Boxster Spyder -- Soft Brake Pedal
09-29-2012, 07:13 PM
#31
Ok OK... I feel compelled to jump in. I like mushy brakes. They allow me to heel toe effectively.
the 1 single caveat is that they stop as well as someone else that had swapped a Gt3 master cylinder......
ok I'll keep quiet now..
BTW, I'm glad there's nothing wrong with your braking system, zellamsee. oh and next time, pls spec the PCCBs, I assure you that feel much less mushy.... (I prefer the steels for feel, but you already knew that).
the 1 single caveat is that they stop as well as someone else that had swapped a Gt3 master cylinder......
ok I'll keep quiet now..
BTW, I'm glad there's nothing wrong with your braking system, zellamsee. oh and next time, pls spec the PCCBs, I assure you that feel much less mushy.... (I prefer the steels for feel, but you already knew that).
09-29-2012, 11:02 PM
#32
Nordschleife Master
Update -- my dealer inspected my rotors, pads and lines and found nothing wrong. The dealer bled the brake fluid again, and while there certainly is some improvement, the brakes are still mushy and "mushier" than I remember. What is interesting is that when the car is off, the brake pedal feel is solid as a rock. There is hardly any brake pedal travel! When the car is powered up, however, the pedal is soft and the pedal travel is long. This tells me that the master cylinder is likely working just fine. Again, perhaps this a function of the booster, and perhaps this is the factory set up. If so, why would Porsche set it up this way??!!!! Argh.
If you ever find a way to get that brake pedal solid again, PLEASE let me know, because I have given up at this point.It was the same with my Cayman R. It felt like it had to be an air leak or a bubble somewhere. After lots of bleeding (ask Alex @ Sharkwerks) and a GT3 MC, it's about 80% 'right'.
I have no idea why Porsche has decided to make the brakes so mushy. As I've written in another post, our 2000 & 2001 Boxster Ss didn't feel like that, nor did the brakes on a 92 Voyager minivan that I'd recently driven.
I have no idea why Porsche has decided to make the brakes so mushy. As I've written in another post, our 2000 & 2001 Boxster Ss didn't feel like that, nor did the brakes on a 92 Voyager minivan that I'd recently driven.
That's just not right... I am 100% convinced that this is a 'characteristic' that Porsche wanted on their cars, with the exception being the GT3. The 997.2 Turbo S, 997.1 C2, 987.2 are cars I have personally tested the brakes on, and they feel the same as my stock master cylinder spyder. I have been able to drive a 997.2 GT3 and 986, and the brake feels exactly like my Mitsubishi Evo (which is perfectly SOLID endpoint).Ok OK... I feel compelled to jump in. I like mushy brakes. They allow me to heel toe effectively.
the 1 single caveat is that they stop as well as someone else that had swapped a Gt3 master cylinder......
ok I'll keep quiet now..
BTW, I'm glad there's nothing wrong with your braking system, zellamsee. oh and next time, pls spec the PCCBs, I assure you that feel much less mushy.... (I prefer the steels for feel, but you already knew that).
the 1 single caveat is that they stop as well as someone else that had swapped a Gt3 master cylinder......
ok I'll keep quiet now..
BTW, I'm glad there's nothing wrong with your braking system, zellamsee. oh and next time, pls spec the PCCBs, I assure you that feel much less mushy.... (I prefer the steels for feel, but you already knew that).
1) mushy brake pedal helps with heel toe? mushy brake pedal makes heel toe difficult, IMO
2) The first time I brought my PCCB spyder to the track, my first impression was: PCCBs are no good because they make the brake pedal super mushy. The car stopped like a champ, but my foot was all the way down to the floor. Not what I'm used to in a sports car, and made it impossible for me to heel toe. Then I proceeded to test out everybody else's Porsches and realized that the pedal feel was the same with all the other cars as well (exception being the GT3). I was very surprised. PCCB brakes are still mushy.
Last edited by orthojoe; 10-01-2012 at 09:59 PM.
