Track forum general chit chat

[SYT_Shadow]

Originally Posted by NYG

I've been thinking about an E46 a whole lot lately

Don't do it. Just don't.

[NYG]

Originally Posted by SYT_Shadow

Don't do it. Just don't.

They're so pretty though.

[nicknaz]

Originally Posted by NYG

I've been thinking about an E46 a whole lot lately

Spec E46 for w2w?

[F80Speed77]

Originally Posted by Montaver

Close to picking up an F80 - question for F8x folks on rev-matching. Does full DSC off in every mode switch it off? Every thread I read seems to have conflicting info, some say its off in Sport+ only. Certainly on my E90 i'm not a fan of the sport plus throttle as its way too twitchy / binary.

I tried a few autocross runs the throttle button in SPORT (everything else SPORT+) and something just felt off like the differential wasn't working as aggressively or something? It felt wayyy more understeery on entry and the back end felt a little disconnected or something. I do think the throttle is just a tad too aggressive in SPORT+, especially for autox, but it is pretty manageable on the track. It would be nice if you could tone down the throttle a little but leave everything else with coding.

[nicknaz]

Originally Posted by F80Speed77

I tried a few autocross runs the throttle button in SPORT (everything else SPORT+) and something just felt off like the differential wasn't working as aggressively or something? It felt wayyy more understeery on entry and the back end felt a little disconnected or something. I do think the throttle is just a tad too aggressive in SPORT+, especially for autox, but it is pretty manageable on the track. It would be nice if you could tone down the throttle a little but leave everything else with coding.

I went to some autoX in my "civic" 2015 F80 with the express purpose of sliding the car around and didn't notice that. I used DSC OFF, Sport or Sport+ throttle and didn't really notice a big difference.

Maybe you have a newer F80 with different coding?

[CanAutM3]

Originally Posted by Montaver

Close to picking up an F80 - question for F8x folks on rev-matching. Does full DSC off in every mode switch it off? Every thread I read seems to have conflicting info, some say its off in Sport+ only. Certainly on my E90 i'm not a fan of the sport plus throttle as its way too twitchy / binary.

It depends on production date.

Earlier cars have rev-match disabled with the Sport+ Engine Response setting.

Later cars have rev-match disabled with DSC off.

[F80Speed77]

Originally Posted by nicknaz

I went to some autoX in my "civic" 2015 F80 with the express purpose of sliding the car around and didn't notice that. I used DSC OFF, Sport or Sport+ throttle and didn't really notice a big difference.

Maybe you have a newer F80 with different coding?

It's a 2015 with DCT, I know it has an Alpine DCT tune but not sure if that would make a difference. Had DSC off too, I think, maybe it turned back on somehow when switching between the two. Went back to my M2 button after like 2 turns lol.

[MyFragileHalogen]

I love this thread! Didn't have time to really read all (even though I randomly dropped a post somewhere up there) but I will catch up later!

Just one thought about brakes- A E92 friend (who's one of fastest local drivers) had a big issues with front brake overheating and he said it was fixed with the MCS. I heard (although it was more serious problem on E92 due to softer stock suspension), a good suspension in general can not only make a car corner and exit faster but also brake with less work on braking system perhaps by keeping wheels pushed onto the road better. So I am curious to try MCS next year (still thinking) along with racingbrake 2 piece rotor conversion. I'd rather drop probably $5000 (part + install + tech support) on MCS than dropping $500 on a flash (CS) tune I can't trust... to improve my lap time lol.

Also it seem to make sense a car with a tune or a CS would be generating a lot more heat on to the brakes. That aforementioned friend has a E46 race car that had a V8 swap and they calculated that going from 137 vmax to 147 put about 2x more energy onto the braking system.

[MyFragileHalogen]

Originally Posted by gman444

That's my mistake. I left the car in MDM when I gave it to him . He wasn't familiar with the car or any of the modes. Although I generally like to drive the car in MDM. Not sure how big of difference this makes but I have the GTS MDM coded in.

