suprfast

im just curious here. i know my FWD suspension well so i need to get aquainted with the RWD. what exactly will happen to my steering if i upgrade the rear sway bar?? will it now want to over steer or understeer? the exact opposite reaction should happen when adding a front sway bar then. just a quick newb question, for someone that isnt a newb
kris

kyle@insight

A larger rear swaybar with a stock front swaybar will make the rearend more prone to coming around.

CarmonColvin

Here is a general rule.

A larger sway bar will decreases grip at that end of the car, front or rear (it does NOT incrase grip at the other end).

Removing the rear sway bar was an upgrade for my track car.

maxcooper

NOT a flame, just interested in some feedback...

On swaybars not changing grip at the other end of the car:

The total lateral weight transfer is determined solely by ride height and the width of the car. If you stiffen the sway bar at the rear (for instance), that will increase the weight transfer at the rear end of the car (reducing grip at that end). Since the total weight transfer remains constant (since you didn't change the ride height or width), that means you will have less weight transfer at the front of the car. That should increase the grip at the front of the car.

I realize many other factors come into it, but I would expect that stiffening the rear sway bar would increase grip at the front for the basic reason described above. What I am missing?

-Max

tmiked

Max

youre right

everybody's right, there just saying it differently

Besides kyle has a better lookin sig so i cant concentrate

CarmonColvin

maxcooper,
You are correct, I just did not explain fully. And I should of said it does NOT increase total grip.

A heavier (thicker) bar does give the other end of the car less weight transfer giving it a bit more grip just on the basis of weight transfer. But other things happen that can negate the gained grip.

As with nearly everything mechanical you do not get 100% return on work. With a larger front bar you may increase the grip at the rear by 6% but you have probably lost 10% of your grip up front. (just bogus numbers for example)

Here is another way that sway bars decrease performance.
Sway bars are essentially springs that only come into play when there is a difference from side to side in the suspension angle and does nothing to support the weight of the car when stationary or traveling in a straight line. It also does nothing when both of the wheels hit a bump at the same time (pavement changes, dips, etc.) But in a turn when the car rolls to the outside or when just one wheel hits a bump they do come into play.

We have shocks on our cars to dampen the movement of the springs and the shocks should be valved and adjusted according to the spring rate for best performance.

But how do you setup shocks to sometimes handle one spring rate when just a half second later it must handle a completely different spring rate? If you setup shocks to compensate for the spring rate counting the added spring rate of the sway bar it will not be the best setup for when just the coil springs are doing the work and it works the other way around if you setup shocks for just the coil springs it will not have enough dampening force when the sway bars do their work.

A lot of what I know about suspension came from a 3 time SCCA Solo II DSP National Champion. He runs NO sway bar in his Fiat. He drove my F-Prepared car for two "fun runs" at an event a few years ago. He was kind enough to spend over an hour talking about what he suggested to do to improve my car. Most of that time was an explination on why I should try running no sway bar.

DamonB

And would this be Mr. Steve Hoeschler? I have seen him drive a few times and he's very quick.

DamonB

The shortest answer as others have said is that stiffening a sway bar at one end of the car tends to make that end of the car lose some grip.

Whether that's good or bad depends on many, many things. Up above Max says it more scientifically than I can. The true use of a sway bar is to tune the lateral weight transfer at each end of the car.

CarmonColvin

That would be him. I used to live in Huntsville and I got to see him auto-x all the time. He used to come down here to Birmingham for events but I have not seen him in over a year.

I wish I could find my archives of the Evolution Auto-x list. There was an awesome thread on there a long time ago where he and others explained in detail the pro's and con's of sway bars.

DamonB

Keep me in mind if you find it. I am on the team.net list but keep forgetting to sign up for that one. You have the signup info off the top of your head? Thanks.

tmiked

Actually, sway bars can increase grip in some situations.
By reducing body roll, they reduce undesirable camber change caused by 'leaning' when cornering. It just depends on the car and the application. Many race cars have driver adjustable sway bars which can be adjusted real time for changing conditions.

The FD has a multi-link suspension which has less camber change when cornering than strut type suspensions. If you are running 40 series tire you probably need more sway bar then if you are running 60 series, as the shorter sidewalls are more sensitive to camber change.

CarmonColvin

This may work.. You might have to join to read them.

http://groups.yahoo.com/group/evolut...s/message/9512

DamonB

Thanks very much.

1stand3rd

So exactly how (for example) would an FD with front and rear sways change the handling characteristics from stock? I can understand if you just installed either front or rear without the other, you'll loosen up that other end. But what if you install both as a set. Does it significantly tighten up the whole car?
The reason why I ask is because on the Racing Beat website, they sell these sway bars as a set.

xchaos

I just installed the RB sways as a set. On the street, they are a huge improvement and work great. I'll have to get on a track to see the difference there, but am thinking the rear will need to be set to the softest setting or maybe even disconnected for my liking.

But I am by no means an expert on suspension, I just try to stay on the pavement.