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      08-26-2012, 11:17 AM   #67
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Quote:
Originally Posted by sle39lvr View Post
I really don't understand how putting just a front sway bar reduces understeer. Doesn't make sense to me.

I was thinking, with a decent set of coil-overs, trying the M3 rear first. Then if it's too twitchy, put the M3 front since it's cheaper and easier to replace compared to back. I am hoping that just the M3 rear bar would be "FUN"..
If you don't have a LSD, imo I'd leave the rear bar alone. Try your c/o first.
sway bars on this forum. A few folks who track their cars have installed and removed a larger rear roll bar due to loss of rear end grip.
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      08-26-2012, 01:40 PM   #68
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Quote:
Originally Posted by cvc 22349a View Post
If you don't have a LSD, imo I'd leave the rear bar alone. Try your c/o first.
sway bars on this forum. A few folks who track their cars have installed and removed a larger rear roll bar due to loss of rear end grip.

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      08-26-2012, 08:22 PM   #69
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Quote:
Originally Posted by cvc 22349a View Post
Do you find the rear M3 sway bar to be too rigid for your car at the track?
No but the car is quite neutral now, which may not be desirable depending how you like to drive. I have to be careful modulating the throttle out of tighter turns; I oversteered today as a matter of fact and had to correct. Rear comes out fast. I think I would be just fine with the stock rear sway; I am thinking about going with a thicker front.
Quote:
Originally Posted by sle39lvr View Post
I really don't understand how putting just a front sway bar reduces understeer. Doesn't make sense to me.

I was thinking, with a decent set of coil-overs, trying the M3 rear first. Then if it's too twitchy, put the M3 front since it's cheaper and easier to replace compared to back. I am hoping that just the M3 rear bar would be "FUN"..
A thicker sway doesn't reduce understeer. All the sway bar does is regulate the time it takes the load to transfer from one side of the car to the other. Putting on a thicker sway will slow that time. However the load will still transfer; it will just happen later and the car will understeer when it does (obviously assuming you put the car in a position where it will understeer).
Every car will understeer. Every single one.

Before I do sways I would:
-Slow down first, then get:
-Grippier tires
-Increase camber (need to get camber plates - relatively inexpensive)
-Upgraded dampers/springs
-Thicker way bar up front for RWD cars - OEM M3 or RDS.
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      08-26-2012, 09:24 PM   #70
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Quote:
Originally Posted by cdgatti View Post
How has the ride quality changed? Could the car still be used to comfortably carry passengers?
This set-up is more comfortable than ZSP. I also currently run PS2 ZP tires and they work very well in combo with the new suspension. On the other hand the V2 improved handling significantly, cornering, braking, high speed etc.

To be honest I don't understand why so many folks are experimenting with shock, springs and suspension bits, mixing them all, without understanding how suspension system function overall just to have problems. If you don't want to deal with coilovers and experiments yet you want sharp handling in a daily driver this is a no brainer in my mind. BMW really did an awesome job with this package. I think that it is going to be just superb with PSS tires. Highly recommend it!!
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      08-26-2012, 11:44 PM   #71
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Ok, this thread is hilarious!! To die hard trackers, I agree, big rear sway can cause problems. For "have fun" street drivers, the M3 rear bar is great. I've even had an H&R rear bar and it was fine, on the street. I never crashed and had a car that felt sharp.

My last E90 had BMW Perf Springs, koni yellows/whites, and M3 front and rear bars and the car was really fun on the street. kinda go-kart-ish.

I now have a stock ZSP E90, and it's pretty dull. I have dinan spec rear shocks waiting, just need front yellows and I'll go from there. May do sways but I'm hoping not to have too. Not as invested in this car.
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      08-27-2012, 12:45 PM   #72
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most tuners i talked to, even harold at HPA recommended OEM sports rear bar due to power these beast put out tuned to the wheels to keep them on the ground. on turns at least, prob not a big deal for rest interested in 1/4 miles
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      08-27-2012, 02:44 PM   #73
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[quote=CJ421;12574039]No but the car is quite neutral now, which may not be desirable depending how you like to drive. I have to be careful modulating the throttle out of tighter turns; I oversteered today as a matter of fact and had to correct. Rear comes out fast. I think I would be just fine with the stock rear sway; I am thinking about going with a thicker front.



