PSA: Think twice before lowering your car

[jet_dogg]

Stock suspension is made for the masses, with compromises, period.

This thread has managed to change...nobody's mind. Sorry cobrah.

[cobra]

Stock suspension is made for the masses, with compromises, period.

This thread has managed to change...nobody's mind. Sorry cobrah.

No need to be sorry.

All I hope is it might enlighten people like me who didn't really understand the system. I had this discussion with my friend today who has been an E46 owner since 2006 just like me. He doesn't care as much about peak performance, and instead wants to be able to slide through corners and have a car that looks a certain way. I respect that as much as someone who wants to keep it stock, or someone who seeks the best lap times.

[maw1124]

Stock suspension is made for the masses, with compromises, period.

This thread has managed to change...nobody's mind. Sorry cobrah.

I see no minds to be changed, just thought to be provoked. Certainly OEMs make all sorts of compromises for all sorts of reasons. Shit, in a 3 series, “cost” is certainly top of the list. The only other cars I have that perform like this one cost literally double in equivalent money, both of which raise and lower, one of which at the touch of a button (the other, automatically). BTW, the one with the button is set low and raises, not the other way around. So clearly that OEM thought lowering worked only to a point. At that height (sorry, at all heights), “stiffer” could also be had at the touch of a button. But keep in mind, all that thought, geometry and engineering cost more than double, almost triple what these cost. That system is also much heavier, more complicated and costly to maintain. I think I can get that “stiffer” here, with zero lowering, for a reasonable amount of cost and headache. People lower those too, BTW, with “arguable” results.

The benefit of boards like this and the dedicated owners who are here (as oceansize said a while back) is to explore the limits of those compromises so others can decide which ones to undo and which ones to live with. Once you know what is Level 10, you can decide whether you want to live with Level 4, 6 or 8. That’s all I’m figuring out anyway — of the 50 mods one could make, which are the 10 that make any sense at all, and out of that 10 how many are worth anything at all TO ME. You can tell what are the most important words there.

So I appreciate the thought being provoked.

maw

[maupineda]

I share the view of the OP, my Z4M is setup to be same as stock for ride height and even got a few mm more travel before engaging bump stops. It did requiere a lot of thought and measurements but it did improve over OE in terms of performance though a bit less comfort as it is more firmly sprung and dampened (about 10% stiffer rates) using linear springs.

it corners flatter due to rates and increased sway bar up front (CSL). And looks good (IMO), plus México is crappy for roads and killer speed bumps, so even stock is too low

[simonnim]

We must also consider that a customer buying an aftermarket coilover kit is expecting it to feel and look a certain way. When you think about a "race car" suspension what do you think of? Stiff, direct, go-kart like handling? Completely compromised comfort in pursuit of performance? Low to the ground for the lowest center of gravity, since a race track is smooth you don't need much travel. But maybe that's not reality. What if someone spent $5,000 on a coilover kit that could achieve the best lap times possible, but felt plush and took an expert driver to extract its capability? Bilstein has to consider what the customer wants versus what might objectively be the "best". It also has to look badass, let's not forget. More compromises even in the aftermarket... especially with sports cars.

Absolutely, totally agree with compromises with aftermarket as well to profit. In my mind, there's always going to be the half way mark. It's like KW V1 vs KW club sports price differences for example. My argument is that, just like you mentioned stiff, direct, go-kart like handling is generally achieved by lowering your car for the aftermarket items provisioned for the amount of money we're willing to invest. And as always, stiffness is subjective to each driver.

I do think that if you as a average driver updated your suspension with $5000 coilovers and properly height and corner balanced it, you'd do better in lap times, even if just a tiny bit. That's mainly due to the higher confidence due to less body roll since you've lowered the center of gravity. But, I for one agree that that one finger gap looks bad ass.

[BlueBimmers]

Really interesting post thanks. The engineering loses me but I was inspired to check my ride height. I bought the car with Fortune Auto coilovers and Swift springs. The car was lowered too much IMO and I had the seller (mechanic) raise it for me. Looks like I'm at 13 9/16". Like the look and like the ride. Was thinking about tweaking toe and camber next alignment. There was excellent article in derBayerische about that recently.

[bigjae46]

There are other factors to consider - aero is one of them - when setting ride height for performance.

The stock suspension rolls too much which equals more weight transfer so you lose grip as you overwhelm the tires where the weight is transferring to. AND you're transferring weight away from some tires which reduces grip even more. The stock suspension is compromised to add under car clearance (finned diff cover anyone?) and more roll to make the car less twitchy. I can clearly get through a combination of corners (like a switchback) and apply throttle on exit MUCH earlier than a car on a stock suspension.

