Do people swap the steel rotors to gyrodiscs, or do people just replace the OEM steel rotors with OEM once they wear out?

 

Track use:
I prefer the GiroDisc vs factory as the factory could develop cracks between the cross drilled holes.
That being said as long as you keep an eye on you’ll be fine, and if you can get your hands on low cost factory ones (new/used) they work plenty fine. I would not replace a factory steel iron rotor for the sake of changing until it is actually time for new ones…..then I’d go GiroDisc.

 

More importantly is getting adequate cool air to the discs. Think Tikt!

 

From personal experience i noticed the factory discs cracking faster than the girodiscs. It could have been weather related where I ran the factory irons on hotter days but it was noticeable

 

I would agree the Tikt ducts are the gold standard of brake cooling ducts for our platform, if and when you find a need, they are currently the ONLY ones to get.

I simply monitor with temp stickers on my calipers, and have yet to need additional cooling from what the GTR PRO offers.
Maybe it’s how I use my brakes, I get into the pedal hard and aggressive initially for a short burst then ease off, and they stay happy.

 

Does the front bumper needs to be cut to install the Tikt ducts? Also, does anyone have the link to the exact model they purchased?

 

https://www.tikt.de/en/product/tikt-...-r-voderachse/ Is this the kit? It looks like you just take off the brake heat shield and mount the duct assembly in the place of the heat shield.

Also, what brake pads are people using for Laguna?

 

Yes and yes ... in that order. #;-)

Use some strong thread-lock on the mounting screws for the TiKT ducts as many have reported that they come loose. I locked mine in and they're still secure after a couple of track-day seasons.

 

I used Pagid RSC1s; a great pad. Mine were for the CCBs and they were rotor friendly as well as having excellent road course attributes. I’m pretty sure you’ll find them for the iron rotor version also.

 

I wonder if FCP Euro stocks the OEM rotors steel rotors for the GTR. They do have them for the GT S, which means I'll be getting a free lifetime replacement on the rotors if I ever manage to wear them out!

 

Ha. I don't know how that is a profitable business venture. I know that a number of BMW guys "use" them quite a bit.

 

GP 30/40 front and GP 25 rear but GP30 rear available soon. Laguna is brutal on our brakes if you are fast. I get 5 days on Girodisc Rotors and 2-3 days on the pads up front. I have Tikt cooling ducts in the front. Not needed for the rear unless you are running CCB. Car is heavily biased towards front brakes. I use SRF fluid. Calipers get over 550 degrees. Rotors over 1000 degrees. After running the hell out of this car and recently replaced all four calipers I decided I need to run 15 min sessions moving forward. They are just getting too hot and cooking everything with full sessions. Heavy fast car at Laguna eats brakes for breakfast.

 

Why were the calipers replaced? You couldn't just overhaul the seals? Also, the did the powder coat color turn brown? In Laguna I always look at the time to make sure that I always do a cool down lap as sometimes they can throw the checker at T8. Taking a nice easy lap really helps with bringing the temps down. On my M3 I totally cooked the front calipers where the powder coat turned into a gross burn green color and the seals went up in smoke. I now run a StopTech Trophy kit on the front and back. Since the calipers are just machined pieces of alum without any paint, there no discoloration to worry about

 

I had them rebuilt once last year. New pistons as well. Towards the end the right front caliper wouldn’t stop leaking out of the bleeder valve. Replaced with new one but continued. Appears the metal just got so hot so many times it just started to fail. The front calipers were eggplant back. Right front gets hottest at Laguna. Rears got hot with more aggressive GP25 pads I tried a few times. They went black too. Melted my parking motors lol. Just didn’t want to worry about them while ripping on track. Friend gave me a nearly new 300 mile pull extra he had from his Pro that dealer damaged the paint on. So figured might as well replace them all and not have to worry about them. As much anyway.

I’m now running a larger annulus prototype rotor, upfront from Girodisc. Has def improved a bit at the expense of added weight. After day one running hard at laguna barely any heat cracking. I have six days on them now vs the five. Might be able to go one more. Passenger side still totally fine. Too bad you can’t rotate them. Still 2-3 days on pads despite them being 33% larger than the other set 🤷‍♂️


Im usually really good about cool down lap and driving slowly around the hills at laguna for another five min after each session. A few times I would hot pit mid first session and air tires down. I stopped doing that. Pretty certain they went black before that though.

I think the only solution for me at Laguna is to limit sessions to 15 min. Heat just keeps building. Wish there was a better option. Perhaps better cooling ducts.

 

@dllhg explain this new rotor please, I’ve talked to them a handful of times and had not heard about it, haven’t asked either though as I have not needed. Is it back to the factory dimension for pad swept area? If so, they sound like they created a new larger pad? That’s nice, as it’s going to act as a bigger “heat soak”.

How much more does it weigh, compared to the standard carbon conversion 402mm steel rotor? Hoping you put on a reliable scale to compare!

I love seeing more of our platform out there, pushing vendors to develop, great stuff!

I would still be curious to if in each brake application on track, you made it a point to stomp the brake pedal hard to floor, teetering on ABS intervention, for a quick count and then a fast but gradual release of pressure, if that would help. I just get shocked to hear all your breaking heat challenges with this car.

