Track report

[SYT_Shadow]

Originally Posted by FormulaMMM

So you experience CELs, limp mode, and other trouble after fuel starvation in the CS? Nothing like that in my case.
.

Car gets seriously pissed off. When I remember to run with more than half a tank everything is fine

[FormulaMMM]

Hoping to install today. If braking isn't solved for good then I quit. Kidding, sort of, not really



Also going to attempt a corner balance. Probably best done without the limitation of the blocking rings, but we'll see.

Revisited the technical brochure on this point. Pretty circular. If you remove the blocking rings, then we'll have to reinstall blocking rings.

If the "race track setup" blocking ring is removed, this may result in the vehicle being lowered by an inadmissible amount. The blocking ring is secured by means of a breakaway screw. The "race track setup" blocking ring is adjusted by BMW M GmbH and is provided with a breakaway screw. As a result, the ring can be removed only by difficulty or with force. In order to perform correct adjustment if the blocking ring has been removed, a new "race track setup" blocking ring is required. Adjustment must then be performed on a chassis and suspension measuring stand (alignment rack) in accordance with the procedure for spring - spring strut replacement.

[coryf]

I removed the rear blocking rings to lower the back a bit more. Was looing for better grip on exit. Worked well for my setup.

[Gomeler]

I've been very impressed with the 9668/9449 brakes. I'm running without dust shields and without cooling ducts, and I had no brake issues after a 45 minute session with ambients around 94F-96F with me driving 8/10ths or so the entire time testing various lines. The tires overheat before the brakes. Think you'll be quite happy with them.

[Lienrocs]

Originally Posted by Gomeler

I've been very impressed with the 9668/9449 brakes. I'm running without dust shields and without cooling ducts, and I had no brake issues after a 45 minute session with ambients around 94F-96F with me driving 8/10ths or so the entire time testing various lines. The tires overheat before the brakes. Think you'll be quite happy with them.

Same here. Last time out, and first time on the 9668/9449 set up with DS 1.11's in front and DS Uno's in the back with 107 degree ambient temps I only got slight slight fade. A fluid change, from oem to srf, and the brakes will literally never overheat. They're fantastic. You'll have no regrets, OP.

As for the block rings, I removed them and dropped the car as low as possible in the rear. Running a 295/35/18 A052 on an 11.5 inch wheel with 2.1 degrees of camber in the rear and I had no rubbing issues but corner exit was night and day better compared to the stock track height. It was a different car.

[Gomeler]

Originally Posted by Lienrocs

Same here. Last time out, and first time on the 9668/9449 set up with DS 1.11's in front and DS Uno's in the back with 107 degree ambient temps I only got slight slight fade. A fluid change, from oem to srf, and the brakes will literally never overheat. They're fantastic. You'll have no regrets, OP.

As for the block rings, I removed them and dropped the car as low as possible in the rear. Running a 295/35/18 A052 on an 11.5 inch wheel with 2.1 degrees of camber in the rear and I had no rubbing issues but corner exit was night and day better compared to the stock track height. It was a different car.

Guess it is time to adjust the ride height, enough people have commented on lowering the rear really helping. I presume you guys are running track height in the front, and below track height in the rear with the lockout collar removed?

[Lienrocs]

Originally Posted by Gomeler

Guess it is time to adjust the ride height, enough people have commented on lowering the rear really helping. I presume you guys are running track height in the front, and below track height in the rear with the lockout collar removed?

I was running a 10mm reverse rake. So I was max low out back and 10mm higher in the front (265/35/18 front and 295/35/18 rear tires). My logic was a little more weight over the rear while static would yield positive dynamic weights. On corner exit I want to get as much weight over the rear axle as possible without sacrificing front end grip. Likewise, in corner entry I didn't want the front to be overloaded so the car wouldn't be pushy. It seemed to work really well. The car was neutral from entry to exit, put power down really well and had a really positive front end.

I've since replaced the springs/dampers entirely and am changing the wheel tire set up as well but the car set up will be similar in philosophy because it worked really well for me.

*take all this with a grain of salt. I'm just out there to have fun and get the car home in one piece at the end of the day so your results may vary.

[coryf]

Originally Posted by Gomeler

Guess it is time to adjust the ride height, enough people have commented on lowering the rear really helping. I presume you guys are running track height in the front, and below track height in the rear with the lockout collar removed?