09-30-2012, 03:51 AM
#34
This is also why it's tougher to learn to heel-and-toe on the streets, because you're usually not braking hard enough to depress the pedal enough, leading to mismatched positions of brake & gas pedals. I used to be concerned about this if I went with GT3 master cylinder, but have since learned that the brake pedal height can be adjusted.
BTW, Joe did you see the link I posted for 987.2 FVD Brombacher exhausts?
09-30-2012, 05:37 AM
#35
as with my usual debate with Joe on this front, you have 2 sides... in the hard pedal corner stands Joe and in the mushy pedal corner is me. Whatever the preference, my main query pertains to whether the stopping power/distance is the same if you apply maximum pedal pressure? To me, it has to be the same.
09-30-2012, 05:42 AM
#36
As far as I remember, using my brother's ex GT3 RS, they feel the same (ie PCCBs on gt3 and spyder). Joe's requirement is quite exact on the braking front hence the Gt3 master cylinder. Although he is far from alone on that front.
09-30-2012, 11:34 AM
#37
Nordschleife Master
I tend to agree with khooni. Having a "mushy" brake pedal makes it easier to heel and toe, at least for me. Why? The brake pedal needs to be depressed a certain amount before you can roll/move over to stab the gas pedal. If the brake pedal is hard and doesn't travel down much, it makes it more difficult to roll or move your heel over to depress the gas pedal. You certainly can, but it requires more finessing of your foot and ankle.
BTW, Joe did you see the link I posted for 987.2 FVD Brombacher exhausts?
as with my usual debate with Joe on this front, you have 2 sides... in the hard pedal corner stands Joe and in the mushy pedal corner is me. Whatever the preference, my main query pertains to whether the stopping power/distance is the same if you apply maximum pedal pressure? To me, it has to be the same.
No way. No how. Impossible. GT3 brake pedal is WORLDS different from ANY 987.2, PCCB or not. I'm 100% positive on that one. I'm willing to take that one to bank. I will take on that challenge at any price, any day. I'll take it to my grave. Sorry Khooni, but your bro's GT3RS had air in the system.
Last edited by orthojoe; 09-30-2012 at 01:25 PM.
09-30-2012, 11:43 AM
#38
Nordschleife Master
quote from savyboy from a while back, who owned both a GT3RS and spyder at the same time:
I HATE my Spyder's nasty, soft, mushy, long-travel brake pedal (PCCB). It is not air, been bled, it is design of system. My GT3RS pedal is rock hard and high, hardly any pedal movement.
09-30-2012, 12:57 PM
#39
Addict
Rennlist Member
Rennlist Member
I'm somewhat green when it comes to modern braking systems but is it possible that the brake boosters are significantly different between the GT cars and the 987's?
Can brake boosters be adjusted?
Can brake boosters be adjusted?
09-30-2012, 01:23 PM
#40
Nordschleife Master
987 engines have a vacuum pump driven off of a camshaft to produce the vacuum for the booster. 986 engines do not have this pump; they just use manifold vacuum like most other cars.
So I wonder if the 986 is not pulling as much vacuum on the booster as the 987 pulls. Pulling a good vacuum would seem to be a non-issue, especially when you have a 3.2L engine running around 6000 rpm with the throttle plate closed. And yet.... Porsche changed this for the 987, so there must have been some issue.
There should be a relatively easy way to regulate the vacuum in the booster, perhaps by installing a spring in the check valve (or putting a stiffer spring in there if there is already one installed).
So I wonder if the 986 is not pulling as much vacuum on the booster as the 987 pulls. Pulling a good vacuum would seem to be a non-issue, especially when you have a 3.2L engine running around 6000 rpm with the throttle plate closed. And yet.... Porsche changed this for the 987, so there must have been some issue.
There should be a relatively easy way to regulate the vacuum in the booster, perhaps by installing a spring in the check valve (or putting a stiffer spring in there if there is already one installed).
09-30-2012, 03:25 PM
#41
Burning Brakes
Thread Starter
^ Fascinating!
Are you sure that the brake booster part number is the same for the 986 and the 987? When I was at the dealer yesterday we checked the part number on my car, a Cayman R (a friend's) as well as a regular Cayman out on the lot. All had a 987 part number on the booster. Perhaps the 986 also uses a 987 part number, but that would be weird . . . .
