Parking brake repairs

JHZR2

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I am having issues with the parking brake on my 91 300D. It’s the only thing that doesn’t work in the car, so I’m doing ok…

The foot pedal doesn’t go down at all. Not one click. it will allow the cable in there to move, but not enough to do anything.

I guess there are two options - the under car mechanism that pulls on the cables going to each wheel, or else the adjustment of the shoes. The car has the typical drum brake in the disc rotor hat design.

I pulled the wheels and tried to adjust the mechanism. The passenger side I could adjust until I couldn’t turn the wheels, then I let off tem clicks. The driver side I did the same, tightening until I couldn’t turn any more, then backed it off. I couldn’t get it more than four clicks.

So somehow I can get the shoes to engage enough, and can back off. But the extent that imcan back it off is different per side. What does that mean in terms of the assembly and situation?

Unfortunately the cable splitter and return spring is under the car in the driveshaft tunnel, and lifting the car on my jackpoint jackstsnds is not high enough to get under safely.

Any recommendations on what to check next?
 
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I would guess one or more cables are rusted inside probably the one(s) going to the wheels. Remove the cables from the parking brake and try the pedal if it is still not moving that is probably the issue, the foot mechism cable is usually not a problem but when you remove the rear from the splitter you can check that.
 
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^ What Trav wrote.

I actually freed up a parking brake cable by removing it from the car, coiling it, uncoiling it, and whipping it against the concrete floor. :D Naturally you may want new parts. The cable may have "taken a set" in its sheath, really really liking its current shape where it bends.

You should be able to move the shoe mechanism with an 8-inch vise grips. It'll be good to go over everything and see where the sticky parts are.
 

JHZR2

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I would guess one or more cables are rusted inside probably the one(s) going to the wheels. Remove the cables from the parking brake and try the pedal if it is still not moving that is probably the issue, the foot mechism cable is usually not a problem but when you remove the rear from the splitter you can check that.
Luckily I had a feeling they weren’t. Because I took a screwdriver and tried to move both arms with the pads maximally slacked by the star wheels. The cables seemed to move and not slack themselves when I tried to move them individually, indicating that they were going in and out of the sheath.

I tried slackening the rest of the cable by the bolt on the mechanism, and that helped. I could apply the pedal one click. I backed it some more and tried to loosen the pads by star wheel evenly. It’s at a point now where the axle holds against the brake and it engages/disengages properly. Hard to tell if just one side is doing the work TBH. The mechanism is a bit crooked still, and now it’s a bit floppy hanging there under the car. I’ll see if it rattles or knocks.

I lubed it all up with CRC power lube because it’s thin and creeps, and leaves a light lubricant with PTFE. Any thoughts on what to use to lube it for the long run? It’s in the driveshaft tunnel.

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It looks like one of the rear cables or calipers is still stuck. The equalizer bar that connects the center lever to the two rear cables should be about equal, not tilted all the way to one side.
 

JHZR2

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It looks like one of the rear cables or calipers is still stuck. The equalizer bar that connects the center lever to the two rear cables should be about equal, not tilted all the way to one side.
That’s what I thought too. It works but maybe one side has more pad?
 
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The caliper has a self-adjusting mechanism so the cable position stays the same as the pads wear down. This is why you have to screw the piston back in when replacing pads, that resets the self-adjuster.

Drum brakes also self-adjust.

See if both cables move when you apply and release the brake lever.
 

JHZR2

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The caliper has a self-adjusting mechanism so the cable position stays the same as the pads wear down. This is why you have to screw the piston back in when replacing pads, that resets the self-adjuster.

Drum brakes also self-adjust.

See if both cables move when you apply and release the brake lever.
I have to wonder if the self adjustment is why the two cables are different lengths. Nothing I can do to adjust makes it better. Can’t waste hours being anal-retentive when it seems that both sides grab suitably. There is enough play in the diff that if they weren’t both grabbing, I’d be able to move one of the half shafts and wheels. When I individually tightened I could see that happening. So it’s grabbing both halves…

Now to lube it fully. Some grease or gel for the mechanism, and silicone for the cable shesths?
 
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