swaybars:st or tanabe?

[suprageezer]

I agree its not just a bunch of parts. Once you install sway bars it really makes your tires work harder. If you have high milage tires (harder rubber) and expect more grip it's not going to happen. This is the reason I believe theres only one thing between your ass and the road, your tires, so never go cheap when your looking for grip using sway bars.

 

[suprabad]

your suspension has to be seen as a system, not just a bunch of parts...

Most definitely...
As I said I was "simplifying" the explanation and only addressing swaybars and whether it was possible to have too stiff of a swaybar.

I'm not going to be able to explain the geometry of double wishbone suspension and it's characteristics when affected by all the vaiables, (weight transfer, camber and caster change under load, component variables etc.) and swaybars affect on the equation in one post. It's taken me years and I'm still learning everyday.:icon_bigg

 

[cuel]

Thanks for the link, Poodles

 

[stevenr816]

this is a very good topic, i'm getting ready to buy a pair myself, and so far am voting for the st's

 

[tekdeus]

I am keen to buy a set soon as well. Still undecided...

 

[IJ.]

I run my car as soft as possible in the vertical plane and let the swaybars handle the body roll as it makes for a much more comfortable GT car.

Most guys here run a much higher rate on coilovers than I do but I find my way works for me and how I use the car (I think NOTHING of doing 1000km's on a Sunday drive)

 

[Grimsta]

<----- has 18kg front & 14kg rear springs. So my stock sways have been good so far. I also have good tires and so i think a move to the Tanabe's will be good since those are the "in the middle" bars. I need the stiff coils for what i do, i've tried others and it made my life hell. The Megans have treated me very well

 

[IJ.]

^ It's all about how the package works as a system Grim

Your approach while different to mine works for you it's when people don't quite get it and try and run your spring rates on normal shocks not valved for them where it turns to shit.

 

[Wiisass]

Exactly, it's all a system.

Personally, for track cars, I like stock or possibly softer than stock. Stock bars are usually decently stiff because they are normally on softly sprung cars and to give the cars any feeling of handling, you need a decent sized sway bar to cut down on body roll. While this may work to cut down on body roll, it doesn't help too much for total grip because of the way sway bars unload the inside tire and transfer load to the outside.

For a track car, I like the smallest bar that you can get that will allow you to adjust the understeer/oversteer balance of the car. I prefer to have the basic balance dialed in with the springs and then with the addition or removal of a front or rear bar to adjust the balance if necessary. Or the addition of both bars, very similar wheel rate addition, to increase overall roll stiffness a little. But this also depends on what spring rates you can get away with considering how much power you're putting down, the type of track, and all of that.

For a street/fun car, stiffer sway bars are usually the best way to cut down on body roll especially if still using soft springs. The negative effects are usually past the range of driving, so the bars work as a nice compromise. You won't be able to get the most grip out of the setup with big bars, but most people who would be running a setup like this, aren't pushing the car to it's limits like that anyway.

As for Tanabe versus ST, I don't know if everyone missed the thread I made the other day about trying to borrow bars for testing, so we can know what rates the bars actually have. I have seen some %stiffer numbers, but who knows how those are calculated. If they're calculated just on the difference in OD, then they're probably way off especially for hollow bars without known wall thickness. And who knows how stiff the stock bars actually are. I'm working on gathering as many different sway bars as possible, so the rates will be known and we can make more educated decisions on our setups. Right now it's like "pick your favorite color" and run that bar or those springs, it's a mess and I don't think it should be like that anymore.

Tim

 

[IJ.]

Tim: Thanks I'd hoped you would post in this thread

 

[tekdeus]

I agree Tim. I feel a little in the dark about which brand to choose, and I know it's important, since everything else I'm running is top-notch. I suppose adjustable bars may be a good choice since you're not stuck with one setting.

IJ: Which bars are you running?

 

[IJ.]

The Prototype Whitelines from 1997

 

[Grimsta]

Nice Tim! You got your official Expert status, sweet! I'll just leave the stock ones one until i exceed their capabilities.

Back to the "system" point. Thats why i went with stiff springs and dampers over sways, because although the sways could keep tires planted, the springs and damper would still compress creating body roll. I personally dont like driving with that amount of spring compression and so I stiffened it up at that point. So now its the lack of spring compression that transfers that body weight that used to be taken up by compression and roll to the tires.

 

[Sawbladz]

I would like to get the input of you guys. I plan to do some minor tracking of the car next summer and I wonder how well the car will behave. Keeping in mind that I drive it on the street 90% of the time.