You're right, I think I just need to take it slow and just practice driving the car with all the nannies off. It'll be nice to see what the car does when its at its "limit". I drove my last event in MDM and I absolutely loved how controllable the car was. The car would kick out a little bit once in a while but it was really easy to reel it back in and it never felt scary (again, not sure how much of this was MDM saving my butt lol)

DSC OFF is where all the fun begins! A completely different car! But please do it at your risk and don't sue us. To me it was helpful to follow some of these people's advice including CanAutM3's when I started out.

1) When track's or tires are cold, start with MDM (like first session). But hey I've seen so many Porsche drivers crashing their cars in first sessions with their advanced TC systems LOL.
2) When track is wet stay on MDM unless you are confident.
3) Like MaynardZed says deliberately plan where you can play and at all cost stay away from the walls!

Sorry the incident costed you the lip but could be a good lesson for nothing more expensive!

[MyFragileHalogen]

Originally Posted by nicknaz

Hi, I got coaching from NASA HPDE also, and they seem to teach that you should hammer down in a straight line, and get on throttle early (that's the bad habit I picked up from HPDE my F80, anyway).

I saw in your vid that you had a low % of throttle before apex in almost all corners, so I think you are doing this same thing also.

I think that is taught to minimize risk from new people

I've since gotten feedback that the proper approach is to max out entry speed by having a short heavy straight line brake, followed by a trailing brake and then pick up the throttle after apex. The idea being to roll as much speed through the corner.

Check out https://nasaspeed.news/columns/drive...he-right-time/ where this is articulated more effectively.

I'm working on this too!

How I understand is that trail braking is to 1) rotate the car at fastest rate to point the car aligned toward exit cone as soon as possible and 2) to start braking as late as possible. Still I have to watch at what speed I am passing at both turn in cone and close to apex cone so that I am going as fast as my target speed. As soon as braking is done I should have my foot on throttle to hold and not lose the speed through mid corner; and throttle is my survival string for controlling oversteer; also throttle steer for corrections. And as soon as I see apex cone and exit cone aligns I am supposed to increase to full throttle ASAP. With help of rotation and good line, I am supposed be on full throttle before apex on pretty much all corners. If I was driving AWD, it will be even sooner. In Miata...way way sooner I can get on throttle- but at the same time Miata's line should be vastly different than M4's line (like earlier apex or close to kart line without even needing to hit the apex cone) which I have not explored yet. But yeah, just another lowerly track dude's opinion.

BTW, good luck on your SM racing and hope you avoid all those cowboys!

[SYT_Shadow]

Originally Posted by MyFragileHalogen

I love this thread! Didn't have time to really read all (even though I randomly dropped a post somewhere up there) but I will catch up later!

Just one thought about brakes- A E92 friend (who's one of fastest local drivers) had a big issues with front brake overheating and he said it was fixed with the MCS. I heard (although it was more serious problem on E92 due to softer stock suspension), a good suspension in general can not only make a car corner and exit faster but also brake with less work on braking system perhaps by keeping wheels pushed onto the road better. So I am curious to try MCS next year (still thinking) along with racingbrake 2 piece rotor conversion. I'd rather drop probably $5000 (part + install + tech support) on MCS than dropping $500 on a flash (CS) tune I can't trust... to improve my lap time lol.

Also it seem to make sense a car with a tune or a CS would be generating a lot more heat on to the brakes. That aforementioned friend has a E46 race car that had a V8 swap and they calculated that going from 137 vmax to 147 put about 2x more energy onto the braking system.

MCS is really great. Once my 2WNR on the CS is well sorted it will be even more fun. It'll be my third set!

The theory behind the braking thing and suspension is just that a proper track setup (800 front 1100 rear) dives way less than stock. Dive transfers too much weight to the front of the car and makes the rear tires have little capacity for braking

I still think the CS is too damn fast to survive serious use without at least a front bbk

[MyFragileHalogen]

Originally Posted by SYT_Shadow

MCS is really great. Once my 2WNR on the CS is well sorted it will be even more fun. It'll be my third set!

