Is it worth upgrading the rear sway bar?

[slater]

This combination, I've heard, is a great "OEM+" upgrade.

Definitely review it!

will do, but will be hard as i will have new springs, dampers, bushings, etc.

peter

[BADCLOWN]

on my old silbergrau ZHP, i had F/R H&R sways (no other mods on the car) and that thing handled on RAILS

[JeffSaysThings]

I've seen some confusing or downright wrong information floating around here regarding sway bars. Needless to say, suspension tuning is complicated and there are lots of variables that influence one another.

That being said, increasing front roll stiffness will usually increase understeer.

When I bought my car, it had a bimmerworld (ground control) front sway bar with the stock rear bar and fat rear tires (265 width). It understeered like a pig in steady state cornering. I recently installed a H&R rear bar (22mm I think?) and it really helped the car rotate. The car is more neutral (still understeers a little) in steady state cornering and will rotate with the throttle.

My previous owner did a lot of auto-x I think he chose the above setup because having a soft (or no) rear sway bar helps the car get power down without an LSD. As for me, I remedied the situation by installing an LSD AND a stiffer rear bar! The car is SO much more fun as a DD.

[NoVAphotog]

I've seen some confusing or downright wrong information floating around here regarding sway bars. Needless to say, suspension tuning is complicated and there are lots of variables that influence one another.

That being said, increasing front roll stiffness will usually increase understeer.

When I bought my car, it had a bimmerworld (ground control) front sway bar with the stock rear bar and fat rear tires (265 width). It understeered like a pig in steady state cornering. I recently installed a H&R rear bar (22mm I think?) and it really helped the car rotate. The car is more neutral (still understeers a little) in steady state cornering and will rotate with the throttle.

My previous owner did a lot of auto-x I think he chose the above setup because having a soft (or no) rear sway bar helps the car get power down without an LSD. As for me, I remedied the situation by installing an LSD AND a stiffer rear bar! The car is SO much more fun as a DD.

Interesting, what'd you do about the tires...and the pig?

[Vas]

Bacon

[rkneeshaw]

I've seen some confusing or downright wrong information floating around here regarding sway bars. Needless to say, suspension tuning is complicated and there are lots of variables that influence one another.

That being said, increasing front roll stiffness will usually increase understeer.

When I bought my car, it had a bimmerworld (ground control) front sway bar with the stock rear bar and fat rear tires (265 width). It understeered like a pig in steady state cornering. I recently installed a H&R rear bar (22mm I think?) and it really helped the car rotate. The car is more neutral (still understeers a little) in steady state cornering and will rotate with the throttle.

My previous owner did a lot of auto-x I think he chose the above setup because having a soft (or no) rear sway bar helps the car get power down without an LSD. As for me, I remedied the situation by installing an LSD AND a stiffer rear bar! The car is SO much more fun as a DD.

This is great feedback.

I think there is a lot of confusing information on the topic but what you posted is pretty clear.

I would propose that "balance" is best measured in steady-state cornering, not how the car turns as you chuck it into a corner which can be very subjective and depends a lot on driver inputs as much as suspension components.

I've always been very confused by reports that a larger M3 front bar alone helps reduce understeer, because its counter to conventional wisdom. Normally a larger bar in the front will increase understeer, and a larger rear bar will increase oversteer.

I've also been confused as to why companies like Eibach, H&R, Turner, hotchkis, etc all create a sway bar kit (front and rear) that increase the stock bar sizes by pretty much the same amount. If our cars really need a larger bar for proper balance, I would think you would see only a marginally smaller rear bar and a much larger front bar in these kits.

What size is your ground control bar up front?

[derbo]

This is great feedback.

I think there is a lot of confusing information on the topic but what you posted is pretty clear.

I would propose that "balance" is best measured in steady-state cornering, not how the car turns as you chuck it into a corner which can be very subjective and depends a lot on driver inputs as much as suspension components.

I've always been very confused by reports that a larger M3 front bar alone helps reduce understeer, because its counter to conventional wisdom. Normally a larger bar in the front will increase understeer, and a larger rear bar will increase oversteer.

I've also been confused as to why companies like Eibach, H&R, Turner, hotchkis, etc all create a sway bar kit (front and rear) that increase the stock bar sizes by pretty much the same amount. If our cars really need a larger bar for proper balance, I would think you would see only a marginally smaller rear bar and a much larger front bar in these kits.

What size is your ground control bar up front?

I think the problem is that it seems the internet wants to put it as a rule of thumb that stiffer front bar = understeer, stiffer rear bar = oversteer. suspension tuning is a fine art and it's almost a black art where the information is never transferred well on the internet. With a stiffer bar in rear, yes you do increase oversteer, but you also decrease high speed cornering stability. In an AutoX car, it doesn't matter too much as they don't get that fast in the parking lot. On a street car where there are numerous different types of situations, I think the anti-roll bar needs to be sized properly but not be too large.

My car has 448/560 spring rates with a 30mm front H&R sway bar and the OE M3 rear sway bar + LSD. My camber is set to -3 in the front and -2 in the rear. With a larger front bar, I felt a better stability during high speed corners (over 70mph corners) at the track. However I noticed for slower speed corners like hairpins on a mountain road, it does have slightly more understeer. I granted have a track car so I'll take that compromise any day.

[05Imola]

I installed the TMS sway bars this week. I installed the front seat bar first with adjustable links. The car immediately felt flatter but the car understeered a lot at lower speeds. I installed the rear a few days ago with adjustable links again. Car is so more balanced. I have it on the middle hole and I might make it softer for the winter. Car still has some roll but that's because I'm running an H&R Touring cup kit. Perfect balance for street in my opinion

[johnrando]

There are likely other factors contributing to the understeer, and perhaps, even a placebo effect.

General rule of thumb - larger rear bar, less roll = faster rotation. That's physics

you just reminded me, time to upload those photos from earlier this year.

Yes, post those pics. I'd also like to do some rear suspension work sometime with you.

Sent from my SM-G900V using Tapatalk

[BumpinAlpine]

Thanks for all the input.

I have a set of BavAuto Sway bars which are solid bars 27mm front and 23mm rear and they are non adjustable. Suspension wise, I'm running the Koni FSD/Eibach Pro kit.
The BavAuto bars helped reduce some roll but I feel like I could do better. I am considering in keeping the rear bar as is at 23mm and getting a Hotchkis 30mm bar up front.

Any thoughts on this?