Cayman S to GT3 Brake Master Cylinder Swap

To anyone who can inform on the suggestion... What about swapping the Cayman S brake master cylinder for a GT3 brake master cylinder ? - Perceived pedal feel and response? - Performance benefits (real; quantifiable)? - Improved brake modulation? - What, when and how would the GT3 engineering benefits be realized? - Overall success with this mod? Thanks in advance... PorscheCaymanS

Works great, easy to do. Higher, firmer pedal, which is what I like in a sports car and inspires confidence at the track. You are not improving brake performance as much as drivability.

Thanks! I'll infer that the changes were due directly to the GT3 part--no other braking systems change contributed to the difference (e.g., stainless steel braided brake lines). Since we're on the brake mod's topic, what's your favorite brake mod? Thanks, again. PorshceCaymanS

How hard is this installation? Also, what parts do I need? Has anyone done this on a Cayman R yet? I'm at the track this weekend and I don't like the mushy pedal feel. The brakes in my BMW 135i felt better even though these stop just as well, if not better.

Install is easy, and all you need is the MC and fluid. I have the part number and a couple of pics here, along with the bleeding procedure http://www.planet-9.com/cayman-boxster-modifications/60294-engine-drop-ttp-accusump-vos-4.html

Can this be done to a 2.7?

I don't see why not. However, the brakes on the standard 987 likely have smaller pistons so the "hard pedal" may be more exaggerated.

I've had probably 5 customers do this - all love it. It is jsut amazing how much the stock CS brakes feel ...like a Buick from 1985, yech.

is it easier to heel toe with a firmer, lower brake pedal? with sport chrono on, it is soo easy. i want to make sure if the pedal gets more sensitive i wont lose the ease to heel toe.

I would think that heel-and-toe would become tougher with a pedal that's higher and firmer. However, I don't have 1st hand experience (just do HT with the standard pedals).

You can adjust the pedal height. Easy heel & toe with the GT3 MS. Brake feel much better.

Is there an installation article for this swap? I want to swap out to the GT3 master cylinder , but I'm not sure I want to fly blind on this one.

why didn't they use this part from the beginning?

Sounds like I need to get it when my Spyder comes! Too late to switch it on the S. Thanks for the review.

I changed to the GT3 master cylinder and bled with the motive + foot work. It was still too mushy for me. So, I cycled the ABS with the Durametric and boom! Rock solid. Hope this helps.

Thank you! That is exactly what I wanted to confirm. Perhaps should start saving for the Softronic Durametric tool... .

The braking on my 07cs has diminished somewhat since new (I have ~10,000mi) but Ive read thats typical. One of the early reviews I remember was that braking from 60-0 was very near 100ft and in one recorded instance was 99ft. That puts the braking on par with any supercharge on the planet. How much better can brakes get? Is this mod primarily for track/de days?

This will not make the brakes stop the car any shorter. This is a brake feel change, and a hedge for hot fluid when on the track. I've done the update and I am very happy with it, the pedal is higher and firmer - exactly what I want for a track day.

Outstanding! (may I ask approximately how much did this cost for parts and labor?) ... Also would you happen to know or have seen threads on why braking new seems to dimmish on CS with relatively low mileage? It seemed when I first got the car the brakes were unbelievable. Now they seem ordinary. Certainly if my car had 20,000 or 30,000 miles I'd definitely expect that there would be pad wear and perhaps some rotor hardening or wear. Is perhaps 10,000 mi and my 5 years about time for a refresh? I had the fluid replaced abotu 2 years ago, a complete flush. (I've never tracked the car...) Thanks! Dave

The part is about $300, you need some fluid and labor was free for me. I would guess two hours for a shop. Diminished braking after 5 years but only 10k miles is probably due more to tire hardening than anything in the brake system, assuming the last flush was done right.

Would the installation of a PCCB master cylinder have the same effect?

