How are your brakes?

2001 C4 cabriolet. My brakes are german rotors with ceramic pads, properly bedded. Redid DOT4 brake fluid with power bleeder so there is no air in the system. For a while now, I've felt that my brakes were subpar. The shop that installed them and another I asked both shrugged and said "normal". I remember the Audi crew used to use boxster calipers to improve braking, and I find it hard to believe my 911 brakes are this bad. If you push down hard, I mean NOW, they stop, but it's like they have no power boost whatsoever. The same effort on my son's BMW 135i would put you in the windshield. I don't think the master cylinder is bad, and there are no other signs of booster issues. Suggestions? Maybe I should find someone local and swap cars for a quick run to compare...

The stock 996 brakes are very underboosted compared with "modern" cars. If you search the forum this is a common complaint. The feel to me is similar to the old unassisted air cooled cars. I personally appreciate the greater ability to modulate the 996's brakes, but yes if you compare it to any overassisted modern car the feel will be very different. That's not necessarily better. How does the 135 heel/toe coming out of a corner? If it bothers you, look into the GT3 master cylinder upgrade, which reportedly improves feel.

If you want stopping power you need to move from ceramics to something more abrasive.

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Yeah, I was looking at Hawk pads, HPS street or maybe HP Plus Sport (I do the occasional autox).

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+1. I think my Akebono pad are way more grabby than what I had before.

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Well, as long as you asked... From your post,,, No need to compare. Something is wrong. Don't know what it is. After owning 7 Porsche thru the years, imo anyone complaining about Porsche brakes has a brake problem no doubt, or are on the track...something is wrong. I also have an 01 c2 cab with 35,000 miles all oem Porsche, never touched (other than maintenance and imsb), garage kept 1 owner before me. Bleed them thru about a year ago and its got a firm pedal at the top of its stroke. Just a little firm pressure and the car pulls down with confidence and predictability, from ridiculous exit ramp speeds. My 02 c2 cab, 38,000 miles, garage kept by the ocean with all its corrosive effects. Brakes not great. I know why. Time for a full brake job. as rotors are all chewed up. But car still stops better than most 'not a Porsche' cars. They look like oem brakes, but not sure of its history. Keep looking you'll find a problem...

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Don�t totally agree, sure he could have a prob but he�s comparing the 996 to a 135i, they�re never going to have the same brake feel. 2 shops already said they�re fine. the stock 996 brakes are great but you have to put some effort in.

Yeah, pads make a huge difference. Sounds like he has fresh brake fluid. Doubt it's the master cylinder. They are pretty durable. Maybe he needs new brake lines or a caliper rebuild. All are possible. But more abrasive pads are pretty easy and cheap to start with and see. But maybe you want even more braking power. Consider the GiroDisc 2 piece floating hat kit. You use your oem calipers and add the Girodisc kit. Pretty impressive kit and reasonably priced versus adding a big brake kit. The kit gives you much bigger rotors, better cooling and stopping power. Looks damn good too. Fills out the wheels nicely. I never fault anybody that want more braking power.

That's one thing I've noticed on my 996 and one thing I'd tell to anyone driving it: "You need more force on the brake pedal than a normal grocery getter but it WILL stop once you do." I've read in another thread it's by design. I saw on a video about F1 cars that they need a LOT of force to get the brakes to activate, something like 250 lbs IIRC. Not that these are F1 cars, I'm saying lack of boost does not equal lack of stopping power. I think the lack of boost you're feeling is normal.