Currently I am running H&R springs and Tockico struts with stock sways. I will have full poly bushings and some LIPP traction arms. Since the H&R spring is progressive I understand it isn't ideal for the track but it's what I have to work with. I also know that I should have the springs paired with a stiffer strut such as the Bilsteins or the Koni's. However, I bought these used as a package for a great deal so I can't complain.

From what I understand my car will have alot of body roll. Would upgrading to the Whiteline bars make the car capable on the track while still being a good street car? I understand that this in not the ideal setup for the track since the stiffer sways would be merely putting greater load on the outside tires.

 

[Grimsta]

Greater load = more traction, more traction = good.
But it also = more stress on the tires so make sure you have some real good tires

What you dont want to do is pick up a tire like IJ

 

[IJ.]

Grim: LOL shhhh it only does it at the very extreme limit of grip
(by that stage it's actually hurting physically so I back off a bit, I'm oldNfragile)

 

[Wiisass]

Greater load = more traction, more traction = good.

But only too a point. It depends on how load sensitive the tire is. With most tires, as the load increases the effective coefficient of friction of the tire decreases. So you approach a point where more load is able to produce less lateral force. And also remember than an evenly loaded pair of tires will produce more grip than a single, fully loaded tire.

Tim

 

[Dimman]

http://www.tanabe-usa.com/stabilizers/default.asp

Tanabe's are hollow chrome-moly and diameter is bigger than ST bars.

30.4mm front Tanabe vs 28mm front ST.
25.4mm rear Tanabe vs 24mm rear ST.

Stiffness of the bar is based on hollow/solid and diameter, but diameter has bigger effect because outside of the bar resists most of the torsion(?). Don't know the exact relation, though. And leverage of the link, too (?)

Can someone clarify this for me?

Thanks

 

[Wiisass]

You have the right idea. The center or a bar in torsion doesn't do as much as the outside of the bar. For this type of calculation you're working with diameter^4, so for all solid bars, you compare the diameters to the fourth power and you can estimate change in stiffness. But with hollow bars, you can't do this unless you know the inside diameter of the bar. It makes a huge difference.

So for example, say the inside diameter of the tanabe bar is 22.1mm, I don't know if it is or not, but just for example's sake. The tanabe bar with a 30.4mm OD and 22.1 ID would have the same stiffness as the ST bar with a 28mm OD. And the Tanabe bar would be about half the weight of the ST bar.

So that's with approximately 4mm wall thickness. Now if the bar were to have 6mm wall thickness. it would be 20% stiffer than the ST bar. So with just a small change in wall thickness/inside diameter, the stiffness of the bar will change.

Oh and since you mentioned it, the length of the moment arm will also change the effective stiffness of the bar. The different diameters and solid/hollow setup affect the actual rate of the bar in torsion. But the length of the moment arm determines how the force is resisted. A longer moment arm will effectively make the bar softer, while a shorter moment arm will make the bar stiffer. This is how adjustable sway bars work.

Tim

 

[Dimman]

You have the right idea. The center or a bar in torsion doesn't do as much as the outside of the bar. For this type of calculation you're working with diameter^4, so for all solid bars, you compare the diameters to the fourth power and you can estimate change in stiffness. But with hollow bars, you can't do this unless you know the inside diameter of the bar. It makes a huge difference.

So for example, say the inside diameter of the tanabe bar is 22.1mm, I don't know if it is or not, but just for example's sake. The tanabe bar with a 30.4mm OD and 22.1 ID would have the same stiffness as the ST bar with a 28mm OD. And the Tanabe bar would be about half the weight of the ST bar.

So that's with approximately 4mm wall thickness. Now if the bar were to have 6mm wall thickness. it would be 20% stiffer than the ST bar. So with just a small change in wall thickness/inside diameter, the stiffness of the bar will change.

Oh and since you mentioned it, the length of the moment arm will also change the effective stiffness of the bar. The different diameters and solid/hollow setup affect the actual rate of the bar in torsion. But the length of the moment arm determines how the force is resisted. A longer moment arm will effectively make the bar softer, while a shorter moment arm will make the bar stiffer. This is how adjustable sway bars work.

Tim

I emailed Tanabe and they got back to me with these specs:


Front: 30.4mm outer diameter; 22.8mm inner diameter
Rear: 25.4mm outer diameter; 19mm inner diameter

Useful?