utkinpol

Hi,

is there anybody here who did a master cylinder upgrade on an 'S' of base 997/996 cars?
http://www.suncoastparts.com/product//SKUGT3BMC.html

my beef with stock part is that even after full clean bleed i still get softness on the pedal and i suspect that bigger displacement of GT3 cylinder may heal this issue even if its origin is somewhere else, clutch line, ABS, who knows.
but it pisses me off, frankly, and part is not extremely expensive. I just wonder if that was done before and if it requires anything special to consider.

regards,

jhbrennan

When you bleed are you cycling the ABS pump as part of the process?

utkinpol

just started another thread with this question, if durametric can do it.

i had mixed results. i had complete flush done at my mechanic once with ABS pump and results were very good for 3-4 events. after another full flush pedal had some softness. i cannot track it down to what an original issue is.

so i only wonder if a bigger displacement of gt3 cylinder will mask it enough or not to become irrelevant. calipers by themselves have plenty of stopping power, i have no problem there, at second 'pump' of brakes they become solid hard too, so, issue got to be in somewhat else.

MagnusB

I have the same issue.

mdrums

Contact ViperBob on rennlist....he has a few customers that have Carrera S car turned into race cars and he has done some different master cylinders.

However this sounds more like a feel of the pads...on my 2007 Carrera S 2009 Carrera S and my 2012 GTS the stock Porsche pads feel rock soild, higher pedal feel than new or used Pagid race pads which feel a little softer. I do have a bit better feel with the Prospeed 683 fluid when on my track pads.

utkinpol

i am going to do another bleed/flush this time with ABS pump cycle, will see if it changes anything or not.

slicky rick

Hi utkinpol, did you get this issue resolved? Any benefits to the abs cycling when flushing?

BevHillsPorsche

I've heard of someone swapping out the brake booster from a 987 Spyder with PCCB for the 997 GT3 unit and that they were very happy with the swap. He was disappointed with the mushy pedal and I think he mentioned that it cured his issue by about 90%. I think he also predicted that if he changed the master cylinder that it might give him that last 10%. Not sure if he ended up doing that as well.

I'm not really sure what the difference is between a GT3 brake booster and a regular Carrera but I have a few people that I could probably ask.

utkinpol

Hi Ryan, I actually did the swap since that time and i like it a lot - it has improved pedal feel big, big time. it was a direct swap, nothing fancy needed, i wish i did it 2 years ago.

MagnusB

What did it cost?

slicky rick

Hey brother what exactly did you do swap brake booster or just the mastercylinder of your car to one from a gt3?

utkinpol

about of $400.

utkinpol

you just unbolt old cylinder and put in gt3 one instead, booster stays where it is. it is a direct swap, nothing else is needed. now on a track i never have to push pedal all the way to the floor.

cylinder is secured by 2 nuts - do not try to use torx bits to undo those studs! only undo those 2 big nuts that sit on those studs. brake fluid container gets simply pried up, do it before you undo those nuts, be careful not to brake off its legs but persistent , shake it around a bit helping with big flat screwdriver from below and it will pop out eventually.

after you will bolt new cylinder in double check how brake lines get in, secure them, then pop in brake fluid can, pour in brake fluid. to do a proper system flush after that you will need both power bleeder and also work on brake pedal several times to clean it up, after the moment when you brake pedal feels strong you need to get on a road and brake hard several times to make ABS work, then go back and bleed again working pedal to push any rest of air out. it all is simple enough but using power bleeder alone i could not get rid of air there, you have to work on pedal too. you may preserve old brake fluid when you do this system re-flash couple of times to save $ but at the last time when you do it - replace brake fluid with new one.

BHMav8r

Soo you did not do the booster?

I am not in love with the soft pedal in my '05 - though bleed at next brake job would fix it. Now I wonder.

Also, did you try the extensive bleed procedure before? I am curious how much was the new mc and how much was the ultra bleed - especially with hard track use.

Thanks.

utkinpol

what do you mean - how much was the bleed? i did this myself, only paid $400 for MC.