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I can respect that.... Me also, as brakes imo are maybe the most important part of a sports car. In another world many many decades ago, I use to specialize in performance/track brake jobs.... I still stand by my above post and claim Porsche brakes oem are some of the best brakes on any production car, and they 'feel' like it. If they feel weak "subpar" like the OP stated above, something is wrong.... A lot goes into refreshing a 25 year old sport cars brakes correctly so it feels like new or better. More than the new rotors/pads we all talk about here. Very rarely here on our forum do we see caliper rebuilds, master cyl rebuilds, or talk about after market caliper pistons/seals. You can't flush out all the gummed up crap behind caliper pistons, or behind the piston seals, with a brake fluid flush. All it takes is gummed up pistons/calipers that still work but not well to detract from brake performance. Just a bubble of old fluid full of water trapped in a caliper or 2 will detract from pedal feel. Once you take apart a 25 year old caliper that has been neglected you'll see what I mean. Or swollen old rubber brake lines can detract from brake performance, as old gummed up master cyls, abs, etc, all can.... Like i said, in many cases its not as easy as a quality rotor pad change and a quick fluid flush...

Here's some historical data from 2007 with multiple 996 owners reporting their experience. This would have been well before any age-related caliper issues. Brake Pedal feeling - 996 Series (Carrera, Carrera 4, Carrera 4S, Targa) - RennTech.org Community

I have c4s. Turbo brakes from factory and still using them. Couple of track days on them, and they impressed me. No fade. Could stand on em at the end of the straights all weekend long with an issue.

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Its not just 25year old age, a lot can happen in 9 years. brake fluid is hygroscopic. I'd hardly call that thread "historical data"... Fact remains, if your 996 brakes feel weak "subpar" as OP claims in first post of this thread, something is wrong imo. Here is a quote from your above thread/link... In 2024, on the net, one can find back up to almost any claim they want... MechanicalEng Members 18 From:MD Posted January 15, 2007 I had a 2000 Mustang GT back when I was in college. I could easily overheat the brakes with 3 panic stops. For me the brakes in my 02' C2 are simply awesome!, the pedal is hard and 100% fade free, they inspire so much confidence and the feedback you get from them is just out of this world.. I test drove a 03 M3 before getting my C2 and I found the brakes to be not as strong as the ones in a C2...

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I have a BMW Club Race car - 1997 M3, Prepared class. When I built the car, I upgraded from the factory M3 calipers to the 993 TT calipers and rotors (Brembo Big Reds). They have been phenomenal over the years. I did also upgrade from the factory holed rotors to Alcon replacement rotor rings. Excellent stopping power, long lasting (with the Alcon rotors - Porsche holed rotors would crack/fail in too few weekends). Never had issues with fade, only issue was the factory M3 ABS and ice mode. My 996 C2 - I have upgraded to the Girodisc rotors - have no issues with braking. -Tom 2003 C2

Yeah, I had the oem brakes on my 996.2 from 2002 thru 2006 and tracked the car with them. But eventually outgrew them. Then I went to the Brembo GT big brake kit with much bigger calipers and much bigger discs of 355F and 345R. Night and day difference in braking power. Never replaced the master cylinder either and still working fine after 22 years. However, i have had the calipers rebuilt a couple of times over the years because stuff gets stuck. Especially on the street from salt, dirt and anything else that you come into contact with. Eventually every 996 will need a caliper rebuild, new brake lines, new master cylinder or bits, etc. Street car or track car or both, it's inevitable with age. But... Assuming everything checks out to be in good shape, brake pads will then make a huge difference.

I've had a few Porsches and the brakes are all awesome. The brake on my Panamera GTS are bad a**. The brakes on my e30 have slowly gone to subpar and I can't figure it out. I bring this up because after I did the engine swap, I had to swap in a smaller booster from a Porsche due the size of the new engine. Brakes wen't downhill, so ..... New fluid, no better. I swapped in a new 7 series master cylinder as an upgrade, no better. Went back to a brand new stock e30 master cylinder, no better. Replaced the Porsche booster with a new Porsche booster, no better. Removed the check valve, no better. (then bought a vacuum gauge, confirmed vacuum is adequate) Rebuilt all 4 calipers, no better. even new bleed screws! New sticky brake pads, no better. Deleted the ABS pump and hard lined it, no better. I'm now at a loss. Frustrating!

