Sway Bar Sizing

Discussion in 'Modifications & DIY how-to' started by dundunskeert, Jul 11, 2009.

  1. dundunskeert

    dundunskeert Member

    I just upgraded to BC Racing coilovers and I have heard that the stiffer the suspension the smaller your swaybars need to be. My COs are 6k/8k.
    My RSB is a whiteline 24mm adjustable set on 24mm. my FSB is the stock 19mm. I have been planning on getting a bigger FSB but I'm not sure that I still need one.

    So... Should I get a smaller RSB? Should I get a bigger FSB?

    Thanks for all advice.

    I guess I'll add that I have fender braces, Front strut tower brace, rear x brace, Whiteline basic rear endlinks, upgraded swaybar mounts, and about to put steering rack bushings on.
     
    Last edited: Jul 11, 2009
  2. Jake

    Jake Active Member

    There are a thousand opinions on this, in the end its what you feel most comfortable driving. The best setup car I've personally ridden in was jason's bugeye with tein flex coilovers (10k/10k) and cobb hollow 30mm sways (equal to about 25mm solids) in the fron and rear. But he also had, sti lca's, all endlinks and steering rack bushings.
     
  3. SubiNoobi

    SubiNoobi Supporting Member

    It depends on what you do with your car. However, I think the smallest I have ever heard of people using for any type of motorsport was 22mm, so definitely upgrade form the stock 19mm.

    If you AutoX, get the biggest bar you can ~27-29mm. If you are DD'ing the car then just do it by feel, a big FSB is just not necessary.

    Leave your 24 RSB alone, if will probably be fine, and you'll regret going to a smaller one.
     
  4. dundunskeert

    dundunskeert Member

    Thanks guys, I will stick with my 24mm rear, I think I'm gonna go for a 24mm fsb.
     
  5. dundunskeert

    dundunskeert Member

    Can anybody else chime in?
     
  6. slowwrx

    slowwrx Supporting Member

    yes, the gc isw a totally different animal, call Doug or Scott they will know exactly what bars to put you on if it was a gd chassis I could help but its not
     
  7. calmnothing

    calmnothing Shlimp Flied Lice Supporting Member

    With Megan coilovers 24/24 seems to work well. It will still understeer if you push it too hard. Try an ALK, whiteline roll center adjusters, and rear strut bar if you don't already have any. It'll help with understeer and rotation.
     
  8. dundunskeert

    dundunskeert Member

    Awesome.
    does the ALK reduce understeer?
    I just put fender braces on and they made my understeer worse.
     
  9. dundunskeert

    dundunskeert Member

    Another thing we haven't touched on yet is simple adjustments.
    Correct my thinking if I'm wrong but If I lowered my front tire pressure it would increase my contact patch giving me more grip and less understeer.
    Also wouldn't stiffening the rear and softening the front suspension decrease understeer?
    We still camber adjustments too. I've heard that it is better to adjust the camber at the bolts rather that at the plates. The top bolt hole in my coilovers is slotted so I can get as much camber as I want until the tire hits the coilover. I'd guess I can get about -4 degrees If I ever wanted to. Right now my setup should be -1.6 front and -1.3 rear. Should I go for more negative camber in the front?
     
  10. SubiNoobi

    SubiNoobi Supporting Member

    In general, the more negative camber you have up front the more grip you will have. I am somewhere over -3 and still see wear on the outside edge of the tire, not as much as when I only had -1.1 though.

    However, for DD, what you have (around -1.5) is fine, don't go nuts like me.

    Concerning tire pressure: you want to inflate the tire to the point that you get maximum grip, this depends on the tire's sidewall stiffness and the camber. You find whatever the optimal pressure is and set that to the front tires. Then you adjust the rear tires for less grip (promoting oversteer). Some people go over pressure, some go under.

    As far as adjusting camber at the bolts vs at the plates, I have heard many conflicting viewpoints. Unless you are a serious competitive driver, I wouldn't worry about it. Caster is more important that where you adjust the camber.

    Now if all this is for your DD, then just keep it simple. Get the swaybar, then take it to a good shop, like GTE and get their recommendation for a good street alignment.

    The degree of oversteer that I am familiar with is ONLY suitable on the AutoX course and is UNSAFE anywhere else, IMHO. I dial everything way back for the DD. I am completely satisfied with my understeer on the highway.

    However, on that note, there is an AutoX event coming up on Sunday August 9th at Turner Field. That would be a great way to safely push your car to the limit and see what it can do, then find out what, if anything needs to be changed.
     
  11. dundunskeert

    dundunskeert Member

    ohhh count me in for the autocross. My tires are still set at 35psi cold from the trackday I did. They are azinis rt-615 id that helps you any. Thanks for the advice.
     
  12. SubiNoobi

    SubiNoobi Supporting Member

  13. clemsonscooby

    clemsonscooby Active Member

    If you are autox'ing the car run higher than 35psi on them. I would set your warm tire temp close to the max on the tire. Stiffer tires are better than flat wobbly tires. Your steering response will suck with low pressure and your tire will just roll on itself until the road sees the wheel rim. Use chalk on the side wall to see how much the tire is rolling on itself. If the chalk wears away near the sidewall up the pressure.

    Do not run -4 camber. That is way too much and will only start to kill your acceleration. -2.5 is probably the most you need to go, but is not recommended for daily driving as you will kill your street tires fast. For a good combo of both go with -2, but don't change from the -1.6 until its necessary.

    Upgrade the FSB, it is probably the most important add-on for autox. It will improve your steering response, make your camber actually work, but can be wild at the limit. Keep the dampening high in the front and you can reduce the rear if becomes to snappy.
     
  14. calmnothing

    calmnothing Shlimp Flied Lice Supporting Member

    So are you autoxing? Or just enjoying your car on roads? It'll definitely help with suggestions
     
  15. dundunskeert

    dundunskeert Member

    I would never run over -2.5 degrees. I was just explaining how adjustable they are. Especially since I dd my car that would just be ignorant. I plan on autocrossing as soon as the dates work out. I also do a few trackdays here and there. I think I might go skydiving august 9th, but if not I'll be there.
    Azinis have a very stiff sidewall, they were a bitch to put on.
    My rsb can be adjusted to 22mm, 24mm, and 26mm.
    I think I'll go for a 24mm adj whiteline fsb. As soon as I get my wheels squared away I'll order it.
     

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