[medphysdave]

I've been following the insta posts from Super Lap Battle. Inertia Lab OG Shark A lot of references to focusing on chassis setup. It's clear that the different shops have their own special sauce.

Where is the focus. Being placed for "chassis setup"?

Where should we be spending our money if we don't have the time for more seat time, but like throwing our money at improving our M2 variants to decrease lap times. Assuming the driver skill is a constant at their current level.

Kinematics , suspension, aero, corner balancing, alignment.

Kinematics seems to be a blanket term for chassis geometry. What parts make the biggest difference without thinking about cost? What parts seem to be the most improvement for dollar spent?

What parts tend to fail? What parts should be a concern for reliability?

Is there a realistic option for aero that can be reasonably added for track days and removed for street duty?

[ThreeStripes]

Originally Posted by medphysdave

Where should we be spending our money if we don't have the time for more seat time, but like throwing our money at improving our M2 variants to decrease lap times. Assuming the driver skill is a constant at their current level.

Sounds like you’re asking for a cheat code, and that’s what’s fun about this activity, there really isn’t one. This is what enables a skilled driver to pass a less skilled driver in a more capable car. The cheat code for lap time out of a novice driver if you had to point to one is horespower and tires, not some shops secret roll center correction or damper valving.

With any of the stuff you mentioned, it requires track time to develop as a package on a car which is what is so fun. There isn’t one recipe. You’ve got to figure out what works for you, which is why all roads for dropping lap times run through seat time. Even as it relates to grip, ask for the best tire and you’ll get several answers. “Tires are like condoms, everyone’s got their favorite brand.” is a paddock joke for a reason.

You can’t write just write a check for a new PB. You’ve got to go earn it.

[medphysdave]

Originally Posted by ThreeStripes

Sounds like you’re asking for a cheat code, and that’s what’s fun about this activity, there really isn’t one. This is what enables a skilled driver to pass a less skilled driver in a more capable car. The cheat code for lap time out of a novice driver if you had to point to one is horespower and tires, not some shops secret roll center correction or damper valving.

With any of the stuff you mentioned, it requires track time to develop as a package on a car which is what is so fun. There isn’t one recipe. You’ve got to figure out what works for you, which is why all roads for dropping lap times run through seat time. Even as it relates to grip, ask for the best tire and you’ll get several answers. “Tires are like condoms, everyone’s got their favorite brand.” is a paddock joke for a reason.

You can’t write just write a check for a new PB. You’ve got to go earn it.

I agree with what you're saying to a point. Which is why I suggested that driver skill is fixed. In theory, you can make two of the same platform that are identical. I'm suggesting that their are performance enhancements that can be done to this chassis that will improve handling, grip, etc. Outside of changing tires. I also agree with you that tuning is also relative to how a driver likes to drive. Let's step it back just a little and look at what improvements to the stock chassis yield the biggest improvement outside of tires.

Different shops are selling different kits, but what are they trying to fix? Or is it fixing nothing, but allowing more adjustment to dial in alignment, camber, etc?

Maybe it as wasted exercise as a car that is set up optimally for a professional driver might not feel particularly comfortable for a novice.

This exercise also assumes the purchase of quality parts setup with the aid of knowledgeble people. Even the best bolt ones can yield lesser performance if set up incorrectly.

Anyhow, what's considered under the unbrella of chassis tuning and how much of it is accessible to your average track day enthusiast? Or how much of it would actually add benefit to a novice?

[ThreeStripes]

Others will weigh in and OG Shark speaks to this better than I can but the ideal path is to not make the car faster until you’re faster than the car. Because, not if but when you make a mistake, you’re only going to be going that much faster. I know that’s not what you’re asking about, but it’s the correct answer regardless.

A stock OG M2 is well beyond a novice, let alone your CS. You have an amazing car. Just go enjoy it.

Ultimately the path is yours alone to choose and if you do want to mod the car and make it faster despite the generally accepted wisdom above, that’s fine too. If that’s the case, check out the video below. Alex Bernstein speaks at length about what it takes to successfully setup a fast BMW for track work and does a great job sharing his knowledge and experience. While he is discussing his E92 M3 the concepts he speaks to certainly apply to the F87.

[rbahr]

Suspensions are a collection of point solutions that are really compromises. They all address specific problems, and unless you have F1 like money to play with, are generally compromises, and it is difficult to find a set that work harmoniously.

Seat time allows you, the driver, to learn the set of compromises that your car displays and make the best of it.

The 'problem' with all of the secret sauces out there is that they work for someone's style, and may not work with your style.

Now throwing money at the problem will help somewhat, but what you are doing are fixing the car's problems not the driver's problems.