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Interesting, maybe I'm wrong. Apart from a caliper rebuild, what else would I do to restore brake feel? (pads are Textar, rotors are older, original soft lines, new ATE fluid flushed last year with power bleeder, car has PSM).

OP - Newer sports cars have brakes that I can jab and not activate anti-lock. Tracking 991 models and newer for a bit, I go back to the 996 and need to get into the first .5” of pedal travel, then can go to the stop. No immediate ‘all brake right now’ works for the stock 996 system. I recall E46 M3 having similar brake characteristics (but with a firmer pedal feel) as 996, but not quite as good at limit or for trailing release. Pads make a big difference. 996 brakes are dang good, as-is. I’ve used Textar, Pagid, Akebono and they don’t flip any switches for me for various reasons. I now daily Porterfields and am very smitten. I’ve never tried any flavor of Hawk pad for daily.

The OP is talking about feel, not performance. I drove two identical 2014 Audi Q5 2.0t SUVs. The brake feel was radically different. Most of the �level of effort� feel comes down to how much assist the booster is providing. Next is pads. Can the booster assist be adjusted?

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Got me, hard to troubleshoot problems like this from my keyboard. Sounds like you've got it covered pretty well. To bad you can't go back to a stock oem setup and see how that works out. As it seems your problem occurred after changing out the oem master for a smaller unit. But thats just an internet guess. Have you replaced the brake lines, or checked them for swelling under pressure...?

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Don't think its a matter of being right or wrong. As we all have our own valid anecdotal experience. I can't tell you whats wrong with your brakes, if anything. Just have to go thru the system as a whole. Any little part of it not working correctly will detract from braking feel/performance. What I can tell you, after owning 5 brand new Porsche from the dealer, Porsche brakes out of all production cars, feel great. With the best ability to modulate braking to scrub off just the right amount of speed entering a corner, with confidence, predictability, repeatability. You can even over run your braking points and still be ok most of the time. They feel stout and stronger than most any other car that cost many times more. Make no mistake, a oem 996 c2, c4, etc, is not set up for lap after lap at the track. The very first Porsche I ever drove, what impressed me most wasn't the engine, interior, styling, suspension is pretty dam good though,, but it was the brakes, When they're right/new, Porsche brakes are phenomenal imo,.... Some iterations of the 996(m96) have serious design engineering problems as you know, but brakes are certainly not 1 of them problem areas. So, when I hear someone say Porsche brakes feel "subpar", something is not right. jmo

I would concur with the Porsche brakes being an extremely easily to modulate setup - the calipers are used on many bbk’s however proper bleeding (and rebuild if needed) and the correct pads are essential. Mike

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Originally worked fine with the porsche booster, it�s also the preferred unit for the engine swap I did. Also have stainless steel lines, no rubber anywhere!! odd, eh? only thing left is to get new calipers I suppose!

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It's really tough to ruin the oem Brembo calipers. I have tried alot of street and track pads over the years on my oem brakes and my brembo brake kit. Every time i had to use more force on the pedal was because either the vrakes werent properly bedded or the pads just didnt have enough bite. I would consider saving some money on calipers and try a more aggressive set of pads.

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Completely second this advice!

I agree with this as well

Yeah, the issue everyone doesn't like is brake dust. Hence the ceramics. I used to change my pads between street and track pads. It got to the point that I didn't like the street pads because they didn't have the bite of track pads and I liked to know that I had stopping power on the street. Today I just run Pagid Yellow R29s year round. But I stop on a dime when needed on the street. Plenty of other pads that are cheaper that have the right levels of abrasion for the street. Some of the guys on RL recommend ceramic coating your wheels which makes it easier to wash off the brake dust. Haven't tried it yet but will after I recondition my wheels. Worth a try as folks weigh what pads make the most sense for them. For sure, stopping power is a wonderful thing.

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I believe the calipers are ATE, it�s an �80�s model. Good call on trying a different pad, no harm in seeing what happens. Cheers!!

