# Stiffer sway bar up front, good idea or bad idea?



## ·clyde· (Dec 26, 2001)

pjgo said:


> A larger front swaybar typically stiffens the front of the car, reduces grip and increases understeer.


In a camber challenged car as you go through a turn if the outside front wheel tilts further leading to positive camber gain the tire's contact patch will shrink as the inner section lifts from the camber. Using a stiffer/larger front bar can help minimize the positive camber gain leading to a larger contact patch and, hence, more grip.

It's not something that works on every car, though.


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## SoloII///M (May 16, 2003)

·clyde· said:


> In a camber challenged car as you go through a turn if the outside front wheel tilts further leading to positive camber gain the tire's contact patch will shrink as the inner section lifts from the camber. Using a stiffer/larger front bar can help minimize the positive camber gain leading to a larger contact patch and, hence, more grip.
> 
> It's not something that works on every car, though.


Clyde is correct. I don't know much about the E46 suspension geometry (nor how a 330 PP differs from a regular 330 with regard to suspension) but with E36 cars the geometry of the suspension limits the camber gain through bump as compared to, say, a double-wishbone car. Lower an E36/E46 and it gets even worse as the control arm passes through horizontal. This is the case with many low-riding strut-equipped cars, which is why you see the top guys running a lot of static negative camber.

When the body of the car rolls, the angle of the contact patch relative to the ground doesn't stay constant. i.e., the roll of the body creates a _ positive camber gain situation _. This is why you'd like to see camber gain through bump - to counteract the effects of the body rolling. Since that doesn't happen with our cars, you have two choices. One is to run a lot of static negative camber. The other is to limit front roll. The only option you have (in B Stock) is to limit front roll, and the only way you can legally do that is with a front bar.

The front sway bar will increase the front roll stiffness relative to the rear, which one would expect to cause a bias towards understeer. However, in this situation, because you are limiting the roll of the body, grip will actually be improved. The car will also be quicker through transitions.

{rant}

There's nothing wrong with spending money on the car AS LONG AS you don't go into it with the attitude of, "My car is too slow, I need to mod it to catch up with the leaders." 95% of the time it's just not the case - the driver needs the most work.

HOWEVER, I understand wanting to modify the car. It's the nature of being a car guy - installing parts and playing with them. Go for it if you have the money! Do the front bar, Koni SAs, a competition alignment, race tires, light wheels, whatever you want! There's nothing wrong with that! Just remember why you're doing it.

...and don't be surprised when someone comes out in a bone stock 330i and whips your butt! 

{/rant}

Have fun Andy..

John V


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## elbert (Mar 28, 2002)

SoloII///M said:


> (liberal amounts of trimming) Clyde is correct...When the body of the car rolls, the angle of the contact patch relative to the ground doesn't stay constant. i.e., the roll of the body creates a _ positive camber gain situation _. This is why you'd like to see camber gain through bump - to counteract the effects of the body rolling. Since that doesn't happen with our cars, you have two choices. One is to run a lot of static negative camber. The other is to limit front roll. The only option you have (in B Stock) is to limit front roll, and the only way you can legally do that is with a front bar...The front sway bar will increase the front roll stiffness relative to the rear, which one would expect to cause a bias towards understeer. However, in this situation, because you are limiting the roll of the body, grip will actually be improved. The car will also be quicker through transitions...John V


OK, that makes sense. Great explanation John. I'm used to thinking in terms of double-wishbone suspensions with the built-in camber change that occurs dynamically, as opposed to the strut suspension.

But I ass-ume there is a point where there will be a diminishing return, where the car is too stiff and will skitter around.


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## pjgo (Oct 4, 2003)

*Thanks!*

Thanks for explaining why adding a front swaybar both stiffens up the front *and* increases grip-- it's great! Does this mean that adding a front swaybar also reduces understeer?

pj


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## SoloII///M (May 16, 2003)

pjgo said:


> Thanks for explaining why adding a front swaybar both stiffens up the front *and* increases grip-- it's great! Does this mean that adding a front swaybar also reduces understeer?
> 
> pj


Depends on when you're getting the understeer.

Corner entry / midcorner / corner exit?

How does the car behave transitionally (i.e. in slaloms)?

It's been my experience that most of the time when a driver says his car understeers that he's just going in too fast. YMMV though. My E36 M3 turns in sharply, _oversteers_ on mid corner and corner exit. Still getting used to the Konis, though.

edit: Just saw the comment posted right after yours. Things are never as simple as "bigger bar = more understeer." There are many different dynamics figuring in here. I guess it boils down to the fact that you have to know your driving style, know what the car is telling you, and know what you want to change.

