reservoir if you leave the bleed fitting open) and pumping the brake with the fitting open. If you have an assistant you can have them close and open the fitting to make yourself feel good about getting all the air out, but if you start of correctly, you will not get any air in there. I have done this for twenty years, to each car when I change pads, and the fluid always comes out blackened (not like Diesel engine oil, but very much discolored) and I run a few cans of fluid through at a couple of bucks a can for all four brakes. Definitely helps keep the calipers happy and not likely to wear out the seal, which causes sticking. Jim

ALTD: Try heating the outside of where the tapered shaft of the ball joint goes thru the tapered hole and rap the ball joint at the end of the threads with a hammer. Quick heating in one area will work better than trying to heat the whole part.

P E H

On my California all its life SE where most nuts and bolts seem barely more than finger tight, I had to take my rotors to a shop to have the hub bolts heated enough to release. Impact wrench wouldn't do it, six foot pry bar wouldn't do it. Could well have been the result of a hack job when they were last replaced. I hope you have better luck if you have to change the rotors.


Sixto
91 300SE
81 300SD

The above is another reason not to replace the rotors if they are not beyond the wear limits. Even if they need machining you don't have to remove the rotors from the hub.

However, I have found that heating with an acetylene torch will get any bolt loose.

Remember, Rotors are dead cheap! After market are available.

I don't consider rotors at $50 each cheap or the correct terminology inexpensive. Maybe to you rich guys they are inexpensive, but to me thats a day's pay.

P E H