matthisk

Hello all,

i looking for options to upgrade the brakes on my GTS with larger calipers and larger discs as i track my car. I have to stick to Porsche brakes as these are the only option to stay street legal.

i thought about the 981 GT4 brakes with 380mm discs or the 718/982 GTS brakes with 350mm discs (front). Would those work and are they plug and play for do i need e.g. any distance-pad?

The 982 GT4 brakes, they the the same as on the 981 ?

thank you!

CaptainSlowly

Gt4 brakes won’t work

Flat6 and Suncoast both have Porsche caliper based upgrade options

1. Flat6 (350mm front and rear girodisc 2pc rotors) - you have to buy your own calipers

https://flat6motorsports.com/blogs/n...ade-episode-17

2. Suncoast has 350mm front and 330mm rear with OEM 1pc rotors/calipers/pads

https://www.suncoastparts.com/catego...SBRAKESBU.html

matthisk

Thank you. So its the 350/330mm combination then. Are these the brakes of the 991 S? So 991351423 and 991351424?

nhnguy12

The 350mm front brakes are shared between the 991S/981 spyder/718 4.0GTS

The 330mm rears are shared between the 981 spyder/ 718 4.0GTS

Kitc2246

Are you in the EU? I track a 2013 Boxster S with a tune. I find the Pagid RSL29s on Sebro slotted more than adequate for my 20-30 minute DE sessions. I run Hankook RS4s for their durability The tires are the limitations on braking at the end of the Summit Point Main straightaway at 140 mph. If you have not tried suggest trying a set of Pagids or Ferodo 3.12s before the upgrading the brakes.

IndigoInkTaco

I'm not doing the upgrade, but wondering (for those who are) what the necessity to upgrade the master cylinder is. I see Flat6 touched on it. Does the oem 981 MC play nicely w/ the larger calipers/pistons? And for anyone who has done it, did they also wind up having to do anything like extend brake lines, use larger dust shields, etc?

Cliff3

Agreed.

I'm running Ferodo 3.12 pads, Sebro slotted rotors, and Motul RBF600 fluid on 200tw tires such as RE71RS, and I have had no braking issues on my mostly stock CGTS. Fwiw, I run in the instructor or advanced run groups and I've done 26 HPDE days in the Cayman. If excessive heat became a problem then upgrading to Girodisc rotors would be my next step, and Girodisc includes spacers in their kit to allow them to work with the stock calipers.

matthisk

Yes, Girodiscs would be the easiest upgrade option but those are not legal in germany. I‘ll check the 350/330 mm option from 981 spyder and discuss with my motorsport partner in 2 weeks. Will report back on what i did.

okie981

OP, If your brakes are overheating/fading with stock 981 GTS brake rotors/calipers, first install the best racing pads you can such as Ferodo 3.12 or equivalent, swap over to the best brake fluid that you can (Castrol SRF or Endless RF-650 for example) and re-evaluate. Even with these modifications, as Kitc2246 posted above, any tire in 981 GTS OEM sizes will be the limiting braking factor unless you use slicks (Hoosiers, etc.). Even if you increase the GTS OEM tire width by 2 cm front and rear (i.e. to 255 front and 285 rear) , the tire will still be the limiting braking force factor (unless you use slicks).

If you get fading using the best racing pads and fluid with tires that aren't slicks, please report back here with details of the track(s) you run on including number of braking zones per lap with approximate car velocity at start and end of each braking zone, and your typical lap time.

Bottom line, if you aren't racing, are doing track days only, and are using non-slick tires, you should not need to spend money on larger rotors/calipers. There are better ways to spend your money. If you want to do it for appearance, that's a different scenario that only you decide.

DriverDaily

OP have you also considered retrofitting the brake ducts from the GT3 / GT4?

It won’t be as big an improvement as swapping the calipers and rotors, but it also won’t add rotating and unsprung mass.

okie981

Based on my experience with my 981 Boxster S for 34 track days at 4 different tracks, several in hot summer weather, revising brake ducts on a 981 Cayman or Boxster isn't a worthwhile exercise of time and/or money. Meaning I never made any changes to my OEM brake cooling ducts on my car and never had any brake overheating issues. Note that I never raced the car (40 or 45 minute sessions for races), I only did HPDE events with the longest session being 30 minutes.

DriverDaily

So you haven't tried it?

The ducts cost like $50 each. I would personally try that to see if it helps before spending thousands on the 350/330mm setup.

okie981

Never needed to "try it". As I stated in my post earlier in this thread, for track use the first brake $$$ to be spent should be on racing pads and racing fluid, nothing else. The 981 OEM cooling ducts front and rear were fully adequate for cooling as I stated. In fact, more cooling than is needed may be problematic leading to premature cracks in the rotor and non-optimum temperature for the race pads to perform. Go read on essexparts.com tech info section about brake cooling ducts. Exxex recommends you leave OEM ducts alone until your particular setup clearly indicates revised cooling is needed. They are the experts, not me.

https://www.essexparts.com/news-blog...n-my-track-car

Kitc2246

Okie has far more track time and as I stated above I track a 2013 Boxster S PDK with tune and Sebro slotted with Pagid RSL29s ..Several years ago my son and I backed to backed the car at VIR using ST43 race pads. At the next DE tech inspection at my local shop discovered that both front rotors had edge cracks. Not severe, but 3 or 4 clearly visible cracks. Luckily it was a timely inspection and quickly ordered replacement Sebro slotted from FCPEuro and then warrantied the old set. I attribute the edge cracks to almost an hour of continuous track time between the two of us. The ST43 pads looked great, probably about 70% and I carry them as a backup. Since then as others have stated the OEM brakes with Sebro slotted and Pagid RSL29s are more than adequate for a 30 minute or less DE.

Not sure how often you track but IMO there are other improvement to spend $$$ to include an instructor. A third radiator, which you already have, radiator screens, adjustable LCAs with -2.5 camber, 18s with 200 TW, a tune, a hybrid HANS and intake screens have been my investments. Just received the additional thermostat hose bracket. A bigger heat exchanger from a 911 would be my next investment, but want to better monitor oil and PDK temps with the new Cobb tune. Never had a limp mode.

DriverDaily

OP has to use factory parts or he won’t be able to pass inspection.