Soft Brake Pedal - Any Other Ideas?

So, I initially decided to replace the pads, rotors and brake lines on my 2000 C4 Cab because the brake pedal was feeling "soft" to me. The other reason to change the rotors and pads was that they were very clearly worn. Had/have to press the pedal about 1/3 way down before it engages and it never felt "firm." Sorry I can't be more descriptive but anyone who has experienced "soft brakes" should have an idea what I am talking about. FWIW, the brakes on my BMW, MB, MR2 and F250 are all "firm" (not soft). Only the brake pedal on the 996 feels soft to me. Anyway, last week my Indy installed the Akebono bads, Brembo rotors and Stop Tech stainless steel brake lines and, of course, did a brake flush and bleed in my 996 and the pedal still felt "soft" -- no real change. WTF? So, I did some reading on the NET, which can be a dangerous thing to do, and it was suggested that the master brake cylinder could be the culprit. The Indy only wanted a little more $ to replace the master brake cylinder w/an OEM part (adding the necessary fluid and bleeding the system again). So, I told him to go ahead and do it. My Indy did the work yesterday BUT still no change!!! So, I'm at a loss. Basically, everything has been changed in the brake system and it still feels soft -- too soft for my taste. I'm tempted to take it to my Dealer to see if they can diagnose the problem (Is a full system pressure test possible to check for leaks?) but before I have to resort to that, does anyone have any other ideas for the possible cause of this "problem?" FWIW, my Indy talked sh*t about the Akebono pads that I asked him (but that he really didn't want) to install. I don't think the Akebonos are the problem because they stop my BMW 335i (which has a very firm brake pedal feel) fine. He also had to remove the front brake pad shims that were on the pads that he replaced w/the Akebonos because they didn't fit on the Akebonos. That bothered him a lot too. Wrote all kinds of CYA sh*t on the work order about it. I further told him NOT to reattach the rear brake pad dampers, which he also didn't like and wrote about up the work order as well. The shims and dampers are only necessary for anti-noise/squeal purposes and the Akebonos have not made any noise or squealed in the 200+ miles that I've driven it since they were installed. The new mgr at my Indy is a kinda of "by the book" and "color inside the lines" kind of guy who I don't really like and am planning to find another Indy shop for work w/in the future on my 3 German cars, including the 911. Liked the previous mgr much better, who also seemed much more knowledgeable than the current one, but he's gone now. In any event, if anyone has any ideas about any OTHER possible causes for the soft brake pedal feel in my 996, I'm all ears!

I don�t have any amazing wisdom bits for you. I could never really understand why some cars have a stiff brake pedal, and a different identical car does not. Most of the time, it�s pads and air in the system. The only thing you haven�t tried yet is the vacuum booster, correct? If that�s the case, I�d check that, along with the vacuum your engine is generating.

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Thanks for the response. I did a vacuum test w/a manometer attached to the oil filter cap to check for an AOS leak and it came back at 4.6-4.7 inH2O, which I understand is spot on. Not sure how to check the engine vacuum otherwise. May ask my Porsche dealer to check the vacuum booster and see if they can find any other possible reason for the "problem." I'm stubbornly refusing to believe the problem is the pads because they are brand new and the Akebonos work fine in my BMW. Also not sure how the pads would affect the brake pedal feel especially since the pedal feels essentially the same as it did before the installation of the new pads/rotors when the old pads/rotors were severely worn. Going to let it go for now. The car stops and that's really all that matters. The only problem would be in a panic stop situation, which I experimented w/a couple of times, and there is a definite delay in stop time/distance that could cause a problem in an emergency. Hopefully that won't happen before I take it into the dealer for a further inspection.

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I swapped out my Textar pads with Akebono a few weeks ago and the pedal feel didn't change. I also used the same shims/dampers and they work just fine with the Akebono pads. As far as your soft pedal, I wouldn't replace anything else until I was SURE the brakes have been bled properly.

