Brake job completed.... - PeachParts Mercedes-Benz Forum

Fuzzball · #1 05-09-2010, 11:22 PM

Well, I just completed brakes on the 84 SD.

Rebuilt the ATE calipers
New Rotors
New Pads
New Hoses
New Wear sensors
New Wear sensor cables

Once everything was done, I have a few concerns....

The pads were very very snug. With the new rotors they seem to drag a bit right from the start. When we took it for a test drive we went maybe 6 miles and when we got back to the house there was smoke coming from the wheels. I may not have gotten all the oil off the rotors before I installed them, so I'm thinking that this could be the cause of that. The smell is not like anything that I have smelled from the car before, so I believe I may need to use the brake cleaner on them a bit more.

Next, I'm not real happy with the feel of the brakes. They just don't feel like they used to. When I apply the brakes I expect an SD to react a lot better, but they seem weak. If I pump the brakes it's like I'm stepping on a brick and stopping power really diminishes.

Any ideas on why these just feel less than "Mercedes" expected?

As a side note, I replaced my voltage regulator due to problems with charging and found that the original one still had plenty of brushes but one of them had a broken spring so was not being pushed to contact the shaft of the alternator. All my lights on the dash now light as they should and we'll see if that fixes everything electrical...I expect it will.

Thanks for any insight on the brakes.

TnBob · #2 05-10-2010, 12:53 AM

That sure does not sound right.

Smoking brakes are not something to be driving around in until you
get things sorted out.

ALL brakes parts need to be spotlessly cleaned prior to installation.

From what your saying ... it sounds like your cylinders are not retracting
fully. Or that you have a bad mix of parts...

JohnM. · #3 05-10-2010, 01:08 AM

Did you bleed the system fully?

snookwhaler · #4 05-10-2010, 08:11 AM

You said that you rebuilt the ATE calipers. You have no mention of bleeding the brakes. But, assuming you did it and did it properly... Did you verify that each piston was moving on every caliper before re-installing? IE: pulling a caliper and putting a c-clamp on one side of the caliper, go in the car and push the pedal a couple times to verify that the piston is moving outward. Then retracting the piston (by hand) and vice-versa for the other side of the caliper.

Junkman · #5 05-10-2010, 09:21 AM

for the record: Bleed valves need to be at the top of the caliper or they won't bleed. Calipers are on the wrong side if the valves are at the bottom.

It is a good idea to do one side at a time so you have the other to use as a reference. Hopefully everything was installed correctly before the current work began. Put a clean rag on the ground under the caliper and lay out the parts when they are removed.

Your calipers don't seem to be releasing. Pads may have glazed. Rotors should be clean before reinstall. That said, a squirt of brake cleaner has done a good enough job that it hasn't been a problem. Consider how dirty many shops and mechanic's hands are.

Diesel911 · #6 05-10-2010, 11:42 AM

I go with re-bleeding the Brakes.
If that does not work I would return the Caliper that the pistons do not appear to be returning on.

Chris W. · #7 05-10-2010, 04:58 PM

Don't forget that the pads themselves may need some breaking in against the rotors. I don't want to start a brake pad holy war as this tends to be a touchy subject, but IMHO some pads respond well to a break-in consisting of a series of stops, cooling off periods, etc. I think if you search you'll find a variety of opinions.

Rgds,
Chris W.
'95 E300D, 313K

Fuzzball · #8 05-10-2010, 05:58 PM

Hi everyone...thanks for all the help.

Here's some amplification of my opening remarks that may make a difference:

I rebuilt the calipers one at a time. Everything seemed to be good.
The brand new brake pads combined with the brand new rotor was a very tight fit. there was not much play in the system at all. With the pistons retracted all the way and the pads fitting snugly up agains the pistons it was still a very snug fit, yet I could spin the rotors by hand.

I bled the brakes as follows:
1. Top off the fluid up above
2. Start at rear wheel, Passenger. Open, pump and hold, close, release and repeat at least 8 times.
3. Rear Driver side, same as above. Daughter was capturing the fluid into a clear plastic bottle so we could watch the stream of fluid.
4. Top off the fluid again
5. Front Passenger, same as rear, but repeat at least 25 times.
6. Top off the fluid agian
7. Front Driver, repeat as above, but only about 8 times.

