goin with the H sport competition sway bar set, there adjustable and with lowering springs and camber plates it shoulld handle pretty well. does anyone know where to get the mounting U clamps and bushings for these bars? thanks

 

i know lots of people use anti-sway bars to control body roll so they can run softer spring rates, i think webb belows to this school of thought

 

I imagine the kit would come with all that stuff.

 

imagine if you were to disconnect both endlinks from the swaybar. you can now rotate one end of the swaybar freely and it will move up and down quite easily. notice there is nothing to resist its movement. now imagine BOTH endlinks PULLING on the swaybar... what happens? the sway bar follows the direction of pull until it hits something. notice that the ONLY way you can keep the swaybar in place if you apply a downward force on one side is to apply an UPward force on the other side. see?

this is perfect. why would they use a chain instead of an endlink if endlinks only pulled? wouldn't an endlink act EXACTLY like a chain and therefore make replacing it with a chain completely unnecesary? the reason the use a chain is to ELIMINATE the compressive force that an endlink would provide on that side.



this is true, the ENDLINK no longer contributes MORE. it is at its limit of contribution. but this does not mean it contributes nothing at this point. it contributes ALL it can. its at maximum contribution, to coin a term.


this is less true. although a binding endlink CAN cause this, it would exhibit other problems as well. MOST of the time this is due to a very stiff rear sway bar and softer or more compliant front bar that allows a car to lean far enough over that the rear bar will pick up the inside wheel since there is no more weight on it. it has NOTHING to do with DESIGN of the ENDLINK. perhaps he was trying to sell you some of his...


the gti had NO endlinks. it had a swaybar bolted directly to the rear twist beam axle (VW guys correct me it i am wrong). at least in my scirocco it was this way. the twist beam axle acted much like a huge swaybar with wheels attached to it. VW simply bolted the swaybar to the axle; it became a part of the assembly and increased the torsional rigidity of the whole axle. completely different system.

as far as a change in performance from endlinks, that is practically impossible. the only way you could gain any benefit is if your old ones were stretching or buckling under load. endlinks to not change the stiffness of the swaybar in anyway, they mearly transfer the forces from the bar to the suspension arm.

 

Re the VW...yes, you are correct as I owned a couple. not sure why Chip said this about wheels lifting; there are plenty of front and rear wheel driven race vehicles with a little air under either the inside rear or inside front.

So, did I explain myself correctly? Not sure I get that impression from your first quoted reply sonichris...as the car leans, the inside wheel extends pulling down the sway bar on that side causing the other side to pull up. If the leaning side in my orientation above caused that endlink to compress, it would also cause the other side to compress. The very origin of the operation is in question and determines eith tension or compression, not both...and not compression in my brain...but I'm old.

And yes, I agree if I wasn't clear here. Once the rear wheel leaves the ground the sway bar will contribute nothing more, meaning exactly that it has contributed all it can, not that it is off line. My poor choice of words...but I more than likely wrote this somehwere else with a little more clarity.

I still do not see how there is any compressive force in a sway bar endlink - re your chain analogy? If one side pulls up, the other must pull down. I understand your reply and its a great question. I don't have an answer...except that stock cars go in a circle and a chain will remove anychance of bind until it is needed???

If I were to merely thin slice this I would focus on the design and delicate nature of endlinks...these cannot absorbe compressive loads without deflecting or failing. They simply are not that strong.

The change in performance was the difference between heim joints and ball joints. A hiem joint has about half the articulating range a ball joint has.

another illustration; If I pull down on one side of the sway bar via an endlink, the other side of the sway bar pulls up.

 

aHA! it doesn't. it pulls down also. maybe this is where you are confused. both ends of the sway bar move in the same direction if there is nothing attached to them.

how about this... disconnect one endlink at the control arm and pull down. now analize the force on the other link... it is resisting the movement of the swaybar by... compressive force. it is acting UP on the bar resisting the DOWN force on the other side. equal and opposite.