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The brake fluid has been bled at least 2 times by my Indy in the past week; once when the new pads/rotors & new brake fluid were installed and again when the new master brake cylinder was installed. Brake pedal felt the same after both events. Of course, I don't know if they were "properly" bled but w/the equipment they have, I can't image that they f*ck it up. This is why I'm thinking to taking it to the dealer as a "last resort." If they can't do anything w/it, probably no one can. Indy said the shims on the old pads (don't know what brand) didn't fit the front Akebono EUR 776 pads that I bought and told him specifically not to install the dampers on the rear Akebono 738 pads. Just didn't think I needed the anti-noise/squeal shims/dampers and, based on the driving I've done so far, I don't. Update : Just made an appt w/my dealer to take a look at it next week. Will report back later w/the results (if any).

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My pads are the 776's and the shims were from AutohausAZ just listed as "OE Supplier" and "O.E.M.".

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Cool. I�m curious what they find.

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Me, too! Took the car up to Sacramento to look for a 2001 Turbo that was supposedly for sale there but never found it. However, the feel of the brakes actually felt worse; brake pedal drops about 1/2 before it fully engages and is very slow to stop. Very worrisome. Also "discovered" another problem that I probably caused that I'll have them look at as well The fuel gauge is now stuck on FULL probably because I've been overfilling (until there was/is some runoff) so that I could more accurately measure gas mileage which seemed erratic to me. Just going to ask if they can fix it w/o doing the whole calibration routine. If not, I'm just going to ignore it and continue to guess as the fuel level base on the miles driven and my manual calculation of fuel mileage. here also seems to be a problem w/excessive back pressure in the tank which forces the fuel nozzle at gas stations to click shut way too fast so that I have to hold the handle in order to fill the tank. Don't know if this is a related problem or not. Didn't start happening until I started overfilling the tank. So, it probably is related. Will mention this to the dealer as well.

it seems you've replaced all the issues that needed to be replaced other than the brake lines. I suspect your culprit is either 1) your pads are softer than you like or 2) it's just the way this car is. My Boxster's brakes felt firm at first with brand new Hawk HT10 pads but then after bedding in, felt softer than I liked. I just got used to it

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Guess we'll find out shortly but I still don't think it's the pads because I have the same pads in my 335i which stops on a dime and I don't see how pads would affect brake pedal travel and feel. Just hope the dealer can figure it out and fix whatever the problem is, otherwise I may try to sell it because I don't feel "safe" in my 996 the way the brakes feel.

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Overfilling can get in tank vent lines and other tank plumbing, You can gain accurate measurements letting it shut off on first or second auto release on Dover handle) One thing you can do to help with shutoff is not put nozzle fully into receptacle. Other thing to try is turning nozzle 180 degree from normal, Shut off works the same. Good luck.

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Yeah, I think I really f*cked things up in the fuel tank. The car's still at the shop (24 hrs now) and they're still trying to figure out what's wrong/how to fix the tank as well as the brakes. Oh well . . .

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About a year ago, I had a similar problem. It turned out to be the ABS Module. There�s a diaphragm that goes bad & leaks fluid out the bottom of the module. You should be able to notice if you�re losing fluid just by checking the reservoir. The problem is you won�t see it on the ground, as it�s in the bottom of your frunk. You�ve got to pull the drivers side liner out and shine a light down there - if it�s leaking you�ll see it. The up-shot is that you can get the modules used, and they�re pretty cheap (less than $100) - the job itself isn�t overly difficult either - 4 brake lines, then bleed brakes. I think I did it in about 1.5 hrs... good luck

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Thanks for the tip. Just spoke w/the Service Mgr (because the Service Advisor still didn't return my calls) and they still haven't figured out what's up w/the car. Gave him an overview of the problems (some of which the Svc Advisor didn't list on the woksheet) and mentioned the tips suggested here. He said he'd get back to me w/a further update tomorrow. Hopefully, he'll have something productive to tell me.

Have you had the brake calipers inspected /overhauled or replaced? If one is sticking it can cause your concern. I have akebono pads on three of my cars ,not one problem.The abs system could have a problem also . I would let the porsche store road test and inspect the brakes ,they will let you know if its normal or not.Have you tested the abs with a durametric or similiar tester for any codes generated? When your tech replaced the pads and rotors did they notice any abnormal wear ,one wheel with less wear on pads or inner pad worn more the outer ? That could indicate a caliper concern.

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^^^ Just don�t let him sell you a new/factory ABS module - not cheap 😉

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That makes sense if you notice it slowly getting worse as time goes by, but if the soft pedal problem exists immediately after filling and bleeding the brakes, doesn't that indicate something else?