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Was thinking about your braking problem. I'll float a few ideas/questions.... When you say vacuum is adequate, what was the vacuum #..? On the engine swap, did you install a boosted engine, or a cam'd engine..? What exactly makes you say brakes in the e30 turned "subpar"...? Whats is doing or not doing..?

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Cheers for showing interest!!! That�s the steady idle number, goes up a tick with revs. Engine is an S50 out of a 95 M3, I rebuilt it before putting back in. Supercharger is a newer addition. For typical daily use, they are fine, but panic stops really become panic stops as the brakes absolutely will not lock up. It�s like they�re about 80% effective under heavy load. I�m not a small dude so it�s not my chicken legs!

Could the supercharger be adding boost into the vacuum booster, thus rendering the booster non-functional? I know other boosted (turbo/supercharger) vehicles go other directions from vacuum boosted brakes. -Tom

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True, but he �s speaking of his engine swapped E30, not of a 996...

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That is typical of a booster not suited to the brake system and/or the vacuum provided by the engine. They all have a spot in their boosting characteristic where, from a certain pedal effort upwards, they do no longer increase boost. It seems like that pressure is lower on the Porsche booster you used to replace the BMW booster, it originally had. Also, since it's smaller it has less reserve vacuum (i.e. it's s used its vacuum after eight instead of 10 [arbitrary numbers] full brake applications with engine off). Add to this, that an ITB equipped engine has less vacuum and more so off-idle and it becomes understandable that pedal force increases substantially to lock front wheels on high-friction surfaces.

As long as we're on brakes, I just had new pads and rotors installed a few hundred miles ago, and I still have a slight 'squeaking' or scratching sound when rolling. Is this normal during break-in, or are my calipers not fully releasing?

Worth it's own thread, maybe? But it literally sounds like pads/calipers are not releasing and a replacement of (at least) the square seal in the caliper could resolve that. OP: get rid of the ceramic pads and put in some normal ones, that don't claim to be dust free whilst at the same time avoiding any 'fast street' or track pads.

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Well, like said above, you seem to have it covered pretty well... As 18"i at idle should be 'adequate. What I don't understand is, you say with some rpm the vac goes up,,, on a boosted engine..? iirr, on a boosted engine under load at rpm there is no vac, hence 'boosted'. No..? Don't super charger engines use check valves with big vac boosters or vac canisters..? But you say it did work good originally with the swap and small booster..?

There's a couple different ways to deal with brake boost on forced induction. G60 Corrados used an electrohydraulic brake system. No vacuum required. Saleen Mustangs used a hydrauluc booster run off the power steering pump. No vacuum required. 996 Turbo as well as most turbo VW's use a venturi to draw a vacuum when under boost and some check valves to use manifold vacuum when the throttle's closed. 997 Turbo uses a camshaft driven vacuum pump. Cayenne turbo uses manifold vacuum and an electric vacuum pump joined with check valves. I'd suggest an electric vacuum pump to E30, and if that doesn't do it then a bigger booster - if possible.

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With an E30 you can just go to manual brakes to avoid a lot of hydraulics hassle - I was struggling with brakes in my race E34 until chucking the entire factory system and running new lines off an E30-specific twin-Tilton-MC pedal box. If you'd like to chat about it we can do PM's to avoid mucking up this thread.

Back to my topic My original pads were Akebono Ceramic. I just ordered a set of Hawk HPS and will see if that improves things.

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Now you are talking. I wasn't getting enough bite from my oem pads on my Audi S8 and went to the Hawks and it was night and day. More brake dust but I didn't care. Very good pads for the money.

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I haven't changed pads/discs yet, so I can't comment, but there was another thread about pads that don't generate a lot of dust ( https://rennlist.com/forums/996-foru...l#post19506843 ), and the consensus there seemed to be ceramics generally behave as you describe. In that thread, the Porterfield's sound like they walk on water -- no dust and but none of the issues with other ceramics. It might be worth looking through that thread.