My E46 has 450lb front and 700lb rear springs, TC Kline doubles and a stock front sway bar, no rear sway bar, a 6" splitter and amazon.com rear wing. My ride heights with a 275/40R17 tires are between 25.3 to 26.1" which is much different than stock. This optimizes the cross weight distribution which has different assumptions that stock (stock I believe assumes 2 front passengers). My car is very different to any E46 I've seen in track paddocks. It sits higher, has a stock front sway bar, no rear bar, departs from the common +100lb spring on the rear. It is within the flat ride parameters but right on the edge of pitch. My E46 rides better than my E90 M3 with Dinan springs, non-EDC dampers, and dinan sway bars. I run lap times on NT01s within a second of E46s on scrubs and Hoosiers.

I mostly drive at MSR Houston which is very bumpy. You need suspension travel because you need soft springs to cope with the pavement. Otherwise its terminal understeer on corner entry and formula drift on exit. On smooth pavement like Eagles Canyon, I need stiffer front springs and COULD lower the car to improve aero performance (even more if I had a flat floor). On high grip tracks like COTA, I also need stiffer springs because the front splitter starts scraping under higher speed braking resulting in a loss of downforce.

[cornerbalanced]

My E46 must really be a mess then haha.

These cars' stock or stock "equivalent" really don't handle well in my opinion. Just incredibly sloppy. Also, funnily enough, some dampers paired with the correct (not overly stiff) spring rates result in a ride quality that is BETTER than factory, not the mention the performance benefits. A fraction of this benefit comes from lowering the car itself of course. With this in mind, it is also important to lower your car "correctly" ... meaning, keep travel & bump stop positioning in mind, and choose the right damper + spring rate combo for your driving style.

[bigjae46]

Stock suspension is created for balance of comfort and sportiness. The dampening, spring height, and ride height are what they were able to achieve with the budget given to the engineering team(which is created to achieve the most cost effective method...you know if you're an engineer) to create that balance. It means, there was a budget and it was met, and if they had no constraints, it would be represented by what is achieved in f1.

I think as long as aftermarket spends the time for research. Example, Bilstein literally sells OEM for BMW. Without constraint they can obviously take what they've learned to create coilovers to lower ride height thus lowering center of gravity and improving handling because of that alone.

As long as you're buying quality suspension, you'll improve handling. Period. Will you achieve balance without updating all of the suspension along with coilovers? Probably not because the balance was engineered alongside the suspension it was designed with.

I don't think Bilstein has much knowledge specific to the E46 or any car. They do what a manufacturer tells them. I know KW never tests their suspensions in the US. If KW did they wouldn't make them so damned stiff. The advice I give when buying coilovers for performance is its cheaper to replace the engine than to put in a new suspension for performance gains. You have to factor in the time, cost and wear/tear because you have to either do simulation or drive the car on track, it might take awhile before getting the suspension dialed. I've seen it take 4+ weekends at the track.

When you buy coilovers, you buy support, advice and experience from real world testing in addition to the hardware. I had my TC Klines dialed in within a weekend because I got great advice.

One other tool to help with suspension setup is the flat ride spreadsheet. After gutting and caging my car, I struggled with my setup. I used the flat ride spreadsheet which probably saved me many weekends of trial and error. Within 2 weekends I had the suspension dialed in.

[simonnim]

I don't think Bilstein has much knowledge specific to the E46 or any car. They do what a manufacturer tells them. I know KW never tests their suspensions in the US. If KW did they wouldn't make them so damned stiff. The advice I give when buying coilovers for performance is its cheaper to replace the engine than to put in a new suspension for performance gains. You have to factor in the time, cost and wear/tear because you have to either do simulation or drive the car on track, it might take awhile before getting the suspension dialed. I've seen it take 4+ weekends at the track.

When you buy coilovers, you buy support, advice and experience from real world testing in addition to the hardware. I had my TC Klines dialed in within a weekend because I got great advice.

One other tool to help with suspension setup is the flat ride spreadsheet. After gutting and caging my car, I struggled with my setup. I used the flat ride spreadsheet which probably saved me many weekends of trial and error. Within 2 weekends I had the suspension dialed in.

Good points. However, they only do what the manufacturer tells them to when creating the OEM order. For aftermarket coilovers depending on the price range the solution will be more specific. The pss10 clearly is sorta specific but also reused technology they've gained from the allowed testing funding for the OEM. Knowledge from all that allows them to create better aftermarket solutions. They also have race line specific orders made to order.

[cobra]

There are other factors to consider - aero is one of them - when setting ride height for performance.

The stock suspension rolls too much which equals more weight transfer so you lose grip as you overwhelm the tires where the weight is transferring to. AND you're transferring weight away from some tires which reduces grip even more. The stock suspension is compromised to add under car clearance (finned diff cover anyone?) and more roll to make the car less twitchy. I can clearly get through a combination of corners (like a switchback) and apply throttle on exit MUCH earlier than a car on a stock suspension.

