TC Kline - finally feeling the balance at Infineon

[jbass524]

I first modified my 335 suspension about 2 years ago with UUC swaybars. Big mistake but what did I know. The overstiff bar disallows a lot whats good about a BMW. Then I installed TC Kline DAs. good but not great.

I couldn't figure it out then after a lot questions and a little experimenting I realize that the swaybars are the cancer.

A BMW is beautifully balanced. Create a quasi-live axle suspension and with swaybars and it's not that same, beautifully balanced car. It's flat into turns but overall grip is reduced. Spring rate is increased and the stock sport dampers aren't good with it. Slower car now that's less comfortable...but a flatter .

TC Kline builds their suspension to leverage BMW handling so when I installed it with swaybar cancer still in the car I never really got the benefit that TC delivers. It was better on the track but not great.

I took out the front bar and put the little tiny stock one back in. Left the rear bar in so I could see what 1 modification at a time would do.

Get to the track this weekend and I am ready for a change. I dial in about -2.5 front camber, put my track wheels on and adjust the suspension: 8 clicks for compression ft and rr with 2 full turns for rebound, ft. and rr.

I could have dialed in some different settings but the over-stiff rear bar could create a bunch of over steer if I dialed in more grip in the front.

The feel was great. Superbly balanced with a bit of oversteer bias. What a pleasure. I could make the car do whatever I wanted it to. When it stepped out, I know it was going to before it did. So fun.

Now I need to get the stock bar back in the rear. I can then dial in more camber in the front tpo create more overall, beautifully balanced grip.

Can't believe it took almost 2 years to figure this out. Oh well.

[God]

I'm not an expert, but there is a trade off when you get a swaybar. Front sways reduce grip in the front, but increase it in the rear. The rear does the oppisite.
Swaybars are not cancer, i beleive what you are experencing is prefrance. You prefer the way the car drives with the stock swaybar. If they were cancer you wouldnt put the stock one back on, you would run no sway (wich some people do, i beleive they compensate with higher spring rates).
Also, did you adjust you sway? There is more than one setting.

[jbass524]

Originally Posted by God

I'm not an expert, but there is a trade off when you get a swaybar. Front sways reduce grip in the front, but increase it in the rear. The rear does the oppisite.
Swaybars are not cancer, i beleive what you are experencing is prefrance. You prefer the way the car drives with the stock swaybar. If they were cancer you wouldnt put the stock one back on, you would run no sway (wich some people do, i beleive they compensate with higher spring rates).
Also, did you adjust you sway? There is more than one setting.

Yes there is a trade off from ft to rr read the on -2.5 ft camber because of this. That's part of creating the balance. Given that what if I could create more grip in the front with more -camber? The rr would be looser. Why? The overly stiff bar.

This is also due to me not wanting softer springs.

You should also know a bar shouldn't be so stiff it is adding to spring rate. Also, an overly stiff bar has a live axle kind of effect by pulling up the inside wheel which in turn creates less grip.

A cancer for sure. Overly stiff bars made a car that was very balanced a little flatter but decreased grip. It was my fault for being naive.

The message is adjust your handling with a sway last.

[europeanspec]

What tires and spring rates are you on for your track days?

[jbass524]

400 / 500 with 18 x 9 Dunlop Direzzas. Can't fit a wider, square setup w/o rubbing. Would love to try more spring but it's my DD too.

[europeanspec]

Yeah, you just can't go with a very high wheel rate with street tires. You need a little weight transfer and lean to get them to hook up.

[jbass524]

Originally Posted by europeanspec

Yeah, you just can't go with a very high wheel rate with street tires. You need a little weight transfer and lean to get them to hook up.

Exactly

[God]

Well, i dont know why all the e36's winning the solo's in scca have a 28mm front sway.

Originally Posted by jbass524

The message is adjust your handling with a sway last.

That is why a sway is more preferance than cancer. It is comon to pic your sway after the rest of your car is set up, and you can adjust the sway to make the car handle the way you want it to.

[OppLock1]

technically, you can even run NO sway bars and just up the spring rates to compensate. i've heard of some speed world challenge cars running no sway, but massive spring rates. i'd rather keep stock sway bars and spend less by changing out the springs.

[genocide98]

Originally Posted by jbass524

Yes there is a trade off from ft to rr read the on -2.5 ft camber because of this. That's part of creating the balance. Given that what if I could create more grip in the front with more -camber? The rr would be looser. Why? The overly stiff bar.

