SC Brake Booster Revisited 2022

[MarkWard]

Hello, have been chasing a sticky brake pedal. It has a stiff section applying and then brakes grab and put your face in the steering wheel. The pedal then sticks returning. Everything has been redone except the booster. So, today I removed the booster knowing they don't seem to be readily available. Lots of rust and paint chips on the inside of the booster. This would be the master cylinder side. I can feel the booster dragging and sticking on the bench. So it's definitely the booster causing the problem.

My 1980 ROW SC booster part number is ATE 3.6832-1001.4. My parts catalog shows it as part number 930 355 027 00

For all the parts available for these cars, the brake booster seems elusive. Pelican, IMC, and WorldPac show the part number but either NLA or no stock. For now, I flushed and cleaned the can as best I can and will douche the inside with silicone spray lube for now. The car is no joy to drive at this point.

So, short of cleaning it out, where are folks currently getting brake boosters new or rebuilt? Thank you if you read this far. Mark

[pampadori]

I just researched this exact topic. I found that Advance Auto Parts (full disclosure, my employer) carries a part number but it's not in stock either. The manufacturer of this part is Cardone. They offer an r&r program where you can ship them your booster and they'll rebuild it and ship it back to you. You basically go to Advance Auto parts and buy the reman booster but they'll have a form you fill out to mail it in to Cardone and 10 to 14 days later it'll be returned to the store, rebuilt.
I've got my booster off the car now and will probably take it to the store to start this process.

[pampadori]

Here is the issue mine is having. Constant vacuum leak while pedal is depressed.

[MarkWard]

Originally Posted by pampadori

I just researched this exact topic. I found that Advance Auto Parts (full disclosure, my employer) carries a part number but it's not in stock either. The manufacturer of this part is Cardone. They offer an r&r program where you can ship them your booster and they'll rebuild it and ship it back to you. You basically go to Advance Auto parts and buy the reman booster but they'll have a form you fill out to mail it in to Cardone and 10 to 14 days later it'll be returned to the store, rebuilt.
I've got my booster off the car now and will probably take it to the store to start this process.

Thank you. I came across the same information regarding Advanced Auto and Cardone. Being an employee should be helpful. Please post up your results. Our Advance Auto Parts are suited for what they have on the shelves and lots of staff turnover. I’d be surprised if they knew what I was asking about. Mine doesn’t hiss and seems to hold vacuum. It’s physically internally binding. The car is was a non running barn find. So, I don’t have any idea of how the brakes were working when it was parked 12 years ago. Looking at photos during my search, the rubber bellow on the pedal side is missing. Might indicate someone had it apart at one time. After the cleaning it is slightly smoother, but still not predictable. Thanks again and good luck. Looking forward to hearing good news. Mark

[schoward]

Subscribing as may have exact same issue. Hissing sound and loss of boost when pedal depressed. Just occurred and discovered this week. Shop can't see me until next month with summer backlog.

Zims lists a rebuilt (with core exchange) on their site. Not sure on how real it is or if really an option....

Question - Can you remove booster without disrupting master cylinder or does all HAVE to come out together?

[Zuffenwerker]

Patrick Motorsports rebuilds boosters. There are also other non Porsche companies who can handle it. Apple hydraulics rebuilds boosters, I’m sure there are others.

[MarkWard]

Update, yes you can remove the booster with the support and leave the master installed. You will need to remove the 8mm bolt inside the car that secures the nose of the master.

Never heard back from the online rebuilders and did put in a call to Patrick Motorsports. They have someone local rebuilding them. I called my local Porsche dealer and new ones are available from Germany. Not sure why Pelican wouldn’t purchase them to have in stock for their customers. My cost with shipping was around $2500.

So armed with that knowledge I watched a couple brake booster videos and removed mine a second time. I marked the halves and carefully took it apart. The diaphragm was intact. The problem was with the cartridge that actually controls the assist. Mine was rusted and seized. I carefully disassembled it, media blasted it, new O ring and lots of silicone paste. I then media blasted the inside of the cans primed and painted in case this worked. Reassembled it and installed. I’m happy to report I have smooth brake operation. The pedal is no longer stiff and sticking. Quite happy with the outcome.

Based on my experience, I would be suspect of the claim it’s completely rebuilt. The cartridge is factory assembled and can not be disassembled to replace the seal if you had them. The diaphragm had a readable ATE part number that was readable. Google returned zero hits. When this one fails, I’ll purchase new from the dealer.

[LJ851]

Originally Posted by MarkWard

Update, yes you can remove the booster with the support and leave the master installed. You will need to remove the 8mm bolt inside the car that secures the nose of the master.