 

Am I thick headed? I must like punishment...

Chris, Jasen,

My last statement suggests, in spirit, what you are asking me to try - they are one and the same. Except, I agree your results and not mine...foolish! The results will be as you state. However, and refer to thick headed above, are you suggesting that all of the twisting and weight transfer is funneled thru that tiny endlink on the outside rear wheel?

If you were to draw with arrows, beginning at X (X being the beginning of the path of weight transfer) where would your string of arrows begin and end - including rotation in the bar?

...and still, i'm not sure i believe the contribution when the wheel is off the ground...at that point the compressed side has all of the bar rate plus spring rate and the opposite side is at full droop or nearly so since the bar is working just a little to compress things. Sp where's the twist...beef? I don't do this for a living and so you guys are asking me to sort of second guess myself...

 

So does the bigger size of the sway bar make the car oversteer more, or is it the stiffer settings of the sway bar?

 

In the rear, a stiffer bar will, wether it be thicker or on a stiffer setting either way. In autocross, sometimes people in gstock (where you are not allowed to change the rear bar) will swap the cooper s front bar for a cooper bar, which is less stiff in order to reduce understeer.

 

our front bars are alot bigger than the rear from the factory. its like 25mm front and 17mm rear from the factory.

 

most competiton sway bar packages feature a thicker front sway bar, will this allow some understeer tocontinue to be a problem?

 

there's another sticking point. the spring force is not transmitted through the endlink. the force on the endlinks comes only from the swaybar. the MAGNITUDE of the force acting on the endlink is proportional to the diameter of the bar, the length of the lever arm (both irrelevant in this discussion as these remain constant) and how far the bar is twisting. that's it. no twist, no force. the force acting on the endlink is a function of how far the car leans over (or the difference in height of one side of the suspension to the other side). so, increasing the spring rate would make the car lean less in the turns (can we agree on this?). since the car is leaning less in the turns, the swaybar is twisting less, and thus transmitting less force on the endlinks.

so you see, those little skinny endlinks don't have a whole lot of force acting through them. the springs actually do most of it. that's why they can be so skinny and still be ok. now, if you put a massive swaybar on there, the force transmitted through the endlinks goes up. that's usually when you see these things buckle or snap - when you increase the swaybar diameter.

 

no. could you still have understeer? yeah, sure in some cases, but will it be enough to be a problem? no. I dont want to get to many different topics going here, if you want more info, PM me, and iwill try to explain it in more detail.

 

actually sorry man, i didnt realize you were the OP. This thread got way off topic on you, tomorrow night i will try to PM you about sway bars. I was going to go your route, then changed my mind. Dont really have time right now to go in depth, but i will try in the next day or two get back to you with some info about the pros and cons of big bars.

 

This is for sure turning into some interesting discussion, hopefully freeskier doesn't mind too much....I'm sure we can take this to it's own thread if need be....
Here is my take:
same situation, RH turn:
The body of the car naturally tries to roll to the left, forcing the suspension into compression (up into the wheel well) on the LH side. As the suspension travels UP (in relation to the body), it pushes the endlink UP with it. This push up on the endlink is what puts the outside endlink into compression. This compressive force on the endlink (pushing UP) is now trying to rotate the swaybar up in it's bushings.

Now lets look at the RH (inside of the car):
As the car rolls to the left, the suspension on the RH side tries to droop down. This downward droop (being pushed down by the force of the spring) now pulls down against the endlink, trying to pull (tension) against the swaybar, which tries to rotate it down.