We didn't stop the process till we had at least 3 times of getting a solid stream of fluid.

The smoke is not a rolling smoke, it's almost like when you get some oil on the exhaust. You actually have to see it at the edge of light, as pointing light directly at it blinds you from seeing it. It goes away pretty quickly, but it's like a plastic smell which is why I don't think I got all the protective coating off the rotors after hosing them with brake cleaner. Nasty smell, not like anything that regularly smokes on a diesel.

Snookwhaler, I didn't use any C-clamps...all was done using only my hands and a wooden handle (tapered handle from a wire brush, so used very carefully). I didn't go to the extent that you describe to test the pistons figuring if I could push them in by hand, they should be ok.

I'm thinking that the smoking will go away pretty quickly. My biggest concern is that the stopping power does not seem to be right. I've put less than 6 miles on the car since I completed the job and only used the brakes about 25-40 times (stomp, release, continue driving, etc.)

I heard someone talk about bleeding the master cylinder reservior...not sure if that's something I need to do.

I'm still open to suggestions...I thought I got everything done right, but it just seems that something is wrong. I only did the front, nothing was done on the back except bleed them.

vstech · #9 05-10-2010, 08:26 PM

the hard pedal makes me think of the booster. did you break the vacuum line? of course if you did that, your car wouldn't shut off...
when you bled the brakes, did you push the pedal all the way to the floor? this is known to damage old master cylinders, a power bleeder is much safer, and simpler. pump up the canister, open furthest caliper bleeder, wait for air to stop. go to next closer, repeat until all 4 wheels are done, no damage to caliper.
a power bleeder can be made from a garden sprayer, and a brake lid from a GM parts isle...

Fuzzball · #10 05-10-2010, 09:57 PM

Dang vstech, I wish I had heard about that before I got started....I may have pushed the pedal all the way down...but I would have LOVED using the power bleeder...

Can you show me how to create one of those? is it water driven or a pump? I am intrigued. I'm willing to do another bleed if people think that will help. My daughter is REALLY frustrated that she's not behind the wheel again....

toomany MBZ · #11 05-11-2010, 08:49 AM

I bought 0109.
http://store.motiveproducts.com/single-adapter-bleeders-c16.aspx

vstech · #12 05-11-2010, 09:08 AM

search on here for power bleeder diy...
basically, you cut the end off a garden sprayer, attach it to a spare reservoir cap, or get a cap from the parts isle at a mcparts for a GM vehicle (the round kind, not the square kind) seal the air bleed vent on the cap with jb weld or something, drill a hole in the center and attach it with the rest of your JB weld, and fill the sprayer with your choice of Dot4, and start pumping.

69shovlhed · #13 05-11-2010, 10:33 AM

Quote:

Originally Posted by Fuzzball

2. Start at rear wheel, Passenger. Open, pump and hold, close, release and repeat at least 8 times.
The smoke is not a rolling smoke, it's almost like when you get some oil on the exhaust. You actually have to see it at the edge of light, as pointing light directly at it blinds you from seeing it. It goes away pretty quickly, but it's like a plastic smell which is why I don't think I got all the protective coating off the rotors after hosing them with brake cleaner. Nasty smell, not like anything that regularly smokes on a diesel.

i hope this was a mis-type: you should not open the bleeder before pumping and holding. pump and hold, then open until its almost done squirting fluid and air, repeat as neccessary to get a good stream.

most rotors do come coated with protective oil or grease; it needs to be cleaned from the entire rotor, even the center, cause it can run back on the braking surface. brake clean and new shop rags.
i have seen cases where the pads come w/ a squeak plate on them, or the piston may have the plate attached to it. the new pads are too thick and the squeak plates need to be discarded for the pads to fit.

chomptown · #14 05-11-2010, 11:51 AM

Did you bleed the master cylinder out? That is probably why your pedals is being spongy. Since you you replaced the calipers, fluid drained from the master cylinder, and the reservoir possibly emptied.