Alignment advice please

[oolas3]

So I've read a bunch of alignment threads but most of them are cars with an aftermarket suspension or the alignment pins have been pulled. I'm looking to stay with my stock EDC suspension and do not want to pull the alignment pins at this point. What specs do you guys suggest for someone that wants to dial out the understeer as much as possible within a stock set-up?

Are the fronts at -1.2 camber/0 toe and the rears at -1.7 camber with 1/32 toe realistic? Is that about the best I can do up front? Does the rear make sense in relation to the front?

Thanks in advance.

[The HACK]

You want MORE understeer?

The E90 chassis does not understeer magically. All understeer is inherently initiated by the driver. The E90 is actually a VERY neutral chassis, especially the RWD version.

Where and when are you experiencing the understeer, and if you can answer either, then there may be a way to resolve it. Otherwise you're just chasing wild goose.

And let me repeat. The E9X is not an inherently "understeer" chassis. Any understeer in the E9X is induced by driver error.

EDIT: And how do you suppose they "align" the car without pulling the alignment pin?

[oolas3]

Originally Posted by The HACK

You want MORE understeer?

The E90 chassis does not understeer magically. All understeer is inherently initiated by the driver. The E90 is actually a VERY neutral chassis, especially the RWD version.

Where and when are you experiencing the understeer, and if you can answer either, then there may be a way to resolve it. Otherwise you're just chasing wild goose.

And let me repeat. The E9X is not an inherently "understeer" chassis. Any understeer in the E9X is induced by driver error.

EDIT: And how do you suppose they "align" the car without pulling the alignment pin?

I want less understeer.

[s14_kev]

You will want max camber in the front to reduce understeer. I don't think -1.2 is achievable without pulling the pins but i may be wrong. What's the reason you want to leave them in?

I'm not sure about stock setups, but general rule of thumb for aftermarket suspensions and alignment is that the rear camber should be about 1 degree more (less negative) than the front. For example, -3 camber in the front works well with -2 camber in the rear. If you were to apply this rule to stock settings, I don't think there would be enough camber in the rear. Maybe shoot for even camber front and rear if you're keeping everything stock.

The best way to alleviate understeer on the E9x M3 is an 18x10" square setup and camber plates TBH. Not much you can do without those two mods IMO.

[bigjae1976]

The reason the car understeers is you lose contact patch on the front axle in a turn due to weight transfer. So you are cornering on tread and sidewall.

Adding negative camber is a Band-Aid by accounting for the dynamic camber change so that you corner on the tread and the tire does not roll over onto the shoulder and sidewall.

So couple of options. Drive in a stiffer EDC setting to increase the damper rate up front to reduce the roll over. Swap in stiffer springs and stiffer sway bars.

Pulling the pins is a good, cheap option with minimal trade off. You shouldn't see much additional wear up to -2.0 camber up front.

[M3 Esq]

There's not much adjustment available without pulling the pins. Even with pulling the pins I was only able to get -1.4 or 1.5 negative camber up front and I couldn't feel much difference. I doubt you'll get enough adjustment out of the stock components to make much difference at all, but I'd at least pull the pins if you going to do anything. It takes like 10 minutes.

[oolas3]

Originally Posted by M3 Esq

There's not much adjustment available without pulling the pins. Even with pulling the pins I was only able to get -1.4 or 1.5 negative camber up front and I couldn't feel much difference. I doubt you'll get enough adjustment out of the stock components to make much difference at all, but I'd at least pull the pins if you going to do anything. It takes like 10 minutes.

Great feedback. I'm starting to think I need to change my plan if differences are minimal.

[oolas3]

Originally Posted by bigjae1976

The reason the car understeers is you lose contact patch on the front axle in a turn due to weight transfer. So you are cornering on tread and sidewall.

Adding negative camber is a Band-Aid by accounting for the dynamic camber change so that you corner on the tread and the tire does not roll over onto the shoulder and sidewall.

So couple of options. Drive in a stiffer EDC setting to increase the damper rate up front to reduce the roll over. Swap in stiffer springs and stiffer sway bars.

Pulling the pins is a good, cheap option with minimal trade off. You shouldn't see much additional wear up to -2.0 camber up front.

