wei350z

hi folks, I installed my BC BR coilover couple months ago, and I find out it has about the same/ or even more body roll than my stock setup. The bc coilover is the only suspension mod on my car so far, other parts remain stock. I'm also running Goodyear Eagle GT 225/45/18 and 245/45/18.And I've done the alignment also.
However, when I approach some high speed corner, I feel the car is spongy. The steering is still predictable, and there is plenty of grip left which allows me to continue accelerating throughout the corner, but you just don't feel confident to do so since the spongy feeling/ and body roll on the car. This feeling especially happens on the driver side when I approach right hand corner.
I wonder if it happens due to the following reasons:

1. I've never tried to push my stock setup before to its limit, so there is def. more body roll/spongy feeling even I installed BC coilover. (however, I do notice that when I approach the same corner at same speed with my stock setup, BC coilovers have about the same body roll as stock.)

2. Since the ride is stiffer, so my tire sidewalls are too soft and the profiles are too high to support it?
I've also increased my tire pressure to about 37-38 psi all around, it seems to improve a little bit but still not enough.

3. Alignment Issue?

This is the alignment I currently running
Front left: -------- Front Right:
-2.0 ----- camber ----- -1.9
8.9 ----- caster ----- 9.1
0.6mm ----- toe ----- 0.5mm


Rear left: -------- Rear right:
-2.7 ----- camber ----- -2.8
0.8mm ----- toe ----- 1.0mm

Any helps would be appreciate, thank you.

terrasmak

iTrader: (8)

Front camber is fine and will be great for cornering, rear camber sucks and should be closer to -2. I have to believe your ride height is pretty low, roll center is screwed up, lowering below roll center adds body roll. Your spring rates are probably a little stiff for the traction your tires offer. Last, BC coilovers are crap and do not really increase performance.

wei350z

thanks terrasmak, my car's height is currently no finger gaps between tires and fenders, not really slammed to the ground. So you are saying I need rear camber kits and also raise my car a little? What's the drop that will make sure I don't lower my car below roll center?
I'm also thinking to get Bilstein B12 pro kit, which is the combo of B8 shocks and eibach pro kit springs. It claims to lower the car about 1.5 inches( 40mm). Would the drop makes my car lower than roll center? Does anyone here have one of the kit and want to share it?

terrasmak

iTrader: (8)

The Z can get lowered about 20mm up front and 35mm in the back before the suspension geometry goes to hell. I bet you are lowered close to 40mm up front and more in the rear.

Yes the car needs to come up a bit.

POS VETT

Apart from the change in roll centers and, ultimately, roll axis, body roll should not be regulated by damping and wheel rate. It's anti-sway bars that should be used to control roll stiffness.

Landon_G03z

How so? I've only seen good reviews?

terrasmak

iTrader: (8)

Here is a great quote. You probably just read the positive reviews and ignore the facts.

stuartc323

I will add the factual reason for why they are crap. Unfortunately, BC Racing, D2, KSport, Stance, and most other cheap coilovers are not R&Ded at all or barely and they arent well made. You can make the argument that they use the same products on their cars in FD or whatever race series but unfortunately it wont be anything sold to me or you. Because of this, they cheap out on the dampeners in the coilovers and match them with really high spring rates. This results in very bad handling limits and reduces the performance of the car.

350Zdj

iTrader: (3)

Yea I doubt they did enough R&D on those coilovers. I've driven a friend's BC-equipped BRZ and it sucked *****. Bumpy ride, not too refined. The good coilovers have shocks that are valved according to the car's weight/balance and spring rates that they go with. KW, for example ride pretty smooth but allow less bodyroll.

Maybe your bushings are also worn out, OP.

Guys, can't roll center adjusters correct the car's roll center? Anyone done this with positive results?

http://www.thenismoshop.com/Megan-Ra...35_p_1675.html

stuartc323

i can tell you its those coilovers, he went too low and they dont handle at all well.

kyle22

iTrader: (4)

What would be considered a decent entry level coilover setup? Anything over $1500?

stuartc323

Sort of, you would want to look for reputable companies.

At that range you can get some Buddy Club, KW V1s, Eibach Pro Street, Truechoice Konis, etc. just need to research and find your options from there

kyle22

iTrader: (4)

Gotcha, how different are KW v1 and v2? im thinking about pulling the trigger on getting the V2 and selling my BC but just trying to make sure I don't make the same mistake again. much difference between True type and OEM type coilovers? or just personal opinion. I know most race applications are true type but don't know the reasoning behind it.

stuartc323

Ok let me answer these questions in order for you.

1. KW V1s have no adjustment for rebound settings, V2 does.

2. True coilovers on a Z provide all their spring rate directly to the wheel in the rear. OEM coilovers use the rear OEM spring location and keep the same motion ratios for the cars suspension. There really isnt a difference on wear and tear except the trues might make your bearings go out a tad bit faster.
IE. calculations for 500in/lb spring rate on rear

True = #500 x.97 x .97 = 471 lb/in

OEM = #500 x.649 x .649 = 210 lb/in

kyle22

iTrader: (4)

Thanks for the clarification Stuart, helped a lot

stuartc323

No problem bro Im here all week

kyle22

iTrader: (4)

Just need to decide on what coils to get. looking between $1,500 - $1,800 maybe a little more if necessary. Setup will mostly be for drift/track events. Leaning towards KW V2 and Tein Flex. opinions on these or any others I should look into?

stuartc323

Honestly bro those are actually really good choices. you wont go wrong with either choice, if you want some added control and handling, replace your bushings while your at it if you can afford to.

kyle22

iTrader: (4)

I have an appointment this Friday to replace my Compression Arm Bushing with SPL and replacing the front lower inner control arm with Whiteline for now till I figure out the next best bushing to install, working my way to replace all of them within the next month or so. sways and tie end rods will be purchased somewhere in there as well lol

350Zdj

iTrader: (3)

I got KW V2 and I love how they perform during AutoX and trackday events compared to my previous Tein SS. Tein Flex would be on par with KW v2

I have another buddy who tracks his car a lot and it has Buddy Club (Racing Spec if I'm not mistaken) and he says the quality is great. Gives him good feel of the car too.