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  #1  
Old 04-16-2006, 10:24 AM
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Location: Dallas
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Pics New Front Brakes, bearing play & pedal feel question

About a month ago I addressed the leaky caliper on the rear of my 300SD. That turned out to be a total brake job (rebuilt calipers, hardware, lines, rotors, and pads). I finally got around to doing the fronts. Glad I did as the fronts had maybe a month left on the pads. They were ridiculously low and the calipers were super exteneded.

A little background - I inherited the car from my mother so I've been doing all the work for the last 3 years. Almost 30K miles later the brakes are one of the last big things on the list. I wasn't real sure when the last time the car had a brake job, but I can tell you whoever did the last time didn't bother with any of the pad sensors or I would have done this job sooner.

The fronts got the full treatment like the rear, including new sensors and sensor wires (the old one's sheaths were disintegrating to pieces). I also did front bearings as well (my first time at that) I tried my very best to measure bearing play right with a guage & magnetic base. At a MB Club get together I have seen it done, but there must be some "art" to this. All measured tight but still rotated fairly freely.

I did discover a broken vacuum hose. Have to replace that shortly though the car seems to be doing well shifting and driving.

Brake pedal feel is a question though. The new calipers are Bendix and my old were ATE (my fluid resevoir is ATE). I have to say I don't like the anti-rattle retainer on the Bendix as much as the ATE. That being said, though I pulled through probably a half liter of MB brake fluid, the pedal still seems a bit soft. Not sure if that is because my old pads were so ridiculously low that the calipers were pushed way out, or that I might still have air in the system.

In the mornings I have noticed in the past that the pedal will drop quite a bit and firm up more as I start driving. I figured it was a slow build up in the brake system (vacuum?). On start up, should the brake pedal be firm (not sink). Right now (especially at startup), it sinks some...

Thanks!

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Pics New Front Brakes, bearing play & pedal feel question-small-brakes.jpg   Pics New Front Brakes, bearing play & pedal feel question-small-brakes2.jpg  
__________________
~shell
As of 2/2010:
2001 CLK55 0o\=*=/o0
13.6 @ 106mph
10K mi
1984 300SD
260K mi and going and going...
97 S600
46K miles
1991 Sentra SE-R (extremely dorked with)
www.se-r.net
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  #2  
Old 04-16-2006, 11:38 AM
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Quote:
Originally Posted by bodyart27
That being said, though I pulled through probably a half liter of MB brake fluid, the pedal still seems a bit soft. Not sure if that is because my old pads were so ridiculously low that the calipers were pushed way out, or that I might still have air in the system.

In the mornings I have noticed in the past that the pedal will drop quite a bit and firm up more as I start driving.
Sometimes it's difficult to get all the air out of them. The SDL is a bit notorious for that.

What procedure did you use for bleeding?
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  #3  
Old 04-16-2006, 11:41 AM
t walgamuth's Avatar
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Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 38,613
are you pressing while starting the car? if so there will be a change in feel. the main thing is after the car is running to have a firm pedal. there will not be a metallic firmness but a very firm rubbery feel. if this is how it feels you are fine. also if the brakes stop the car right and dont pull. another thing is the pads will take some miles to bed and seat and there will be little extra softness til then.

tom w
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Old 04-16-2006, 12:16 PM
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starting to think air

I did a lot of reading and searching since the last post, and now I'm thinking I have air in the system. I had someone pumping the brakes while I was at the bleeder valve. I think we should have done the "push & hold" meathod instead of pump - pump - pump.

Think that was the problem?

I might invest in a bleader that puts pressure at the resevoir fill cap and try it all over again.
__________________
~shell
As of 2/2010:
2001 CLK55 0o\=*=/o0
13.6 @ 106mph
10K mi
1984 300SD
260K mi and going and going...
97 S600
46K miles
1991 Sentra SE-R (extremely dorked with)
www.se-r.net
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  #5  
Old 04-16-2006, 12:34 PM
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Join Date: May 2002
Location: Blue Point, NY
Posts: 25,396
Quote:
Originally Posted by bodyart27
I did a lot of reading and searching since the last post, and now I'm thinking I have air in the system. I had someone pumping the brakes while I was at the bleeder valve. I think we should have done the "push & hold" meathod instead of pump - pump - pump.

Think that was the problem?
You can do the pump - pump - pump method. But, you need to run a bleeder hose from the bleeder nipple into a small jar with some fluid. The hose must remain below the level of the fluid. I use a horseradish bottle. The system cannot draw any air back into the caliper because the hose and the bottle are a closed system.

Or, you can use the traditional method.......much slower. Open bleeder....... press down on the pedal........close the bleeder.........let up on the pedal........repeat.

If you used the pump - pump - pump method without hose into a bottle, and without closing the bleeder screw on the upstrokes, this would allow air into the system and is most likely your culprit.

BTW, when using the hose and small jar method, you must close the bleeder screw before removing the hose from the bleeder, or removing the hose from the jar. You must turn the hose and the screw.....together. Therefore, don't open the screw more than 1/2 turn when you do this procedure......that's all you need to bleed.
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  #6  
Old 04-16-2006, 02:15 PM
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Join Date: Nov 2002
Location: Dallas
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ah...

I have the hose below the caliper going into a container.

I think my problem was that I was not closing the bleeder valve before the next pump stroke. I was getting a continual flow of fluid with just a touch of tiny bubbles in the stream.

I went driving today. Once I get started the brake pedal feel pretty good sitting at a light. Depresses down to about the same level as the go pedal. When the car is cold and I start it, the pedal definately sinks.

Thanks for the replies!

__________________
~shell
As of 2/2010:
2001 CLK55 0o\=*=/o0
13.6 @ 106mph
10K mi
1984 300SD
260K mi and going and going...
97 S600
46K miles
1991 Sentra SE-R (extremely dorked with)
www.se-r.net
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