John V


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## racerdave (Sep 15, 2003)

I agree with John V here. Bigger front bar does not always mean more understeer.

Like he and clyde said, if the car "camber-challenged" and melting the outside edge of its tires, then a bigger anti-roll bar can actually help lessen understeer. When the 16-valve GTI's were new and competitive in stock classes, that was how they made them faster... stiffening the front to limit camber change. 

In that case, stiffer front bar = less understeer.


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## racerdave (Sep 15, 2003)

Andy... question for you. Do you want to remain in stock class for the forseeable future?

There's a reason I'm asking, so I'll await your response...


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## Andy (Jul 16, 2003)

racerdave said:


> Andy... question for you. Do you want to remain in stock class for the forseeable future?
> 
> There's a reason I'm asking, so I'll await your response...


racerdave,

That's a good question... I know for sure that want to remain the B-Stock for all of next season and do my best to qualify for nationals. That's my goal for next year, is to just qualify.

There is nothing more I want to do then to install a 3.46 LSD, PSS9 coilovers, front AND REAR sways and even install a CAI and engine software. That is my wish list of mods, however I'm not sure of my 330i is the right car to do this to. By the time I have enough money to do that, I would really like to purchase an e36 M3 "track only" car and put all those mods on it. Of course my long term plan would be to get into club racing and I would prefer to do that with a track only car instead of my daily driver.

So I guess, to answer your question, yes, I would like to eventually get out of the stock class, but will more then likely do that with a different car.

Now, on a side note, I want to make one thing perfectly clear... I absolutely love my car stock. It is by far the best car I have ever owned. I previously owned a 2001 330i non-SP and this car is night and day different then my previous 330i. It has surpassed my expectations in handling and performance on and off the track. I am no way wanting to mod my car because I think it sucks. In fact, I don't think you'll ever hear me say that "my car sucks". I absolutely love it!!

I guess what started me thinking about race tires, front sway bar, adjusting camber, etc. is when I saw the race results from nationals. 90% of those cars are Honda S2000s. I guess I was wanting to reduce the edge that those cars have over mine as much as I can. Now granted, I know that my driving ability is nowhere near the ability of those guys, I guess I was just thinking ahead.

Now, just to let you guys know, I just got finished uninstalling the front and rear sway bars and put the stock ones back on. I decided to put the stock front sway bar back on because I know I wouldn't have time to adjust the camber before Sunday's race. I'm still torn at this point about keeping the UUC front sway and adjusting the front camber or just selling the entire set and use that money to go toward my new tires for next year.


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## FSelekler (Jan 15, 2002)

TeamZ4 said:


> Andy,
> 
> ...Truthfully, I should have known better to engage in this particular discussion ...
> Mark


 :rofl: :rofl: :rofl: :thumbup:


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## SoloII///M (May 16, 2003)

Andy said:


> racerdave,
> I guess what started me thinking about race tires, front sway bar, adjusting camber, etc. is when I saw the race results from nationals. 90% of those cars are Honda S2000s. I guess I was wanting to reduce the edge that those cars have over mine as much as I can. Now granted, I know that my driving ability is nowhere near the ability of those guys, I guess I was just thinking ahead.


Andy,

I have sad news for you. The 330i PP isn't going to be an S2000 fighter. Now, someone like Mark may go buy one and make me eat my hat, but the Z4 has the same motor, less weight, and other factors that make it a better autocrosser inherently than the 330i PP - and it's still fighting a 300lb uphill battle against the S2000s. I understand the desire to "narrow the gap" against them - but you probably won't ever catch them.

In fact, with the S2000 2.2 coming out this year...  uh-oh.

Every autocrosser comes to the crossroads eventually. Whether to modify a car with the things you suggested to make it a fun street car and run it classed wherever it happens to fall, or keep it stock-legal and "deal with it" on the street.

Like I said before, if you want to mod, mod! If you like the balance with that front sway bar on there, want to upgrade shocks, etc, just go for it! Do what makes you happy. Not everyone has to have aspirations of Nationals trophy finishes. It's just fine to learn on a mildly modified car if it makes you happy.

However, if you really have dreams about being a world-class autocrosser, take Mark's advice. Spend the money you saved on schools, tires and seat time. It *will* pay off in the end. Heck, if you get really good, maybe a local hotshoe autocrosser will ask you to warm tires for him and his S2000 at Nationals.

Sorry for my long rants. I understand where both you and Mark are coming from.

