Front or Rear Sway Bars?

[Hector]

Which sway bars make the biggest difference: front or rear? I heard from a reliable source that you get the most bang for the buck with the rear sway bars. True?

[Robin-535im]

Which sway bars make the biggest difference: front or rear? I heard from a reliable source that you get the most bang for the buck with the rear sway bars. True?

If you just get rears, then you'll probably end up with understeer since the stock setup is pretty well balanced as it is. If you make the back stiffer than stock, the car will handle poorly unless you stiffen up the front to compensate. The standard packages (Dinan, Racing Dynamics) for front and rear tend to make the front too stiff when both set on the stiffest setting, hence the "fronts full soft, rears full hard" advice from e34.net.

- Robin

[Mr Project]

Actually, stiffening just the rear will reduce understeer, and possibly create oversteer. Most E34s are closer to the 'understeer' side of the equation, so people like to stiffen the rear first sometimes.

Oversteer - the rear end wants to come out
Understeer - the front end wants to push and not turn

[Hector]

Might start with the rears. BMA has the M5 for about $150 or so.

[rickm]

Pacific BMW had them for cheaper if you price the parts according to the list on Bruno's website. Once I finish paying for some classes I'm ordering mine.

[Brandon J]

They both make a difference. Remember that these are for sway. A tighter rear will increase oversteer-for more neutral handling, but the front will still sway/lean. A tighter front (w/o the tighter rear) will yield more understeer. The BEST option is to get both Fr&Rr and have a more neutral handling car and have both the front and rear sway less. It can get confusing with the effects, but it is always good to have a complete balanced system.




Which sway bars make the biggest difference: front or rear? I heard from a reliable source that you get the most bang for the buck with the rear sway bars. True?

[NoSpeedLimits]

Are planning to take your car to the track? If not, then I would stick with the stock set-up. No reason to mess with the design, cause I believe that the gains will be hardly noticeable. And, yes, most cars are intentionally designed to push (have understeer) because it is easier for a non-skilled driver to correct their pour driving habits (ie. picking the incorrect time to turn the wheel when entering a corner). Most people tend to enter a corner sooner than they are suppose too, and end up having to straighten the car and then re-turn the wheel to complete the turn. If the car was set up loose (oversteer) that condition could cause the unskilled driver to loose control of their car real quick, especially if they went into the turn hot. It is very important to understand how weight is being transferred from corner to corner when initiating a turn and more importantly how the suspension change would effect the transfer of weight and the results that can be expected. It is not something that is easy for the non-profession driver to grasp over night. That is why I am curious if you plan to go to the track with your car. If you've already spent hours on the track with your current set-up and feel that something needs to change in-order to improve your handling, then I say give it a try. But, keep-in-mind, any time you make a change, DO ONE THING AT A TIME. It is the only true way to know which change improved your set-up. I hope that helps with your decission, cause I hate to see people waste money on something they really do not need. Most people can improve their cars handling characteristics by simply learning how to be smooth behind the wheel. Unfortunately, it is easier said then done.

[Unregistered]

This may be a duh, however I found the most dramatic diference switching to an "R" rated tire compound, OK so they only last about 10,000 Km however the performance is measurable in the seat of your pants. The next most dramitic thing I have felt is the springs and shocks, I have found to make a "seat of the pants" diference with sway bars it needs to be a dramatic increase, small increases can change a track time by a few tenth's. It is not as simple as hot roding an economy car which tend to be tuned to keep your mother safe in a snow storm, the BMW's tend to be engineered for driving in the first place.

Voice from the baren North

[NoSpeedLimits]

I agree, that so many things effect your handling, including those items you mentioned. Even the temperature and humidity level play a huge roll. I have found though years of racing, that most people can not truly notice changes in their suspension. Not only have we've done it to fellow racers, but I have heard many confirming stories around the track which help support my claim, we tell a drive that we made changes to his/her car and never touch a thing. Guess what they typically come back and say? Yep, you probably guessed right. Man what ever you did was excellent and it really helped the car. Conclusion: the drive is typically the problem and not your set-up. Learn how to drive smooth and you can beat the best equipment on the track, with a very limited budget. Just my 2 cents.

