Sway Bar Configurations for track

[derbo]

Hey guys,

I would love a discussion about the optimal sway bar configurations for track days. Kyle brought the topic when I believe John bought only a front Hotchikis Bar. I am currently in the market to replace my front UUC 330i sway bar and rear OEM m3 sway bar. I am planning to sell the UUC 330i sway bar set and have a new setup.


1. Front Bar Stiff, Rear bar OEM/soft
2. Front Bar Medium, Rear bar Stiff


I see config 1 being slower on turn in, but allows the power to be put down faster on exit. This seems optimal for auto-x but I don't know enough to say it would benefit track days with the 330i having so little power.

config2 seems to be better for the 330i but I can see it being an issue for the M3 not being able to put the power down after the quick turn-in.




Kyle,
I would love it for you to chime in.


Others,
I would love a good discussion too!

[LivesNearCostco]

You know my recent choice--Hotchkis front bar and stock rear bar--but I haven't driven it on track or AutoX yet so cannot comment. For onramps and offramps, the car seems to corner flatter but I cannot tell if there is more or less grip because I rarely push the card hard enough on the street to get understeer or oversteer, or engage DSC.

People who have stock or close-to-stock springs seem to buy front and rear bars in a matched set, whether it's from Hotchkis, Turner, H&R, or Eibach. Track and AutoX nuts do weird things like replace just one bar (limitation of SCCA Stock AutoX ruleset), buy the really expensive but infinitely adjustable Ground Control front swaybar, or run a very stiff front with no rear. But some of those nuts have coilovers with specifically selected spring rates. (Not calling you a nut or anything!)

Would you consider front medium, rear soft/OEM? My front is currently at soft, which is 31% stiffer than stock. I was planning to do the middle setting, but thought the bar would hit control arms if I did that, until I get adjustable swaybar links.

[derbo]

My immediate decision prior to your recent purchase was to order TMS M3 set of bars.

Currently the present setup does have my UUC sway bar in the front set to medium. perhaps I should just do a HPDE this way and see how I like it. Chances are I would prefer the oversteer from a stiffer rear sway.


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[LivesNearCostco]

Yeah I would guess using an aftermarket rear sway in the stiffest position would usually lead to oversteer/fun!

Do you--or anyone here--know if going to a stiffer sway generally means one should set more or less rebound damping on the shock or strut? What about compression damping if you have it (I don't)? I'm thinking of buying some used 650lb rear springs and moving my 547lb springs to the front, to try it out. But maybe I should do a track day and AutoX with the new swaybar first.

[M0nk3y]

I'll get my information in here after work later tonight. Didn't forget about you guys.

Typically, sway bar is the last thing you need to adjust

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[derbo]

I'll get my information in here after work later tonight. Didn't forget about you guys.

Typically, sway bar is the last thing you need to adjust

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Cmon Kyle you are slipping! :)


Plans are to buy the TMS bars but I think I will do a track day without them and run the UUC sway at few settings to see how I like it. :)

[M0nk3y]

Hey guys,

I would love a discussion about the optimal sway bar configurations for track days. Kyle brought the topic when I believe John bought only a front Hotchikis Bar. I am currently in the market to replace my front UUC 330i sway bar and rear OEM m3 sway bar. I am planning to sell the UUC 330i sway bar set and have a new setup.


1. Front Bar Stiff, Rear bar OEM/soft
2. Front Bar Medium, Rear bar Stiff


I see config 1 being slower on turn in, but allows the power to be put down faster on exit. This seems optimal for auto-x but I don't know enough to say it would benefit track days with the 330i having so little power.

config2 seems to be better for the 330i but I can see it being an issue for the M3 not being able to put the power down after the quick turn-in.




Kyle,
I would love it for you to chime in.

My fault! :(

I'm very good friends with the Internet Manager @ TCKline in Columbus. I've talked with him heavily about sway-bar set-ups.

Initially, I wanted to get a front/rear match set for my car, and Eric Maxwell, refused to sell me a rear bar. He told me "If you want to give me money, go ahead, but I would never run a rear bar"

Just to clarify, Eric Maxwell has raced Z4Ms, E36s...etc and never ran a rear bar. He actually removed them.

Kale, the internet manager, told me that TC Kline's theory is that if you make the suspension too stiff, you won't be able to get weight transfer, which equals grip on the real wheels.

You'll see a lot of cars lifting front wheels, which actually benefits what I was told above. The inside wheel, is off the ground which equals no grip. Obviously the grip needs to go somewhere, so it is transferred to the inner rear wheel.