John V


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## racerdave (Sep 15, 2003)

Ok, that helps.

But why would you have to adjust the camber after a anti-roll bar change? Anti-roll bars shouldn't affect static camber by themselves.

Anyway, what I was going to suggest was if you want to keep it in BS, then put the stock rear bar back on for daily use as well as event use. Have it be consistent... but you already did that. 

However, this fun event might be a perfect opportunity for you to *test* the bars against one another. Run the stock bar in the AM, and the UUC in the PM... assuming of course that the bar isn't impossible to change on a set of jack stands. But it will give you the closest possible idea of how the bigger bar will help.

Now, it's not perfect in that the surface grip could change slightly between heats as it gets cleaned off and more rubber is laid down. But it's about as good a test as you'll get... same course with the only difference being the front bar. It's worth considering... IHMO. 

As for the S2k, it's a lot lighter than the 330. That's tough to overcome in an autocross, so you might be tilting at windmills trying to beat them in BS.

As for your track-car idea, I think that's the best place to focus your mod $$ if you want to mod *and* autocross. Not to say you can't mod and autocross... but to have a car that's truly great on an autocross course generally means having a car that's not very comfy or driveable on the street.

Having a track car will keep your street car comfortable on the street, and make your track car perfectly suited for its role too. I'm autocrossing a 125cc shifter kart for that reason... and going way faster than *any* stock E46 M3 while I'm at it.

Even with the "stock-class" cars, the really top-level ones are not really streetable anyway, at least the way they are tuned. They have aggressive shocks and alignments that aren't suitable for street driving, so most top-level folks trailer their stock cars to the events. There may be exceptions, but that's generally the case.

So you're better off doing a track car if you want to go really nuts.

Again... just all IMHO! :thumbup:


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## racerdave (Sep 15, 2003)

Andy said:


> racerdave,
> 
> Now granted, I know that my driving ability is nowhere near the ability of those guys, I guess I was just thinking ahead.


Andy... this caught my eye again.

Hey, we *all* can improve our driving, so don't belittle yourself. At this fun event, have a "hotshoe" ride with you to critique your driving. You might learn something that helps you.

But in that same vein, driving ability, in this case, might not amount to a hill of beans. A properly-driven S2000 is simply faster than a ZHP on an autocross course.

I've been in uncompetitive cars (and a ZHP in BS is an uncompetitive car relative to the S2000) and while you might get close, you'll be amazed what happens when you actually get in that competitive car. It makes life *far* easier.

So my last 0.02 is to always work on your driving, enjoy your ZHP for what it is -- don't try to make it be an S2000, cuz it ain't never going to be -- and go nuts on a track car when you have the opportunity.


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## ·clyde· (Dec 26, 2001)

Andy,

I think part of the frustration stems from the pattern of your posts. You ask a question, or indicate that you're going to mod your car in some way and you explain your situation/circumstances. Based on that, people respond. Frequently, the responses have run counter to what you've indicated that you would like to do and the people posting have generally backed up their reasoning why they think you should do something different. Then, you come back, and thank everyone for their input and indicate that based on the comments you have changed your mind and will take the advice that's been offered. Fast forward a few days. Repeat. Same question/mod idea.

I don't think that there's anything wrong with that. I can understand why someone that's trying to help you would get frustrated with it though. Don't think too much on it though...that's just the way it goes sometimes.


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## GregD (Feb 5, 2003)

Andy said:


> You know, I use to enjoy coming to this site.
> 
> So long friends.
> 
> Andy


I hope this doesn't mean that you won't be posting anymore. I've generally enjoyed the threads you've started and would be disappointed if you stopped. I don't know why TeamZ4 jumped down your throat the way he did, without knowing where you were coming from. Perhaps he had a bad experience giving advice in the past, perhaps he had some problems in his real life and took it out on the web, perhaps who knows. The fact that he removed all of his posts from this thread indicates that perhaps he would prefer that he hadn't posted some of the things he did. We don't know, so don't worry about it.

I think you've gotten a lot of good feedback from many other people on the forum, so as the saying goes, don't throw out the baby with the bath water. Besides, you can always count on the support of a fellow ZHP owner. A ZHP may not be the best car for autocross, but it's a hell of a car nonetheless.


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## TeamM3 (Dec 24, 2002)

yeah right, you have me all figured out for sure

:tsk:


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## SoloII///M (May 16, 2003)

TeamZ4 said:


> yeah right, you have me all figured out for sure
> 
> :tsk:


Mark, grow up. You may be a nationally competitive autocrosser, but that gives you no right to berate people because they don't make the choices you've made; never mind the fact that you never contributed _anything_ in this post to Andy's original question. I agree with your point of view, but not with your method of delivering it to him. You are not God's gift to new autocrossers - get over yourself.

