Are the brakes supposed to be terrible?

Yea, I’m just outside of Atlanta and there are plenty of shops. I was trying to get this all sorted myself though. I really got the car for something to wrench on when I found spare time. The fun is finding the issue myself. I think I have to drive a similar year to see if I’m just crazy or if there is actually a problem.

Porsche factory brakes on that car are phenomenal. Just go with Porsche Paas and rotors.

Don’t skip the AOS !

I think there's actually a problem. I have never felt anything but confidence in the stock 987 brakes. This is kind of a smoking gun in my mind. I would speculate that either a previous owner had the same problem and was trying to fix it with a new booster, or they replaced the booster for some reason and messed something up.

I was thinking the same. They must have been chasing a problem that they never found. The pads are oem equivalent and the rotors seem fine. I haven’t found a vacuum leak as of yet, but maybe it’s somewhere else. But the vacuum test seem to work, pumping with it off and having the pedal drop when starting and also testing that it hold when I shut the car off. I’m lost but still not willing to bring it in to the dealer or a shop just yet.

The NT530 will do the ABS bleed cycle. I'd have to hook mine up to find what menu its buried under, but I've used it on my 2009 to do exactly that, and it made a big difference in brake feel (my mechanic was surprised to see air flow through the bleeder line the first time I activated each circuit. That said - that didn't help on my '11 Cayenne Turbo - I had a similar sort of feel, which in a 500HP 3 ton vehicle isn't a good thing.. I never completely solved it. I had my mechanic replace the brake booster with one I got from a junk yard. Didn't help. The check valve in these boosters is located in the vacuum fitting going into the booster. We replaced the seal for that fitting. Didn't help. Finally added a second check valve to the vacuum line (one from a Volvo that used an external check valve) - didn't help. New pads did help. Even though the ones in it were the factory pads. It wasn't as good as it was when I got the car, but it was much better and a bit more confidence inspiring. Good luck, and keep us up on what you find out..

The pain continues!! So someone was in here a few times playing around with a bunch of things. The ABS pump is missing a single bolt, so that was screwed with at some point. I pulled back the master cylinder to make sure the linkage wasn’t getting jammed up and it moves smoothly without the master cylinder connected. I don’t think the pin is preloading it either, it wasn’t under pressure when I removed it. I went to check inside the booster and sent a picture to chat. The diagnosis was a missing rubber reaction disk on the pin of the brake booster . Is that a thing on the Boxster? Could it be losing vacuum because of that? I’ve attached a photo, is something missing in there? Could this be the whole problem?

I’ve decided to order a used booster and master cylinder off of eBay. Looks ok from the pictures and for $80 I’ll take the chance. I can’t imagine what else it can be.

Having a similar issue with another non-Porsche vehicle and I’ve been watching videos and reading up on brake systems. Scratching my head over your problem, and wondering if there is an adjustment on the lever that connects the brake arm to the lever that acts on the brake booster , which in turn pushes against the master cylinder . Could the lever in the brake booster be reaching its max before it exerts full pressure in the master cylinder ? If there is an adjustment, which I came across in some vids, maybe it’s out of adjustment and not giving full travel when pressing on the brake. In any case, since you have the parts ordered, maybe this will be the solution to your problem. Your brakes as you’ve described are definitely not normal, as a properly functioning brake system should be stopping you firmly and confidently. Good luck with the replacement parts. Waiting to hear your final results.

I separated the booster from the master cylinder and the pedal moved smoothly with no binding. The measurement seems correct for the booster pin so it doesn’t seem preloaded. I think since I’m buying a used booster with linkage and the master cylinder still attached, I’ll just install them all as one unit. I ordered a vacuum gauge today as well, just to check how much vacuum there is. More to come.

More info. I guess l should have checked how much vacuum I had at the booster before I bought one, oh well, I’ll have an extra booster and master cylinder in case it goes bad. Turns out I only have 10 in of vacuum at cold start and 8 at idle. This is at the check valve, so that can be the problem or it can be further back. Anyone have the vacuum routine guide? Either way I’ll start tracing it back tomorrow to see where that line is either cracked or separated.