Yes, track height for the front and a few turns up from max low in the rear with the collar removed worked well for me. It helped a lot on putting the power down on exit. I didn't want to go lower on the front because it is still driven on the street so wanted a little front clearance. I would like to find the M4 GT4 ride height numbers to compare to. Would be curious what the factory rake is.

[FormulaMMM]

AP Racing kit installed, impressed with the quality, components, fitment. Hope to bed pads later today. Quite the difference in engineering approach.



I didn't get the pad tensioners. System is remarkably musical without them, can't say I wasn't warned.

Interesting feedback on this point from the auto engineer who was assisting with the install. Indicated that sustained pad pressure on the disc is something they've actually focused on and try to mitigate for the purposes of improved fuel econ, but it's a balance since they can't have pads clanging like the AP kit. For the lowest rolling resistance, perhaps improved cooling, some pad movement off the disc is superior. Wheels spin with virtually no resistance now. It's crossed my mind before when I've manually spun the front wheels with the car elevated. Requires some effort due to pad contact pressure. If a couple pounds of wheel weight "matters," not sure why that friction resistance wouldn't.

Small in the scheme of things, of course. But something to consider if you're installing the AP kit.

On a related note, recognized how truly claustrophobic the oversized OE carbon ceramic front brake setup was after installing the 9668. Dust shield tight to the disc, minimal caliper clearance to barrel, huge pads. There was no room for breathing in there...

Corner balancing: Weight came in at 3,514 lbs. with weight cutting measures detailed on the previous page. No driver, about 7/8 tank of fuel, full water tank. Looks like those fuel pumps are going to have to run hot since I insist on achieving <3,500 lbs. on track

Starting cross was 45.9%.

With me in, (confusingly...) adjusting front right ride height up between 1/4" and 1/2" from the blocking ring, and with a minor adjustment back left, cross weight improved to 47.9%. Corner balancing is black art stuff.

That's where we left it. Didn't have a new shock absorber screw for the rear, so left all of the blocking rings in place for now as well.

Don't doubt that lowering the back produces the best results. When I first installed Clubsports on the E90, shop dialed in Fall Line alignment specs. Rear was slammed. Did one track day in that setting before we had to adjust back up for a blend of street/track use. Just wasn't livable, but was incredible on track, remember the rear being very hooked up.

+1 on GT4 ride height specs. Would be great info to have for reference.

[Lienrocs]

Originally Posted by coryf

Yes, track height for the front and a few turns up from max low in the rear with the collar removed worked well for me. It helped a lot on putting the power down on exit. I didn't want to go lower on the front because it is still driven on the street so wanted a little front clearance. I would like to find the M4 GT4 ride height numbers to compare to. Would be curious what the factory rake is.

I would imagine the GT4 Racecar has some positive rake to maximize the front aero efficiency and it's running a 305 slick up front so I can imagine there would be a problem overloading the front end. But I'd like to see the factory ballpark spec as well.

[Lienrocs]

Originally Posted by FormulaMMM

AP Racing kit installed, impressed with the quality, components, fitment. Hope to bed pads later today. Quite the difference in engineering approach.



I didn't get the pad tensioners. System is remarkably musical without them, can't say I wasn't warned.

Interesting feedback on this point from the auto engineer who was assisting with the install. Indicated that sustained pad pressure on the disc is something they've actually focused on and try to mitigate for the purposes of improved fuel econ, but it's a balance since they can't have pads clanging like the AP kit. For the lowest rolling resistance, perhaps improved cooling, some pad movement off the disc is superior. Wheels spin with virtually no resistance now. It's crossed my mind before when I've manually spun the front wheels with the car elevated. Requires some effort due to pad contact pressure. If a couple pounds of wheel weight "matters," not sure why that friction resistance wouldn't.

Small in the scheme of things, of course. But something to consider if you're installing the AP kit.

On a related note, recognized how truly claustrophobic the oversized OE carbon ceramic front brake setup was after installing the 9668. Dust shield tight to the disc, minimal caliper clearance to barrel, huge pads. There was no room for breathing in there...

Corner balancing: Weight came in at 3,514 lbs. with weight cutting measures detailed on the previous page. No driver, about 7/8 tank of fuel, full water tank. Looks like those fuel pumps are going to have to run hot since I insist on achieving <3,500 lbs. on track

Starting cross was 45.9%.