I can see #2 giving you trouble if you run an open diff, since you'll reduce this weight transfer and may spin the inner wheel.


If you want some professional opinions. I suggest you call TCKline racing. They are awesome people that are willing to help people whether or not you're buying from them

[LivesNearCostco]

So mmmmmm.... TC Kline's shop is saying it's a good thing I didn't buy the Hotchkis rear bar?

[derbo]

Thanks Kyle! I was just pushing your response about it :)


My specs currently is this:

Ground Control Coilovers + Swift Springs F 448lbs/in R 560lbs/in
Camber F -3 R -2
Toe F -0.02' R 0.11'
UUC Front 330i Sway bar (I believe set to medium if I remember correctly)
M3 OEM Rear Sway bar

I did install an M3 rear end so that is yet another variable to the characteristic change of the 330i now.


Sounds like I may need see if my front sway can go to full stiff and see how it feels.

[M0nk3y]

You certainly have enough camber to try full stiff. There becomes a law of diminishing returns if you have limited camber and try to throw a huge bar on the front, you'll create an understeer pig

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[LivesNearCostco]

Was going to ask you folks if I should move my Hotchkis bar to medium stiff before AutoX this Saturday... I believe it's slightly stiffer than the UUC sway. My spring rates are slightly lower than Derek's and my camber also slightly less negative (around -2.9F, -1.9R). But my tires are not as sticky.

Is it correct to assume that
--Stickier tires can handle stiffer swaybar?
--More negative front camber can handle stiffer front swaybar?
--Going to stiffer springs means should make swaybar less stiff?

[derbo]

Was going to ask you folks if I should move my Hotchkis bar to medium stiff before AutoX this Saturday... I believe it's slightly stiffer than the UUC sway. My spring rates are slightly lower than Derek's and my camber also slightly less negative (around -2.9F, -1.9R). But my tires are not as sticky.

Is it correct to assume that
--Stickier tires can handle stiffer swaybar?
--More negative front camber can handle stiffer front swaybar?
--Going to stiffer springs means should make swaybar less stiff?

Did you end up making it stiffer in the front?


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[LivesNearCostco]

Yes and not sure if it has more or less grip than at soft. Ran soft at Laguna Seca and it felt good. Ran medium for AutoX and it felt good. Conclusion is that both soft and medium on Hotchkis front bar are better than stock bar, but not sure which setting is better. Next steps are...
1) Practice looking ahead at next AutoX
2) Practice driving closer to tires' limit more of the time
3) Wear out XtremDW tires and buy either Hankook R-S3 or Bridgestone RE-11a

My thinking is even if the medium stiff setting is not faster now, it will be better than the soft setting once I get better tires.

[M0nk3y]

Yes and not sure if it has more or less grip than at soft. Ran soft at Laguna Seca and it felt good. Ran medium for AutoX and it felt good. Conclusion is that both soft and medium on Hotchkis front bar are better than stock bar, but not sure which setting is better. Next steps are...
1) Practice looking ahead at next AutoX
2) Practice driving closer to tires' limit more of the time
3) Wear out XtremDW tires and buy either Hankook R-S3 or Bridgestone RE-11a

My thinking is even if the medium stiff setting is not faster now, it will be better than the soft setting once I get better tires.

Avoid RE-11a tires. Rated nice on tirerack, and that is where it ends. Look into Dunlop ZIIs

Medium stiff now with OK tires currently will overpower the tires and limit grip. Keep it on soft until new tires are on.

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[LivesNearCostco]

What is the downside of RE-11a tires? In a recent Tire Rack test, they showed less dry grip than the Star Spec ZII or the BFG Rivals, but had less road noise for street driving. Since should be dedicated track tires, I was thinking road noise is not my biggest concern.

Do they not handle heat well?

[M0nk3y]

What is the downside of RE-11a tires? In a recent Tire Rack test, they showed less dry grip than the Star Spec ZII or the BFG Rivals, but had less road noise for street driving. Since should be dedicated track tires, I was thinking road noise is not my biggest concern.

Do they not handle heat well?

They hate heat, and cannot hold grip for long.

In sweepers, for example, the tire will hold, and release and give up grip. You have to back down and let the tire settle down before regaining threshold grip, and it will start to grip again....but it will let go early. It cannot hold grip throughout a turn, only early.

I didn't like them when I drove on them

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[LivesNearCostco]

thanks for the tips! Guess my next tires need to be StarSpec IIs or Hankook R-S3s.

