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  #1  
Old 03-12-2006, 11:00 PM
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either my cable is broken or it needs adjusting

Talking about my emergency brake cable, well at least if it is indeed a cable. I noticed on my friends newly aquired 300SD that the emergancy break worked fine! but my eb im not so sure. I park it in the garage but i do notice it rolls foward a bit then stops im assuming the tranny is wats holding it which i know is bad!!

Were do i check? much help appreciated!!

EDIT: sorry this is for my 83 SD.

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Old 03-12-2006, 11:29 PM
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Why is it so bad if the tranny is what is holding it? You know emergency brakes also warp rotors. Granted some brakes also adjust by using the emergency brake, so there is some good too. I have never heard of any bad news from not using the emergency brake. I am interested to hear your thoughts.
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Old 03-12-2006, 11:37 PM
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Quote:
Originally Posted by fay31
Why is it so bad if the tranny is what is holding it? You know emergency brakes also warp rotors. Granted some brakes also adjust by using the emergency brake, so there is some good too. I have never heard of any bad news from not using the emergency brake. I am interested to hear your thoughts.
It doesnt warp rotors... heat does that. It could warp them if you leave the parking brake on.

The parking brake saves the parking paw in the transmission... The paw was explained to me by my uncle as "a pin that slides into a hole in a gear, inside the transmission" everytime you park on an incline, that pin and the holes get warn. Think of how hard it is to force it out of park sometimes on an incline...

THE TRANSMISSION IS NOT A KICK STAND, AND YOUR PARKING BRAKE ISNT JUST FOR EMMERGENCYS
do a search, plz
~Nate
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Old 03-13-2006, 12:18 AM
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Interesting, I just didn't know. I didn't know there was some such pin. I have noticed that on an incline. Funny thing though, I have had two different mechanics that said not to use the parking brake, because of the rotors. One of these was a transmission specialist, and he never mentioned anything bad. I will call tomorrow though and ask. Thanks for the input. Yes I am well aware it's the heat. I understand how metal expands and contracts, but the simple fact is when the rotors are really hot clamping down on them with that parking brake causes them to warp as they cool. There's no physical way they can't, it's extra pressure on an expanded piece of metal that is contracting while it cools.
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Old 03-13-2006, 12:31 AM
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Your rotors and pads also heat up when you stop too... I think it takes a great deal of heat to warp them (or theyre under turned)
I wouldnt think that theyll warp the rotors if you put the parking brake on, unless you allready waped them from stomping on the brakes hard. When the rotors's moving, and the static pads touch it, thats when heat (and stopping power) are created... If theyre hot enough to warp the rotor AFTER you put the parking brake on, youve got bigger problems


heres a parking paw assembly (tks howstuffworks)
http://auto.howstuffworks.com/automatic-transmission12.htm

I guess its not really a gear with holes, but more like a specially cut gear, with notces for the paw

~Nate
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Old 03-13-2006, 12:43 AM
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First off, the parking brake is a completely seperate system from the service brakes. The parking brake consists of 2 seperate drum brakes inside the rear rotors that are cable operated. Using the parking brakes will have nothing to do with warping rotors, I have no idea how someone could come up with a conclusion like that.

Second, the park mode in the tranny uses a parking pawl to engage a "window" which mechanically locks the output shaft of the tranny to the case of the transmission. I have never heard of it "wearing out." If you park on a steep hill, it is adviseable to use the parking brake in addition to the park mode on the transmission.

On your issue, either the parking brake cable has stretched and needs a readjustment or someone did some excessive driving with the parking brake on and wore out the parking brake shoes inside the rear drums.
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Old 03-13-2006, 01:02 AM
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great info, now how do i fix my emergency break
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Old 03-13-2006, 10:34 AM
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That's all pretty interesting. I wonder why so many mechanics say not to clamp down very hard on the parking brake though, since so many hear feel differently. Pretty interesting. I do know that I never use it unless I am on a steep hill, and my rotors never warp, when they used to. My experience seemed to correspond to what they had told me. Who knows. But the info about tranny pawl is very interesting. Pretty neat stuff there.
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Old 03-13-2006, 04:53 PM
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First pull the rear discs and inspect the shoes to make sure they are still their. If they are then I am 90% sure you can adjust them like a regular drum brake, their is a click thing you turn with the rotor on. Their is also a spliter up underneath the car in front of the rear flex disc and above the driveshaft. Thats where you adjust the cable, like if the pedal isn't coming up enough to turn the light off. I *think* MB specs 3-4 clicks before it is tight. At least thats where mine is on the SDL, with new shoes 3-4 clicks will hold the car no problem. 90% of the W126's I come across have poorly adjusted or non working parking brakes...

Also according to the manual you are supposed to engage it while driving at 30mph for a few seconds. Never understood why, havn't done it yet I don't want to glaze the shoes.

If the parking brake is working properly you shouldn't need to clamp hard.

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