Girodisc vs OEM rotors w/ cooling ducts

[MRzcp]

Hi everyone. I have tried several solutions for overheating issues with my braking setup at the track, and have not been completely satisfied with the results so far. I am looking at purchasing a set of Girodisc rotors for my car, but wanted to hear others' experiences before doing do. Below are things I have tried and their results after ~20 min sessions. (Socal tracks such as Buttonwillow/Chuckwalla)

OEM Rotors/calipers, PFC 08s, Castrol SRF - Pedal becomes long enough to reach the floor after a few laps

OEM Rotors/calipers, PFC 08s, Castrol SRF, Cooling ducts - No significant improvement

OEM Rotors/calipers, PFC 08s, Castrol SRF, SS lines, no ducting - Noticeable improvement, but the pedal still gets quite long.

I have not tried re-introducing the cooling ducting after noticing an improvement with the stainless lines, but at this point, I am tired of fiddling with the brakes and am ready to bite the bullet and upgrade the rotors if it is the right step forward. My question is, have many people using Girodisc rotors with OEM calipers noticed a significant improvement after experiencing brake fade prior?

[amg6975]

The SS lines are probably a placebo or other environmental factors improving fade.

The Girodisc rotors made a night and day difference for me. Cured most of my braking issues.

The other thing to look at is the 08, that's an endurance pad and will overheat pretty quickly. Try the 12 and it will help the fading a lot.

The last thing to note, with Girodisc rotors, no dust shields, SS lines, air scoops, I still get a long pedal after a few push laps. The brakes still work fine, it's just a little concerning. I'm planning on doing the rocauto F80 "BBK" this winter as I think that will fit in my wheels and hopefully improve the braking feel.

[VtecforV8]

I have tracked your first set up probably 10-12 days at VIR and the pedal has been OK, but probably a function of environment/track layout etc. Good luck!

Re the F80 kit, FCP's youtube channel put out an install video a week or two agao w/ the new package that includes brembo "Xtra calipaers" made for the F8X instead of needing the BMW calipers. Looks pretty good and will probably be what I do when my current set of rotors is done.

[MRzcp]

Originally Posted by VtecforV8

I have tracked your first set up probably 10-12 days at VIR and the pedal has been OK, but probably a function of environment/track layout etc. Good luck!

Re the F80 kit, FCP's youtube channel put out an install video a week or two agao w/ the new package that includes brembo "Xtra calipaers" made for the F8X instead of needing the BMW calipers. Looks pretty good and will probably be what I do when my current set of rotors is done.

This seems like it would be a great setup, but at $5k, it doesn't seem very cost effective. I am mostly looking to optimize the factory components for casual track work. With FCP now stocking Girodisc for our cars, it seems like a pretty sweet deal if they have been shown to be greatly beneficial.

[Ximian]

The thing that concerns me is the long pedal after only a few laps. Might have a little bit of air in the lines so before spending money on new rotors or anything else, I'd do an ABS bleed with ISTA. Use regular brake fluid for that since it easily use up 3 liters of brake fluid.

[tdott]

I agree that issue doesn't sound right. I know several fast guys still on stock brakes that track alot, or as much as me. Aside from going thru alot of pads/rotors, they dont have those issues.

Perhaps try another brake fluid, while I dont have an issue with SRF, one guy I know never liked the feel of SRF and is much happier with EndLess fluid, he said it feels much better in his opinion.

[jmeenach]

Originally Posted by MRzcp

This seems like it would be a great setup, but at $5k, it doesn't seem very cost effective. I am mostly looking to optimize the factory components for casual track work. With FCP now stocking Girodisc for our cars, it seems like a pretty sweet deal if they have been shown to be greatly beneficial.

At that price, you might as well spend an extra $500 to get a true BBK

[tsk94]

I ran stock brakes (race pads, good fluid, and ducting) for a few seasons and never had issues. Switching to a PFC BBK made almost no discernible in performance or 'fade' resistance, to my surprise and honestly disappointment.

Do/did you have 'proper' ducting going to the center of the rotor hat? Not just one of those junk deflectors that some people do, that really aren't that effective.

[sperkins]

Question for the experts: If the pedal goes long, is that a sign of fluid boil? If so, would you see it coming out of the caliper seals? Or is it too much air in the lines?

If you have a stiff pedal, and not much braking, that is usually a sign of the pads overheating.

Also, after a few laps if the rotors start to shake, that could also be overheating or inconsistent pad deposits.

I have ST60 front calipers. I moved from stoptech aero rotors & hawk DTC 70's to Girodisc/Cobalt XR2.
I also added ducting. Happy to report all of the above disappeared.

FWIW I use Endless RF650 fluid. Excellent pedal feel, and no chance of boiling.

You might want to reach out to Eddie @ Cobalt Brakes. He's a racer and knows everything about our cars. Eddie set me straight.

I hope you get it sorted.

-Steve

[MRzcp]

Originally Posted by tsk94

I ran stock brakes (race pads, good fluid, and ducting) for a few seasons and never had issues. Switching to a PFC BBK made almost no discernible in performance or 'fade' resistance, to my surprise and honestly disappointment.

Do/did you have 'proper' ducting going to the center of the rotor hat? Not just one of those junk deflectors that some people do, that really aren't that effective.

Proper enough, I think. Cut a big hole and riveted a 2.5" flange to the dust cover with a GT4-style splitter. Bad photo attached.

