'81 300D parking brake not working
 

Guys, what's the most common sense thing that would cause my parking brake to not engage? My pedal pushes to the floor and BRAKE light comes on dash as expected, but when I shift it into gear the car moves. The disengaged peddle has a little slack/play as well... When I disengage the parking brake it doesn't pop all the way back up. I have to pull it up with my hand a few inches to get the BRAKE light to turn off. Is this an easy adjustment? This was the only thing keeping me from passing inspection today...

Check under the rear rotors....
 

removing them reveals the parking brake shoes. If they are shot or full of cracks, they have them available here-

PeachParts FastLane Mercedes Parts Store

Replacing the shoes should restore function to the parking brake, and get that thing to THUMP when you release the brakes.

snapped_bolt

Something I can do in a couple hours over a weekend?

I would try adjusting the E brake shoes. You turn a "star" with a screw driver (or special tool) through a lug nut hole like the old VWs. Do you have a Haynes manual? There is another adjustment in the cable underneath.

I do have a Haynes manual and I'll have to try those adjustments. Thanks guys.

In every case of the E brake pedal going WAY down, that I had, the shoes just needed adjusting, I had to pull the rotor on the last one as the star was being stubborn, all pretty easy.

Thanks -- what's the right tool for adjusting the star?

The screw driver that fits in the hole, was good enough for me, but maybe they have something better in the MB tool dept. :)

before you go taking the rear wheel apart
 

simply.. Check the cables and linkages for the P Brake.

I tightened the star screw thru the wheel which was a magical thing... But it still didn't tighten enough to hold my car still up to 1400rpm (required for the inspection).

I found an inspection station that wasn't as picky and that solved my problem with getting a sticker.

However I didn't make any adjustments to the cable/linkage, so I'll try that this weekend and if that doesn't fix the problem I suppose the only thing left is to replace the p-brake boots.

Either way I got my sticker so now I move on. Thanks guys!

Over here you can't cheat the brake insepction cos it's all computerised... tho a weak emergency brake can creep up to spec if the tester should happen to rest her/his foot on the main brake pedal when testing the parking brake...

You followed the instructions in the Haynes manual and tighten the stars up till the wheels wouldn't turn then backed off a little?

When you change the Parking Brake Shoes there is a Specal Tool to remove the Retaining Springs.
Is there a DIY method to do that without the Tool?

Yeah, most American vehicle inspection isn't all that strict, and some places don't have it at all.

Sure did. Manual says to click pbrake down about 3 clicks. Then tighten down the stars on both sides, backing off 2-3 teeth on the stars. When I pushed the parking brake down all the way, it felt good. Nice and tight. But when I put it into drive, it held like the little engine that could but if I pushed the accelerator even slightly the car moved. Then, I inspected the stars again... I could be crazy but it seemed like they loosened a bit on their own when the car moved. Is that possible?

The manual suggested tightening the cable also underneath the car with a wrench. I didn't have time for that part but not sure if that would also increase effectiveness of the pbrake.

Yeah in this state these inspection stations are hit or miss. Seems like everybody and their brother has one. Some of them seems to only care about the blatant stuff and others are very respectable. I had a local woman tell me about an inspection station that slapped a sticker on her windshield after literally just driving her car around the building.