The swaybar sees the outside trying to push it up, and the inside trying to pull it down. This is the torsion.
My thoughts on the swaybar's effectiveness once the tire lifts from the ground are like this:
The swaybar adds to roll stiffness due to the fact that it is linking both springs together, an infinitely stiff swaybar would double the spring rate because the suspension now has to compress BOTH rear springs.
Once the inside tire is off the ground, any further lateral acceleration is going to try to roll the vehicle more which is going to try to compress BOTH springs more due to the swaybar. Lets say for the sake of argument, the tire lifts at .8 g's but the car is still capable of pulling 1.0 g's. The lateral acceleration between .8 and 1.0 g's is causing more roll of the car, and that extra roll is still asking the swaybar to do work.

You might be really surprised how stiff the wimpy stock endlinks actually are. Up until they buckle at somewhere around 1600 Lbs of compression, they have a effective spring rate of something like 1000 times that of the springs themselves. In the view of the entire system, the endlinks actually do mighty good on the compression side.

I agree with this statement, the swaybar makes the outside (compressing side) have a stiffer spring rate that with the spring alone. Outside rear tire has lots of weight transfer, which means the inside front is is also "heavy".

I'm not too familiar with stock cars, so take this for what it's worth....I think the reason they can do this is because the car is only designed to turn left, so the chain is used instead of a solid link on the inside, which would only see tension anyways (assuming the swaybar is mounted on top like it is with our MINIs). This wouldn't hold true if the car was asked to turn left AND right.
I've heard that Chip makes a quality endlink and I don't question that, but I don't think he fully understands the mechanics of swaybars if this is what he is stating. I'm not trying to bash him or be disrespectful.

My experience with upgraded endlinks is different than yours, but who knows......
This isn't punishment, this is fun stuff!
Yes I am, I think you need to give that little old endlink a bit more credit, it is capable of doing a very large amount of work, not as good as a beefy aftermarket unit, but still a capable piece.
I'm on it.......

When the tire is off the ground, things get a bit simpler actually:
The swaybar and opposite spring are acting as two springs in series they can be treated as ONE spring with an effective spring rate somewhere less than either by itself
This ONE effective spring is working with the spring already on the outside, so the outside suspension effectively now has TWO springs making it stiffer than if it did not have the swaybar at all.










Not exactly. Because the swaybar is trying to compress the spring on the inside of the car, the swaybar and endlinks are transferring this spring force to the outside suspension.

In suspension lingo, this is called "auxiliary roll stiffness" The contribution to roll stiffness of the swaybar is expressed in percentage of roll stiffness due to the springs.....

Yes, the springs do more work than the swaybar and endlinks, and yes, the larger the bar the more stress on the endlinks. Even so, those endlinks are holding quite a bit of force.

Now, let me see how many typos I can find once I hit "send"

Jason

 

It all depends on the rest of your setup and your intended use.
The lower the speeds, the greater the tendency for the car to understeer. If you are setup for autocrossing where the speeds are relatively slow, the big front bar might be a bad thing. If you are setup for a open track where you are talking higher speeds, the autocross setup might make the car way too oversteer prone and the big front bar might help.

Jason

 

Well, one thing is true, I am thick headed...there is a term in Italian...but we'll leave it off the table for now. I sincerely appreciate your efforts, Chris and Jasen, to remain calm while I throw some really odd ball stuff back at you guys. And my apologies to the OP!!! But hope he is enjoying the ride??? Er, she?

First...Chris...brain block about pulling down on the link. Got it! I dunno where that came from ...read on...

Simpler stuff first...heavier springs = less contribution from the swaybar. The message here is light springs will allow more twist - not new news to many of us. What's interesting here is that as dampers become more capable of handling higher and higher spring rates, sway bars become the high fidelity - to an even higher degree - components in the suspension make up - relative to race setups.

The fundamental problem with my entire view was the direction of twist; my view is opposite reality and this essentially corrects most of my thinking.

The contribution the sway bar adds to rate is a tricky one yes? Among the variables, rising rate suspension, motion ratio and perhaps a few other elements? But, 1,600lbs of compressive force? I suspect that is ideally thru the center of the endlink??? But here I see a problem...adjustable sway bars often use one static location while the other is adjustable. to my way of thinking this places some very un-natural loads on an endlink out of vertical load - pure vertical load???

