Brake pedal feel

[Marc_986]

With the inspection out of the way, time to turn my intention to improving things I don't fully like yet. One of the bigger ones is the feel of the brakes. First question is whether this is expected behavior for these 986 cars or whether it is my specific car having an issue.

The thing I don't like is that the pedal continues to move down when increasing brake effort. So going from light to hard braking means my foot goes down more. What I would like is to have a rock solid brake pedal. Once starting to brake the pedal shouldn't move down noticeably when increasing brake effort.

I have driven a fair amount of different cars, old and new and found that it differs car by car. New toyota cars having a fairly spongy pedal, older BMWs having a solid pedal etc. So as for the first question, what is the Boxster supposed to be like?

Little detail is that I have the 'S' brakes on my base model. But also the base brakes were feeling the same to me. All out brake power is fine, I can decelerate quickly.

Thanks for any input pointing me to either fixing my car or improving

P.S. I have talked to a few 996 owners and a common thing seems to be to change brake pads to aftermarket brands to improve brake feel. For me that is a bit of an odd thing, because although I understand the physics and see how that can improve the braking, I'd like to think that OEM pads should at least feel ok.

[elgyqc]

Are you sure that your brake master cylinder is OK? I have had a couple of cars where the master cylinder has an internal leak that allows the brake pedal to to descend without it having an effect at the wheels.

[Marc_986]

No, not sure this is ok on my car. From your reply I'm guessing my 'soft' pedal is not the way it should be.

I have been thinking a little bit about possible causes, retracing the time I have had this car. The brakes have never been really nice, it was a complaint I had from the start. So despite having replaced the fluid a few times (which could mean I still have some trapped air), I'm leaning towards some other cause. Hoses are new, lines have all been swapped out, different ABS unit, different calipers (which wouldn't be the issue anyway).

So what is still left is everything from pedal to ABS unit. Maybe I should swap out the MC before I give it another bleed.

[Newsguy]

If they haven't been changed out already, you have 25-year-old soft brake lines to the calipers
I changed mine to braided steel. It doesn't feel vastly different but it sure makes for some confidence.

[BrakeExpert]

I've driven tons of cars, the boxster brake feel is relatively direct. Some factors of course, sounds like your brakes may need a flushing, lots of people don't know how to bleed them on the 986, its not hard, but that's a first guess. Also what type of brakes are you running. The OEM brakes use the german "soft iron" rotors with pretty hard metallic pads made by Pagid Jurid or Brembo most likely. If the brakes have been changed to use off the shelf regular grey cast iron rotors (like Autozone blanks), people like to use ceramic pads with these, but there also exist less agressive ceramic pads, which removes the all to common ultra black brake dust that Porsche has had since forever with its heavy amount of dark iron debris every time you stop. Though these are aluminum calipers and are monoblock, they're pretty stiff for a roadcar. I would absolutlely check your brake fluid first, and then of course look inside the car around the brake pedal to make sure nothing is wet, brake fluid smells sort of kind of like celery? At least to me.

The brake 'feel' on the Base and S model is pretty much the same, same pads, only with a ton of heat will the difference show.

If you are wanting a pedal that you can push hard and doesn't sag as much, the standard upgrades of more aggressive metal pads and stainless lines are gonna be what people recommend.

[The Radium King]

... and don't forget to activate the abs with a durametric or similar to get the air out of it as well.

[Newsguy]

Actually, I never needed to to activate the ABS pump with Durametric when I installed steel braided lines last year. Oddly, I did need to do so on the 911.

[The Radium King]

probably depends on how much fluid you lost in the process, and how quick you were to bleed after (ie before the air could travel to highest point - the abs pump).

if the pedal has a lot of travel past initial engagement then something has some 'give' to it. first culprit is air in system, then perhaps flex in old rubber hoses. the other thing might be improperly bedded pads; the inital engagement is only partial pad/rotor contact.

[997_986]

For reference

[Marc_986]

Little update: brake feel is improving

First off, a lot of brake parts are new (or new to the car). The flex hoses are all new, rigid lines partly new, partly replaced by perfect condition ones. The calipers are from a (unknown to me) Boxster S. Rear discs are new, pads came with the caliper (90% meat on them). Front discs come from my wreck, they had some rust on the hub part, but almost no wear on the brake surface. Again pads came with the calipers. ABS unit came from the wreck.

So I am thinking that the improvement is simply coming from the bedding in / wearing in of all the parts. Travel is better now, pedal is stiffer and brake force improved as well. I have changed a fair amount of brake parts in the past, but never had such a bad feeling as I had this time. That said, those have always been new parts....

Next step up will be a pressure brake bleed when fall arrives. The ABS discussion is an interesting one to me. The manual states there is no need for ABS only units to go through the activation process etc. I guess I will just ensure that air comes out by braking into the ABS a few times Which would be a good confirmation that it actually works in my car now...

[JFP in PA]

The ONLY time you need to cycle the ABS/PSM system during a bleed or flush is if and when you get some air entrained within the ABS pump or control network, just to get it out.

If the brake system is intact and functioning, the ABS system can be left out of the process.

[997_986]

^^^^^this, and also important to note that if ABS bleeding is not carried out correctly, it can do more harm than good and may even damage the ABS pump, which is not designed to run for long periods.

[JayG]

try changing the brake pads. I had a similar issue and after trying many things changed the pads and BINGO, that fixed it

[Newsguy]

I also wonder if you have bedded the pads. Do the series of hard stops as outlined by most pad makers and you may see improvement. Gentle stops in normal driving never get you peak performance.