Never heard back from the online rebuilders and did put in a call to Patrick Motorsports. They have someone local rebuilding them. I called my local Porsche dealer and new ones are available from Germany. Not sure why Pelican wouldn’t purchase them to have in stock for their customers. My cost with shipping was around $2500.

So armed with that knowledge I watched a couple brake booster videos and removed mine a second time. I marked the halves and carefully took it apart. The diaphragm was intact. The problem was with the cartridge that actually controls the assist. Mine was rusted and seized. I carefully disassembled it, media blasted it, new O ring and lots of silicone paste. I then media blasted the inside of the cans primed and painted in case this worked. Reassembled it and installed. I’m happy to report I have smooth brake operation. The pedal is no longer stiff and sticking. Quite happy with the outcome.

Based on my experience, I would be suspect of the claim it’s completely rebuilt. The cartridge is factory assembled and can not be disassembled to replace the seal if you had them. The diaphragm had a readable ATE part number that was readable.
Google returned zero hits. When this one fails, I’ll purchase new from the dealer.

Mark, could you share a few pictures of the disassembly process if you have them ?

I have a booster I need to do this to.

[MarkWard]

Sorry, I did not document it with photos. I was more curious to see what was physically wrong with the booster before I shelled out the dough for a new OE one. The can is spring loaded, but is a soft spring. I put a pair of vice grips on the pushrod to act as a stop to prevent it from wounding me but was likely unnecessary. I used a press to hold it together while I recrimped the sides. Its really not that complicated. I used a cold chisel with a section of tube to pry the original crimps back. You need to be careful not to bend the shell of the booster prying. Even being careful, it was slightly distorted.

If you can get the can apart, the rest is fairly obvious. Feel free to PM me if you have specific question. One thing I learned. It did not make sense that the booster used vacuum to apply the brakes. Also why aren't the brakes applied if the check valve is holding vacuum? From watching you tube videos, its the change in pressure on each side of the diaphragm that create the assist. I found this video the most helpful to understand how it should work.
https://www.youtube.com/watch?v=wbTUvp-tD5M `

If you are hearing vacuum, it's likely not the diaphragm, but the cartridge that handles the equalization. Mine was stuck in the plastic tail housing. Sorry I didn't document it. This was not a difficult task, but there are no parts that I could find, so you may risk not getting your core charge if you send it out for rebuild after you find something damaged beyond repair. Also, its the brakes. You need to be sure you get the can crimped back together well. If not, it could pop apart applying the brakes in a panic stop and that would not be good. Fortunately, the master is bolted to the firewall from inside that should hold it secure regardless. You need to make a clear index mark between the two halves before disassembly. I didn't think it through and realized going back together its very important that the mounting studs and the master cylinder studs are square to each other before you crimp. An exact mark would have avoided this. Good luck. mark

[schoward]

Originally Posted by MarkWard

Update, yes you can remove the booster with the support and leave the master installed. You will need to remove the 8mm bolt inside the car that secures the nose of the master.

Mark - I am thinking / wondering if I can remove just the booster - leaving the Master Cylinder in place in the car to avoid disturbing 40 yr old brake line connections and having to lose fresh fluid / bleed job done last month. No indication anything is wrong with the MC. Looks tight be but maybe possible? When you say installed above I assume you mean on the booster. I am thinking on disconnecting the MC from the booster in place if possible. Tight squeeze to the two bolts securing the MC to the booster.... Any thoughts? Thanks.

[MarkWard]

Sorry I wasn’t clearer. I was able to remove the booster leaving the brake lines connected to the master. Inside the car, disconnect the pedal pushrod clevis and remove the 8mm bolt under the dash next to the floor vent.

Now in the trunk, Remove the 10mm bolt that connects the flat brace that runs up from the pedal cluster. Remove the cardboard cover over the blower housing. Remove the two 8 mm nuts that secure the reservoir to the booster and set aside. Remove the 4 8mm nuts in the trunk floor that secure the aluminum booster bracket. Remove the 8mm nut from the r/s of the master with a 13 mm wrench. I have an L shaped 13 mm wrench for the other master cylinder nut, but by this point you can pull the booster and bracket forward and access the nut with the regular 13 mm wrench. Then with some pulling, prying, and lifting, you remove the booster with the aluminum mount. You can separate the mount and the booster on the bench.

All of this makes more sense once you start. The master will remain supported by the hardlines. I left the brake switch harness connected too.

I have to repeat, you need to remove the bolt that comes up from inside and threads into the nose of the master from below. This gives you the movement you need. Obviously don’t get carried away and kink the hardlines. Good luck.