Andy: I've been autocrossing for about eight years now and still feel like a newbie at times, haha. There are some really genuine "good guys" out there - Jeff Cashmore from my old Milwaukee region comes to mind - that are world class autocrossers but also willing to _help_.

If you ever go up to do an event in Toledo next season (Ne-Ohio region) let me know. I'm up there pretty frequently and I would be more than willing to chat about setups, techniques, whatever.

John V
95 M3


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## racerdave (Sep 15, 2003)

John, that is wild... old Milwaukee regioner huh? I've been autocrossing on and off for about 13 years there.

Yes, take people up on asking for advice. Cashmo is good that way.

However, when I think BMW, I think Bob Clark from the Milwaukee Region. He's called BMW Bob around here. Some national folks may or may not know him. He drives a medium gray 89 325is. He still goes to nationals with it... didn't do that well this year, but finished in the top 10 like the last 3 of 4 years or something like that.

IN AN 89! I mean, it's a nice car, but performance-wise is way behind the E36 and E46 due to it's high/narrow stature. 

Bob is very smooth, tidy and creative in line selection. He's also a great teacher, so if there's a new BMW autocrosser around that's struggling a bit, I point them to Bob. He's always willing to help, and the new BMW drivers always feel more comfortable somehow with someone who drives a car related to theirs.

I know he's toying with the idea of getting a 330, so we'll see. But if Bob gets in a competitive BMW model (and the 330 was competitive in DS), look out, because he's very, very good.


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## SoloII///M (May 16, 2003)

racerdave said:


> John, that is wild... old Milwaukee regioner huh? I've been autocrossing on and off for about 13 years there.
> 
> Yes, take people up on asking for advice. Cashmo is good that way.
> 
> However, when I think BMW, I think Bob Clark from the Milwaukee Region.


Dave, that is funny. I'm sure you don't remember, but I campaigned a black 2nd gen Turbo RX-7 back from '96-99 in Milwaukee (#109 ASP and BP). I also occasionally drove Steve Taylor's Silver non-turbo RX-7 in CSP. I always found Milwaukee region people to be very friendly, and I fondly remember watching Marshall Moore and Darrel Padberg duke it out in their Corvettes. You guys still run down at the old AMC proving grounds in Burlington, and out in Brookfield? I remember driving an event at the Miller park lot right after the crane failed  Sad. I miss you guys!

I do remember watching Bob.. very smooth. So is Cashmo! I could never figure out how he hustled that Celica around so quickly.

I think it's amusing that the SCCA moved the 330i PP (why do people call it a ZHP anyway? The BMW literature I have on the car refers to it as the 330i Performance Package...?) to BS where it will never be competetive. It wasn't even a class killer in DS. The S2000 is much more of a "ringer" in BS - really, that car should be placed in AS with the times it runs. Oh well.

Take it easy,

John V


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## GregD (Feb 5, 2003)

SoloII///M said:


> I think it's amusing that the SCCA moved the 330i PP (why do people call it a ZHP anyway? The BMW literature I have on the car refers to it as the 330i Performance Package...?)


ZHP is BMW's option code for the performance package. Referring to it as PP sometimes leads to confusion with the premium package, so ZHP.


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## racerdave (Sep 15, 2003)

Hey John... it's kind of funny, because I probably started autocrossing in about 89 or so. 95 and 96 were probably my most active years, but I moved to Boston in the middle of the summer in 96. I was actually leading Bob in the points that year, but since I never got to finish the season out... who knows how it would've ended up, but it was fun trading wins back and forth with him.

So when you were in Milwaukee... I wasn't. 

I came back to Milwaukee in 1998, but didn't autocross much at first. I autocrossed again more frequently in 2000, then nothing in 2001 (bicycle racing), yadda yadda.

Oh, and the crane. I was probably at that same event. I remember looking into the "bowl" of the stadium just afterward at that event... seeing the crane crumpled there and the carnage was unbelievable... very humbling.

I'm now attempting to master a shifter kart -- what a fun, challenging, vexing, unusual little beast that is. If you have a chance to drive one, do it. You might get hooked too. 

Yep, Steve is still out there I think, as are Marshall and Darrel --- now the reigning CP champ.

There's good competition there and, like you said, everyone is willing to help, so it's a nice place to autocross.


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