Wasn’t able to find a vacuum line routing diagram, but this description makes sense and should be able to help when tracing the existing line. Hope this helps. The Porsche 987 brake booster vacuum system uses a hard plastic/nylon line that runs from the front-mounted brake booster under the car's center tunnel straight back into the engine bay to source high-engine vacuum. [ 1 , 2 ] Routing Path Front Connection: Connects via a push-to-connect fitting and check valve directly to the top/housing of the brake booster canister located under the front service cover/frunk area near the master cylinder.[ 1 , 2 ] Underbody Tunnel: The main hard line drops through the bulkhead and travels rearward shielded inside the central underbody chassis tunnel alongside the main coolant pipes and brake lines. Rear/Engine Bay Connection: The line enters the front/lower section of the engine compartment and links directly to the designated high-vacuum source port on the intake manifold assembly (driver's side/left or via specialized distribution points depending on exact model spec and manual/Tiptronic configuration)

Thank you. Tomorrow starts the hunt.

Update for everyone. So I traced the booster vacuum line into the wheel arch, 8 in-hg, kept going back to the connector just below the door going into the pump, also 8. Followed that up to the pump, everything looked good so I tested the pump, 30+ in-hg! Then I checked that line, thinking it was good, but found the top nipple broken off and a small vacuum line hanging around there. So I epoxied the nipple closed and capped off the small line for now so I can check the brakes and everything is perfect!!! I didn’t drive much but the brakes are now confidence inspiring. I ordered a new hose from Porsche for $107 plus shipping, which isn’t bad. FedEx will be here tomorrow with a master cylinder and brake booster I really don’t need, so I guess I’ll sell it on marketplace. The internet is telling me that the small line is the secondary vacuum circuit and operates the intake manifold change-over/resonance flapper. Not sure how much that is messing up the drivable of the car, but it feels fine, no CEL and no dash lights. Thanks for everyone’s help.

I love it when a solution is posted.. and great work tracking down the issue that was causing your problem. Posting the solution makes the thread really valuable to anyone else experiencing the same sort of symptoms. Thank you!

Great job! Always gives you a good feeling to tackle one of those pesky problems and stick with it until you hit the solution. AND you save some money. And sharing your results will help someone else down the line. Now you have the braking response you were expecting.

Not only was it great that Adam posted the solution, it also goes to show that you should trust your feeling (especially regarding brakes!). If something feels off there likely is a cause.

Congrats, good find! Oddly I can't find the vacuum pump on the online parts diagrams. But if it goes up, yeah, it probably feeds the flappers so you'll loose some intake efficiency/power if it's not working I'd guess. If you have the Porsche Sport Exhaust that also won't work. I don't know if that also connected to the OVS (that needs a vacuum source, so probably?) but if it is the OVS then won't work right. Either way I'd suggest fixing the pump properly, at least to get the intake flaps working right.

So I just got this 2005 box S and I’ve been sorting through it for what I believe is missing maintenance. Did the oil change, changed the gearbox fluid, flush the brake lines and bled the clutch. The brake fluid was blue so I guess that hasn’t been changed in a while. I thought that might help with the brake issues I’ve been seeing, but it didn’t. So the brakes feel really hard to stop. If I come to a stop, come off the brake slightly and then tap the brakes again it’s like rock hard. My driveway is really steep so I have to come down slowly and the brace don’t feel like they’re holding on the way down. Very odd feeling for what I thought would be excellent breaks considering the size of the calipers. I checked to see if there was vacuum and there is at least there is at idle. I’m unsure of the pads they use previously or the break-in so that might be my next step but these brakes are terrible. Any suggestions on street pads? Really don’t care about dust. I only drive it every other weekend and I’m fine with washing it often. But unless I’m doing something completely wrong, the brakes don’t feel like they will stop if needed.

That absolutely does not sound normal, no. The hard pedal thing sure sounds like the brake booster . You checked for vacuum but have you checked if the booster is holding vacuum, or if it's working? I think these cars have a vacuum pump, it's also possible that the pump is failing or there's a leak in the hose to the booster . Do a search online, there are a few ways you can test the booster pretty easily. Like, when you start the car you should be able to feel the pedal drop, after you turn off the car if you press the brakes multiple times you should feel the throw changing as each stop bleeds off vacuum, that sort of thing. You'll find better explanations than I can give if you search.