The theory behind the braking thing and suspension is just that a proper track setup (800 front 1100 rear) dives way less than stock. Dive transfers too much weight to the front of the car and makes the rear tires have little capacity for braking

I still think the CS is too damn fast to survive serious use without at least a front bbk

Hm...so stiffer springs are what help that? It was a shop guy at the track who told me that MCS helps brakes to work less while not telling me why! Perhaps he wanted to just sell me that thing. I am now a believer of that system though. Totally believe 3 sec improvement after seeing so many people jumping onto it.

I feel my base M4 without power mod is already fast when these track tires hook up, and vmax was only 2-3 mph less than a '18 GT3! I'd guess CS would be another level.

BTW, on the spec sheet M4CS has max torque of 442 ft-lbs, and the new X3M with S58 still has same 442ft-lbs max torque??

[SYT_Shadow]

Originally Posted by MyFragileHalogen

Hm...so stiffer springs are what help that? It was a shop guy at the track who told me that MCS helps brakes to work less while not telling me why! Perhaps he wanted to just sell me that thing. I am now a believer of that system though. Totally believe 3 sec improvement after seeing so many people jumping onto it.

I feel my base M4 without power mod is already fast when these track tires hook up, and vmax was only 2-3 mph less than a '18 GT3! I'd guess CS would be another level.

BTW, on the spec sheet M4CS has max torque of 442 ft-lbs, and the new X3M with S58 still has same 442ft-lbs max torque??

Stiffer springs --> less dive, so less work for the front brake. Also, having a track suspension means you can go through turns faster so less braking... although in the end i don't think this is a net advantage as your average speeds creep up

With the same tires I've seen 2 second improvement. Then you can use stickier rubber and gain another 2.
On the stock CS suspension you don't gain anything from running a R1/R7 vs a RE71 style tire because the suspension cannot handle them

The M4 is really, really fast. It's deceptive because it's a huge car and people think it's a grocery getter, but on track... you'd better hold on! Lol

About torque: i'm glad the s58 won't have any more. I prefer lower torque in general as it aids with traction.

[nicknaz]

Originally Posted by MyFragileHalogen

How I understand is that trail braking is to 1) rotate the car at fastest rate to point the car aligned toward exit cone as soon as possible and 2) to start braking as late as possible. Still I have to watch at what speed I am passing at both turn in cone and close to apex cone so that I am going as fast as my target speed. As soon as braking is done I should have my foot on throttle to hold and not lose the speed through mid corner; and throttle is my survival string for controlling oversteer; also throttle steer for corrections. And as soon as I see apex cone and exit cone aligns I am supposed to increase to full throttle ASAP. With help of rotation and good line, I am supposed be on full throttle before apex on pretty much all corners. If I was driving AWD, it will be even sooner. In Miata...way way sooner I can get on throttle- but at the same time Miata's line should be vastly different than M4's line (like earlier apex or close to kart line without even needing to hit the apex cone) which I have not explored yet. But yeah, just another lowerly track dude's opinion.

BTW, good luck on your SM racing and hope you avoid all those cowboys!

Thanks for the good wishes. It’s fun and I wish I got into it sooner. But even cheap w2w adds up. Lol.

I do think you should re read that article I posted ( the whole point of which is that you shouldn’t be on throttle that early)

I don’t know about some of the Miata advice your giving man.... I’d still want to hit the apex markers, and should be carrying so much more entry speed that you need to wait until apex go back to throttle (this is specifically what I’m working on. My “feel” of a good entry speed is from 3500lb street tires car still, and it’s now got to be 2200lb competition tires car) , and wouldn’t early apex

It’s really not that different tracking SM and F8x, in my opinion. It’s just that the momentum spec car exposes any technique gaps in a pretty brutally honest fashion. (Eg you come in last)

Well, I guess a key difference is my maintenance and tire bills per hour of seat time are a lot lower, and if there’s an off or mechanical it’s a lot cheaper (eg $500 Gearbox and $2k used engine with 20k miles)

[CanAutM3]

Originally Posted by SYT_Shadow

Stiffer springs --> less dive, so less work for the front brake.

I am not sure I agree with you on this one.

