.MM

iTrader: (3)

some people say that if you install a rear sway bar onto the car that is too stiff, that it could cause the inside rear wheel to actually lift and cause a loss of traction.

but...i was thinkin about this a lot today, because i was home sick from work, and wouldn't you be able to correct this problem by stiffening the rest of the car?

for example: (not actual specs or info or products)

if you installed a 27mm rear sway, set it to full stiff
then you installed a 25-26mm front sway, along with a hardcore coilover setup and all the appropriate bushings, strut bars, x-braces, tie bars, blah blah blah

in my mind, it would make sense that if the stiffness of the front and middle of the car were increased dramatically, wouldnt it make it a lot harder for the car to lift in the rear?

i would think...that if the car was neutral and rigid through both the front and rear of the car, that it would try to lift both inside tires instead of just the rear, which is much harder...or maybe just drift to the side and not lift at all...

maybe im losing my mind, but someone help me here

sorry if i cant explain this well

AWDrift07

iTrader: (2)

Stiffer End Links work well

mayhem

iTrader: (9)

In short, if you added all that to the front end...yeah probably. Will it provide a better setup...who knows? We're not talking specifics here anyway.

Lets take a steady state turn for example just to make it easy. We're assuming only lateral acceleration, no longitudinal forces (braking, throttle). Once the rear outside suspension becomes 100% saturated with load transfer it will begin to move all additional load to the front outside. Additional load will not move to the front outside until the rear is 100% loaded. The trick will be to increase the front anti roll couple to begin absorbing all excess load immediately. I think this is impossible to do, but in real life the increased front roll stiffness can reduce the wheel lift, but maybe not completely prevent it. The drawback is that you're now removing load from the front inside and it's all piling up on the front outside.

Now things you can do (but not simple) to reduce lateral load transfer is increase track width and lower your CG.

In the end you tune by feel and lap times because of so many variables and possibilities. The inside rear tire may be lifting, but ask yourself, "is that bad?" "The rear tire is lifting, but am I still understeering?"

.MM

iTrader: (3)

thanks for the responses

when you say stiffer endlinks, do you mean endlinks for the rear sway? such as perrin?

Silencer

iTrader: (4)

Siffer endlinks? Endlinks do not flex in this aspect. I think he meant adjustable, like the perrin endlinks. Possibly to pre-load or take away the pre-load when lowering your car. You should also play with front and rear ride heights. You would be surprised of how the car reacts with different ride height adjustments.

Dave

chrisw

iTrader: (2)

stiffer end links won't do squat to stop the inside tire lifting.

you need to control the body roll of the car without limiting the suspension travel. Swaybars work by transfering some of the load to the opposite side. The side effect is limiting your suspension travel which can cause the inside rear to lift if you corner hard enough.

having played with uber stiff swaybars, I can say that the evo generally responds better to increased spring rates over bigger swaybars. Been there done that.

Another trick that I recently learned was to lower the rear roll center of the car so that at full body roll, the inside rear suspension is still within the full stroke of the suspension travel, keeping the rear wheel on the ground. After doing this my tire temps front to rear were more consistant (I actually got heat in my rear tires for once)

With that in mind, I have a lot of suspension tuning to do, but I think I can eliminate the rear wheel lifting by manipulating the spring rates and leave the swaybars alone.

.MM

iTrader: (3)

when you talk about the roll center for the rear...

does someone make a roll center adjuster for the evo?

or are you referring to adjusting something else?

sorry, im new to evo's, im use to my integra type r

mayhem

iTrader: (9)

There is no RC adjuster. The roll center is found through connecting some dots of the suspension geometry. Basically where the lines from each wheel Instant Center-tire contact patch cross is the RC. I know you're probably thinking, "What?" but depending on how much you actually want to know will guide you to where you want to look for the answers. There are some good books and a couple websites that can help explain it a lot better than I ever could.

Chrisw,
Did you get custom arms made to change your RC?

I do have to pick on one thing you said. Anti-roll bars do not transfer load back to the opposite (which I assume you mean inside wheel) wheel. They only aid in resisting the roll moment of the front/rear. In a steady state turn you can just add in the bar resistance + wheel rate to get total roll resistance. The most the bars will push back is equal to the centrifugal force being applied.

edit: after reading that last sentence it still wasn't clear and not completely correct. I know you probaby know what I mean, but I'm having trouble putting this in words.

.MM

iTrader: (3)

ok, thanks

any more comments or feedback is always welcome from anyone who feels like commenting

JohnBradley

iTrader: (30)

One thing I noticed right off is this line. The reason its not correct is you forget that swaybars have their own spring rate that can be used to calculate total effective spring rate. I dont have my suspension book nearby, but there are lots of combos that can be used to achieve the same goal. Super Stiff spring+weaker sway vs. Hard Spring+Hard sway. Suspension is like engine building, while there are plenty of formulas and "right ways" to do something, there is always room for artistic interpretation.

chrisw

iTrader: (2)

no I didn't get custom arms made, RC was a poor choice of words I guess. I was having similar communication problems. All I did was lower the rear of the car a bit to keep the body roll within the full stroke of the rear coilover.



that's true. I have my evo setup where I like it. Ultimately there is no absolute answer to this threads question.

mayhem

iTrader: (9)

John,
I'm not sure what you're trying to say. Can you give it another try?

I get that the bars have their own spring rate, but at no point does it push a wheel down, it only resists roll. My overall point was that when in a turn you can not change the lateral loads from the outside to the inside. Unless of course you have a center of gravity that is below the ground...and that's impossible. You can resist those lateral loads caused by centrifugal force, but you can not resist more than that. That would be like saying the ground pushed up on my feet with more force than gravity is pulling me down with. In which case the ground would launch me into the air.

.MM,
Good luck with your project!

JohnBradley

iTrader: (30)

Spring rate x swaybar spring rate/swaybar rate
(or something, I still cant find my book).

My point was that the spring rate is multiplied on the load sided thusly resisting roll. For instance lets run with my undoubtedly flawed formula for the sake of arguement:

(8.5 kg/mm * 10 kg/mm) / 8.5 kg/mm would give an effective spring rate of 10 kg/mm when cornering, savvy? All it does is stiffen the loaded side. Maybe I didnt say it in english ( I have that problem sometimes).


Not too cloud the issue but this is possible. Its called a trampoline. Which being that it uses spring tension helps illustrate the point.

mayhem

iTrader: (9)

In relation to a turn exit, I can see load plus some returning to the inside wheels. But during a steady state situation, no.

Are you trying to figure wheel rate or roll rate?