Exactly it occurs during weight transfer in sharp corners or S curves. Good advice on the EDC as I rarely run at the firmest. After this feedback, I'm seriously considering the stiffer spring option as well.

[bigjae1976]

The opposite is true...soften up the rear too.

Under steer is inherent to BMW's Macpherson strut suspension design. They really should upgrade to a double A arm...BMW kind of cheaper out here.

[M3 Esq]

Originally Posted by m3m3mr

Exactly it occurs during weight transfer in sharp corners or S curves. Good advice on the EDC as I rarely run at the firmest. After this feedback, I'm seriously considering the stiffer spring option as well.

Be careful changing out springs. Those are usually just for looks and rarely improve handling. If your going to upgrade the suspension I'd look at a coilover system that will have matching springs and dampers. Or you could try camber plates. I ran vorshlags with stock EDC and the turn in was much better. Just make sure you have a competent shop with experience in track setup do the install/alignment. Of course then I just went full coilovers after a few months.

[bdaddylo]

Originally Posted by The HACK

You want MORE understeer?

The E90 chassis does not understeer magically. All understeer is inherently initiated by the driver. The E90 is actually a VERY neutral chassis, especially the RWD version.

Where and when are you experiencing the understeer, and if you can answer either, then there may be a way to resolve it. Otherwise you're just chasing wild goose.

And let me repeat. The E9X is not an inherently "understeer" chassis. Any understeer in the E9X is induced by driver error.

EDIT: And how do you suppose they "align" the car without pulling the alignment pin?

All BMWs are designed to understeer. Do a few laps around the skid pad in an E90 in the dry or wet and it'll understeer. Is it excessive? No, but it still understeers.

[The HACK]

Originally Posted by bdaddylo

All BMWs are designed to understeer. Do a few laps around the skid pad in an E90 in the dry or wet and it'll understeer. Is it excessive? No, but it still understeers.

And all the understeer is initiated by the driver. If all you do is read magazine reviews, you will likely find that they'll mentioned even cars like the mighty Ferrari Italia will understeer when you initiate it.

"Understeer" is a term that is toss about too much by people who has no clue what it is. Understeer happens under different states, and is inherent in a sprung chassis with two axles. When the front axle looses traction, ANY chassis will understeer. But how it looses traction is what you will need to know in order to "dial out" understeer.

For example, any RWD chassis that is relatively equal in weight distribution, when throttle is applied abruptly upon corner exit, the front end will "get light" and lose grip because weight is shifted to the rear of the car. Or on corner entry, if you apply braking too abruptly, the weight does not transfer quick enough to increase the front grip, the front end will lose grip. Those are two cases where "understeer" needs to be cured through driver's input.

When in steady-state skid-pad, no matter what you do, if you increase the speed/throttle input from said steady-state (even if you do it smoothly), eventually the front end will release its grip first. It's just nature of physics. The only way to overcome that, is if you can apply dynamic mechanical grip to the front end...Dynamic as in increasing front grip as speed increases from the limit of adhesion. And the only way to do that is through aerodynamics and suspension settings (suspension, as in the further the suspension loads, the more camber increases, therefore more grip available as weight is further placed on the outside wheel). But the natural state from ANY basic chassis layout on the skid pad is to understeer as the driver initiates more speed/throttle.

BMWs aren't designed to understeer. BMWs "understeer" because it's inherent in all chassis. The "BMWs are designed to understeer" is a myth perpetuated by people who DON'T KNOW. A car that doesn't understeer is a car that has far more mechanical grip than its engine power can overcome, which would be a very sh*tty car to drive (unless it's got a metric sh*t load of both mechanical grip AND HP, then we're talking). Now, if you want to talk about how BMW intentionally engineered a lower threshold for understeer in their cars for safety? That would be correct. These cars are designed so that when push came to shove, push wins because it's easier to manage.

Stop thinking about these chassis as "understeer" and "oversteer" and start thinking about it in terms of a teeter totter, with understeer on one end and oversteer on the other, in a constant tug-of war against physics. BMW just happens to put a 250lbs line-backer on one end, as opposed to a 90lbs waif (and if we're talking about econobox FWD platform, a 500 lbs sumo)

[MPowerZ32]

Originally Posted by The HACK

Or on corner entry, if you apply braking too abruptly, the weight does not transfer quick enough to increase the front grip, the front end will lose grip.