And finally, the lifting tire again - sorry . Jasen, would your argument be true if the car could manage to increase lateral grip from .8g to 1g? I know, I simply re-asked a sentence you wrote above, but how do we manage this on three wheels? I guess my assumptions were that cornering power drops off as the inside tire leaves the ground bringing an end to additional cornering power. I suppose it is vehicle or setup specific? I used the lifting wheel as my cue to set the limit of my swaybar settings. My thinking was that I would not gain any additional cornering power - or control/balance - but would have reached a sweet spot where an optimized amount of weight transfered to the inside front tire helping my front driver place power down more effectively???

You guys are my new heros Listen, I contribute a lot here, but I am far from an expert. For the most part I have wisdom, not knowledge to share. Wisdom is knowledge gained from making lots of mistakes. As a child, I could not understand how all that lava traveled thru so much water to get to the top of a volcano. When I got it, I decided to become a landscape architect...about a decade and a half later...not really, but it's amusing!

To the OP, hope you are okay with all of this wonderful information. Someone had to ask the stupid question...actually, one of my statements was corrected...okay two or three.

 

I'd expect that the inside spring is still going to exert more force as it continues to be compressed by the sway bar. Thus, even once the inside wheel is lifted, you could get more torque all the way to the end of the travel of the inside spring.

But that's just a guess from a n00B.

 

hahah, thanks guys, glad to see people got so into this thred and thanks to those of you who helped me out and beecher, it would be great to hear from you before i go and buy my bars. thanks

 

yes, the endlink is trying to compress the spring, but where is this force coming from? it's coming from the other endlink pushing up on the bar. in other words, the endlink is acting on the spring with force that is proportional to the diameter of the bar and the length of the lever arm. at this point, however, i think it's all semantics. we seem to be in agreement on how swaybars work, i say we let the OP get his question answered... wait... has it already been answered? i don't even know anymore. sorry for riding the tangent mobile on this one, but i love a spirited discussion!


P.S. i can't spell either, but i have a secret weapon--->

 

Okay, from Doug Milliken himself.

Michael,

Ha! You found our "Achilles' heel"--sometime after the book was done we realized that we didn't include any pictures of an anti-roll bar.
The revision/update process from one printing to the next (currently 10th printing) only allows us to make small changes in the text that stay on one page, so we have not been able to fix this.
Wikipedia has a nice article, the version I just read didn't have any glaring mistakes (but of course it can change at a moment's notice.
http://en.wikipedia.org/wiki/Sway_bar
When cornering with a typical installation, one link is in tension, the other in compression. Adding an anti roll bar increases the roll stiffness (roll rate) of the suspension, typical units are foot-pounds per degree of body roll angle.
Always happy to hear from someone who is using our books,
Doug Milliken
www.millikenresearch.com

I think Chip did much more to cloud my thinking than he did to clear anything up...

 

Gatcha, but - and cornering is never as elegant as we think it is, if lateral Gs (drop off) or remain constant, how will the bar 'add' more contribution?

A guess from a noob...we're all new at something, welcome! You're just new here.

 

The sway bar's response isn't just a function of lateral G's. It's a function of the number of degrees of body roll. Imagine holding the car in a tight circle, perpetually holding a particular G force and the inside tire is just off the ground. Now suppose that some magical force comes along and tries to add more body roll, without any lateral G's. Assuming the springs haven't bottomed out, the sway bar should provide more force resisting the rotation.

 

Understood. But in steady state there are no changes in roll angle or g load and maybe thats where I'm off. I know this is not real life, but some isolated ideal is always a good beginning.

This is like reading a book by Emanual Kant; you have to keep a finger on every thought to make the connection and I've unfortunately run out of fingers ...I step back when I should look close and look close when I should step back...kinda like getting lost in a setup.