My E46 has 450lb front and 700lb rear springs, TC Kline doubles and a stock front sway bar, no rear sway bar, a 6" splitter and amazon.com rear wing. My ride heights with a 275/40R17 tires are between 25.3 to 26.1" which is much different than stock. This optimizes the cross weight distribution which has different assumptions that stock (stock I believe assumes 2 front passengers). My car is very different to any E46 I've seen in track paddocks. It sits higher, has a stock front sway bar, no rear bar, departs from the common +100lb spring on the rear. It is within the flat ride parameters but right on the edge of pitch. My E46 rides better than my E90 M3 with Dinan springs, non-EDC dampers, and dinan sway bars. I run lap times on NT01s within a second of E46s on scrubs and Hoosiers.

I mostly drive at MSR Houston which is very bumpy. You need suspension travel because you need soft springs to cope with the pavement. Otherwise its terminal understeer on corner entry and formula drift on exit. On smooth pavement like Eagles Canyon, I need stiffer front springs and COULD lower the car to improve aero performance (even more if I had a flat floor). On high grip tracks like COTA, I also need stiffer springs because the front splitter starts scraping under higher speed braking resulting in a loss of downforce.

Interesting perspectives, I never really consider aero for my uses case but it's definitely a thing for serious track guys. At what point did you decide to remove the rear swaybar, and what did you notice as a result? I am considering doing the same but might not have stiff enough springs to enable it.

[simonnim]

There are other factors to consider - aero is one of them - when setting ride height for performance.

The stock suspension rolls too much which equals more weight transfer so you lose grip as you overwhelm the tires where the weight is transferring to. AND you're transferring weight away from some tires which reduces grip even more. The stock suspension is compromised to add under car clearance (finned diff cover anyone?) and more roll to make the car less twitchy. I can clearly get through a combination of corners (like a switchback) and apply throttle on exit MUCH earlier than a car on a stock suspension.

My E46 has 450lb front and 700lb rear springs, TC Kline doubles and a stock front sway bar, no rear sway bar, a 6" splitter and amazon.com rear wing. My ride heights with a 275/40R17 tires are between 25.3 to 26.1" which is much different than stock. This optimizes the cross weight distribution which has different assumptions that stock (stock I believe assumes 2 front passengers). My car is very different to any E46 I've seen in track paddocks. It sits higher, has a stock front sway bar, no rear bar, departs from the common +100lb spring on the rear. It is within the flat ride parameters but right on the edge of pitch. My E46 rides better than my E90 M3 with Dinan springs, non-EDC dampers, and dinan sway bars. I run lap times on NT01s within a second of E46s on scrubs and Hoosiers.

I mostly drive at MSR Houston which is very bumpy. You need suspension travel because you need soft springs to cope with the pavement. Otherwise its terminal understeer on corner entry and formula drift on exit. On smooth pavement like Eagles Canyon, I need stiffer front springs and COULD lower the car to improve aero performance (even more if I had a flat floor). On high grip tracks like COTA, I also need stiffer springs because the front splitter starts scraping under higher speed braking resulting in a loss of downforce.

Driver mod could also be the case. I have a buddy with an exceptional e36 suspension set up but is 3 seconds slower around thill west. He also has a buddy with the same car, cheaper suspension but a little bit of aero, and times 8 seconds faster than him.

[Casa de Mesa]

Driver mod could also be the case. I have a buddy with an exceptional e36 suspension set up but is 3 seconds slower around thill west. He also has a buddy with the same car, cheaper suspension but a little bit of aero, and times 8 seconds faster than him.

Driver mod, ha! Very true.

That said, proper aero is the real deal. At VIR full course, without changing a single variable other than adding a wing (a real wing mounted up high in clean air) and a splitter, I dropped 2.5 seconds per lap first session out. That's before I optimized the car with stiffer springs, different shock valving, etc. A car with good aero is an amazing thing - it's better everywhere.

[cobra]

Driver mod, ha! Very true.

That said, proper aero is the real deal. At VIR full course, without changing a single variable other than adding a wing (a real wing mounted up high in clean air) and a splitter, I dropped 2.5 seconds per lap first session out. That's before I optimized the car with stiffer springs, different shock valving, etc. A car with good aero is an amazing thing - it's better everywhere.

Case in point

https://www.youtube.com/watch?v=5JYp9eGC3Cc

[maw1124]

Case in point
https://www.youtube.com/watch?v=5JYp9eGC3Cc

“Driver mod” is hilarious!! My man here is straightening curves like LH44. But to the point of this thread, you need the car set up to do so. Just ask Toto this year…

maw