I'm not sure I understand this part. I was under the impression weight transfer is instant under braking. It's after all the immediate effect of slowing down. Could you elaborate?

[bdaddylo]

Originally Posted by The HACK

When in steady-state skid-pad, no matter what you do, if you increase the speed/throttle input from said steady-state (even if you do it smoothly), eventually the front end will release its grip first. It's just nature of physics. )

I think you're missing what physics is. The end that releases grip is the end with the lesser amount of traction period.

Any vehicle may understeer or oversteer at different times based on road conditions, speed, available traction, and driver input. The design of a vehicle, however, will tend to produce a particular "terminal" condition when the vehicle is pushed to and past its limits of adhesion. "Terminal understeer" refers to a vehicle which, as a function of its design, tends to understeer when cornering loads exceed tire traction.

Terminal handling balance is a function of front/rear relative roll resistance (suspension stiffness), front/rear weight distribution, and front/rear tire traction. A front-heavy vehicle with low rear roll stiffness (from soft springing and/or undersized or nonexistent rear anti-roll bars) will have a tendency to terminal understeer: its front tires, being more heavily loaded even in the static condition, will reach the limits of their adhesion before the rear tires, and thus will develop larger slip angles. Front-wheel drive cars are also prone to understeer because not only are they usually front-heavy, transmitting power through the front wheels also reduces their grip available for cornering.

Although understeer and oversteer can each cause a loss of control, many automakers design their vehicles for terminal understeer in the belief that it is easier for the average driver to control than terminal oversteer. Unlike terminal oversteer, which often requires several steering corrections, understeer can often be reduced simply by reducing speed.

[bigjae1976]

BMWs tend to be oriented towards understeer because of the front engine layout and the MacPherson Strut front suspension design.

A car with a double wishbone or upper/lower link front axle will produce significantly less dynamic camber change making it easier to dial up the grip on the front axle.

So the front axle, irregardless of the driver, is limited by what level of weight transfer will begin to reduce contact patch due to the outside front tire rolling over onto the sidewalk. This is the same reason why BMW suspension tuning is backwards.

So most BMWs, particularly every 3 series, will understeer no matter the driver. The difference with the E9X platform is you have a ton of power and a much better rear suspension design to power out.

Newer 5 series and up and SAVs I believe have a double-A arm setup because the cars are so heavy.

[Melchior]

Originally Posted by bigjae1976

BMWs tend to be oriented towards understeer because of the front engine layout and the MacPherson Strut front suspension design.

A car with a double wishbone or upper/lower link front axle will produce significantly less dynamic camber change making it easier to dial up the grip on the front axle.

So the front axle, irregardless of the driver, is limited by what level of weight transfer will begin to reduce contact patch due to the outside front tire rolling over onto the sidewalk. This is the same reason why BMW suspension tuning is backwards.

So most BMWs, particularly every 3 series, will understeer no matter the driver. The difference with the E9X platform is you have a ton of power and a much better rear suspension design to power out.

Newer 5 series and up and SAVs I believe have a double-A arm setup because the cars are so heavy.

Have you ever driven an NA Miata? Double A arm front, F/R chassis ... and I'd say stock for stock more understeer than an E92 M3. A true SLA front suspension does have benefits (not as many when you start talking street cars), but the reason BMW chassis push has to do with the spring/bar/dampers/wheel/tire combo the engineers choose the car to leave the factory with. I've setup and driven numerous McPherson cars that were neutral or even loose, it's all about the setup.

How is setup backwards on these cars?

The OG wants to know how to maximize what he has ... So yes convert the car to SLA.

Max out front camber (probably be around 1.2-1.3* with pins pulled), stagger camber front to rear (shoot for ~.5 less in rear for OEM). If it's a track or autocross environment then I would stagger tire pressures as well (optimal for tire in front and higher than optimal in rear). Spacers on the front will help as well. How much are you willing to tweak?