Bet it’s got pads that like to heat up before they work. I always warn everyone “you will think the brakes don’t work. Press harder!” so they are definitely Not over boosted! but your sound like something else.

Sounds like there's a bigger problem going on... and like @gubi said,this is not normal. Blue brake fluid was a thing in the past - ATE sold this until the US stopped allowing it. This happened in 2013, but someone could have had it left on a shelf, though that would be a problem by itself since brake fluid doesn't keep well for very long anyway. I would give the entire brake system a look over. As I typically work on my cars, I would check the pads and rotors since they're easy to get to and inspect. While there, check the calipers to make sure they aren't seized or something. Frankly, I'd replace them if they look worn down. If they look new, then maybe not. Also, see what kind of pads they are - maybe they're race pads or something? Post what you find if you can't identify it yourself... but remember race pads need heat, and are not really well suited for street use... especially in cooler areas (I'm in CT, so they are TERRIBLE for me). Beyond that, you said you flushed the fluid... that's good. Did you bleed it well? I would assume you did, but I have to ask. How did you bleed the system - pressure or vacuum? Or the two-person method? I know on the 987-series, flushing the ABS is recommended as well, and requires a tool to activate the bleed mode there. If you haven't done that, it could be some of the problem... if there's air stuck in there, then it would cause all sorts of problems, of course. Since you're having issues, I would be sure you bleed through that as well. Lastly, if you have a manual, the clutch is driven through this fluid as well, I think... and that can affect the overall hydraulics as well, so you may need to bleed that as well. As for hardware, I love the Sebro slotted rotors I got for my 987.2 from FCPEuro. I also got Akebono pads and they dust VERY LITTLE. I know you said you don't care about that, but beware as the stock Textars are VERY dusty (again, on my 987.2). The Akebonos performed equally well on the street, to the Textars... so I wouldn't bother with them ideally. Any brand would be fine otherwise... but any well known brand should be fine.

Depending on one’s DD experience and more importantly marque, the Brembos can feel very hard. For example, my mom has a Subaru and I find those brakes to be over boosted and twitchy. My Ford is even more boosted than my Porsche by a large measure. It takes some time to acclimate but in my opinion the Brembos are like that with purpose because it gives you more latitude and bandwidth of brake application. Next time you drive it in an uncrowded place slow down with some purpose, if when you’re in them they don’t inspire confidence and grip? Then something needs attention.

Thanks for all the replies, a lot to unpack for sure. I did the basic vacuum check, pressing the pedal starting in the car getting it give a little bit, and the pedal moves slightly. Not sure how much is necessary, but it moved. Also, did the pressure test to see if it would hold it seem like it was holding vacuum. I think I need to dive into the vacuum a little bit more that seems more likely to be the issue. Anyone know common breakage points ? I pressure flushed the brakes and clutch, starting with the clutch getting all the fluid out that was still blue then moving on to the brakes. I didn’t see any air left in the lines after it all ran clear. I have a foxwell NT530 but didn’t bleed the ABS, guess that should be my next step huh? I should probably pull the brake booster check valve, not sure if that’s a common failure.

If the fluid is clean, it may be " Blue Racing Fluid ". Not really any difference in the fluid, just the color so you can see track side changes easier. If it has Blue Fluid, it might have racing pads that need a bit of heat before they start grabbing. If they are firm, and get firmer on a second press I would bet most everything is good except the pads. Unless they don't release cleanly, then I would suspect swollen hoses.

They release, the just don’t feel like they will stop. As soon I’m coming to a stop, they feel hard and like take a while to bite. Going down my driveway, I think it will run into the garage. Not very confident in its stopping abilities. tomorrow I’m going to pull the wheels off and check what kind of pads they are. Probably bleed the abs if it’s not to bad of a job. Anyone bleed the abs before?

Just do a regular pressure blead and you will be fine. If the brake peddle is not soft, there is no air in the system.

So far sounds like your checking of the brake booster and fluid seems good. Could it be possible that the rotors and/or pads could be heat glazed? If a previous owner braked hard when the rotors and pads were already hot, it can cause a hardening of the surface of the pads and rotors, making it difficult for the pads to get a good bite on the rotor .