This is true even with a 13 or 14mm rear bar and why I didn't go with the M3 rear bar. It would be nice if the rear of my car felt flatter but not at the expense of increasing throttle oversteer, which is a little harder to modulate w/a turbo car.
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      08-28-2012, 12:19 AM   #74
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Quote:
Originally Posted by cvc 22349a View Post
This is true even with a 13 or 14mm rear bar and why I didn't go with the M3 rear bar. It would be nice if the rear of my car felt flatter but not at the expense of increasing throttle oversteer, which is a little harder to modulate w/a turbo car.
Agreed in full. The BMW turbo engine feels relatively linear on the street but on the track it is not; modulating the throttle is a skill set in itself. An LSD helps tremendously with control.
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      08-28-2012, 08:36 AM   #75
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Quote:
Originally Posted by Fraggy View Post
For "have fun" street drivers, the M3 rear bar is great.
But you don't really need bigger bars for the street. Less grip in the rear makes it easier to lose the traction in the rear, which can be fun, but it can make your car slower rather than faster.
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      08-28-2012, 11:17 PM   #76
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Quote:
Originally Posted by jippii ensio

But you don't really need bigger bars for the street. Less grip in the rear makes it easier to lose the traction in the rear, which can be fun, but it can make your car slower rather than faster.
It's the flatter feel that is fun for street fun. Most don't go fast enough to engage the nannies let alone lose traction and speed.
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      09-10-2012, 11:35 AM   #77
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Quote:
Originally Posted by HP Autowerks
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To make thing more complicated. The sways bar stiffness should also match the spring rate?
Yes, you are correct.

We would typically tune with spring rates first, then use anti roll bar or bars at the very end to balance the handling or make fine balance adjustments. Remember, larger/stiffer isn't better. Lifting the inside tire off of the ground in a turn may look cool, but it's the the fastest.

If you can't alter spring rates, a larger than stock bar or bars or adjustable ones will have to do.
Let say I am planning to put 400/ 900 on my 335 e93. Since I believe I have to install M3 bushing with this high rear rate, I better install rear sway together. I have exprience that 400 front with ohlins on sti is very comfortable. Will 900 safe on the e93 subframe? Is 20mm rear sway a good match with 900 or I need thicker? ( I rather put on a LSD than changing the rear sway if it doesn't match)
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      09-10-2012, 11:37 AM   #78
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Quote:
Originally Posted by HP Autowerks
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Originally Posted by e679 View Post
To make thing more complicated. The sways bar stiffness should also match the spring rate?
Yes, you are correct.

We would typically tune with spring rates first, then use anti roll bar or bars at the very end to balance the handling or make fine balance adjustments. Remember, larger/stiffer isn't better. Lifting the inside tire off of the ground in a turn may look cool, but it's the the fastest.

If you can't alter spring rates, a larger than stock bar or bars or adjustable ones will have to do.
Let say I am planning to put 400/ 900 on my 335 e93. Since I believe I have to install M3 bushing with this high rear rate, I better install rear sway together. I have exprience that 400 front with ohlins on sti is very comfortable. Will 900 safe on the e93 subframe? Is 20mm rear sway a good match with 900 or I need thicker? ( I rather put on a LSD than changing the rear sway if it doesn't match)
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      09-10-2012, 09:46 PM   #79
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900# rear is too high, the car is not engineered to handle that. 800# is max. I would think twice before going with an 800# rear for street use unless you have a very good damper. And adding a stiffer rear sway bar into the mix on top of that ... way way too stiff IMO. Research, research, research ...
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      09-11-2012, 01:27 AM   #80
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Quote:
Originally Posted by CJ421 View Post
900# rear is too high, the car is not engineered to handle that. 800# is max. I would think twice before going with an 800# rear for street use unless you have a very good damper. And adding a stiffer rear sway bar into the mix on top of that ... way way too stiff IMO. Research, research, research ...
You should consider going with a higher spring rate up front to balance it out. 900 rear is pretty high. It's possible and some race car's do run slightly north of that but your really going into some different territory there. Most track guys run somewhere around 400f/800r for this platform. I currently have it and I think it rides just fine on the street. I would probably bump up the front spring rate a bit to ~500 if I were to do it again and keep the rear the same.