Spend time and learn about suspensions, then experiment a bit with your car. Also playing with good sim systems will help as they sometimes have good physics models. If you are new to this game, say less than 2 seasons on the track - call it 10 days, you should be running the car stock, with street tires.

My experience is that this is a very expensive slippery slope, having built far to many track cars now.

I had ~ $200K in receipts for my GT3 excluding the cost of the car, and it still wasn't good-enough, AND it was no longer streetable.

It just occurred to me that spend money on a good data collection system - AIM or even Motec and learn how to use it.

Ray

[medphysdave]

All good advice. The video above was spot on. He pointed out the areas that yielded the most improvement.

My goals are going to be different than others, but knowing that throwing some money at good dampers and chassis adjustability is likely money well spent.

I also noted the discussion point about 275 vs 295 on a 10.5" wheel. I run 295s. I don't think I'd try to stick an 11" wheel up front, but I might try a 275 tire if I don't get the wear results I'm looking for

[ThreeStripes]

Originally Posted by medphysdave

All good advice. The video above was spot on. He pointed out the areas that yielded the most improvement.

Thought that one was right up your alley. Good luck with everything.

[OG Shark]

medphysdave the answers to your questions are yes, no, and maybe...

rbahr put it perfectly when he said suspensions are a collection of solutions that are really compromises. Essentially what we are doing is trying to find the least worst set of compromises for any given situation. When you are talking about a dual usage car there are a whole lot of situations you have to try to account for. Even singular focus builds (street vs track dedicated) are a series of finding the best compromises to complete the task as best as possible.

On the F87 I believe the best money spent is in dampers (which is why I started down that path with Nitron). Using the dual usage setup as an example - we worked the dampers to deliver what we found was the best mix of street manners and performance for us. For us is key as we are all a bit different in our preferences but I do think it translates to others in this case. But while the improvement in the dampers fixes some of the issues they are still a compromise in other areas. If you lower the car the stock geometry has now been compromised. Now if you address this situation you have now possibly opened up the door for increase NVH. So do you just keep heading down this path until you have a race car or do you at some point call it good and stay put? For each of us that answer is for sure different. My tolerance for a harsh car that is driven quite a bit on the street is very low - I'm past those days of beating myself up regularly. On occasion I'm ok with it for sure - but definitely not an everyday thing I want. So for me this kind of thing is what dictates my development path for a street/track car. From there we branch out but the bulk of our focus started with the dampers. Not sure if this helps at all but this is how I view it and what dictates our development.

But the dampers are just a part of the whole system. If you are changing other components then you need to make sure they are working with them instead of against. You mention aero - effective aero is going to need stiffer spring rates. My Pcar we are getting ready to go with 1250/1400 due to the aero load and that might not even be enough. That's going to be brutal on the street so will be doing this only for track time. With our street/track M2 we are still working our way up to find the spring rates for the Zebulon aero package we just installed. We will likely be in the 1k range and this is the smaller of his two packages that was legal for the street class at SLB. What I'm getting at hear is that once you start moving into other areas the focus becomes not just on that part but the whole system. As you add more they changes must work together and be driven to compliment each other. There is no secret sauce in just for instance focusing on the alignment - the focus is on everything in the system and how they interact with each other. The more narrow the usage of the car then the more narrow you can dial in the peak operating range and develop towards the benefits being realized in that window. The more generalized the usage the less focused you can be in one area and have to keep the car happy throughout that range. So really for you as the end user your job is to know what your goals are and then work to align the modifications with that. How do you know which modifications are best? Unless you have access to all and the ability to test then you are really limited to research and discussion.

When it comes to your personal usage and wanting to shave off as much time on the track as you can - I can build you the most edged out setup that is completely capable of a very high level of performance. Once we have Schnucki dialed in and everything playing nice then this car is going to be very quick. But in it's track configuration it is not a car that appeals to me to drive on the street much at all. It will be way too stiff for my liking. Now the car is still very much a street car and we will soften her up considerably between full bore track outings (i.e. competitions). Being a shop owner however makes this feasible for me while it might not be exactly the most realistic option for most. With our dampers we have several options but the most common by far is the one that plays friendliest in the general usage. While we have shown these to be extremely capable yes we can push further to start to shave time - but is that a direction you would want to take your car? No right or wrong answer there just something you need to factor into a build.

You want to know something that is readily available that can help lap times (besides driver mod)? Tires. Tires are the most powerful tool a track rat has for improvement. They are consumable so you have ample opportunity to either keep status quo or make a change. They have a huge impact in every facet of performance and they have a very wide range of characteristics. When you can master a "low grip" tire you can easily move up and start working on improving your skill set to master this next level. Rinse, repeat. Suspension obviously has its benefits but do not overlook how powerful tires can be.

