[ksfrogman]

Unlike with the e46, beware that the e90 factory rear sway bar cannot be removed without first lowering the rear sub-frame. This setup is similar to that on the Mini Cooper. However, in the e90, the exhaust and brake lines are just below the subframe. This job would take longer, but be less mechanically challenging if the driveshaft, exhaust and brake lines were removed first. Dan from International Dreamcars in Redondo Beach performed the install. I noticed several modified go-carts, a Porsche 914, two Maseratis and a Ferrari at his shop so I felt I was in good company with an experienced mechanic who was trusted by others.

Here are the photos:

[ksfrogman]

The subframe was dropped no more than a few inches. This allowed ample room to remove and install the rear bars.

[ksfrogman]

Roll Bar Stiffness = C*D^4/(L*A^2)

C = a constant
D = roll bar diameter
L = length of bar
A = length of lever arm

Stiffness increases to the 4th power relative to incremental bar diameter increases.

SWAY BARS:

Stock
F 26.5mm
R 13mm

Eibach
F 28mm
R 15mm

H&R
F 27mm
R 20mm

[HRC]

You got the H&R's right Michael? I look at that H&R rear bar and

How's the car feel now?

Danny

[ksfrogman]

Originally Posted by HRC

You got the H&R's right Michael? I look at that H&R rear bar and

How's the car feel now?

Danny

Yes, I have the H&R Sport Springs, H&R front and rear sway bars.

After the springs and front bar were installed, I was a little disappointed that there wasn't an appreciable difference in handling. I could feel the road bumps ever so slightly more, and the car actually plowed (understeered). The major difference of course was the car's lower side profile. Remember, because of the unexpected difficulty with the e90 rear suspension, the rear bar installation was unsuccessful.

I'm grateful for the rear sway bar install. The rear bar makes a huge difference! I'm so happy with it. The car feels lighter, is more composed and turns with less sway and fanfare--more like a luxury go-cart. Before when, say, making a quick sharp right turn, the right rear tail would pop up. Now the car turns as a unit without the unsettling forward and aft up/down movement. I'd be curious to do a timed slalom manuever comparison.

This all makes sense as you can see from the photos and specs. The H&R front sway bar is only 0.5mm bigger in diameter than stock, but the rear increased from 13mm to 20mm, which gives a very noticeable exponential increase in stiffness.

[HRC]

Originally Posted by ksfrogman

Yes, I have the H&R Sport Springs, H&R front and rear sway bars.

After the springs and front bar were installed, I was a little disappointed that there wasn't an appreciable difference in handling. I could feel the road bumps ever so slightly more, and the car actually plowed (understeered).

The rear bar makes a huge difference! I'm so happy with it. The car feels lighter, and turns with less sway and fanfare--more like a luxury go-cart.

Yea, it must have SUCKED to drive the car with only a bigger front bar! Exactly the opposite of what you want! I would've hated driving that car like that. I'm soo jealous! I want a H&R rear bar!!

Danny

[ward]

glad to hear you got that bad boy up in there!

those sways are probably the only mod i'd consider!!

[larryn]

Question ksfrogman: How long did the actual install take, from time of taking the rear wheels off to putting them back on?

Thanks in advance! It looks as though you have to take the springs out and then drop the rearward subframe by removing those two large carrier bolts.

[ksfrogman]

Originally Posted by lni

Question ksfrogman: How long did the actual install take, from time of taking the rear wheels off to putting them back on?

Thanks in advance! It looks as though you have to take the springs out and then drop the rearward subframe by removing those two large carrier bolts.

It took Dan about 2-3 hours for the install. The subframe had to be lowered very carefully by teetering it from the car's center using a Jackstand as the fulcrum. This allowed just enough room to access the bar without damaging parts underneath (exhaust and brake lines).

[ksfrogman]

Dan, the mechanic (seen in the 2nd photo), is down-to-earth, knowledgeable and fun to talk to. He was nice enough to take the install photos for me (I was away). I would highly recommend him to anyone in this area who needs this done.

Didn't have my camera at the time, so I used my camera phone. Here are a few other vehicles being worked on at the shop:

[StewtheBassman]

That is very cool, ksfrogman, nice thread too!

[markE90]

I drove ksfrogman's car..I can say that it is much stable on turns..I REALLY LOVE THE RIDE!
can someone take over my car payments? I wanted to get a stick 330...arghhhh! why didnt I met you last october doc?!!!!

[ksfrogman]

Thanks Stew

Originally Posted by marcus

I drove ksfrogman's car..I can say that it is much stable on turns..I REALLY LOVE THE RIDE!
can someone take over my car payments? I wanted to get a stick 330...arghhhh! why didnt I met you last october doc?!!!!

Thanks Mark. You say that as I drool over your wheels.

[MIKEYMIKE]

So frogman,

If you had to do it all over again...would you just get the rear and not the front?