With me in, (confusingly...) adjusting front right ride height up between 1/4" and 1/2" from the blocking ring, and with a minor adjustment back left, cross weight improved to 47.9%. Corner balancing is black art stuff.

That's where we left it. Didn't have a new shock absorber screw for the rear, so left all of the blocking rings in place for now as well.

Don't doubt that lowering the back produces the best results. When I first installed Clubsports on the E90, shop dialed in Fall Line alignment specs. Rear was slammed. Did one track day in that setting before we had to adjust back up for a blend of street/track use. Just wasn't livable, but was incredible on track, remember the rear being very hooked up.

+1 on GT4 ride height specs. Would be great info to have for reference.

My ap's hum constantly because the pad is always in contact with the disc. I always have the windows down and sometimes I forget what causes the noise and have a mild panic attack when I drive by a concrete divider that bounces the sound back. I think that's an effect of the anti knock back springs. As far as not running the anti rattle clips I salute you. I don't mind nvh but I went about thirty feet before I had to circle back and order them. There was no way I could deal with that chatter.

You're gonna love the brakes. They're so good on track. Way better feel than the ceramics and they look cooler when you pull up to your local cars and coffee. I would swap the fluid for something better though if you do a full re bleed to make sure there's no air in the system after the swap. The factory fluid can only do so much as good as it is. They make it look like you mean business. 👍

[FormulaMMM]

Originally Posted by Lienrocs

My ap's hum constantly because the pad is always in contact with the disc. I always have the windows down and sometimes I forget what causes the noise and have a mild panic attack when I drive by a concrete divider that bounces the sound back. I think that's an effect of the anti knock back springs. As far as not running the anti rattle clips I salute you. I don't mind nvh but I went about thirty feet before I had to circle back and order them. There was no way I could deal with that chatter.

You're gonna love the brakes. They're so good on track. Way better feel than the ceramics and they look cooler when you pull up to your local cars and coffee. I would swap the fluid for something better though if you do a full re bleed to make sure there's no air in the system after the swap. The factory fluid can only do so much as good as it is. They make it look like you mean business. ��

The rattling is considerably worse than I expected and constant. Think I've succeeded in making the GTS the most anti-social car I own. if it saw any more street miles than the seldom back road for testing, would install those tensioners asap.

Positive impressions after an initial bedding session. Always a bit unsettling immediately after install when it feels like no one is home. Got some heat into the system, pads became very vocal and started biting like hell. Substantial braking force. I'll need the 3R's to be fully up to temp to exploit. First impression is that there's > modulation capability than the carbon ceramic. Look forward to getting them on track.

Power bleed, then 2 rounds of manual bleeding. Went through 2+ bottles of this, so all stock fluid should be long gone https://apracing.com/race-car/brake-...e-fluid-cp6005

[Gomeler]

My pads clatter a bit, but the biggest issue is the unholy screech if I forget which car I'm in and lightly hold the brake to stop at a light. I'm not bothering to swap pads around since the car is almost exclusively used in canyons and at the track, but I feel like a real asshole sometimes entering/exiting my garage.

I have had much better luck trail braking with the steel brakes over the CCBs, but part of that could be getting more accustomed to the platform.

[fanatic1]

Originally Posted by FormulaMMM

Hoping to install today. If braking isn't solved for good then I quit. Kidding, sort of, not really



Also going to attempt a corner balance. Probably best done without the limitation of the blocking rings, but we'll see.

Revisited the technical brochure on this point. Pretty circular. If you remove the blocking rings, then we'll have to reinstall blocking rings.

If the "race track setup" blocking ring is removed, this may result in the vehicle being lowered by an inadmissible amount. The blocking ring is secured by means of a breakaway screw. The "race track setup" blocking ring is adjusted by BMW M GmbH and is provided with a breakaway screw. As a result, the ring can be removed only by difficulty or with force. In order to perform correct adjustment if the blocking ring has been removed, a new "race track setup" blocking ring is required. Adjustment must then be performed on a chassis and suspension measuring stand (alignment rack) in accordance with the procedure for spring - spring strut replacement.

You’re gonna love these!!

just replaced the friction Disc - and on my third set of 25mm DS3.12 - first set of brakes that holds up to Repeated lapping at Laguna Seca

[FormulaMMM]

Originally Posted by fanatic1

You’re gonna love these!!

just replaced the friction Disc - and on my third set of 25mm DS3.12 - first set of brakes that holds up to Repeated lapping at Laguna Seca

have a pic of that disc by chance? I'd like to see worn state.