[Russell]

did you go from an H to an R rated tire?

[Hector]

The reason why I brought up this topic is as follow. My car handles ok and so far I haven't had any complaints (i.e., talking about it with you guys) with such. After I drive my GF's '98 Passat, however, I walk out with a good feeling, and that I should experience the same with my car... and serves as a constant reminder that my car is not up to snuff in this area. Her car handles very tightly when cornering. There is very little body roll and feels great, and immediately after cornering and you begin to drive in a straight line the car recovers very quickly with hardly any of that swaying.

Usually before I delve myself in unknown territory, like this topic, I do a little research on the matter. This time I got lazy and thought I'd poke at it by shooting it over to you guys to chew. From the feedback, it sounds like sway bars may not do much for just everyday normal driving but I also read the improvements are noticeable from previous threads/posts in the past. It also sounds as though the suspension in my 14-year old ride may need an overhaul. I remember a while back someone on the board said that after replacing shocks/struts that they felt a noticeable improvement in ride. I'll give sway bars/struts/shocks some more thought but I'm not going to buy anything yet until I get the car up and running, and after I install the BBS 17" wheels I got in mothballs. If I do purchase the sway bars, then I'll get a complete set as suggested. We will see.

[Boggie1688]

Hmm...I'm planning on getting sway bars too....

I just ordered my eibach pro kit...and my next planned upgrade is the eibachk adjustable sway bars. Are the eibach sway bars good?

I don't know much about how the sway bars will affect my cars handling...I'm just looking to keep the car more stable and have less body roll. You guys say by changing the settings in the rear and/or front I can get more oversteer and/or understeer...personally that sounds like fun to just experiement with. :D
On the weekends it will give me something to play with...lol. Currently I like how when the car is pushed the rear will slide out....its fun to play around with, do you think sway bars is a good upgrade for me? I don't hit the track at all, maybe when I turn 18, but for now its mountain driving with my buddies and sometimes some crazy street driving late at night.

[Hector]

sawy bars. You care to chime in? Did you notice even a small improvement?

http://www.bimmer.info/forum/showthread.php?p=12221#post12221

[AirKuhl]

The best advice was given by NoSpeedLimits. Learning to corner properly outweighs any mod ever made. I've been passed by Miata's on the track and have in turn passed Ferrari's.

Having said that, your 14 yo suspension is probably shot, and wasn't that tight even when new. By your description it sounds like the damping circuits in your shocks are shot, and a stiffer sway bar won't really help, maybe just mask the problem a bit.

Get new shocks and springs, do a DE event, and learn why people that enter corners more slowly turn quicker laps.

Cheers,
--Pete

[Robin-535im]

They both make a difference. Remember that these are for sway. A tighter rear will increase oversteer-for more neutral handling, but the front will still sway/lean. A tighter front (w/o the tighter rear) will yield more understeer. The BEST option is to get both Fr&Rr and have a more neutral handling car and have both the front and rear sway less. It can get confusing with the effects, but it is always good to have a complete balanced system.

I thought anti-sway bars made the car stick better. If stiffer sway bars make that end slide out, then why add them? If a tighter rear increases oversteer, it sounds like tightening the rear makes it more slippery!

Sway bars make the car tend toward flatness, distributing the weight of the car evenly across both tires instead of all on the outside tire, right? Thus you have more rubber supporting the lateral load (two tires instead of one) and the rubber can do it's job, i.e., stick you to the ground. So flatter = stickier, right? That should mean that stiffer rear sways stick the rear to the ground more and give you understeer (rear sticks, front slides, car understeers)

Help me out - am I in the dark here?

- Robin