Because I am considering getting some sways, but the front seems kind of pointless if its just a bit thicker.

Thanks bro

[ksfrogman]

Originally Posted by MIKEYMIKE

So frogman,

If you had to do it all over again...would you just get the rear and not the front?

Because I am considering getting some sways, but the front seems kind of pointless if its just a bit thicker.

Thanks bro

Hi Mike,

I would not change out just the rear bar, because of the risk of having too much oversteer. The car feels pretty balanced now. When you look at that formula I posted above, you can see how even a small incremental increase in roll bar diameter results in an exponential increase in stiffness (specifically to the 4th power). I don't like the feeling of dramatic body roll, and having both front and rear sway bars combined probably do a better job of minimizing roll than having any one of them alone.

Mike, where in California are you located?

[aphall]

Out of curiousity, would it be overkill to install front and rear sway bars, AND a strut bar?

[ksfrogman]

Originally Posted by aphall

Out of curiousity, would it be overkill to install front and rear sway bars, AND a strut bar?

This topic of the strut bar keeps popping up. A sway bar and a strut bar function differently. A strut bar simply braces the two strut towers together to help stabilize the unibody frame. They don't link to the control arms the way a sway bar does. The strut bar in theory minimizes body flex, but does not prevent your car from overall body sway (roll) relative to the road.

I don't know how to more simply explain this. Okay, let's try this. Think of a fence made out of wood. It sways from side-to-side in the wind. You can reduce fence flex by strengthening the wooden crossmembers with metal L-brackets (analogous to your strut bar). Alternatively, you can prevent the entire fence from swaying in the wind by strengthening the fence foundation by pouring concrete around the posts (think sway bar here). How's that explanation?

[HRC]

Originally Posted by aphall

Out of curiousity, would it be overkill to install front and rear sway bars, AND a strut bar?

Not overkill at all. I've run rear bar, springs, dampers, lower tie bars and strut bars all at the same time.

Danny

[romain]

Can I install the rear bar myself? I was thinking to do it myself, but it seems prety hard.

[ase2dais]

Originally Posted by ksfrogman

Hi Mike,

I would not change out just the rear bar, because of the risk of having too much oversteer. The car feels pretty balanced now. When you look at that formula I posted above, you can see how even a small incremental increase in roll bar diameter results in an exponential increase in stiffness (specifically to the 4th power). I don't like the feeling of dramatic body roll, and having both front and rear sway bars combined probably do a better job of minimizing roll than having any one of them alone.

Mike, where in California are you located?

I agree with KS, for recently I thought of changing the stock 14mm rear sway on my other Exv6Accord to 20mm(an Acura TL stock rear sway), leaving the front 25mm alone. I was adviced by the other forum that the Acura TL Stock sway front/rear are 27.5mm/20mm respectively, so it would necessitate for me to replace the fronts too.

Another fello in my similiar situation that did only the rears(20mm) and left his 25mm stock the same, and he felt a very unsafe oversteer during an emergency maneuver.

He changed the 20mm to a less agressive 17mm to be conservative. Otherwise it would need to change the fronts too to 27.5mm to be mechanically tuned correctly.

I just opted to do 17mm, to be in the middle of the spectrum and be safe, and the car handles correctly. for I dont want to change both.

[ksfrogman]

Originally Posted by romain

Can I install the rear bar myself? I was thinking to do it myself, but it seems prety hard.

The mechanic (F1 Motorsports) who has had extensive experience changing out the e46 rear sway bar was unable to install the sway bar on my e90. He wasn't willing to accept the liability of risking damage to brake lines by lowering the chassis subframe.

In answer to your question, you can probably do it, but understand that the safest way to tackle this involves removing your exhaust and brake lines first, but this would be a headache, and very time consuming. The other mechanic, Dan at International Dream Cars, left those in place, but he carefully lowered the subframe with a separate jack he kept in place to avoid damage to the components below.

[aphall]

Originally Posted by ksfrogman

This topic of the strut bar keeps popping up. A sway bar and a strut bar function differently. A strut bar simply braces the two strut towers together to help stabilize the unibody frame. They don't link to the control arms the way a sway bar does. The strut bar in theory minimizes body flex, but does not prevent your car from overall body sway (roll) relative to the road.

I don't know how to more simply explain this. Okay, let's try this. Think of a fence made out of wood. It sways from side-to-side in the wind. You can reduce fence flex by strengthening the wooden crossmembers with metal L-brackets (analogous to your strut bar). Alternatively, you can prevent the entire fence from swaying in the wind by strengthening the fence foundation by pouring concrete around the posts (think sway bar here). How's that explanation?

Ooops, sorry if I sounded like I didn't understand the difference. I knew the difference, just wanted to know if there would be any significant increase in performance by adding the strut bar as well. But I figured after posting that it probably wouldn't hurt and every little bit of strength would help. Either way, great explanation.