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Cayman R brakes - misunderstood?


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I have been watching the start of the F1 season and there has been a lot of talk about brakes. One comment I keep hearing is relating to the fitness of the drivers and the sheer force with which they press the brake pedal in an F1 car in order to get it to stop. I have mostly been driving my BMW 320D recently and force is not something required in order to get the brakes to work. In fact, if I were to use force, the car would shudder to a standstill with the hazard lights on and the ABS lights flashing. However, today I drove the Cayman R and at first thought how poor the brakes were. Then I realised, the harder I pushed the pedal, the better they were. Then I tried braking late for a roundabout and realised I required really quite a lot of pressure to get a good response from the brakes BUT the brakes were completely effective.

 

This got me thinking. Did Porsche design the brakes on a Cayman R to operate more on the F1 principal than as a typical road car? Perhaps thinking that the effort of applying the brakes was part of the 'driving experience'. 

 

Just a thought...

Mick

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Its not just the Cayman R, my plain ol' Cayman is exactly the same. The first couple of times I drove it I thought there was something wrong, Its quite linear, pressure in = pressure out. Takes a bit of getting used to when switching between cars, Ive almost gone through the windscreen of my Mini after a couple of days in the Cayman :)

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8 hours ago, eponymoose said:

Spec of the MC and the booster in an R in fact adds up to significantly more servo and significantly less effort than Porsches from previous generations - even compared to the 986 and 996 cars.

 

A 987 has 30 percent more brake boost / servo than a 986, for instance. 

 

Compared to a lot of moderns, the R has relatively low levels of servo, however. But the real problem with the R (and all 987s) is the small diameter master cylinder. This makes for a relatively long travel and soft pedal. So for me the R's pedal (and other 987s) is distinctly mediocre. I want a pedal that needs a good shove, but I want short travel and a firm feel. All 987 brake pedals are pretty mushy and soft by historical Porsche standards.

 

So while modern cars with uber assisted pedals are pretty awful for H&T, the 987 isn't that great either. A nice firm pedal would be a lot better.

 

You can improve this by fitting the bigger diameter master cylinder that's fitted to the 997 GT3 4S and Turbo models. It shortens pedal travel and firms the pedal. But be aware the pedal will require even more effort.  

This is correct. There is a factor called hydraulic multiplivation so the wider the bore on the MC the less travel but the hydraulic multiplication on the caliper pistons is less so it will require more pedal pressure, but this is hardly noticeable on the R when fitting GT3 MC but the reduced travel on the pedal transforms it amazingly.

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13 hours ago, eponymoose said:

Spec of the MC and the booster in an R in fact adds up to significantly more servo and significantly less effort than Porsches from previous generations - even compared to the 986 and 996 cars.

 

A 987 has 30 percent more brake boost / servo than a 986, for instance. 

 

Compared to a lot of moderns, the R has relatively low levels of servo, however. But the real problem with the R (and all 987s) is the small diameter master cylinder. This makes for a relatively long travel and soft pedal. So for me the R's pedal (and other 987s) is distinctly mediocre. I want a pedal that needs a good shove, but I want short travel and a firm feel. All 987 brake pedals are pretty mushy and soft by historical Porsche standards.

 

So while modern cars with uber assisted pedals are pretty awful for H&T, the 987 isn't that great either. A nice firm pedal would be a lot better.

 

You can improve this by fitting the bigger diameter master cylinder that's fitted to the 997 GT3 4S and Turbo models. It shortens pedal travel and firms the pedal. But be aware the pedal will require even more effort.  

 

I've just done this mod, and it does make a big difference to the feel of the brakes. Much shorter travel and firmer. I also fitted Pagid RS-14s, which have a much sharper initial bite, although are a little noisy at low speed (as expected). However, should be much better on track.

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1 hour ago, ian964 said:

 

I've just done this mod, and it does make a big difference to the feel of the brakes. Much shorter travel and firmer. I also fitted Pagid RS-14s, which have a much sharper initial bite, although are a little noisy at low speed (as expected). However, should be much better on track.

 

Did you fit the MC yourself Ian?

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On ‎23‎/‎04‎/‎2016 at 19:25, Beanoir said:

 

Did you fit the MC yourself Ian?

No, I got my garage to do it, as it needed new disks and a geo as well. They managed to get -1.15 on the front, and -2.3 at the back, I'll see how that goes though I suspect I may need to reduce the back a little, though it does feel a lot more pointy now which I like.

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24 minutes ago, ian964 said:

No, I got my garage to do it, as it needed new disks and a geo as well. They managed to get -1.15 on the front, and -2.3 at the back, I'll see how that goes though I suspect I may need to reduce the back a little, though it does feel a lot more pointy now which I like.

