Ok here goes. I know that adding a larger rear sway bar, or anti-roll bar, helps induce more over steer. But why? To me the how and why are just as important as the end result. The way I see it, the bars help reduce body roll by connecting the body to the suspension. Also, if a huge bar is used it makes the suspension act more like a solid axle in that what happens to one wheel affects the others.
So when a car tri-pods, the huge rear bar is forcing the opposite tire to stay up with the tire on the opposite side that is being compressed. Four tires have more traction than three tires any day of the week. So why does using a large rear bar that makes one tire come off the ground make the car go faster? I guess that could be reducing the rear grip is the same result as increasing front end traction?
So when a car tri-pods, the huge rear bar is forcing the opposite tire to stay up with the tire on the opposite side that is being compressed. Four tires have more traction than three tires any day of the week. So why does using a large rear bar that makes one tire come off the ground make the car go faster? I guess that could be reducing the rear grip is the same result as increasing front end traction?
It depends on the car and how it is set up.
An aggressive sway bar on a FWD car will make the rear end of the car rotate around corners, giving you more grip in the front which is how you go faster as the front wheels are doing the most work.
A RWD car with an aggressive rear sway bar will over-steer as well, but the reason it's slower is because you've essentially placed all the grip on the front wheels and they're not doing anything.
An AWD car with an aggressive rear sway bar will be slower than an AWD car with a more balanced suspension. Since all four tires are doing the work, you want to be planted at all times.
It's all relative though. You can't just put a huge rear sway bar and expect results. You have to tune the whole chassis to work the way you want to drive the car.
For instance, my stock SES suspension was relatively soft but the rear sway bar was stiffer than normal. It rotated very well, but it was too mushy everywhere else to be of any use. When I upgraded to the Ford Racing suspension, the mushy handling is gone, but now I need a stiffer sway bar to get the same kind of rotation.
Problem I always have is, it's not specif to the Focus.
All suspension systems do not operate the same. Upper & lower A-Arm types do not function the same as McPherson type, 4-Link does not work like Control Blade.
I am feebly trying to fix that --> http://www.focusfanatics.com/forum/showthread.php?t=394154
& any technical help with that is appreciated
Fort the OP at least, before we have fun with changing geometries & special cases like autocross....
Imagine an evenly balanced car when it's cornering, same slip front & rear - doesn't oversteer or understeer. Anti-roll bars added would be the same size front & rear to maintain this balance while helping the car corner flatter.
Now take one that's heavier in the front, front tends to slide out more (understeer) so speed is limited by that - once the front starts slipping you can't go faster & stay on the road. Adding a rear anti-roll bar (or larger in rear than front) puts more force on the outside rear tire so it starts slipping sooner. Front to rear balance is gained and you can round the corner without one end sliding more than the other.
Tail heavy? Might want more bar in the front so it doesn't stick TOO well as the tail comes around.
This leaves out a TON of details that can change the equation, driving wheels aren't even mentioned for starters. It DOES give an idea how anti-roll bars can be used to fine tune handling through use of different sizes front to rear.
You guys are AWESOME! [ffrocks] With school, trying to autox, work and all I don't have a lot of time to look at everything right now. Maybe I bit off more than I can chew right now? Just know I appreciate it and will look at everything as soon as I can.
You have a fwd car to start with. Add a bigger rear sway adds diagonal weight tranfer, increasing inside front traction. Set up your suspension 1st & then do sway bars. Sway bars are a tuning device. Some drivers like more & some like less. I've tried 3 different rear bars my self & 2 front ones. Add a diff like a torsen & you'll really take advantage of your setup. Lot more involved then just sway bars, add a driver & his/her style of driving. Do you left foot brake to add a little front grip in the corners? You a slow in, fast out? Diamond the corners? Try a different driving style. If you get the change & its worth it is a driving school.
The sway bar is used to balance at the limit grip. A thicker bar will actually slightly reduce grip in a perfect world.
Most front engined compacts are very noise heavy and are tuned for understeer since this is "safer". A thicker rear bar slightly reduces rear grip, making the car more neutral usually. That's why a thicker rear bar is a go to mod on a stock suspension.
Once you go more in depth, adjustable bars make more sense...but it's very easy to get lost in the weeds.
I just installed the Steeda big bar for Autocross. I've been going for 2 seasons now and the bigger rear bar made a huge difference for cornering. It allows the front to have more traction. Yesterday I beat many s2000 which I could never do before. With stock sway bars I had way too much understeer ( front would plow through the corner)
I'm on a budget so I'm using new svt shocks with hr race springs. Steeda big bar in the rear and svt front bar. I have the svt disc brake setup so I run 16" rotas. The front feels a little loose. I have the poly bushings for the front that still have to go in. But getting around the corners is much quicker with the big Steeda bar. I would like to disconnect the front sway bar to see how it handles next time.
Okay, so after literally a year since I started this thread I'm gonna see if I can bring it back. I got back to autox I still have not got a rear bar. I finally decided to pull the trigger and I am going to get one. But, of course I have a question for you guys. Opinions on if the Steeda bar is to big for my setup? Otherwise I am going to get the Eibach bar. I still have Ford Racing springs, KYB adjustables, and the Massive's rear camber and toe arms. I realize I may need to buy a different bar latter to tune it, but I don't want to overkill it right off the bat. Thoughts?
I guess now I'm just wondering how the car handles with no front bar. Does the back end come around easy or just nice and neutral?
For the Eibach guys, Does the car still slide the front a little or is it more neutral?
Granted I'm running the Ford Racing springs and KYB AGX (budget setup) not coilovers or better tuned springs and shocks, so I know my results will/may probably vary.
Also, thanks for the input and advice, you guys are awesome! [ffrocks]
I have had good success with both F/R Eibach bars. No bars and a lot of spring is what the fast guys are going with. I may also be experimenting with dropping the bars at a TnT this weekend but I'm on H&R Race springs, may not work for my setup so I will have an SVT rear bar to swap in if I get ambitious. Gotta love a TnT!
Why do you want to turn your independent rear suspension to solid axle? I wouldn't use anything bigger than 24mm. If you need more stiffness in the back increase the spring rates of the springs.
This is not my first go around in setting up a FWD car for Autocross, I am fully aware of the implications of substituting a rear swaybar as opposed to stiffer rear springs.
With that being said, as stated in my build thread, I am not putting coilovers on this car so a rear sway-bar will have to do. With RE-71R's and the current 25mm Rear swaybar the rear does not rotate nearly as much as I want it to.
I am new to autocross in a FWD car. I am running my SVT in HS so the only thing I car really do is change the rear bar. I am currently running a full new stock suspension with poly bushings on the rear bar. Has anyone run stock suspension with a different bar set up that worked well for them?
Any suggestions here are welcome.
Honestly, if you're running a stock SVT suspension, you're in really good shape.
You could increase stiffness on the rear bar, but again - the balance of the full setup is key. Until you've maxed out your driving ability with your current setup I wouldn't change a thing. SVT has a great setup.
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