The amount of weight transfer that results from the Cg moving about the pitch center is negligible relative to the weight transfer that occurs due to the braking forces. That latter weight transfer is dependent on wheelbase and Cg height and longitudinal position. So lowering the car will have a noticeable effect, but stiffening the springs will have a negligible effect, on the braking proportion the front tires need to make relative to the rear.

[NYG]

Originally Posted by CanAutM3

I I am not sure I agree with you on this one.

The amount of weight transfer that results from the Cg moving about the pitch center is negligible relative to the weight transfer that occurs due to the braking forces. That latter weight transfer is dependent on wheelbase and Cg height. So lowering the car will have a noticeable effect, but stiffening the springs will have a negligible effect, on the braking proportion the front tires need to make relative to the rear.

With more nose dive, you're adding momentum in the gravity + caster vector so the brakes would have to counter more energy on top of just your initial momentum.

[nicknaz]

Originally Posted by NYG

With more nose dive, you're adding momentum in the gravity + caster vector so the brakes would have to counter more energy on top of just your initial momentum.

If someone has aim data from before and after suspension swap, we could look at the brake pressure over time and speed change under braking in a few key corners to see if there’s any differences.

In your hypothesis, I would expect to see the total braking force reduced, and in CanAut’s hypothesis there would be similar braking events pre and post swap.

[NYG]

Originally Posted by nicknaz

If someone has aim data from before and after suspension swap, we could look at the brake pressure over time and speed change under braking in a few key corners to see if there’s any differences.

In your hypothesis, I would expect to see the total braking force reduced, and in CanAut’s hypothesis there would be similar braking events pre and post swap.

It wouldn't be too accurate. Too many variables including human error.

The most accurate way, though not feasible at all, is to measure heat before and after a corner on identical corner entry speeds. Then scale by ambient temps but then you run into the issue of initial temperature of the rotors/pads and relative coefficient of friction of the pad with increased temps.

[CanAutM3]

Originally Posted by NYG

With more nose dive, you're adding momentum in the gravity + caster vector so the brakes would have to counter more energy on top of just your initial momentum.

Say what ?

[CanAutM3]

Originally Posted by nicknaz

If someone has aim data from before and after suspension swap, we could look at the brake pressure over time and speed change under braking in a few key corners to see if there’s any differences.

In your hypothesis, I would expect to see the total braking force reduced, and in CanAut’s hypothesis there would be similar braking events pre and post swap.

I think it would be difficult to find an appropriate A-B test where only the spring rates are altered since most suspension modifications also involve a change in ride height.

[nicknaz]

Originally Posted by CanAutM3

I think it would be difficult to find an appropriate A-B test where only the spring rates are altered since most suspension modifications also involve a change in ride height.

I’ve seen members post about switching out from 1 set of full coilovers to another, and presumably they would keep right height similar after corner balancing, and keep the alignment the same as a first pass.

And didn’t you have a base m4 and now CS? Is there a spring rate difference but not ride height difference there?

Edit; nyg, I have some spare channels in the logger of my SM. If you send over some infrared sensors and a baller jrz coilovers setup, I’ll keep the ride height the same between the “spec” competition suspension and the jrz and we can test and tune and get to the bottom of this

[CanAutM3]

Originally Posted by nicknaz

I’ve seen members post about switching out from 1 set of full coilovers to another, and presumably they would keep right height similar after corner balancing, and keep the alignment the same as a first pass.

We would need to get data logs from those specific members for those specific runs while ensuring no other changes were made. Not impossible, just quite difficult.

Originally Posted by nicknaz

And didn’t you have a base m4 and now CS? Is there a spring rate difference but not ride height difference there?

Both cars were not running the stock springs. My 2015 M4 was on Eibach while my CS is on the MP-HAS. Different ride height and spring rates from stock and between both cars. Also, the CS ABS has been extensively recalibrated over the GTS to better leverage the extra grip provided by the R-comp tires, so not an apples-to-apples comparison.

Further, to be able to leverage the weight transfer benefit from any suspension adjustments, one would also need to change the front-to-rear brake bias through either pad compound or mechanical/electronic means.

Fine tuning a chassis is a complex science, easier to screw up than to improve upon.