 

I left my rear camber stock 

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3 hours ago, ian964 said:

No, I got my garage to do it, as it needed new disks and a geo as well. They managed to get -1.15 on the front, and -2.3 at the back, I'll see how that goes though I suspect I may need to reduce the back a little, though it does feel a lot more pointy now which I like.

Is the stock setup adjustable? 

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1 hour ago, Red Square Images said:

Is the stock setup adjustable? 

There is a certain amount of suspension adjustment available. Standard cambers are -45' +/- 15' front and -1deg50' +25'/-5' rear, so about -0.75 and -1.8 decimal. I asked them to see what the maximum they could get was, which was -1.15 and -2.3, so an extra 0.4/0.5. Any more would require modifications.

 

I don't think there's any adjustment in the braking system other than through changing components (m/c, pads fluid)

Edited by ian964
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Mick, As you have my old car it has RS29 pads all round  and imo does not need the GT3 MC , the RS29's work so much better than the oem pad with more bite.

And as I fitted them right they don't squeal like pigs like most people moan about :-)

 

Travel is a personal thing, I am happy with the travel in the R with track pads plus a  fresh bleed, and would never fit the larger MC to the car.  even the PCCB car with 6 pots and 350MM disks all round does NOT use the GT3 MC, although it does use one in between sizes.

 

You also have my geo tweaks, so it's pretty much set up with out going in full and throwing a lot of money at it, I would add 7mm spacers though as I took them off, lucky you have longer bolts on so can refit some to the front for £30,

 

I plan a little upgrade to my new R on the brakes, again RS29 pads but with larger 340MM gyro disks and a spacer to bring the caliper out a bit, with motul 660,  again not fitting the GT3 MC.

I really think the longer travel helps you threashold brake keeping you off the ice mode the 987.2 suffers with if you get the ABS to ever cut in.

 

I guess it's personal if you want long or short travel pedal, but it won't improve your brakes or your hard end point , just make it harder to press ! if one likes that then that's personal I guess.

 

My new set up will improve the bite, brakes and cooling over the oem setup, the travel is fine imo.

 

Edited by PorscheGT4
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Pedal travel has quite a lot to do with the Pad, as some people hate the feel of the car not slowing down enough once pressed 4 ", so want to press it more and harder ! ,  fit a pad which bites better and you don't have that "I have no brakes" feeling.

try pressing the brake with your left foot with RS29's in and tell me it don't brake or has no feel ! you will put your head on the windscreen !!!  now think about having 2" travel , how much harder it is now with your left foot to not trigger ABS, or threashold brake, it's now much much harder !!!

 

It changes the whole feel of the system having a pad with more bite,  the pedal is not vague, the more you press the more pressure you are giving to the calipers pistons , it is nothing like having vague steering !!!

Vague steering has no feel, a longer travel pedal gives you a proportional range of pressure to a finer extent. hence why it's far easier to threashold brake, or trail brake into that corner apex without lock up.

 

the vague issue on the 987.2 brakes is no hard end point and that's a brake booster issue not a MC issue !!! the end point feels the same which ever MC you have fitted !

 

A shorter pedal now gives you a much smaller windows to ease off the brakes into the apex just before ABS cut in, I may want to bleed off 2 mm travel to stop the ABS cutting in, now with a 3rd less travel you now need to only bleed off 0.6mm travel, well good luck with that !!! take off the same 2mm travel and I 'll fly right past under brakes !!

 

As I have stated all well and good forum talk, but you have not fitted a GT3 MC to your car and in fact have not even driven a car with one fitted !

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you have never driven a car with one fitted as stated and you have had your car a long time and not fitted one,

As I said forum talk. Pushing a fix it all mod you have never tried !!! credibility  well let the readers decide.

 

I have owned 6 porkers with 4 pots , 6 pots PCCB , GT3, gen1 , gen  2's, GT4's  etc etc  all modded in some way,  you have one and it's stock !

 

fit one and I wager I can out brake you in any of the 3 porkers I own. £100  on it to heart foundation ,  cannot be fairer than that,  you can choose which of the 3 cars you want to go up VS yours GT3 MC car , IF you never fit one !! which I doubt. Trigger ABS in the test and instant fail.

Edited by PorscheGT4
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12 minutes ago, PorscheGT4 said:

brave move after last years PCGB track day ;-)

 

What after I passed you!! Even though you were in a much modded Spyder with PCCB  LMFAO!!!!!

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Well at least the question of the thread has been answered...clearly, misunderstood.  

 

The result of increasing bore size of a master cylinder is (all other things being equal) just a simple matter of physics and will result in increased pedal effort and decreased pedal travel.   

 

Our customers requirements on braking systems differ quite a lot dependant on the individual driving style, the application, the vehicle, the weather...

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