[oolas3]

Originally Posted by M3 Esq

Be careful changing out springs. Those are usually just for looks and rarely improve handling. If your going to upgrade the suspension I'd look at a coilover system that will have matching springs and dampers. Or you could try camber plates. I ran vorshlags with stock EDC and the turn in was much better. Just make sure you have a competent shop with experience in track setup do the install/alignment. Of course then I just went full coilovers after a few months.

Coilovers probably aren't any option because I really want to retain the EDC. I do a fair amount of city driving. I'm now considering the Dinan Stage 1 spring set-up and camber plates.

[oolas3]

Originally Posted by Melchior

Have you ever driven an NA Miata? Double A arm front, F/R chassis ... and I'd say stock for stock more understeer than an E92 M3. A true SLA front suspension does have benefits (not as many when you start talking street cars), but the reason BMW chassis push has to do with the spring/bar/dampers/wheel/tire combo the engineers choose the car to leave the factory with. I've setup and driven numerous McPherson cars that were neutral or even loose, it's all about the setup.

How is setup backwards on these cars?

The OG wants to know how to maximize what he has ... So yes convert the car to SLA.

Max out front camber (probably be around 1.2-1.3* with pins pulled), stagger camber front to rear (shoot for ~.5 less in rear for OEM). If it's a track or autocross environment then I would stagger tire pressures as well (optimal for tire in front and higher than optimal in rear). Spacers on the front will help as well. How much are you willing to tweak?

So front around -1.3 and rears at -.8 with more air in the rear tires. It sounds like this is the best I can do within the stock range but do you think it will make a noticeable difference?

[admranger]

Originally Posted by Melchior

Max out front camber (probably be around 1.2-1.3* with pins pulled), stagger camber front to rear (shoot for ~.5 less in rear for OEM). If it's a track or autocross environment then I would stagger tire pressures as well (optimal for tire in front and higher than optimal in rear). Spacers on the front will help as well. How much are you willing to tweak?

Agree with pulling the pins and the camber stagger.

Curious as to the air pressure recommendation though. I'm more of a 1-2 psi lower in the rear to get the rear to bite better. Maybe I need to try it higher and see what happens (wait for the crunching sound...)?

[Melchior]

Tires have an optimum pressure (for the size/wheel width/camber/toe/spring rate/surface/temp ... Lots of variables). As you increase or decrease pressure from optimal the coefficient of friction goes down and you lose grip. I've tried both over and under pressure to take away grip from one axle and I always feel over pressure seems to breakaway more consistently. When I've under pressured to reduce grip I felt like that axle was on pins and needles to drive.

In theory over and under pressuring will work.

[bigjae1976]

Originally Posted by Melchior

Have you ever driven an NA Miata? Double A arm front, F/R chassis ... and I'd say stock for stock more understeer than an E92 M3. A true SLA front suspension does have benefits (not as many when you start talking street cars), but the reason BMW chassis push has to do with the spring/bar/dampers/wheel/tire combo the engineers choose the car to leave the factory with. I've setup and driven numerous McPherson cars that were neutral or even loose, it's all about the setup.

How is setup backwards on these cars?

The OG wants to know how to maximize what he has ... So yes convert the car to SLA.

Max out front camber (probably be around 1.2-1.3* with pins pulled), stagger camber front to rear (shoot for ~.5 less in rear for OEM). If it's a track or autocross environment then I would stagger tire pressures as well (optimal for tire in front and higher than optimal in rear). Spacers on the front will help as well. How much are you willing to tweak?

Read the whole thread. Where did I say to convert the front end to a double-A arm will fix the issue and buy an SLA? Right, I didn't.

I've never heard of any reputable BMW tuner or people who setup BMWs recommend reducing negative camber in the rear to reduce understeer. I'm not saying that its wrong...never heard of it. Most want to increase front negative camber and stay close to stock negative camber (usually between -1.5 to -2.0).

Typically, most recommend increasing the front tire pressures to reduce the rollover onto the edges of the tires. Not arguing that your tire pressure strategy doesn't follow normal suspension tuning guidelines. Just never heard it mentioned when talking about a 3 series BMW.

[1MOREMOD]

Bigjae1976 I hate it when I roll over onto the sidewalk