Stiffer rear sway bar is entirely unnecessary especially once you get more power down to the ground and stiffen up the suspension. The back end will be coming out enough as it is without the help of a bigger sway bar.
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      04-12-2013, 06:29 AM   #81
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So just to correct something posted at the beginning of this thread:
M3 rear bar is 23.6? and M3 Convertible is even thicker?

I really don't want to change my front bar. But I am worried that just 23.6 in the back is too stiff.

H&R makes a 20mm bar. Would that be a better choice you guys think?
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      04-12-2013, 09:30 PM   #82
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Didn't you read your thread? You got the straight scoop from guys who've modded their susp quite a bit and drive their cars at the track. Leave your rear bar as is unless you add a larger bar up front and even then the M3 rear bar is probably too big. E93 M3 is 23.6 mm. E90/2 M3 is smaller. If you want to reduce understeer, add grip up front with wider, grippier tires and neg camber.
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      04-12-2013, 10:42 PM   #83
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Yea, I guess the confusion was about two M3 Rear bar sizes. There's a 20mm and a 23.6mm.
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      04-24-2013, 06:06 AM   #84
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Ok I am about to buy an M3 rear sway bar.

E93 M3 Convertible has 23.5mm rear sway.
I was told that E90/E92 M3 rear sway is 20mm, but HPA lists it as 22.5:

http://hpashop.com/BMW-OEM-M3-Rear-A...bar-e9x-m3.htm

Is this correct? I need the smaller of M3 rears.
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      04-25-2013, 11:56 PM   #85
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Just to compare, E46 stock sway bar sizes:

Quote:
1999/2000 Standard......Frt 21.5mm...Rr 15mm
1999/2000 Sport...........Frt 24mm......Rr 19mm
2001+ Sport................Frt 23.5mm...Rr 18mm
2001+ Standard...........Frt 23mm......Rr 18mm
Convertible..................Frt 23.5mm...Rr 20mm
M3.............................Frt 26mm......Rr 21.5mm
M3 CSL ......................Frt 30.8mm...Rr 22.5mm
I just ordered the M3 coupe/sedan rear sway bar for E90, 22.5mm. I have a staggered set up and really hope not to do front at all. If it oversteers dangerously, I WILL get M3 Front.
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      05-14-2013, 11:55 AM   #86
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My rear E90 M3 bar came from HP Autowerks.

I have two questions:

1. It came with bushings and the mounts. I guess I have to reuse the same bolts. Bushings seem to be really small for the bar. How did you guys put the bushing to mount? I spent hours and cannot get it to work...

2. It didn't come with end links. So I will have the stock non-M end links in the rear. Would this be fine for now?
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      05-14-2013, 06:29 PM   #87
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Quote:
Originally Posted by sle39lvr View Post
My rear E90 M3 bar came from HP Autowerks.

I have two questions:

1. It came with bushings and the mounts. I guess I have to reuse the same bolts. Bushings seem to be really small for the bar. How did you guys put the bushing to mount? I spent hours and cannot get it to work...

2. It didn't come with end links. So I will have the stock non-M end links in the rear. Would this be fine for now?
I still have stock endlinks front and rear with my UUC swaybars. Its something to replace at some point but it'll be fine at first.
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      05-14-2013, 07:00 PM   #88
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Quote:
Originally Posted by sle39lvr View Post
If it oversteers dangerously, I WILL get M3 Front.
I would be very careful only doing the rear bar. I had the BMW performance suspension (ver 2) on my E92 and did the M3 rear sway along with my M3 rear subframe bushings and Quaife LSD. With the DSC/TC on there was no problem but when doing AutoX with the nannies off the car would oversteer VERY easily. You would think about turning and it would oversteer. I took it off for the stock pencil thin bar the next day and the handling was more predictable and the car was balanced almost perfectly.

I assumed that with the stiffer front bar that came with the PS that it would be okay...I was wrong and it was an expensive experiment for me.

So with your stock suspension and no LSD, I would recommend against it. So proceed with caution or get the M3 front bar and install in along with the rear.
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