This is also due to me not wanting softer springs.

You should also know a bar shouldn't be so stiff it is adding to spring rate. Also, an overly stiff bar has a live axle kind of effect by pulling up the inside wheel which in turn creates less grip.

A cancer for sure. Overly stiff bars made a car that was very balanced a little flatter but decreased grip. It was my fault for being naive.

The message is adjust your handling with a sway last.

Yes, sway bars are a means to adjust to taste. My uncle drove his e30 m3 for years with a huge bar in the rear before one day deciding to leave it off. He never went back... sits in his trunk to this day, even tho he doesn't drive it at all.

Due to misinformation, or ignorance, people think sways are usually a good first upgrade. The problem is while the car might FEEL faster, and it might even be faster with a stock suspension, when you start modifying the rest, changing the ride height and spring rates, you actually lose a lot of what you gain with the sways on stock suspension.

With a good set of coilovers and fresh bushings you can really dial out most of what the swaybars are commonly used to bandaid. Then, if you still have too much roll work your way up a size or two on the sway front until you find a compromise between the driver's need and what is faster on the track.

So yes, misinformation and ignorance in relation to sway bars is definitely a cancer of the automotive enthusiast world. That, fart cans, ugly HIDs/altezza lights, and unnecessary spoilers.

[=BA=]

Fat swaybars are a good upgrade for roadcars, they eliminate some roll but still give you a comfy ride at high speeds, as driving over high speed bumps are not as harsh. Usually this can create a sporty feeling without beeing overly harsh. BMW do this themselves, ie on a E36 M3 about half of the roll stiffness is from the stock swaybars already.

There are various drawbacks however. You lose a bit of traction with bigger swaybars. Also when you use them with otherwise stock suspension, the difference between pitch and roll stiffness will become very big and you need to make sure the dampers can space the gap. Otherwise roll will be underdamped and pitch is ok, or damping in roll is ok but pitch is way overdamped.

Typically in professional racing you could pull some trick with swaybars and spring combinations, ie when braking zones are bumpy it could be an advantage dropping the front springrates a bit and make up the difference with a bigger ARB. However not many people on these boards are working on that level. Most put on a suspensionkit and be done with it.

I run my E36 trackcar on stock swaybars with a race oriented suspension system, and never felt the need to go with thicker swaybars.

[God]

Originally Posted by =BA=

Fat swaybars are a good upgrade for roadcars, they eliminate some roll but still give you a comfy ride at high speeds, as driving over high speed bumps are not as harsh. Usually this can create a sporty feeling without beeing overly harsh. BMW do this themselves, ie on a E36 M3 about half of the roll stiffness is from the stock swaybars already.

There are various drawbacks however. You lose a bit of traction with bigger swaybars. Also when you use them with otherwise stock suspension, the difference between pitch and roll stiffness will become very big and you need to make sure the dampers can space the gap. Otherwise roll will be underdamped and pitch is ok, or damping in roll is ok but pitch is way overdamped.

Typically in professional racing you could pull some trick with swaybars and spring combinations, ie when braking zones are bumpy it could be an advantage dropping the front springrates a bit and make up the difference with a bigger ARB. However not many people on these boards are working on that level. Most put on a suspensionkit and be done with it.

I run my E36 trackcar on stock swaybars with a race oriented suspension system, and never felt the need to go with thicker swaybars.

I put on an H&R front sway, and as you can see in my sig there is still lots of lean. The total amount is reduced though.
The problem i had before my say was that it was harder to exit a turn while the car was leaning so much. So with the stiffer front bar i feel i am entering the turn a little slower, and going through it a litte slower. I then have a greater exit speed though, because i can give it more throttle out of the turn.
I also think in some of the sweeps (expecialy after tight turns) i can be at full throttle while going through the turn, because i get more traction.
I am a rookie for sure and i should prolly focus driving skill, but will say that with the way i currently drive, my sway brought my times down.

[=BA=]

Originally Posted by God

I put on an H&R front sway, and as you can see in my sig there is still lots of lean. The total amount is reduced though.
The problem i had before my say was that it was harder to exit a turn while the car was leaning so much. So with the stiffer front bar i feel i am entering the turn a little slower, and going through it a litte slower. I then have a greater exit speed though, because i can give it more throttle out of the turn.
I also think in some of the sweeps (expecialy after tight turns) i can be at full throttle while going through the turn, because i get more traction.
I am a rookie for sure and i should prolly focus driving skill, but will say that with the way i currently drive, my sway brought my times down.