[derbo]

I really liked the re11 vs my star spec 1 but that was the old generation. I want to try the star spec 2s


Sent by Mobile

[derbo]

bump since the topic arose again and I didn't replace my front bar yet.

[M0nk3y]

Well, in my opinion....I didn't like the Z2s

As well, my earlier posts regarding a rear bar...I have since added one to remove understeer

[derbo]

Well, in my opinion....I didn't like the Z2s

As well, my earlier posts regarding a rear bar...I have since added one to remove understeer

On the 1?

[M0nk3y]

On the 1?
Yes, on the 1

The Z2s are hard,IMO to drive at the limit.

The hard sidewall encourages quick responses, but when the tire reaches ultimate grip there is a very quick fall off and the tire cannot recover.

I have 1 event on the new RS3s and they are much, much better

[derbo]

Thanks for the review Kyle. Will have to look into the RS3s when my tires go out. Have you tried the RE11A yet?

[M0nk3y]

Thanks for the review Kyle. Will have to look into the RS3s when my tires go out. Have you tried the RE11A yet?
I've driven on them with a Miata. Not really that impressed....not a top competitor of the go to tires IMO

[derbo]

I will have to try RS3s.


My current sway bar setting:

Full Stiff UUC front non-M sway bar

stock M3 rear bar.


The front feels planted and ultimately there isn't much understeer.

[JohnBlaze]

I used to auto-x a lot with a 3.46 and 3.38 open diff and was always competitive. I ran both TC Kline DA's and AST 4100's on varying spring rates from 500-550F and 550-650 R. Once my spring rates were that high the number one mod that had me gaining real time on people I had always benchmarked around the same times was removing the rear swaybar. It goes like this, when your car is leaning hard the sway bar picks up the inside rear tire causing the one wheel peel. Without the rear sway and stiff rear springs the inside tire stays in contact more and helps get power down through turns, and a stiffer front sway will help too.

[derbo]

I used to auto-x a lot with a 3.46 and 3.38 open diff and was always competitive. I ran both TC Kline DA's and AST 4100's on varying spring rates from 500-550F and 550-650 R. Once my spring rates were that high the number one mod that had me gaining real time on people I had always benchmarked around the same times was removing the rear swaybar. It goes like this, when your car is leaning hard the sway bar picks up the inside rear tire causing the one wheel peel. Without the rear sway and stiff rear springs the inside tire stays in contact more and helps get power down through turns, and a stiffer front sway will help too.

This is pertaining to an open diff right? With an LSD, it seems like it wouldn't matter.



I just bought Matt's Hotchkis front sway bar.


its a 30mm front sway bar.. oh man.. :)

[Smilez]

Btw I have hotchkis and eibach and h&r sway bars. :P

[derbo]

Btw I have hotchkis and eibach and h&r sway bars. :P

LOL Ray.

[M0nk3y]

This is pertaining to an open diff right? With an LSD, it seems like it wouldn't matter.



I just bought Matt's Hotchkis front sway bar.


its a 30mm front sway bar.. oh man.. :)
Yea with an open diff a rear bar would be quite intrusive

[derbo]

Yea with an open diff a rear bar would be quite intrusive

I just installed the 30mm sway bar with it on the medium setting. I think the setup is a little bit much for the street. I test drove the car on the local mountain road , King's Mountain Road. I noticed on 10mph hairpins, the car understeered like a pig. I also realized my XP12s are terrible for the street as they can never get warm enough..and the dunlops felt like they never were warm enough.

I will leave the setup like this for now and test it at the track and see how it performs.

http://i.imgur.com/vUPmOUb.png

[M0nk3y]

Do you have any temps for the Dunlops? They do not need much heat.

As far as the bar, 10 mph you're going to understeer regardless.

For example, from the data this weekend I had a 30 mph turn. The car pushed like a pig, but that is just the BMW way.

At higher speeds you should see a difference

[derbo]

Do you have any temps for the Dunlops? They do not need much heat.

As far as the bar, 10 mph you're going to understeer regardless.

For example, from the data this weekend I had a 30 mph turn. The car pushed like a pig, but that is just the BMW way.

At higher speeds you should see a difference

That's what I figured. I don't have temps on the dunlop but it definitely felt slippery up there. It might have been slippery conditions as well.

I hope I will see a good difference at the track.

[M0nk3y]

That's what I figured. I don't have temps on the dunlop but it definitely felt slippery up there. It might have been slippery conditions as well.

