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Brake Pad similarities/differences between 4-piston S197 Brembo and S550 6-piston Brembo

1,240
1,030
Exp. Type
HPDE
Exp. Level
5-10 Years
Philly Metro Area
I currently have the S197 4-piston Brembos I used to run the PowerStop Track Day pads and loved them for the initial bite and overall stopping power - and value. However I felt that I was outgrowing them and switched to new rotors with G-LOC R12 pads. While their modulation seems a bit better than the PowerStops, they do not have that strong initial bite and do not seem to stop as well as the PowerStop Track Day pads - especially at the end of a 135-140mph straight at Pocono. I'm thinking that I probably should have gone with the R16s instead. Castrol SRF flushed with SRF with the new pads and rotors.

Looking ahead, I have a set of S550 GT PP Brembo calipers that I will install as soon as I get my second set of Apex wheels - for next season. Since the pads are significantly bigger than the S197 4-piston Brembos, are the pad recommendations equivalent or is there a 1 to 2 level difference? For example, will an R12 on S550 PP Brembos make the car stop like an R16 (or even R18) on S197 4-piston Brembos? Or is the initial bite/modulation the same with an R12 (or whatever compound) on either caliper with the main difference being heat dissipation and reduced fade.

With brake cooling in all cases.

While the example of above uses G-LOC/CarboTech compound designations, the same question applies for all manufacturers with multiple track pad compounds.

Thanks
Chris
P.S. In my opinion, the G-LOC GS-1 street pads are not as dusty but not nearly as good stopping as the PowerStop Z26 street pads.
 

Norm Peterson

Corner Barstool Sitter
939
711
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
I've been looking for mu vs temperature plots for Carbotech/G-loc, but to date all I have is this.

G-LOC Pad Compound Chart (data from Vorshlag)
GS-1 ~0.45 ambient up to 800°F (426°C) - Street pads
R6 ~0.51 ambient up to 1000°F + (to 537°C+) - Autocross pads
R8 ~0.55 74°F-1250°F+ (23°C to 676°C+) - Entry level track pads
R10 ~0.59 118°F - 1475°F (47°C - 801°C) - Track pads
R12 ~0.62-0.63 173°F to 1860°F (78°C to 1015°C) - Track pads
R14 ~0.60 210°F to 1400°F (98°C to 760°C) - Endurance pad for light cars
R16 ~0.65 255°F to 2000°F (123°C to 1093°C) - Aggressive track pad
R18 ~0.70-.71 610°F to 2100°F+ (321°C to 1149°C+) - Aggressive track pad

From the above, I would guess that if you were running a 12/10 combination that going to 16/12 would retain about the same slight front bias (in terms of both mu and low temperature). Knowing mu vs °F might resolve some of the guessing. Same if moving from 12/8, I think you'd pick 16/10.


Norm
 
1,240
1,030
Exp. Type
HPDE
Exp. Level
5-10 Years
Philly Metro Area
I've been looking for mu vs temperature plots for Carbotech/G-loc, but to date all I have is this.
Norm, thanks that's good info to know. But my main question is since I currently have 4-pot S197 calipers using an R12 compound that's not quite to my liking, what pad compound do I use when I upgrade to S550 PP 6-pistons?

Will the R12 on the bigger S550 pad improve my initial bite so much that I'll be much happier? Or based on my perception that the R16 would have been better with with my 4-pots that I should also choose R16s for the new S550 6-pots?

Same applies if I was using Ferodo DS1.11 or Raybestos ST-43 on 4-pots and was not happy. Would those compounds feel so much better on 6-pot S550 calipers or would I go with DSUNO or ST-45 pads?

Hell, maybe using the PowerStop Track Day compound on the S550 6-pot calipers is an acceptable option...



 
866
1,345
Exp. Type
Time Attack
Exp. Level
3-5 Years
SoCal
I recently converted from the 4 pot Brembos to the S550 PP calipers, running R16 G-LOC in both. (R12 rear) The initial bite is consistent despite the change in caliper/pad size. With the larger calipers, I can apply more force which is where they stop more aggressively than the smaller caliper. I find it easier to modulate the S550 setup as well - less of an on/off switch, making the pedal stroke much more linear through the range. Some have noted they feel the stroke is longer with the PP calipers - I’m not sure if it’s that, or if it’s just more linear. Regardless, trail braking is greatly improved with my current setup.

I would recommend trying the R16 when you make the change to the S550 calipers - their heat range is similar to the R12 so they come into range really quickly and they have a nice aggressive initial bite IMO. The R16/R12 combo was recommended by Tim at OP Mustang.
 

Mad Hatter

Gotta go Faster
4,793
3,610
Santiago, Chile
Hi Coz, I tried the Gloc R16/R12 setup and it had plenty of bite with the big S550 pads. I switched to Pagid RST3 pads for the wear. Both pads did a great job on stopping the car but the pagids were softer on the disks and lasted twice as long.

With either the Gloc R16 or Pagid RST3 pads on the S550 brembos, the car could brake on par with a GT3. Highly recommended!!
 

Norm Peterson

Corner Barstool Sitter
939
711
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
Norm, thanks that's good info to know. But my main question is since I currently have 4-pot S197 calipers using an R12 compound that's not quite to my liking, what pad compound do I use when I upgrade to S550 PP 6-pistons?
Mean effective pad radius differences between the S197 and S550 PP would be something else to consider. I don't offhand know what that amounts to, but the S550 6-pots might be enough of an upward change from the S197 4-pots to want a little less stagger in your pad compound choices. At least as long as your actual decelerations remain about the same and the ABS doesn't do anything unwanted.


Will the R12 on the bigger S550 pad improve my initial bite so much that I'll be much happier? Or based on my perception that the R16 would have been better with with my 4-pots that I should also choose R16s for the new S550 6-pots?
I don't know. Effective pad radius is a bit bigger, so you'll get more bite from the same mu and total caliper force, but I doubt that this effect alone is going to be worth much more than about 10%.


Same applies if I was using Ferodo DS1.11 or Raybestos ST-43 on 4-pots and was not happy. Would those compounds feel so much better on 6-pot S550 calipers or would I go with DSUNO or ST-45 pads?

Hell, maybe using the PowerStop Track Day compound on the S550 6-pot calipers is an acceptable option...
No basis in experience with those pads, but I'm not seeing a 10% - 15% change in effective pad radius being what it'd take to take all of the "not" out of your "not happy".


On edit . . . nice to see some actual race experience here, so now you've got opinions from both directions.


Norm


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