That is because your car rolls more than a ocean liner

That much roll will have an influence on camber etc, as you can see in your sig the outside wheels are actually on positive camber. Keeping the body flatter will reduce this effect and making grip better. Also with just a front sway you are shifting roll stiffness to front bias, unloading the rear tires somewhat so you get a more stable rear end.

If you aready have a proper suspension kit for race use, and alignment for track use, there is so little roll that the effect of the swaybars is not so big anymore, they are just used to finetune balance then. Wheels don't go into positive camber anyway etc.

[God]

Originally Posted by =BA=

That is because your car rolls more than a ocean liner

LOL, this is true.

[///M3Augy]

Originally Posted by God

I'm not an expert, but there is a trade off when you get a swaybar. Front sways reduce grip in the front, but increase it in the rear. The rear does the oppisite.
Swaybars are not cancer, i beleive what you are experencing is prefrance. You prefer the way the car drives with the stock swaybar. If they were cancer you wouldnt put the stock one back on, you would run no sway (wich some people do, i beleive they compensate with higher spring rates).
Also, did you adjust you sway? There is more than one setting.

That's completely false. On an E36 a bigger front sway bar increases front grip....

[=BA=]

Only in certain circumstances, ie when you have mega bodyroll the reduction in bodyroll keeps the wheels in a better part of their cambercurve.

If that is not the case a front bar will not give you more grip.

Ie this is about as much roll I get, stock swaybars, in a 1,6G turn:



Front swaybar would not do a lot for me except shifting the handling to more understeering balance.

[Aarodynamics]

^^^ what spring rates are you running on your track car?

[=BA=]

Think I was on +/- 950F and 450R on that day if I recall correctly (rear coil over)

[Fair]

I don't usually post in this sub-forum, but someone asked me to take a peek in this thread. I admit - I'm not claiming to be a swaybar guru, and I have no preference towards one brand over another. Its a piece of tubular steel with some bends and holes in it. One of the dumbest, simplest suspension pieces on a given car.

Originally Posted by God

I'm not an expert, but there is a trade off when you get a swaybar. Front sways reduce grip in the front, but increase it in the rear. The rear does the oppisite.

Not an expert? For someone with the audacity to use "God" as his screen name, you sure are being humble.

A lot of this is feel, and testing is irreplaceable, but after two decades of autocrossing and many years designing suspensions for BMWs I can usually see a picture of a car in a loaded corner and tell if it needs a bigger swaybar. This is one of the reasons we take a lot of pictures at all the events we go to.



The car in your sig, for instance, is in dire need of a more front roll stiffness. I'd double or triple the spring rate you are using, for starters, and use a lot more front bar, too. Look at me - telling God what to do. I'm going to Hell for sure!

H&R Race springs are not springs I would ever recommend for autocrossing. They are more suited for the hard parking crowd... sorry. They are way too soft, and allow too much bodyroll, which causes most of the front camber to be lost right at turn-in. It might even "feel" neutral, but I can tell from the picture alone you are giving up a ton of front end grip. That outside front tire is deep into the positive camber realm.

This flies in the face of "conventional internet wisdom", which is often wrong in practice. Which is = "big front bars make the car push" or understeer. When in fact the opposite is often true... this has more to do with maintaining front end camber under load, than roll couples or textbook roll stiffness calculations. The first thing most Stock class autocrossers do to combat understeer is to put the largest front bar on money can buy - and even that isn't big enough for some racers, who have bigger ones custom made.

People argue about rollbars than they need to. If they ran even remotely close to the ballpark of spring rates they needed, then swaybars would end up as little more than a tuning tool, and not the crutch for lack of spring rate.

Originally Posted by God

Swaybars are not cancer, i beleive what you are experencing is prefrance. You prefer the way the car drives with the stock swaybar. If they were cancer you wouldnt put the stock one back on, you would run no sway (wich some people do, i beleive they compensate with higher spring rates). Also, did you adjust you sway? There is more than one setting.

Again, its often a preference thing - do you go with crushing spring rates or less spring rate and more swaybar? I like to do stiffer spring rates and big bars, then fine tune the bars for changing conditions/tracks/etc. Its usually easier to adjust a bar (~120 seconds) than changing springs out, especially at an autocross where things happen very fast.