I hope I will see a good difference at the track.
Is this your first time out on the tires?

They have quite a bit of mold release that needs to come off. They need at least 2 full heat cycles to be their quickest

[derbo]

Is this your first time out on the tires?

They have quite a bit of mold release that needs to come off. They need at least 2 full heat cycles to be their quickest

They have been heatcycled at 3 track events already. They should feel grippy...lol

[M0nk3y]

They have been heatcycled at 3 track events already. They should feel grippy...lol
Interesting.

I'm going to chalk it up to either them not getting to temp or the surface conditions

[derbo]

Interesting.

I'm going to chalk it up to either them not getting to temp or the surface conditions

Yea I'm thinking because the road is mainly in the shade because of trees and relatively low speed, the tires did not get enough temperature in them. Also the road conditions weren't 100% clean so it was very ideal conditions. That road is not heavily traveled by the public so surface conditions could be the main culprit. I will continue to drive it on the medium setting to get a feel for it. :)

[rkneeshaw]

Bumping this primarily to revive the conversation.

Stock ZHP sway bar sizes are 23.5mm front and 18mm rear
Stock M3 say bar sizes are 26mm front, 21.5mm rear
M3 CSL sway bar sizes are 30.8mm front, 22.5mm rear
Most aftermarket non-m sway bars sets are 27mm front, 21mm rear
Most aftermarket M3 sway bar sets are 30mm front, 25mm rear

Until now a lot of the conversation has been around recommending a sway bar setup for someone with custom spring rates and lots of camber.

To create the most balanced car (or at least cut down on understeer as much as possible), what sway bar setup would you recommend for:
1. Stock ZHP suspension and stock alignment specs (I believe -1.5 camber front and -2 camber rear)
2. Stock ZHP suspension and aggressive alignment specs (-3 camber front, -2 camber rear)

Sounds like most are recommending a stiffer front bar, but leave the rear bar stock?
In my previous life with a FWD car, everyone wanted a larger rear bar to increase oversteer/reduce understeer, but that doesnt seem to be what everyone wants to do in our ZHP world?

And, what to make of this on Turners website:

We put together this special sway bar set for the SpecE46 racing class (SE46) and any other E46 that gets heavy track time. We use the 30mm M3 front bar combined with the 21mm E46 non-M rear bar. From our time racing the E46 in World Challenge, Grand-Am, and SCCA club racing we found that the E46 likes a stiffer sway bar and less spring rate. Taking the M3 front bar, which is solid, is exactly what we wanted. They are adjustable in the front (3-position) and the rear (2-position) to fine tune the handling. Bushings are included and new adjustable links are optional. These bars are crafted from a special spring steel that is both stronger and more resilient than competitive sway bars. They have been shot peened and heat treated, and feature precision forged ends.

Setup: The bars are adjustable so any driver can find an ideal setup for the type of driving they are doing. The sway bar becomes stiffer in the holes furthest from the end of the bar. The holes at the very end of the bar are the softest setting. We would generally recommend starting out with the front bar set to the stiffer setting and the rear bar positioned in the soft setting. Adjust to your liking from there.

[rkneeshaw]

To create the most balanced car (or at least cut down on understeer as much as possible), what sway bar setup would you recommend for:
1. Stock ZHP suspension and stock alignment specs (I believe -1.5 camber front and -2 camber rear)
2. Stock ZHP suspension and aggressive alignment specs (-3 camber front, -2 camber rear)


Anyone have any thoughts on this?

I'm tempted to pick up a M3 front sway and try it out. I'm due to replace my sway bar links and bushings, but dont want to buy new rear bushings if I'm going to end up going with a larger rear bar too.... not sure what to do??

[slater]

good bump. i was reading about this a few months ago and picked up a used M3 front bar for $45 shipped on ebay! have not installed it yet, but i picked up some poly bushings for it and some poly bushings for the stock rear bar. going to try out that setup with my bilstein PSS (also not yet installed...) and see how it goes...

peter

[sillieidiot]

hmm not sure about stock suspension. usually you either go with stiffer springs or sway bars. stock rates are so low, that i think you would need both bars still. are you running stock wheels too? what is the purpose for the car? usually you do everything else to try to reduce understeer and then add the sways last.

