Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster Racing Forum

Reply
 
LinkBack Thread Tools Display Modes
Old 12-05-2017, 10:22 AM   #1
Registered User
 
Join Date: Dec 2016
Location: Clifton, NJ
Posts: 526
Anybody using a GT3 master cylinder

Anybody running one of these?

Would like to firm up the brake pedal a bit (for reference, brakes are bled and they don't sink as the session goes on, the pedal has just a bit too much travel to make heel/toe seamless.

part number is 99735591030 , made by TRW

Any reviews would be great, as well as any install tips.

thanks!
Quadcammer is offline   Reply With Quote
Old 12-05-2017, 12:38 PM   #2
Track rat
 
Topless's Avatar
 
Join Date: Nov 2006
Location: Cucamonga CA
Posts: 3,567
Garage
Nope, but a bunch of 987 drivers did at some point for the reasons you suggest. A lot of them reported: "awesome!", "totally transformed my brake pedal" "solid as a rock now".

My impression after driving hot laps in several of their cars vs mine with stock master cyl? It did not do what they wanted it to do. I noticed no significant difference between the two. I chalked-up the comments to confirmation bias. YMMV
__________________
2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor
PCA Zone 8 DE/TT Chair (SoCal, AZ, NV)
Topless is offline   Reply With Quote
Old 12-05-2017, 01:52 PM   #3
Registered User
 
rastta's Avatar
 
Join Date: Feb 2014
Location: Cowtown CA
Posts: 295
Quote:
Originally Posted by Topless View Post
Nope, but a bunch of 987 drivers did at some point for the reasons you suggest. A lot of them reported: "awesome!", "totally transformed my brake pedal" "solid as a rock now".

My impression after driving hot laps in several of their cars vs mine with stock master cyl? It did not do what they wanted it to do. I noticed no significant difference between the two. I chalked-up the comments to confirmation bias. YMMV
Since I have a 987 Cayman S as well as the Boxster - I had been following the forums and I never quite understood the whole GT3 Master Cylinder thing. My Cayman's pedal is very firm. Same with my 986 Boxster S. Pedal location on both is fine for heel/toe as well.
rastta is offline   Reply With Quote
Old 12-06-2017, 05:44 AM   #4
Registered User
 
Lemming's Avatar
 
Join Date: Apr 2016
Location: B'ham, AL
Posts: 189
I think this is more about personal preference. My spb brakes feel over boosted, making it very easy to over brake. My last race car had a dual-master cylinder setup with no boost, which, when set up properly, made it very easy to modulate the brake, but you had to push HARD. I believe the GT3 master and vacuum setup do the same (you must increase foot pressure to get the same brake pressure) for the spb, but I'm finding it hard to justify the cost when I have other items still on my list.

Larger MC = equals shorter throw, but more foot pressure to build brake pressure.
__________________
Tim
1998 Boxster (project car)
1999 Boxster (SPB)
2015 Boxster (daily driver)
CDI Alabama Region PCA
Lemming is offline   Reply With Quote
Old 12-06-2017, 08:04 AM   #5
Registered User
 
Join Date: Dec 2016
Location: Clifton, NJ
Posts: 526
Tim, the part can be had for $180, so really not too bad.

Its made by TRW, part number is the same (99735591030), and arizonaautohouse (use abrreviation for arizona and german word for house) has it for $181.

I think i'll give it a shot.
Quadcammer is offline   Reply With Quote
Old 12-06-2017, 12:02 PM   #6
Registered User
 
Lemming's Avatar
 
Join Date: Apr 2016
Location: B'ham, AL
Posts: 189
Quote:
Originally Posted by Quadcammer View Post
Tim, the part can be had for $180, so really not too bad.

Its made by TRW, part number is the same (99735591030), and arizonaautohouse (use abrreviation for arizona and german word for house) has it for $181.

I think i'll give it a shot.
Priorities, right now I need a two post lift and tire mounting and balance machines first.
__________________
Tim
1998 Boxster (project car)
1999 Boxster (SPB)
2015 Boxster (daily driver)
CDI Alabama Region PCA
Lemming is offline   Reply With Quote
Old 12-06-2017, 12:31 PM   #7
Registered User
 
Join Date: Dec 2016
Location: Clifton, NJ
Posts: 526
haha, I know how that is and I want a tire mounter/balancer in the worst way, but no place to put them.
Quadcammer is offline   Reply With Quote
Old 12-19-2017, 07:50 AM   #8
Registered User
 
Join Date: Dec 2016
Location: Clifton, NJ
Posts: 526
ok, pulled the trigger on this. will report back my findings.
Quadcammer is offline   Reply With Quote
Old 01-21-2018, 12:35 AM   #9
Registered User
 
Join Date: Sep 2013
Location: uk, notts
Posts: 141
I fitted one to my 986... although I also had larger calipers so it needed the extra push. Made a great difference.

We also did it on my brother's Cayman R. That had a really long pedal as stock but the GT3 cylinder made it how it should have been IMHO.

TRW PMN 166 if you are doing a search.
jimk04 is offline   Reply With Quote
Old 03-01-2018, 01:01 PM   #10
Registered User
 
Join Date: Dec 2016
Location: Clifton, NJ
Posts: 526
GT3 MC is in. Pedal feel is superb. Travel is reduced.