Yes, with a bigger bar (when set on stiffer adjustment holes) you lose some suspension "independence" on that axle, and the ride quality can even go down. Soft springs and soft bars = soft ride. But that's for stock vehicles, not enthusiasts and especially not racers. The roll stiffness does go up with the stiffer settings. This is why many road racers go with stock, smaller, or even no rear bar. This allows the rear stay fairly soft to maximize rear grip, but again, there's a tradeoff in other areas, and a lot of "personal preference" goes into in this "no rear bar" setup. We've tried it on BMWs and I don't like the way it feels in transitions without a rear bar, or with softer rear rates. Doesn't work as well for autocrossing, which has lots of transitions.

Not as big of an issue on a road course, where everything..... happens.... so.... slowly... but on an autocross course there isn't a "ten count" between corners, and when you turn the wheel the car has to respond NOW. Some autocrossers even swear by this setup, though. I cannot stand to drive these squishy cars, usually. The front end usually has more problems to deal with, and more agreement is to be found on front rates than rear, on BMW setups.



I'm still trying new stuff on these cars every year, too. We tried a tiny stock rear bar (and huge H&R adj. front bar) on an E30 that had no LSD (by class rules) and ended up with rear spring rates softer than we normally use, too. This was from testing - I kept swapping springs and let the clock tell us what was faster (rear spring rate changes alone made 1 full second difference on our test course). It worked well on that setup, but it had custom-built triples on the back to help tune out some of the soft rear nastiness.

Swaybars are often used as a crutch for soft spring rates. In reality most BMWs that are tracked heavily or autocrossed competitively need bigger (adjustable) bars and stiffer spring rates, front and rear. That's my opinion after years of testing, but it is my opinion and not meant to be definitive. BMWs come from the factory with stupid soft spring rates. For competitive autocrossers we usually recommend 5x to 6x the stock spring rates, with high end monotube adjustables. For a more supple street ride, though, we tend to use 3x to 4x the spring rates. Don't use more spring rate than your shocks can deal with - ask your shock supplier for the limits.


Making over 1.2g lateral on 180 treadwear street tires. Notice the front camber control and lack of body roll. Rear could use a touch more camber from this pic, tho

Originally Posted by europeanspec

Yeah, you just can't go with a very high wheel rate with street tires. You need a little weight transfer and lean to get them to hook up.

Well, that's debatable. Its hard to make these blanket statements without the data to back it up. My wife won two ST auto-x championships (plus I managed two top 10 trophies in it) on street tires in a BMW with relatively "high" spring rates (higher than anyone else was running in that class/car at the time). Testing was what dictated these rates, not theory or guesswork. She won her class one year on TCKline doubles and the next year on AST doubles. 600 #/in F, 750#/in rear springs were used on both setups. She even outpaced the Open class one of those years on one course. She still drives it to work every day on these rates and the AST 4200s. But yea, on a car with real R compounds, especially track cars, the rates can go up considerably from there. Our Alpha car's track setup had 900 #/in rates on 315mm Hoosiers, and weighed only 2600 pounds.

OK, that's all I have to say on that. I'm sure someone will say I'm 100% wrong, but that's a given.

Thanks,

[=BA=]

The debate thick swaybar vs big springrates is something which will probably go on forever. I think the optimum solution is not always easy unless you have very track specific data.

I've tried both ways with my cars and balance wise you can achieve very good handling both ways.

As for the adjustability which swaybars give you, we have actually solved that in a different manner:



The lower collar allows you to lock in the lowest ring of the spring in 4 different positions, giving me adjustability between roughly 850 lbs/in and 1200 lbs/in on the fronts and 350 lbs/in to 570 lbs/in. (obviously I use metric springs but rates converted to imperial to make it easy)

It's a part made by Intrax in Holland but I have seen some made by H&R as well on their motorsport stuff.

[Fair]

Originally Posted by =BA=

The debate thick swaybar vs big springrates is something which will probably go on forever. I think the optimum solution is not always easy unless you have very track specific data.

Agreed. Many ways to skin this cat...

Originally Posted by =BA=

The lower collar allows you to lock in the lowest ring of the spring in 4 different positions, giving me adjustability between roughly 850 lbs/in and 1200 lbs/in on the fronts and 350 lbs/in to 570 lbs/in. (obviously I use metric springs but rates converted to imperial to make it easy)

It's a part made by Intrax in Holland but I have seen some made by H&R as well on their motorsport stuff.

Pretty slick stuff! Very clever, those Dutch.