[schoward]

Originally Posted by MarkWard

Sorry I wasn’t clearer. I was able to remove the booster leaving the brake lines connected to the master. Inside the car, disconnect the pedal pushrod clevis and remove the 8mm bolt under the dash next to the floor vent.

Now in the trunk, Remove the 10mm bolt that connects the flat brace that runs up from the pedal cluster. Remove the cardboard cover over the blower housing. Remove the two 8 mm nuts that secure the reservoir to the booster and set aside. Remove the 4 8mm nuts in the trunk floor that secure the aluminum booster bracket. Remove the 8mm nut from the r/s of the master with a 13 mm wrench. I have an L shaped 13 mm wrench for the other master cylinder nut, but by this point you can pull the booster and bracket forward and access the nut with the regular 13 mm wrench. Then with some pulling, prying, and lifting, you remove the booster with the aluminum mount. You can separate the mount and the booster on the bench.

All of this makes more sense once you start. The master will remain supported by the hardlines. I left the brake switch harness connected too.

I have to repeat, you need to remove the bolt that comes up from inside and threads into the nose of the master from below. This gives you the movement you need. Obviously don’t get carried away and kink the hardlines. Good luck.

Thank you! Exactly what I was thinking esp. your note on the 8mm bolt for the master cylinder - just a little movement/wiggle room for the left side 13mm bolt which is tight as is with all bolted in place. I see the path here and may do it vs. having shop do it and save the labor $.

Best,
Scott

[pampadori]

Got my booster back from A1 Cardone. No leak now!
They didn't paint the booster so I'm on the fence if I should bother painting it or not before I install it.

[mike sampsel]

Originally Posted by pampadori

Got my booster back from A1 Cardone. No leak now!
They didn't paint the booster so I'm on the fence if I should bother painting it or not before I install it.

Easy for me to say: "paint it".

[MarkWard]

Thanks for posting back. I’d hit it with some satin black before installing. I noticed the rubber boot that wasn’t on mine or yours before you sent it out. How does the inside look where the master mounts? Any indication they took it apart? I don’t suppose they included the old parts or a detail of the work done? Glad it worked out for you.

[LJ851]

Originally Posted by pampadori

Got my booster back from A1 Cardone. No leak now!
They didn't paint the booster so I'm on the fence if I should bother painting it or not before I install it.

I just went to my local advance auto and they looked at me like I had 3 heads. Store manager was not in yet, will call her this afternoon. Do you have any clues to helping my store find this form to fill out so I can get my booster rebuilt ?



Edit: Never mind. I went to another Advance Auto and found a manager willing to help. I probably spent an hour there as he figured the whole process out. I’ve got the forms and will ship the booster today.




..

[pampadori]

Yeah it isn't a common practice i guess. From what i was able to learn they ring you up for the cardone brake booster part Num: 53-5755 or they can use the "special order SKU". Then the print and fill out the R&R form on StartingLine. Then they ship it to Cardone's TX location for you and call you when it is returned all rebuilt.

^^^hopefully that will help others willing to ship it off for rebuild.

Just test drove mine. I also replaced the master and the brake lines (which I made here in my garage with my hydraulic crimper and dies) and used my fluid extractor to pull in new dot 4 fluid. Brakes work well but do feel a little different. At the very first bit of pedal movement i feel a slight detent. but they release fine and have plenty of stopping power! And the main part - no fluctioning AFR when pedal is depressed which was the whole reason for me going down this path.

[spuggy]

Originally Posted by pampadori

No leak now!

Excellent...

Originally Posted by pampadori

They didn't paint the booster so I'm on the fence if I should bother painting it or not before I install it.

You can't see much of it; not like it's the hood or something. So it doesn't need to be perfect.

My 930 booster had a scabby trail of lifted paint/rust where brake fluid had leaked. I take the view that paint is primarily to prevent rust...

Removed the rust, rattle can a few coats of primer & black. Looks fine, really didn't take much effort or very long..

[LJ851]

I got my spare booster boxed up and shipped to cardone this afternoon, I’m mainly posting this to document how long it takes. Thanks for your help pampadori. My boosters both act like yours did, vacuum leak when the pedal was depressed.

[schoward]

Originally Posted by LJ851

I got my spare booster boxed up and shipped to cardone this afternoon, I’m mainly posting this to document how long it takes. Thanks for your help pampadori. My boosters both act like yours did, vacuum leak when the pedal was depressed.

Found some info via Cardone and Advance Auto parts site - can you share price? I see in the realm of $150 not incl shipping - that right? Seems low.

Thanks.