Are you sure that the brake booster part number is the same for the 986 and the 987? When I was at the dealer yesterday we checked the part number on my car, a Cayman R (a friend's) as well as a regular Cayman out on the lot. All had a 987 part number on the booster. Perhaps the 986 also uses a 987 part number, but that would be weird . . . .
09-30-2012, 03:48 PM
#42
Nordschleife Master
^ Fascinating!
Are you sure that the brake booster part number is the same for the 986 and the 987? When I was at the dealer yesterday we checked the part number on my car, a Cayman R (a friend's) as well as a regular Cayman out on the lot. All had a 987 part number on the booster. Perhaps the 986 also uses a 987 part number, but that would be weird . . . .
Are you sure that the brake booster part number is the same for the 986 and the 987? When I was at the dealer yesterday we checked the part number on my car, a Cayman R (a friend's) as well as a regular Cayman out on the lot. All had a 987 part number on the booster. Perhaps the 986 also uses a 987 part number, but that would be weird . . . .
If you look at the circled areas, there are 3 entries for the same part. The first entry is for the boxster, the second is for the spyder, the third is for a PCCB equipped boxster (boxster S I450)
I looked up some part numbers on PET. Apparently the brake booster in a 986 IS compatible with the 987s (996 355 923 00) because it's the same part number as the brake booster used in a 987 equipped with PCCBs. Unfortunately this means I already have the brake booster from a 986 in the car since my car was equipped with PCCBs.
Those of you without PCCBs, I wonder if a PCCB booster and master cylinder swap would give back that perfect brake pedal feel....
I may be out of luck in that search for a rock solid pedal...
I took a look at my brake booster. Interestingly, the part number does not match what the PET specifies.
PET says PCCB 987 brake booster part is: 996 355 923 00
The part number on my PCCB spyder is: 997 355 025 11
Likely the same part despite the number, but it would be very interesting if they are in fact different parts....
PET says PCCB 987 brake booster part is: 996 355 923 00
The part number on my PCCB spyder is: 997 355 025 11
Likely the same part despite the number, but it would be very interesting if they are in fact different parts....
https://rennlist.com/forums/987-981-...our-987-a.html
09-30-2012, 04:17 PM
#44
Three Wheelin'
Joe, if you find the fix, I'm in.
We have a 2000 Boxster S, a 2008 GT3RS and a 2012 Cayman R. The Cayman R brake pedal, with the GT3 MC upgrade (and PCCBs), is not quite as good (firm or consistent) as the 2000 Boxster S. The GT3's brake pedal is close to perfect.
Also, the mushy pedal does not seem to be 100% consistent, unlike the rock hard pedal. Even with the GT3 MC upgrade, the Cayman R's brake engagement height seems to change slightly... unlike the GT3 or the 2000 Boxster.
Beyond the 'argument' (classical definition) of which is easier to heel/toe, a mushy pedal does not inspire confidence to many of us who grew up with cars where a mushy pedal was the first sign of overheating, leaking or otherwise failing brakes.
We have a 2000 Boxster S, a 2008 GT3RS and a 2012 Cayman R. The Cayman R brake pedal, with the GT3 MC upgrade (and PCCBs), is not quite as good (firm or consistent) as the 2000 Boxster S. The GT3's brake pedal is close to perfect.
Also, the mushy pedal does not seem to be 100% consistent, unlike the rock hard pedal. Even with the GT3 MC upgrade, the Cayman R's brake engagement height seems to change slightly... unlike the GT3 or the 2000 Boxster.
Beyond the 'argument' (classical definition) of which is easier to heel/toe, a mushy pedal does not inspire confidence to many of us who grew up with cars where a mushy pedal was the first sign of overheating, leaking or otherwise failing brakes.
09-30-2012, 04:46 PM
#45
Burning Brakes
Thread Starter
I just checked my Spyder and the part number on the booster is different! 987.355.025.00. Weird. I wonder if we are narrowing in on the problem, and a possible solution.