 

I’m super surprised that as long as the car has been available that AP Racing hasn’t yet produced one of their BBK kits for the car, as all braking issues would essentially be ‘cured’.

I talked to Jeff Ritter at Essex Racing when I first got my ‘18 and he said if someone would provide them a car; they’re in NC, they could probably find one of their kits that would be a direct replacement. I was never able to get it to him unfortunately.

If anyone is close I bet Jeff would still arrange to try and get a kit fabricated if Essex could have the car for a while.

 

This seems _very_ strange. My GTR Pro has TiKT brake-cooling ducts front 'n rear and I have temp-sensor "stickers" on both front and rear calipers. On the fronts, I have two -- one on the top back side and one on the bottom back side of the calipers.

Our local track is brutal on brakes: 1.35 mi (2.17 km) with 3 sharp/slow switchbacks so a lap looks like:
- coming down main straight: brake from 200 kph (124 mph) down for a min-speed ~60 kph (43 mph) switchback
- accel to 120 kph+ (75 mph) and brake for sweeping switchback at ~75 kph (46 mph)
- accel to 170+ kph (105 mph) and brake for min-speed ~45 kph (28 mph) switchback
- accel to 150+ kph (93 mph) and light/trail brake for 3-turn sharp chicane with min-speed mid-corner at ~45 kph (28 mph)
- accel to 145+ kph (90 mph) and brake for sharp left-right corners with min-speed ~70 kph (43 mph)
- accel to 80+ kph (50 mph) for sweeping corner with exit onto main straight
.... repeat this every <1:20 sec, on average, for a 20 min session and you'll definitely heat up your brakes! Given that there are 2 major and 1 significant braking events each lap, there's minimal time for brake to cool down. On this track, my C63 S would not complete 3 sessions before destroying a set of stock pads (and yes, I do threshold braking early with trail braking that attempts to keep the G-forces at 1+ Gs throughout the turns).

Even so, after 7 track days on this track (and many others on other tracks), my GTR's front-caliper temp stickers show that they've reached at least 188 deg C (370 deg F) but not 209 deg C (408 deg F).

 

they are still a prototype at this stage. I’m the test mule 😁. The pads are actually from a ZL1 slightly modified. Also temporary. Pads are 33% larger than the conversion setup. Significant. The rotors not quite as big as the CCB rotors. Also a little thicker by 1 mm. I just weighed them yesterday when changing out. The prototype rotors after six days were 1.5 lbs heavier than the regular conversion rotors after two days. So I’d need to talk to Girodisc about actual weight difference. I’d say at least 2lbs heavier both being new.

verdict is still out. One of the issues is we were also experimenting with more aggressive rear compounds. Helped the fronts but rears overheated resulting in pads lasting 2-3 days and rotors life cut in half. They are working on getting a GP 30 compound for the rear that should help balance the system out a lot.

The set I just took off has 6 days at Laguna Seca on them. They are done. Looking at my records I was getting a max of 5 days on the other ones. Improvement but not a ton. 20% more life. Pads are way bigger , same compound but somehow not lasting longer 🤔. I got 2.5 days and had to flip in between each track day to get that. Basically the same as the smaller pads …. Doesn’t make sense to me. I think that was the second set of pads on the rotors so they were running hotter due to less rotor material.

I do threshold brake and trail brake into corner. Before I wasn’t trail braking much and had same wear though. TC dial four reds.

 

my understanding is Laguna is particularly hard on brakes. Lot of speed and a lot of elevation changes and they never get to rest. Stickers on tried were pegged at 550 on drivers right.

the pace makes a huge difference too. Running even two seconds slower at Laguna brakes last quite a bit longer. 4 seconds and they last a lot longer.


my temp stickers were on the front of caliper where it runs hotter being further from cooling ducts.

 

here you can see just how much hotter the outside of caliper gets.

Second picture is the massive pad used with prototype rotors. 😮

 

Laguna is the hardest on brakes out of all of the track in California. There are quite a few long and hard braking zones where the car is doing well in excess of 100mph. I wonder if Alcon or PFC make a caliper that would work. I think Brembo also has calipers that are just purely machined so that the paint wouldn't burn.

 

Do you have the pic of the Tikt brake ducts installed in the car? I wonder how low is the actual intake compared to the bottom of the car. Maybe most of the intake is in the wheel well area and hence can't get sufficient air flow. Also, do you know if the GTR Pro has anything different in the brake cooling department?

 

Here’s a thought: Instead of constantly wearing through expensive iron rotors and pads, and then experimenting with other components trying to increase longevity, pick up the phone and talk to Jeff Ritter at Essex. Ask about whether there is now a potential Radi-CAL solution to the GTR braking issues, or if there’s not ship your GTR to Jeff so Essex can measure to see if an off the shelf solution exists now, as there are multiple kits available.

F & R Radi-CAL kits which include 1” thick pads will run you about $11K upfront, but when it’s time to trade cars, you’ll get 66% of that upfront cost back on the used market.

 

At least based on the F80/82 track forums, the Essex rotors don't last longer than gyrodisc, and the caliper has a known issue that can cause wedged pad wear, which requires frequent pad rotation to maximize pad life.

Edit: The main issue typically is the lack of airflow vs one caliper being better than other.

 

I spoke with them last year. They said they had no plans to offer a kit on this platform ☹️.