I have to pull the pads but they looked new. They are also Tan so I think they threw in some cheap pads some time ago. Rotors don’t look grooved so that’s a bonus. I’m leaning towards vacuum still. Maybe a smaller leak that’s only very noticeable when just idling speed? Maybe brake booster check valve. Tomorrow I’ll know more.

Ok, Update! I don’t think it’s vacuum anymore, and now more confused. I hadn’t pulled the plastic around the master cylinder until tonight, and now see that the brake booster appears to have been changed with a different one. It’s a TRW which I’m unsure is the oem one but it was definitely a used one because someone wrote in yellow paint pen, 05 Porsche Box. There seems to be no leaks, but while checking it out, it seems like the pedal has no travel, which I think is the cause of all my problems. When I press the brakes, it only travels about an inch or two, then it’s rock solid. so maybe the booster is bad or they installed it with the booster pin set correctly causing preload. So I guess my next steps are to put the car back up on stands, pull the front wheels, and crack open a bleeder valve. If it flows freely when I press down the pedal, then the booster is fine, and I must have a frozen piston. If the pedal doesn’t move more than it currently does, then the linkage or set pin are wrong. Does this sound right?

Sounds logical. I’m actually going through the same exact scenario on my runaround beater car, a Honda Element and I read that the connecting rod from the vacuum booster to the linkage on the brake arm may be adjustable. It’s quite possible that part, obviously from a dismantler, is not the exact replacement. On a recent drive, the brakes started grabbing until they finally locked up. Had parked just in time before it was immovable. Brake pedal hard as a rock, put in drive and give it gas but no movement. Left to sit long enough and it seems normal, but after depressing the brake pedal up and down my driveway the pedal gets stiff again. On this vehicle there is no vacuum booster check valve, it is built into the vacuum hose from the engine to the booster . Tested and good. Next target in troubleshooting is one of the rubber brake lines. I’ve read that when old enough the inner liner can collapse, creating a one way-like valve that doesn’t release hydraulic pressure on the caliper when you lift your foot off the brake pedal. If that hits a dead end, then the only component left is the ABS modulator valve assembly. Which is the most expensive part of the system, so I always start at the least expensive remedy when troubleshooting. Good luck, keep us posted.

read this https://www.pelicanparts.com/techarticles/Boxster_Tech/48-BRAKES-Bleeding_Brakes/48-BRAKES-Bleeding_Brakes.htm

Another Update. I’m starting to think this is just normal for these brakes. So I can’t find an issue to correct. None of the calipers are seized. The brake booster is installed correctly, and I can’t find a vacuum leak. I’m starting to think it’s me or this is just how the car is. The travel is very short and stiff, but maybe it’s just like that. The pads have plenty of meat left, and they are Textar's standard WVA series pads. I’ve never seen pads with the weights on top like that but they are the correct models for the car. The rotors are Sebro brand and seem within tolerance. There’s a decent lip on the top but that’s not an issue. I may change the pads for something more aggressive for the street and don’t really care about brake dust, I wash the car regularly and enjoy that. Am I the only person disappointed in the brakes? I know it’s a 2005 but I’d be very cautious going all out on back roads. My last comparable car would be an Audi S5 and those brakes were great. But I’m sure it’s apples to oranges. Any suggestions on pads?

What was your previous drive? You can try pulling the pads and lightly sanding them in a flat surface. Wash off the rotors well with brake clean and put it back together.

Since each car and driver is unique in feel and expectations, the brake response is subjective. What feels great to one person is passable to another. Maybe you could have another Boxster owner drive your car and vice versa. For comparison’s sake, the brakes in my 2008 base are exceptional. They stop the car smoothly and confidently with little effort. I imagine yours should be on par with that, if not definitely drive another Boxster for the true litmus test.

I daily a dodge charger and recently sold my Tesla Model 3. Previous sportier car was an Audi S5. These brakes are like none of those.

I’m going to find someone locally. It doesn’t seem right but I’m ordering pads anyway. Just in case.

Porsches are pretty renowned for the quality and durability of their brakes, as long as they are properly maintained. I certainly have more confidence in the brakes in the Porsches I have owned than any other brands I’ve driven, so if you aren’t feeling comfortable with their performance, then there must be something wrong. Do you have any independent Porsche service places in your area (I assume you are avoiding taking it to a dealer intentionally) who could check it?