Brake Booster lever ball and socket worn out

[kach22i]

Car: 1977 Porsche 911S Targa with 140,000 miles

Just installed master cylinder and rebuild pedal cluster, still no joy.

Took apart brake booster for core deposit and discovered it is an AT with blue lable and signs of leakage/wear/rust on lower half.

However off the assembly it plunges well, spring and diaphragm sounds good.

Problem
The main shaft of the brake booster has a ball at the end of the shaft and the receiving ball socket on the control arm comes off.

There is a retaining ring like a race inside of the arm socket that fishes about, but I have no idea how to get it out for replacement, or if there is a replacement.

I doubt simply replacing the booster with a rebuild will solve my problem unless it is common for the ball to wear down over time.

I hope I'm wrong.

What would you do?

Photos not loading, will try again later.

[kach22i]

Loading photos.






Looks past due date, right?

[RWebb]

yes - why not get rid of it and backdate to real brakes w/ no boost...

[kach22i]

Originally Posted by RWebb

yes - why not get rid of it and backdate to real brakes w/ no boost...

Because it sounds like more work?



This is just too ugly to stay in the car.

Is there a clip for the ball joint that I can put on similar to the little clip on the throttle linkage near the pedal cluster?

[Fairview]

I have an extra booster, pivot arm and housing if you need it. So the socket snaps over the ball end and as you can see, is strong enough to support the weight of the vacuum booster. I gather yours is coming apart?

[kach22i]

Originally Posted by Fairview

......as you can see, is strong enough to support the weight of the vacuum booster. I gather yours is coming apart?

I may have been premature in my assessment and too rough in my testing process.

My test was when arm is attached to ball on booster shaft pulling back on the arm as to retract the internal spring and membrane.

I had it pulled back all the way until it let go.

In retrospect, in regular operation the spring would be pushing back and not being pulled upon.

I've cleaned up the booster inside and out, cleaned off rust and painted.

I'm about to put it all back together and see how it goes.

FYI all sources for rebuilt brake boosters are out, only Zimms Autotecnik at +$400 sans check valve and another place at about $525 w/check valve are available.

Cannot get through Porsche dealership either.

I cleaned my insides by soaking in clean brake fluid, draining it and then flushing with denatured alcohol.

I used a hand pump siphon to suck it dry. Some rust came out of the insides, but has good seal inside.

If anyone can recommend a lubricant to spray to pour inside please feel free to recommend something. Letting this unit sit while the external paint cures/dries out.

[Fairview]

Been down a similar road recently. Is your brake action like you’re pushing against a block of wood?

[kach22i]

Originally Posted by Fairview

Been down a similar road recently. Is your brake action like you’re pushing against a block of wood?

Long story, brake pedal assembly was frozen, hence the recent rebuild and new bushings. Took the force of a trucker to depress and had to pull up by hand. That is now fixed, smooth as silk now, all lubed and new springs all around.

However in the process of forcing, dislodged ball from socket. This felt like no range of motion and some clicking (arm hitting inside of housing) One indicator of this happening that should not be ignored is the top plastic cap on control arm housing in front trunk popped off then the arm backed into it.

Very frustrating diagnosis.

Discovered when booster taken off for core deposit.

Note: not seen in any other thread, clutch rod with lever arm - the most inner part was bonded to brake arm tube. Wood block and 3 lb hammer did not work, torch and direct hammer worked. Had to re-braze flange. Re-rounded end of tube for bushing.

This is what happens when your car sits too long.

[Fairview]

My car sat for 20 years but didn’t suffer quite as badly as yours (pedal pivots were fine). I cleaned out my booster as you did and I didn’t think the booster was the problem. I rebuilt calipers, new master cylinder, new flex lines, cleaned proportioning valve....Still, I had to get a rebuilt booster to finally get excellent brakes. Wish I had faced facts to begin with, would have saved pulling the assembly twice.

[kach22i]

Originally Posted by Fairview

........Wish I had faced facts to begin with, would have saved pulling the assembly twice.

Thanks for the insight, but cheap me is going to wait for the post Covid-19 supply chains to be restored. I doubt rebuilt brake boosters go back down to $120, but $500 right now does not make sense. It would have to be a new one from a dealership at that price.

[RWebb]

lube with brake paste if you can reach anything; otherwise new fluid

[kach22i]

Originally Posted by RWebb

lube with brake paste if you can reach anything; otherwise new fluid

Is there a difference between "brake paste" and "brake grease"?

I was thinking of a spray but can get in there with an artists brush. Not sure how to get an even coating with shaft and spring in way.

Want to retard rust formation inside the booster. May have left stuff on the inside surfaces, just cannot see everything from the small opening.

[OSC911]

Originally Posted by RWebb

yes - why not get rid of it and backdate to real brakes w/ no boost...

I agree - boosters are overrated😁

[kach22i]

Ball and socket not worn out, things connected to it in the path were FUBAR.

Pedal cluster refurbished, new master cylinder and brake booster cleaned inside and out.

Final act was lubing the internals of the brake booster with so-called brake paste. This made a huge difference.



Safe on rubber and plastics.

[kach22i]

I also moved the reservoir over so the targa top will fit in the ftrunk unfolded.



Oh and that little hose at the bottom off the check valve, be nice to it. I only saw it at one place (AASALES?) that carried it, and for $75.

Mine is in good shape despite the nasty looking hose clamps.

Now that I see the photo should have cleaned up the retaining strap for the new reservoir.

[Geneman]

Kach. I sent you a pm, here is the pic. did you have to replace the 2 nylon bushings that hold the lever to the aluminum. housing?
I cannot find them anywhere
Thanks. FRank

[Flojo]

Originally Posted by Geneman

the 2 nylon bushings that hold the lever to the aluminum. housing?
I cannot find them anywhere

928 423 542 00

[Geneman]

Thank you Flojo!! excellent!

[kach22i]

I did not have to replace mine, but I do recall trying to put them back on in the wrong place, and that slit design being a giant puzzlement.

Keep your cell phones handy and document each step when you take things apart, it could be weeks before you get all the parts and put it back together.

Thanks for posting that diagram Flojo, I'm sure it will help a few other people.