[M3SQRD]

Originally Posted by tsk94

I ran stock brakes (race pads, good fluid, and ducting) for a few seasons and never had issues. Switching to a PFC BBK made almost no discernible in performance or 'fade' resistance, to my surprise and honestly disappointment.

Do/did you have 'proper' ducting going to the center of the rotor hat? Not just one of those junk deflectors that some people do, that really aren't that effective.

Which PFC brake kit did you install - z54/z45 calipers with 372/355 mm OD rotors or z31/z31 calipers with 372/371 mm OD rotors? Which pads are you using? I use both on two different e92 M3s and I found they were superior to the stock brakes in all braking categories.

[Redd]

Driving style might also have something to do with it. On days that I brake a bit earlier and longer, I find my brakes fade a lot less compared to days I go for that absolute late braking point.

[M3SQRD]

Originally Posted by Redd

Driving style might also have something to do with it. On days that I brake a bit earlier and longer, I find my brakes fade a lot less compared to days I go for that absolute late braking point.

Braking earlier and longer will result in even higher rotor temps because the energy being absorbed is the same but absorbed over a longer duration, driving temps higher due to the pads remaining in contact for a much longer duration. Braking hard and staying on the brakes for a shorter duration reduces peak brake rotor temps because the energy is absorbed more quickly with the pads remaining in contact with the rotor for a much shorter duration reduces peak.

[tsk94]

Originally Posted by M3SQRD

Which PFC brake kit did you install - z54/z45 calipers with 372/355 mm OD rotors or z31/z31 calipers with 372/371 mm OD rotors? Which pads are you using? I use both on two different e92 M3s and I found they were superior to the stock brakes in all braking categories.

It was the Z54 kit on the E92. Also had a full PFC kit on an E36 M3 race car, which was fantastic.
On stock brakes and the PFC kit it was PFC08 and 11 pads, used both on both setups.

If I had the chance to drive both on the same day, same conditions, maybe the difference would be more obvious. The most notable difference was less pad knockback with the PFC kit vs stock.

It wasn't bad by any means. I just expected a big jump from stock, which in my case it wasn't.

[M3SQRD]

Originally Posted by tsk94

It was the Z54 kit on the E92. Also had a full PFC kit on an E36 M3 race car, which was fantastic.
On stock brakes and the PFC kit it was PFC08 and 11 pads, used both on both setups.

If I had the chance to drive both on the same day, same conditions, maybe the difference would be more obvious. The most notable difference was less pad knockback with the PFC kit vs stock.

It wasn't bad by any means. I just expected a big jump from stock, which in my case it wasn't.

In my case with Z54 front and Z45 rear, there was a massive increase in fade resistance and consistent braking for 20-45 min sessions. Primary pad used was the PFC 11. My brake pedal travel, which was short, remained the same from the beginning to the end of a session. Any chance air was trapped in the ABS/DSC system? Similar performance from the Z31/Z31 kits. Biggest differences are the Z31 is a monoblock caliper (PFC engineer told me it’s the stiffest caliper they’ve made because it’s so compact), Z31 caliper has to be removed to change the four pads per caliper, and the pad thickness is only 18 mm (more frequent pad changes).

[tsk94]

Originally Posted by M3SQRD

In my case with Z54 front and Z45 rear, there was a massive increase in fade resistance and consistent braking for 20-45 min sessions. Primary pad used was the PFC 11. My brake pedal travel, which was short, remained the same from the beginning to the end of a session. Any chance air was trapped in the ABS/DSC system? Similar performance from the Z31/Z31 kits. Biggest differences are the Z31 is a monoblock caliper (PFC engineer told me it’s the stiffest caliper they’ve made because it’s so compact), Z31 caliper has to be removed to change the four pads per caliper, and the pad thickness is only 18 mm (more frequent pad changes).

I found some photos on when I installed, it was the Z54 system, and 08 pads.
Definitely no air, it was bled with INPA.




Fade resistance was improved. I did start to get slight fade at the end of 15-20 sessions with Hoosiers, when I used the PFC kit I didn't experience any fade. That said, pedal travel and pedal feel was virtually unchanged. Not that it was bad before though. Less pad knockback as well. But again, that was rare with the stock brakes but it did happen occasionally.
My comments are not a slight against the PFC system, I think it's a great kit (that's unfortunately no longer available). I do not regret buying it on the E92. If anything, it's more so a testament to how well you can get the stock brakes to work if you did everything I did to them (solid caliper guides, SS lines, proper ducting w/ GT4 front lip, Endless fluid, good race pads, and titanium shims), and you drive without overworking the brakes.
Would they have worked as well for me on a track that's harder on brakes, or somewhere the climate is warmer (like CA or TX)? I don't know. I just know in my case, at the tracks I used them at, and up here with our mild climate, I had them working really well.
I upgraded to the PFC kit for better heat tolerance, which they did improve upon. Longer consumable life. And honestly... looks, LOL.

For reference, on the new E92 I'm building I went with a Brembo Pista setup. So I'm not a die hard 'stock brakes are the proper solution', lol. I just think the majority of people WAY overdue how 'bad' they are. They just require ducting to keep the temperature in check. But, I get why not everyone wants to go through the effort of doing ducting. Especially on a car that is also street driven and not a dedicated track/race car like mine was.