The part that is most prone to failure in my experience is the driver... I can tell you that as a driver I suck right now. Last year I had I believe 5 total track days. ThreeStripes and Anonymoose got to see about half of that time and can attest to how long it takes me to get up to speed coming off of extended layoffs. A dialed in and consistent car certainly helps the process but nothing can overcome the amount of time it takes me to knock the rust off and get to 9or10/10s with the car. Now it is what it is on my part - my life dictates that right now but for lap times that is where the greatest failure is on my cars. There is just no replacement for seat time. I am also out of shape and overweight. This is big negative on pace - endurance, strength, focus, reflexes are all negatively affected as you get tired. Again this is a failure on the driver not the car. This is the area I can tell you will realize the most benefits in pace - the driver of my cars needs to get on the same level as the performance potential of the cars...

[medphysdave]

Originally Posted by OG Shark

medphysdave the answers to your questions are yes, no, and maybe...

rbahr put it perfectly when he said suspensions are a collection of solutions that are really compromises. Essentially what we are doing is trying to find the least worst set of compromises for any given situation. When you are talking about a dual usage car there are a whole lot of situations you have to try to account for. Even singular focus builds (street vs track dedicated) are a series of finding the best compromises to complete the task as best as possible.

On the F87 I believe the best money spent is in dampers (which is why I started down that path with Nitron). Using the dual usage setup as an example - we worked the dampers to deliver what we found was the best mix of street manners and performance for us. For us is key as we are all a bit different in our preferences but I do think it translates to others in this case. But while the improvement in the dampers fixes some of the issues they are still a compromise in other areas. If you lower the car the stock geometry has now been compromised. Now if you address this situation you have now possibly opened up the door for increase NVH. So do you just keep heading down this path until you have a race car or do you at some point call it good and stay put? For each of us that answer is for sure different. My tolerance for a harsh car that is driven quite a bit on the street is very low - I'm past those days of beating myself up regularly. On occasion I'm ok with it for sure - but [...]

Thanks for taking the time to write that up. I think aero would be a step too far for me with this car. After the suspension upgrades I plan to get on track more. I'll see where that takes . E.

When the time comes to order the e-trons what info should I be prepared to have in hand regarding current state and end goals of modifications?

[M1500Z]

I try not to post unless I have something to add, but I think about this a lot so hopefully these words I wrote aren't just rambling/rephrasing what's been said.

Kinematics
Kinematics is a subfield of physics and mathematics, developed in classical mechanics, that describes the motion of points, bodies (objects), and systems of bodies (groups of objects) without considering the forces that cause them to move. Kinematics, as a field of study, is often referred to as the "geometry of motion"...

Wikipedia

Most of the parts in this area have 2 priorities:

1. Providing adjustability—for static alignment and/or transient characteristics like bump steer, anti-drive, anti-squat, etc.
2. Reducing the flex under load

There are additional items that correct or compensate for compromises made, ex. correcting axle roll centers after a car has been lowered. To start, all your typical DE driver really needs is to prevent shift/flex under load due to soft rubber bushings and getting a proper alignment to improve tire wear.

Setup is a window and the idea is to get the car working to the best of it's mechanical ability for a given set of variables (track layout, surface condition, environment, etc) for a given driver. I emphasize driver because as rbahr and OG Shark mentioned, the driver must have confidence to drive the car at pace. And because tracks evolve over time, that window shifts and can shift very rapidly. Endurance race setups are well strategized and full of compromises for this very reason.

In a way, you can look at setup as a bit of a science and an art. The science portion is adjusting what is available to provide the most grip in a given environment. There are massive tomes that cover this in-depth with pages upon pages of formulae. And since it's a system, you typically can't adjust one thing without affecting something else. The art part is to then take whatever setup and make it work for the driver—this might actually mean compromising the scientific part! For example, providing a stiffer platform—which can reduce overall grip—so the driver can feel more confident and thus perform better, or reducing grip at the rear so the car is more on the nose at corner entry.

A quick note on setup to expand on what was said about tires. Everything revolves around the tires (heh)—they influence what spring rates you should run, which affects your roll rates, which in-turn play with camber and on and on. And of course you need an appropriately matched damper to control that spring—it's all linked together and should be thought of holistically. Usually stickier tires mean you want higher rated springs.