It has the same effect, only slightly less so. The PCCB M/C has a smaller bore than the GT3 M/C. This means less effort but more travel. Still, an improvement over the stock M/C. Since the price was the same I went all the way with GT3 . Here is the GT3 part: http://www.planet-9.com/cayman-boxs...yman-boxster-modifications/60294-engine-drop-ttp-accusump-vos-4.html#post584869

The diminished braking is that it seems I have to apply lots more pressure to get the car stopped (or slowed) than I did when new. It's pretty noticable. When the car was brand new the brakes seemed to just dig in an haul the car down with authority. I had the impression I could stop on a dime. The brakes have a wooden feeling now, numb and where pedal pressure doesn't seem to do much unless you vary the pressure greatly (so it's not as linear as it was ... if that makes sense...) Bore size increasing would tend to generate less pressure wouldn't it? There would be less pedal travel because of the increased volume of fluid. Would changing out the MC impact any of the abs s/w algorithms in the DME or potentially impact the dynamic stability stuff?

Less line pressure for the same pedal pressure is correct with a larger master piston. Empirical evidence shows that ABS and PSM are not dependent on the M/C size. Since these are driven by a separate pump this makes sense.

I finally gave in and drove a 2007 GT3 today (which I have avoided for all the obvious reasons). The 2 things that caught my attention that I did not expect to be so different - the shifter, almost as nice as a Honda S 2000 which I think set a standard that may never be met, and the brake pedal feel - wow.

That's what I was talking about on the other thread. And the clutch. Some people complain about the clutch but it's a GT3 for cryin' out loud.. How awesome those things were instantly apparent when I hopped back in my car... p.s. I keep hearing great things about the S2000 shifter. I never tried it personally.

yep S2000 I owned had the best shifter I ever drove.

Laugh you want but the manual shift standard is the early Miata (MX5) with 5 speed. Rifle bolt precision. I can't say what the latest model from Mazda is but MX5 shifters were renouned ?sp for their crispness. The early S2000 trannies weren't the smoothest, but overall the car was / is rigid, quick, precise and utterly Honda. Certainly one of the finest examples of far east engineering ever.

I've never felt the need to change my Cayman 's MC, and I do LOTS of track driving. Then again, I never drove a GT3 . So, I may not know what I'm missing! Ignorance is bliss, I suppose... +1 on the original 5-speed Miata . THE best shifter I've ever felt (but no, I haven't driven an S2000 .) I literally flicked my wrist to shift gears; no forearm movement was required. My 5-speed Cayman , retrofitted with Porsche sport shifter, comes close. It has that similar "rifle bolt" engagement, but the throw is still too long to use only wrist action.

I'm living proof! :hilarious: I'll also agree on the Miata. (And the S2000 for that matter.) IMO putting the OEM short shifter in the CS brought it close to either of those, though still not quite as precise. But still very nice!

Is TRW the manufacturer for Porsche ?

I have a slightly used GT3 master cylinder for sale if anyone is interested. There are maybe 10 race weekends on the part and I will sell it for 60% of new list (?). It was professionally installed and removed. Cheers,

where are you located, and how much for the part?

Sorry, but it's been sold. Not to me, BTW. Just helping Krokodil out with replies.

Vetman, my I ask you why does Krokodil has French benefits...? LOL .

Damn just posted about this issue in another thread! Missed the boat.... 2007 Cayman S , MT, Atlas Grey/Terracotta

I swapped to the GT3 master this weekend along with SS brake lines, new rotors, and GT3 brake ducts. The difference is amazing! I would call this an easy install but time consuming due to the amount of brake system bleeding required (possibly a bit more due to the SS line installation) . I bench bled the master cylinder after installing and that worked fairly well. Total of about three hours and 3L of ATE Super Blue with clutch bleeding. Did not need to screw with the ABS although I have the Durametric and could have bled the ABS system as well. I just cycled the ABS system while bedding the new brakes. This is a must do upgrade for Cayman owners.

Yes, this was confirmed by a member on another forum who bought both the " Porsche " GT3 MC and the TRW . Said the only difference was the box it came in. I ordered the TRW .

The Japanese have an obsession with shifter feel which never really caught on with the Germans. Miata , S2000 , RX-7, if you've owned one of these cars when you come to a Porsche it's a surprise that the Germans seem somewhat indifferent. I installed a 997 SSK in my Cayman and although its not 'Japanese' in its pursuit of perfection in shifter feel, its a very good shift feel and enough that I probably won't chase those last few percents (with something like Numeric 's SSK which looks like a piece of art).