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the most obvious problem would be that there�s still air in the brake lines, or the ABS module. I was just relating an actual experience that I had with my car. The most baffling part of it was that I was clearly losing brake fluid, but all the lines were dry and there was none on the ground/floor...

Well, it took 3 days but I finally got an assessment of the problems w/my car: Problem #1) Soft Brake Pedal: The Service Advisor said that they fixed the brakes and that the pedal is now firm. Claims that mechanic found some air pockets in the lines that he got rid of by replacing the brake fluid (again) and bleeding it a couple of times. Hope he's right. Will only find out after I get the car back and drive it again. Total cost only $250. That's the good news. Now for the bad. The back story. I've only had my car since Sep 2019 and the fuel gauge always seemed inaccurate to me. Would never read totally full after filling the tank and letting the nozzle click-off by itself and still read at 3/4 full when I was refilling w/7-8 galons at 1/2 tank down, I have a phobia about running out of gas and wanted to be sure that I was properly estimating the range of the car. Since the fuel gauge didn't seemed to be accurate, I decided to top off the tank unitl the gas overflowed to get a consistent measurement. Bad idea. After I started doing this, the fuel gauge got stuck on "full" and I could not refill the gas tank w/o holding onto the gas nozzle because it would always click off on the lowest setting. So, I apparently causing these problems by overfilling the thank. So . . . Problem #2) Fuel Gauge: I was told that I need a new fuel guage sensor which requires dropping the tank (partially) and going thru the gauge recalibration procedure. Total cost $1200. Ouch!!! Problem #3) Fuel Tank: I was told that I need a new fuel tank filler neck bleeder valve. Overflowing gas probably flowed into the charcoal canister in the bleeder value destroying it; it's only supposed filter the gas vapors. Total cost $650. Just more punishment. So, I turned what would have only been a $250 brake repair into a $2100 brake/fuel gauge/fuel tank value tab. Probably won't get the car back for at least 5 more days (including the weekend). One good thing about my dealer is that it provides a free Uber ride to/from home (or elsewhere) when you get your car serviced there, which is not trival in my case because I live over 30 miles away from the dealer. I can blame Problem #1 on my Indy not "properly" bleeding the brakes after changing the rotors, pads, brake lines and master cylinder BUT the rest is on me. The moral of the story: 1) make sure your brakes are bled properly and 2) don't overfill the gas tank on your 996. Good thing that I have more $ than sense. LOL!

I replaced my fuel pump, and level sensor in my garage in ~90 minutes for ~$500.....very easy job.....no need to drop tank....remove battery, and everything can be accessed from the top....."re-calibration" was filling with a specific volume of fuel......been dead-on ever since it was all replaced.....

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u didnt pay yourself $210 per hour. That adds up quick.

The "stealership" is raking you over the coals...Won't be the first time, won't be the last...

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Yes, I realize that but it's the price I have to pay because I don't have the skills and/or desire to do the work myself anymore. At my age, it just easier to pay others to do the work and I really have no problems w/that as long as they do the work "right" and provide me w/the perks that come w/the price.

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As noted above, I don't have the experience, skill or desire to do this work and paying an "extra" $700 to get it done w/o needing to get my hands dirty with a free Uber ride 30 miles back to the shop to pick it up when it's done is a fair price to pay for the dealer to do it IMO.

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I�m with you, but I also look for a good Indy that can do work for a fraction of the price of a dealer. Is there no good Indy by you?

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I "had" a good Indy shop until the previous manager left for a "better" job in SF w/Muni where I assume he can now get a pension/medical beneifts that were probably not available (or limited) in the small Indy shop that he managed. Liked him a lot and he was easy to deal with; not so the new manager who I really don't like. So, I need to find a new Indy shop that will charge less and install aftermarket parts that I buy w/o complaint. Was taking all 3 of my German cars to lthe Indy shop near me but, given the poor attitude and service i got w/the new manager doing the recent brake work (which they apparently didn't do exactly 'right"), I'm going to have to look for another shop. In the meantime, as long as it doesn't involve the installation of non-OE parts, I think I'll just take my Porsche, BMW and MB to the stealerships for general maintance and other required work. You pay mre but you know they'll do the work right (or make it right) and there are certain perks that come w/taking your car there.

