[StealYourFace]

I have a 330i with the stock sport srpings, v1 perf struts, m3 front wish bones and tension rods, alignment piun pulled and will soon have a 3.38 lsd (had a 3.64 but that broke). PSS on 19" rims.

My use is 20k miles a year, autocross and more track days ahead.

I figure since I am dropping the rear end again to do the diff, I will do the rear sway bar.

Possible combos I am thinking of:

Stock 26.5 front bad and an e91 rear bar which is 14mm
Stock 26.5 front bad and an e90 M3 rear bar
M3 e90 front and rear bars
M3 e93 front and e90 M3 rear
M3 e93 front and rear.

Is there even much difference between the sport e90 and m3 e90 front bar, they are the same size.

It's a lot to think about, and a lot of time and effort and money involved with going back and forth between various options so I want to nail it on the first try.

[cvc 22349a]

There is quite a difference between the E90 M3 front roll bar and the E90 bar. The E90 bar tapers down in the middle and at the ends of the bar where it curves making it less rigid than the M3 bar. I've driven similar cars with the M3 front bar and OE sport bar and the M3 bar definately has less roll, but it affects ride quality a bit on bumpy roads.

I have the PS front sway bar, which is perfect for my car, and the 14mm rear bar. With 265 PSS's, PS springs and an LSD, I wish I had installed the 15mm rear bar from the E93 335i. Those PSS's stick like glue and make the rear feel a little soft when pushing it.

Most folks will probably tell you to get E90 M3 front and rear bars. I think that rear M3 bar is too stiff for a non-m. The M3 weighs a bit more, has a wider track and a much better LSD. imo, get the E90 M3 front bar and the 15mm E93 335i rear bar OR the Dinan rear roll bar.

[CALWATERBOY]

Originally Posted by StealYourFace

I have a 330i with the stock sport srpings, v1 perf struts, m3 front wish bones and tension rods, alignment piun pulled and will soon have a 3.38 lsd (had a 3.64 but that broke). PSS on 19" rims.

I figure since I am dropping the rear end again to do the diff, I will do the rear sway bar.

M3 bars pretty good - E93 bars if you gotta E93.

Never the rear bar w/o LSD - you say yours broke?!? What mfg?

[StealYourFace]

Calwaterboy- the diff broke because it had a broken tooth- was a fluke.


At any rate I am leaning towards e93 m3 front and e90 m3 rear bars. I might give Harold a jingle and see what he thinks.

[CJ421]

I have the front and rear M3 bars (not sure E90/E92/etc). The rear is too stiff on the track which makes it tricky for a less experienced driver; the car will oversteer before it understeers.

We are RWD; just use the gas pedal to bring the rear around, you don't need a stiffer sway bar to reduce grip back there. Only on FWD cars does it make sense to do a stiff rear sway, they don't have many other options to help bring the rear around.

Edit: also it hasn't been mentioned, but installing the rear sway is expensive because it requires lowering the subframe + mandatory alignment. I would replace my M3 bar with the stock one if it didn't cost so much.

[StealYourFace]

CJ thanks for your input.

I want the bigger rear bar to help the car rotate during autocross. Plus I feel like the smaller (e90) m3 bar with the larger (e93) front M3 bar will help to keep the car from being overly tail happy. That, along with tc/dsc and a hell of a lot less torque than a 335i should keep the rear from stepping out too bad. In addition, the rear sport springs are a lot less stiff than the rear springs in an m3.

All told it's just a guessing game and I hate that. There's so many variables and I would definately rather rely on experience of others.

But I agree, since it is such a bitch to swap bars I would like to get it right the first time.

[cvc 22349a]

Why not try PS or Dinan springs first? They'll also reduce dive and squat, not just roll.

[StealYourFace]

Springs aren't really an option because I don't want the car to sit any lower- I need that ride height for the snow

[CJ421]

The Performance springs won't lower the car that much. I think cvc is on the money with the spring recommendation since you already have the Performance dampers. The stiffer springs will do more for your handling than the sways by a long shot; sways will help only in turns. Rule of thumb when upgrading a suspension is to address the main issue first and not work around it. Sways count as the latter, aka a band aid for the too-soft stock spring rates.

[cvc 22349a]

Originally Posted by CJ421

The Performance springs won't lower the car that much. I think cvc is on the money with the spring recommendation since you already have the Performance dampers. The stiffer springs will do more for your handling than the sways by a long shot; sways will help only in turns. Rule of thumb when upgrading a suspension is to address the main issue first and not work around it. Sways count as the latter, aka a band aid for the too-soft stock spring rates.

OP: I didn't want to lower my car either cuz I have to crawl in and out of my garage cuz I scrape the bottom of my bumper if I don't. I installed PS springs to reduce roll, squat and dive and didn't lose any clearance. Maybe 1/2" drop from zsp springs if that..
adding: labor is way more to install that rear sway bar than change springs and bumpstops. LSD swap doesn't require you to drop the rear subframe; rear sway bar does. Just a suggestion. g/l

[Mavus]

Originally Posted by StealYourFace

CJ thanks for your input.

I want the bigger rear bar to help the car rotate during autocross. Plus I feel like the smaller (e90) m3 bar with the larger (e93) front M3 bar will help to keep the car from being overly tail happy. That, along with tc/dsc and a hell of a lot less torque than a 335i should keep the rear from stepping out too bad. In addition, the rear sport springs are a lot less stiff than the rear springs in an m3.

All told it's just a guessing game and I hate that. There's so many variables and I would definately rather rely on experience of others.

But I agree, since it is such a bitch to swap bars I would like to get it right the first time.

CVC and CJ are on the $ here.

I installed PS V2 kit and am really impressed compared to ZSP. I think it is a great set-up for dd and tracking. If you notice BMW engineers did not change the rear sway bar with that kit, I am guessing they know "something" about this suspension. I would recommend that you get matched dampers and springs. The height changed only in the rear by about 1/2in, so not much. I had three instructors drive the car and they were also impressed with the V2 kit. I asked them about M3 bits and they said that is the last step after wheels/tires, brakes and lsd. I will not be installing M3 sway.

CJ, CVC - what rear toe arms would you recommend. I read there are some issues with joints with HPA parts. Meyle or other?

OP - hope you don't mind the question in your thread

Hope this helps.

[cvc 22349a]

Originally Posted by NokTurNaL 330i

CVC and CJ are on the $ here.

I installed PS V2 kit and am really impressed compared to ZSP. I think it is a great set-up for dd and tracking. If you notice BMW engineers did not change the rear sway bar with that kit, I am guessing they know "something" about this suspension. I would recommend that you get matched dampers and springs. The height changed only in the rear by about 1/2in, so not much. I had three instructors drive the car and they were also impressed with the V2 kit. I asked them about M3 bits and they said that is the last step after wheels/tires, brakes and lsd. I will not be installing M3 sway.

CJ, CVC - what rear toe arms would you recommend. I read there are some issues with joints with HPA parts. Meyle or other?

OP - hope you don't mind the question in your thread

Hope this helps.

That's OT here. Read my RE toe link thread