[tkundhi]

I just stumbled across this thread. I group (4) of us are setting up our cars now. HPDE experience on average is 15+ year. We've got varying degrees of experience setting up different M cars: E30, E36, E34, plus a vintage 911. There are 2 schools of thought, soft spring with big bars or stiff springs with soft bars. The comment from TCK are accurate, a suspension won't work if the tire aren't in contact with the track. Our group all uses the cars as DD and track, plus we're old so we want don't want ride quality to suffer. All four of us are leaning to soft springs and bigger bars.

Back to swap bars, I had a lengthy conversation with TC a couple weeks ago. He insist that the fastest track setup for an E46 is a big front bar with no or a soft rear bar.

Setups
M3 F / 330xi rear [sedan]
M3 F / stock rear [coupe]
UUC F/ UUC R [sedan]
stock F / stock rear [sedan]

I'll check with the other guys and see if they are willing to share the info we've put together. Sharing the swap bar information alone has limited value. We have some data on springs, wheel and tires too. We also have lap times from same day, same track that we compare. Once the cars are setup we will swap drivers and see if the differences are the driver/car or combo. Goal is to have the cars setup for 9/4 - 9/6 at Hallett. Come join us if you can.

[pawa_k2001]

Trying to read through all the threads regarding sway bars for 330i ZHP sedan. I have a E46 M3 that I track and I went with only a stiff front Hotchkis bar. This is what everyone runs and it works amazing with the 275 series tire square setup I have.

I just picked up a 2004 BMW 330i ZHP sedan and am interested in a sway bar upgrade, what I have is my stock E46 M3 front sway bar laying around. There are a lot of people on these forums saying that you need a set of sway bars, not just a front. This is the complete opposite of the E46 M3 forum. The way I see it, you add front grip by going with a square setup(my ZHP has that), this changes the balance of the car towards more bite on the front axle so the car can afford a front sway bar. I don't want to get a rear bar because like in the M3, I want to be able to put down the power. With a non-LSD diff, a stiff rear sway bar will be lifting up my inside rear tire even more and make the one wheel peel even worse.

I will be installing a E46 M3 front sway bar(26mm vs 23.5mm on ZHP) soon since it will not cost me anything. If I get more understeer, I will go back to stock sway bar. The current setup on my ZHP is:

- 18x8.5" ET38(square) Apex ARC-8 wheels
- 245/35/18(square) Michelin Pilot Super Sport tires
- Poly FCABs

Would be nice if I can swap top hats from a E46 M3 so I can rotate them to get 1.8 degrees camber up front.(what I did to my M3 before going with camber plates)

[sillieidiot]

Sounds like a plan. That's what I would try to. You can just punch out that alignment stud on our top hats to get some more camber too. Iono how much though.

[derbo]

I'm currently happy with my 30mm front (medium setting) bar and stock M3 rear bar on my car.

It isn't that great on the lower speed corners but my mid-high speed corners have vastly improved.

http://i.imgur.com/vNModGGh.jpg

I will have to try full stiff on the front one of these days..

[rkneeshaw]

I'm currently happy with my 30mm front (medium setting) bar and stock M3 rear bar on my car.


I'm trying to remember, you're running a square setup arent you?

[derbo]

I'm trying to remember, you're running a square setup arent you?

Ahh yes. Forgot about that. I'm running 17x8.5 arc8 245/40/17


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[sillieidiot]

don't you also have the m3 rear end?

[derbo]

don't you also have the m3 rear end?

Oh yea that too. [emoji23]


-Sent from Mobile

[thegenius46m]

Anyone have specs on a vert non-m rear bar? I hear the verts non-m's have the stiffest rear bars stock. Can anyone confirm if a regular non-m vert has the same thickness as a zhp vert rear bar? Would like to experiment with this one since they're virtually free.

[Galapolis]

If I'm not mistaken, the xi has the stiffest rear bar stock at 20mm.

[BMWCurves]

If I'm not mistaken, the xi has the stiffest rear bar stock at 20mm.

I am pretty sure the rear 330Ci convertible bars are 20mm as well.

https://www.ecstuning.com/b-genuine-bmw-parts/rear-sway-bar-20mm/33556751267/

[t.er]

Since this topic has been bumped, anyone have a Hotchkis M3 or GC front bar they're willing to part with?

[thegenius46m]

So realoem is showing that vert rear bar fits 325ci verts as well. Obviously it fits, just curious if it came on all verts? There are two 325ci verts at pick n pull near me and I kinda want to grab them since the bar would be virtually free from there lol. If I have to I'll bring a caliper to measure the diameter to confirm but would save me a trip if I could confirm now if those cars have it as well.