[FormulaMMM]

Originally Posted by Gomeler

My pads clatter a bit, but the biggest issue is the unholy screech if I forget which car I'm in and lightly hold the brake to stop at a light. I'm not bothering to swap pads around since the car is almost exclusively used in canyons and at the track, but I feel like a real asshole sometimes entering/exiting my garage.

I have had much better luck trail braking with the steel brakes over the CCBs, but part of that could be getting more accustomed to the platform.

Is that mild clatter with or without the tensioners?

DS3.12 legit killed my ears during bedding process. Loudest pad I've ever had. Chuck dust too, and 666M look better with a layer. Good to be back with proper race pad characteristics.

[SYT_Shadow]

The APs rattle even with the tensioners, it is very annoying.

I wish I had built brackets for my PFC Z45 rear kit from the E9X for the F8X. Rotors last a lot longer than the AP rear kit.

If any of you are missing the rear RadiCal setup I will be selling mine soon

[fanatic1]

Originally Posted by FormulaMMM

have a pic of that disc by chance? I'd like to see worn state.

You can see in this image, one side is more crack damaged and the other side a little more wear into the J hook. Still have the old friction rings at home, will try and shoot some better pictures tonight.

[Gomeler]

Originally Posted by FormulaMMM

Is that mild clatter with or without the tensioners?

DS3.12 legit killed my ears during bedding process. Loudest pad I've ever had. Chuck dust too, and 666M look better with a layer. Good to be back with proper race pad characteristics.

No tensioners, clatters a good bit. Don't notice it on the track with my helmet on, so not a big deal.

[Lienrocs]

Originally Posted by FormulaMMM

Is that mild clatter with or without the tensioners?

DS3.12 legit killed my ears during bedding process. Loudest pad I've ever had. Chuck dust too, and 666M look better with a layer. Good to be back with proper race pad characteristics.

How did you like the 3.12's?

[FormulaMMM]

Originally Posted by Lienrocs

How did you like the 3.12's?

Felt mega once bedded. Crazy loud. Hoping to get on track next week.

[FormulaMMM]

Another track day, first time out with the AP Racing brakes and seat fully sorted. Quite a machine. Wild, alive, always entertaining. Love it.

AP Racing + DS3.12 feedback –

Better than the stock carbon ceramics across the board. Just slightly more variability in pedal feel here and there, but that’s about it, and never a lack of stopping power. Get what you pay for applies. Obviously a world class racing system. There was a GT4 (I think) Mustang next to me in the pits with the same.

Notably, front wheel barrel temperatures post-session with AP Racing must be minus 75 degrees or more as compared to stock. Used to just about lose skin adjusting tire pressures with the carbon ceramics sometimes. The heat reflective tape I use to keep the wheel weights down actually lost adhesive and peeled back, never seen that before. The AP Racing is obviously a much better sized/packaged and cooled system. Dust shield removal probably helps. BMW packaged the brakes way too tight for track use. Looking back, should have removed those dust shields while running the ceramics. Couldn’t have hurt.

Roll cage camera view this time. Horrible audio, sorry, but gives an impression of how what a handful she is. Pretty ragged lap, really… never a dull moment piloting the GTS.

Front end is planted, turn in is immense, going to back off a couple clicks rear rebound next time around (that would be 1 softer than BMW recommended track spec), see if I can get the rear end to settle down a bit in combination with trying lower pressures.

On psi – speculate the on board readout might not be quite real time. I keep checking it trying to immediately correlate feel to pressures/temps, but impression is there’s a lag there. On this run, for example, believe the rears were higher pressure & hotter than indicated. Not sure why that would be, just my impression.

3R’s are holding up very well despite the abuse. Again, the type of dry condition bias & durable r comp spec that M should have fitted to the GTS.

Small improvement over last time in best lap and best rolling. Full track running only for the morning sessions before an engine fire on 10b forced a rerouting onto old 10a for the remainder of the day. Had one of my most entertaining lead-follow sessions in a long while with a ZL1 1LE during the reconfiguration, so that was cool consolation.

An example of track conditions influencing lap time potential – down ~4 mph on the back straight this time out as compared to last. Slightly hotter conditions and a headwind. Was 0.8 up on previous best exiting 10b on this run, then lost all but 0.1-0.2 of that on the back then front straights.