To me, this concept of setup is one that becomes narrower, in a way, the further you get from the competitive side of things because the number compromises increase significantly and constrain what you can (or are willing to) engineer into the car. Think about how much you must compromise if drive your car on the street, even just to and from events. Your alignment can't be optimized because of tire wear or your ride height might need to be higher for clearance. You want to make downforce that's balanced? Good luck driving around with a 6" splitter 2" off the ground. Having a sporty car that's still comfy is nice—but it's hard to hide a high rate spring at low speeds. Race seats and harnesses are probably the absolute best thing to have and while quite comfy limit rear seat access (if you keep the rear at all).

The point I'm getting at (I think) is one of personal goals or philosophy. What do you want out of this—why do you do it? Do you want to drive to the best of your ability or do you want to have the best engineered setup you can and still have fun? Most of us probably lie somewhere in between, and competition is a whole other world of rules and compromises. If the goal is to be the best driver you can be, which may not necessarily mean the fasted person on track, I think the path is pretty clear:

• Get as much seat time as your time/budget allow
• Make sure the car is predictable and reliable
• Use a good data system with video that shows track position and your inputs, and...
• Get a coach—online, right seat, at the track video review, whatever works for you that is a consistent way to get feedback.

Alternatively, if you love the platform and want it to be engineered to the best it can be, there's plenty of established race shops that will take your money and there's nothing wrong with that either. Well, as long as you're not that guy who's bragging about how fast you are when your car is significantly more capable in someone else' hands—don't be that guy. Alternatively, you can take the time to learn and DIY something as is common in the Japanese track world. Personally, I love seeing awesome builds driven by slow people who are just genuinely out there having a blast.

One last note is, if you're like me, and this is the only platform you've tracked, seek out ways to drive or at least ride in as many other cars as you can. One thing that I often struggle with due to a lack of experience is understanding if my car is truly doing something poorly—say understeering at exit because I complain about this a lot—or it's actually not as bad as I think and my expectations are just incorrect. The more breadth of experience you get will better help you communicate what you want to change for a given setup.

[Karmic Man]

OP, I don’t see there is anything that can be adjusted (other than what has been mentioned by the others) that will make a substantial improvement in track time. If there are BMW would have done the work already. They did their homework well with the F87 being such a capable platform out of the box.

I believe you are running 295 RE71RS square and with that amount of grip the stock suspension is not capable of maximising the grip capacity of the tires. Getting a set of quality coilovers with matching spring rates and proper alignment can probably cut down your time by 1-1.5s over a 1min technical track with everything else untouched.

To go even faster without going extreme on the chassis you have to take weights out.

If you can take out, say 100kg from the car you will be faster everywhere on any track. That can be achieved with 2 CS Racing carbon doors, pair of Recaro Pole Position, M performance carbon rear trunk and a titanium exhaust.

It’s $$$ but if all you want is to go faster without turning your car into a full on racing car, this is probably the most reasonable route for a track/street dual purpose vehicle. The rear seats and sound deadening insulations have not been ripped out yet

In terms of aero, the sky is the limit and it is very costly, mostly used on time attack vehicles

[Track/S]

This would be my list for your car:

F&R Kinematics
Drexler diff with dual mount bracket
Lithium battery
Recaro Pole Position
Carbon rear trunk
M2 CS Racing door trim panels


I would leave coilovers for last.

Aero only in case of converting the car 100% for track use.

[OG Shark]

Originally Posted by Track/S

This would be my list for your car:

F&R Kinematics
Drexler diff with dual mount bracket
Lithium battery
Recaro Pole Position
Carbon rear trunk
M2 CS Racing door trim panels


I would leave coilovers for last.

Aero only in case of converting the car 100% for track use.

Dampers are one of the easiest things to switch and address one of bigger (if not the biggest) weaknesses on the platform. Although I like pretty much everything you listed I cannot see where that combination first over good coilovers would make for a better/quicker/more comfortable car. And even minor aero makes a bit of difference on this car. M235iR wing or similar while not very powerful can add a bit of stability to the twitchy rear nature of this platform and make a noticeable improvement through the high speed stuff. Only harm in running even a small wing is being seen on the street with one... Even moderate aero can find a place on this car without going overboard on spring rates but would definitely want it to be removable.

[CSBM5]

Veering a bit off the topic perhaps, but there's always the choice of retiring the CS from tracking by picking up a higher mileage M2C slicktop with DCT to be built out for track use. Let that be the beater that takes all the rock and debris hits, hammers into the gators at the apex of a 60 mph turn, etc. Proper coilovers, camber plates, perhaps monoballs, Apex forged wheels, decent tires, BM3 CS tune, etc, etc. You could build it out while saving all the stock parts. When you're done with the M2C beater in a number of years, part it back to stock, sell it and sell all the parts.

I can't help but think the CS will thank you for that.