IE hollow 25mm vs uuc swayBarbarian 22mm

[nando]

they are both way, way too large.

a 25mm rear bar is almost 900% stiffer than the stock 12.5mm rear bar.

unless you're drifting, there's just no reason to use a rear swaybar that stiff. it's likely to make the car oversteer on corner entry and understeer in steady state. See how many track guys actually remove the rear bar altogether or upgrade the front instead.

[CorvallisBMW]

The resistance to twist increases exponentially with increase in the diameter. So while the 25mm bar may be hollow in the middle, that material that has been removed does a nearly insignificant amount of work when compared to the material further out along the radius.

The 22mm bar, while being solid instead of hollow, lacks 1.5mm of radius compared to the 25mm bar. Even though it may be solid I'm 99% sure it's not as stiff as the 25mm. I could run the math but I'm lazy (and I don't know the diameter of the hole in the 25mm)

they are both way, way too large.

a 25mm rear bar is almost 900% stiffer than the stock 12.5mm rear bar.

I think he's talking about a front swaybar. I know IE makes a 25mm and UUC makes a 22mm front, but only IE makes a 22mm rear (and it's solid, not hollow)

[nando]

I think he's talking about a front swaybar. I know IE makes a 25mm and UUC makes a 22mm front, but only IE makes a 22mm rear (and it's solid, not hollow)

ah, I thought he meant rear. 22mm is also way too big :p

if you wanted to double the stiffness of a 12.5mm bar you only need to increase the diameter to ~17mm.

[george graves]

With that said, two bars that are identical, one being hollow, and one solid, the solid bar will be stiffer.

[CorvallisBMW]

With that said, two bars that are identical, one being hollow, and one solid, the solid bar will be stiffer.

Correct. It that case all depends on the diameter of the hole. A 22mm bar with a 12mm hole with certainly be less stiff. A 22mm bar with a 1mm hole would be identical, you'd never be able to measure the difference.

[george graves]

tisk, tisk, tisk.

Hollow bars are stiffer. Do your hw.

[NC325iC]

i would be willing to bet on the 25mm being somewhat stiffer, though it does depend on the thickness of the tube they used.

based on some quick calcuations and assuming they are actually using inch tube if the tube wall has a thickness of at least 0.162 the hollow one will be stronger. If anyone cares to check the calculation thats fine.

and yes i am bored, and yes i am looking for a Mechanical Engineering job if you are hiring :)

[Hellabad]

i would be willing to bet on the 25mm being somewhat stiffer, though it does depend on the thickness of the tube they used.

based on some quick calcuations and assuming they are actually using inch tube if the tube wall has a thickness of at least 0.162 the hollow one will be stronger. If anyone cares to check the calculation thats fine.

and yes i am bored, and yes i am looking for a Mechanical Engineering job if you are hiring :)

You are correct. The math is simple, and then even simpler than simple, if you just compare the 4th powers to each other.

[Bothfeetin]

so for the least amount of body roll your saying go with the IE and yes im going to buy a rear sway bar as well 25 mm hollow front and a 22mm rear instead of the 22 mm front 18 rear by uuc which is a little bit less stiff by a fraction from what im hearing right?

[CorvallisBMW]

Personally I think the 25/22 combo is overkill for anything but a dedicated track rat.

22/19 is more of an aggressive all-around setup that can be used on the street and track.

[SkinnyVT]

Stability is all about balance. You can get there with either bar, just depends on the rest of the set-up.

^This is the key, just throwing parts at a car won't make it handle better or go faster if they don't work together. As somebody else stated, a lot of people (myself included) don't even run a rear bar. It all depends on the rest of your suspension setup, how you are gonna use the car, vehicle handling preference, etc.

[nando]

I bet you'll find a lot more street cars running a 25/22 or 22/19 setup than track cars.

[Bothfeetin]

well i am starting to go to the track alot not lately because of the weather but on sharper turns it feels like im gonna flip i have so much body roll so thats what i want or trying to fix

[george graves]

22/19 is more of an aggressive all-around setup that can be used on the street and track.

There's also the issue of e30 vs e30 m3 front mounting point. I can't imagine e30 m3 strut mounting point and a 25mm bar.

[bimma360]

I currently have the IE 25/22 sways on the Dinan. On my last e30 I had the Suspension Techniques 22/19 setup. Both cars have H&R Sports, Billy Sports, and e30 m3 control arm bushings. The 22/19 setup just felt worlds better to drive than my current setup. The 25/22 is so overkill to me, and I cant wait to get into something milder.