LOL! The car's been at the dealer for a week. The new fuel gauge sensor/fuel tank breather valve were installed yesteday but it threw codes related to an ABS problem that arose after they did the work. This is exactly why I don't try to do my own work anymore. So, they still have the car. Good thing I have 4 other vehicles to drive. Just drove my BMW 335i today. What a wonderful car! Blew by a Model S on a twisty back road where s/he cut me off at the turn thinking that they would be faster. NOT!!! The S may be faster but it's the driver not the car. I'll will be driving my MR2 on Sunday to look at a S2000 that I'm also thinking of buying which will make a nice addition to my MR2 and 911 of the same vintage if I buy it. Life is good.

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Sure is. All this cars are great

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Indeed! I really like my 911 but I'm not wedded to any brand. If I buy the S2000, I'll have IMO3 of the best sports cars made in the last 20 years in my garage. I also saw a 2000 Ducati ST4s for sale for just $3500 that I'm thinking of buying as well (even though I'm running out of garage/storage space). Haven't ridden for about 5 years but one of my last motorcycles was a Ducati 998 (a much different beast) but the sport touring ST4s would be right up my alley and $3.5k? Really? That's just spare change for me. Heck, the upcoming bill for my 911 will almost be that much. LOL! Still have all my m/c gear (and my m/c license) but should buy a new helmet. So, I may buy them both. We'll see . . .

Did they fix your brakes yet?

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They said they fixed the brakes but I haven't seen/driven the car again yet because they are still working on the fuel tank/gauge problem. Said that after they installed the new fuel gauge sensor and fuel tank bleeder valve, the car threw some codes and the ABS light turned on. They've had the car for 8 days (11 days come Monday) and are still trying to figure out what the problem is. Not going to worry about it. Assume they've figure out the problem sooner or later. I've already been given quotes for the work and I know what I'm going to have to pay. They won't increase the bill unless there is addtional work that needs to be done that's unrelated to the original work estimate; the codes are their problem, not mine. They'll pay for my ride back to the shop when it's ready. In the meantime, I've got 3 other cars and a truck that I can drive and I'm going to be looking at another car that I might buy tomorrow.

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And trying the installers recommendations.

Update 7/21/2020: I've been dealing directly w/the Service Manager for the past 5 days or so, after I complained that I was NOT happy w/the Service Advisor assigned to my case. So, today, I finally got word that the car is "fixed." Apparently, the codes and ABS light that were thrown after the new fuel gauge sensor and fuel tank breather valve were installed were caused by a bad MAF sensor. WTF? Anyway, long story short, the Servcie Manager said that he was NOT going to charge me for the new MAF sensor and that he's going to put it thru a couple of drive cycles before releasing the car to me tomorrow. Got my fingers crossed. LOL! BTW, it'll be 2 weeks to the day if I get the car back tomorrow.

Ok, just got the car back, yea! Got a free 35 mile Uber ride back to the shop, a full tank of gas and a car wash for $2100. LOL! The shop mgr was in the service area to greet me and he told me it was good to go. Said the brakes were hard/firm and he did not charge me for a new MAF sensor, even though he old MAF sensor was not part of the requested work. The fuel guage looks like it works and will fill it up after a drive (WITHOUT topping it off) tomorrow to make sure that's working too. As for the brakes, truth be told, they feel the same to me (too soft) but the service manager swore that they were the way they were supposed to be. He's driven a lot more 911s than I have and as long as they stop the car, I guess that's just the way they are. End of story (for now). Update 7/23/20: Took the car out for a short drive this morning. Same "feeling" about the brakes. The only thing that might make me happy is to install a BIG BRAKE kit all around (or at least in front) but it would be really hard to justify the $2.5k-$8k price of doing that. Short of that, I might experience w/other brake pads later. The only "good" thing that happened out of this ordeal was that my fuel gauge seems accurate now. The gauge showed the tank just below 3/4 when I drove into the gas station w/65.7 miles on the ODO. The tank took 4.472 gals at click off -- which was just about right -- and I did NOT try to top it off -- not making THAT mistake again. Calculated mileage was 14.69 mpg and is about what I was calculating previously using the ill considered "top off" procedure. So, I'm just going to use 14 mpg to estimate gas usage in the future and will have to verify the accuracy of the gauge at the lower end later.