That might not work on all E36 setups, of course. On the E36, as with many McStrut front suspension setups, its sometimes critical to get the entire spring package and lower perch above the tire, to maximize inboard tire/wheel room. If you don't want to run a widebody setup or flares with wide tires, it would be tough to run a tall spring perch setup like that without compromising tire clearance considerably.


This is a heavily fender rolled E36 325i with 18x10s and 285/30/18 tires. Every millimeter of room counts on this setup

I just spent several hours last week working on a customer's E36. It was relatively easy to get his suspension setup to work with 255mm tires on 7.5" wheels, but quite another thing entirely when we put the 18x10" wheels on. The front had to come up .75" to get the spring package above the tire (but it was too low beforehand).

Again, not to take anything away from that Intrax setup - that's very cool if you have the budget and tire room for it. Thanks for posting that, BTW. Just know that package might not work for everyone, especially crazy Americans that run big tires without flares.

[=BA=]

Hehe We actually run 17x9 ET25 wheels under there, without flaring. Altough we use a pretty low profile tire, only 610mm tall.

What they have done with the front struts is make the bottom mounting points longer, bottom one slightly longer than the top. This way the strut sits nearly vertical and you get a lot more clearance over the normal setup. The car actually already has 4 degrees of negative camber with the camberplates sitting in about the centre of the hole in the strut tower (altough that is hacked up as well on mine, they put in a plate with the opening off centre, this way we can get 5 degrees of camber while still running 7 degrees or so caster)

If you look at this picture, look at the points where the spindles go (different shock type but same idea):


That shows the bottom mounting points are a lot bigger as you would see in off the shelf kits

[jbass524]

Glad I wrote this up. Great stuff. Helps me understand why I believe some things work for me and why some things don't. BTW, My vorshlag plates are a big part of why I love my setup...besides the giant sway. I cannot recommend them enough.

Based on my Direzzas, tracks I drive at - Laguna, Infineon and T-Hill- my driving style and my car I have never been more sure that the TCK DAs w/400/500, stock bars, Vorshlag plates are exactly what will make the happiest.

I go 1:58 at Infineon and feel like there's another 2 seconds in my car if I never progress as a driver. I might jump up and down like a little girl if I went 1:56 on street tires. Don't laugh if you see me.

Love = BA = car and info. Thanks for your input Terry.

[Aarodynamics]

Big thanks to BA and Fair!!! Great thread you guys.

[God]

Originally Posted by Fair

Not an expert? For someone with the audacity to use "God" as his screen name, you sure are being humble.

Well im not a christian, and GOD to me is not GOD to you or the next guy. Its all relative, and i didnt mean to affend anyone. To be honest it was an accident (my screen name that is), i have contemplated changing my name because i get F***ed with all the time.

The car in your sig, for instance, is in dire need of a more front roll stiffness. I'd double or triple the spring rate you are using, for starters, and use a lot more front bar, too. Look at me - telling God what to do. I'm going to Hell for sure!

I am aware that my car needs a lot, and i just dont have the funds. Given i had enough money to spare, i am confident i could build a very compitent car; but i am more confident that i would make mistakes, and thats where i would learn from experience.
Though i will say that the sway seems to have yeilded less grip in the front (not a huge difference). The only reasons i think i could be mistaking this is:
1- i replaced all me rear bushings, and put in an lsd (at the same time as the sway), somehow making it feel like its pushing
2- the last two autocrosses were colder that when i didnt have the sway, so my tires just wernt heating up as well
3- its all in my head and im an idiot

Again, its often a preference thing - do you go with crushing spring rates or less spring rate and more swaybar? I like to do stiffer spring rates and big bars, then fine tune the bars for changing conditions/tracks/etc. Its usually easier to adjust a bar (~120 seconds) than changing springs out, especially at an autocross where things happen very fast.

I completely agree. Though i would say i dont even know what i prefer, i just know i dont like my current setup.

Not as big of an issue on a road course, where everything..... happens.... so.... slowly... but on an autocross course there isn't a "ten count" between corners, and when you turn the wheel the car has to respond NOW. Some autocrossers even swear by this setup, though. I cannot stand to drive these squishy cars, usually. The front end usually has more problems to deal with, and more agreement is to be found on front rates than rear, on BMW setups.

I honestly, to some extent, almost said this. When i thought about it though, i havnt done any road racing, so i didnt want to speak to anything i had no experience with.