Excellent mod in my book.
Quadcammer is offline   Reply With Quote
Old 03-01-2018, 01:41 PM   #11
Registered User
 
steved0x's Avatar
 
Join Date: Dec 2012
Location: FL
Posts: 3,635
Quote:
Originally Posted by Quadcammer View Post
GT3 MC is in. Pedal feel is superb. Travel is reduced.

Excellent mod in my book.
DIY thread!! How easy was it, any tricky gotchas?
steved0x is offline   Reply With Quote
Old 03-01-2018, 01:51 PM   #12
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 2,655
does it mess w your heel/toe?
The Radium King is offline   Reply With Quote
Old 03-01-2018, 04:56 PM   #13
Registered User
 
Join Date: Dec 2016
Location: Clifton, NJ
Posts: 526
Quote:
Originally Posted by steved0x View Post
DIY thread!! How easy was it, any tricky gotchas?
Not even necessary. Its dead simple. suck or drain the fluid from the MC, remove the two hard lines and the push in clutch line. pull off reservoir (friction fit), and then two bolts. reverse to install, then bleed. piece of cake

Quote:
Originally Posted by The Radium King View Post
does it mess w your heel/toe?
Its much better actually as I felt the pedal travel was too long for me to heel and toe well (i use the ball of my foot on the brake and side of my foot on the gas), which makes it harder with a pedal height mismatch. less useful if you actually use your heel and toe.
Quadcammer is offline   Reply With Quote
Old 04-06-2018, 04:44 AM   #14
Registered User
 
Join Date: Oct 2012
Location: claremont, ca
Posts: 39
i have the GT3 master cylinder upgrade on my spec boxster, definite plus. Firm hard pedal, I found myself needing to bleed brakes often trying to firm up brake pedal. Very confident braking.
bkovac is offline   Reply With Quote
Old 04-06-2018, 05:20 AM   #15
Registered User
 
Join Date: Dec 2016
Location: Clifton, NJ
Posts: 526
after the track at lime rock dried up on thursday, I really got to get a feel for this mod and really believe it was helpful in my situation. While the pedal requires a firm push to really get on the brakes hard, the reduction in travel means the pedals are more evenly aligned for me to heel/toe, which is hard for me with a height mismatch since I use the ball of my foot and the side.

Pretty happy overall.
Quadcammer is offline   Reply With Quote
Old 04-06-2018, 10:52 AM   #16
Registered User
 
steved0x's Avatar
 
Join Date: Dec 2012
Location: FL
Posts: 3,635
Quote:
Originally Posted by Quadcammer View Post
after the track at lime rock dried up on thursday, I really got to get a feel for this mod and really believe it was helpful in my situation. While the pedal requires a firm push to really get on the brakes hard, the reduction in travel means the pedals are more evenly aligned for me to heel/toe, which is hard for me with a height mismatch since I use the ball of my foot and the side.

Pretty happy overall.
Any videos!!!!
steved0x is offline   Reply With Quote
Old 04-06-2018, 11:01 AM   #17
Registered User
 
Join Date: Dec 2016
Location: Clifton, NJ
Posts: 526
unfortunately I haven't gotten to the video stage....add go pros to the list
Quadcammer is offline   Reply With Quote
Old 04-16-2018, 01:47 PM   #18
Registered User
 
Join Date: Nov 2016
Location: Cresson
Posts: 3
I testing and fully switched to this the minute it was announced. The shorter braking travel helped my speed to apex as I can apply it the millisecond I wanted to and create the shortest distance possible to brake. It's also more consistent throughout the lifespan of the race. I don't want my pedal travel to modulate throughout a race and feel this upgrade helped considerably.

--
#750 SPB / Drake
FirePowered is offline   Reply With Quote
Old 06-22-2018, 11:44 AM   #19
Registered User
 
Join Date: May 2010
Location: Austin
Posts: 2
Just to confirm, the part number 99735591030 (which is the 997 GT3 master cylinder, not the older 996 version) fits on the 986 Boxster without any modifications required? I saw a reference to this unit in another forum that implied the poster may have had to use a thread adapter?
longhorn986 is offline   Reply With Quote
Old 06-23-2018, 05:06 AM   #20
Registered User
 
Join Date: Jul 2010
Location: Houston, TX
Posts: 26
Garage
So where in the rule book does it say that using a GT3 master cylinder is a legal SPB modification?

5. Brake System
A. Brake pads are free.
B. Steel braided brake lines are allowed.
C. Emergency brake, lever, cables and associated parts may be removed.
D. Brake cooling systems are allowed if they use only air. Air may be vented through the front air dam. Dust shield may be removed.
E. One piece stock size steel rotors are required. Rotors may be cross‐drilled or slotted.

SPB Class Rules and SPB Eligible Models
All parts must be factory stock from one of the eligible years, except where modifications are specifically allowed below. Modifications not specifically listed are prohibited.
__________________
Brian
Current: SPB wanna be Boxster
Past: 10 944s, 2 924 Turbo, 911SC, 993, Cayenne, Boxster S, and Cayman S.
Future: Macan GTS

Last edited by harnishclan; 06-23-2018 at 05:13 AM.
harnishclan is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 01:43 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page