[j28s]

OK - trying to figure some settings out. I have the PSS9's installed and at the track I adjust them from my daily driver settings...same with the adjustable swaybar I just got. I played around with the swaybar a bit and the car performed better and better, but just ran out of time to get it to the best point (I was there for another car...not my daily driver). In any case, I'm trying to figure something out. I understand a swaybar is like a torsion spring and making adjustments is similar to spring rates (fast way to put it). On my race car I have an adj rear bar and it was pretty easy to set because of my high spring rates and prob b/c I was lucky in the settings. BUT, I'm trying to understand the adjustability settings. Is it fair to say the adjustment points is like shortening the length which is reducing the leverage ratio which increases rate? If so, can you have different adjustments on either side (i.e. on 1st hole one side and 2nd hole on the other along with different lengths of endlinks which are adjustable) which will give you more role stiffness on one side versus the other? Note: I don't want to preload the suspension so don't want to hear that.

On OEM tires I'm getting better rear hook up on heavier throttle out of turns (i.e. more traction under accleration toward the end of the apex). I just didn't want to make an adjustment to the point of reduced suspension movement thus making the traction worse through pre-mid-post apex of turns.

Thanks in advance. I didn't know if anyone had any experience with this on their car...

[elbert]

Originally Posted by j28s

I understand a swaybar is like a torsion spring and making adjustments is similar to spring rates

yes

Is it fair to say the adjustment points is like shortening the length which is reducing the leverage ratio which increases rate?

yes

If so, can you have different adjustments on either side (i.e. on 1st hole one side and 2nd hole on the other along with different lengths of endlinks which are adjustable) which will give you more role stiffness on one side versus the other? Note: I don't want to preload the suspension so don't want to hear that.

You can put one side at hole #2 and the other at #3 as a half-step between 2/2 and 3/3. It will not be asymmetrical in roll if you adjust the endlinks properly. If you don't adjust correctly, you will have preload and roll will be different.

To adjust the endlinks, all 4 tires must be on the ground. Make sure the suspension is settled. Adjust on a level surface (i.e. you can't use ramps. If you're too fat to get under your car without ramps, find a skinny friend).

On OEM tires I'm getting better rear hook up on heavier throttle out of turns (i.e. more traction under accleration toward the end of the apex). I just didn't want to make an adjustment to the point of reduced suspension movement thus making the traction worse through pre-mid-post apex of turns.

Then I wouldn't mess with the rear bar, work on the front.

[j28s]

Elbert - thanks for the info. but I disagree with putting left side on hole #1 and the right on #2 making it non-asymmetrical. What would make it non-asymmetrical (just trying to understand)? It is still asymmetrical only more roll stiffness to one side not the other. Granted I did put the car on ramps to adjust the endlinks and did check them again on flat ground to make sure they weren't preloaded and they weren't. Once I get the rear to react to my driving style, I'll work on the front bar...just need some more time at the track which is getting less and less as the race season approaches and need more time in the racecar than the daily driver.... Thanks again and let me know what you think...

[S4to335]

Originally Posted by j28s

Elbert - thanks for the info. but I disagree with putting left side on hole #1 and the right on #2 making it non-asymmetrical. What would make it non-asymmetrical (just trying to understand)? It is still asymmetrical only more roll stiffness to one side not the other. Granted I did put the car on ramps to adjust the endlinks and did check them again on flat ground to make sure they weren't preloaded and they weren't. Once I get the rear to react to my driving style, I'll work on the front bar...just need some more time at the track which is getting less and less as the race season approaches and need more time in the racecar than the daily driver.... Thanks again and let me know what you think...

I have heard that using two different holes makes the setting in between the two. So, I understand what he is saying. I have also been in a Spec Miata race where I just unhooked the rear sway altogether on one side when racing in the rain to keep all four tires on the payment.

As for the parameter settings...I think you are trying to do too much at once...I would get the pss9 settings down..and then add the complexity of the sway bar to the equation ...starting with the least stiff sway bar setting. Try that for awhile..and "maybe" go back and adjust the rear pss9 setting to something higher in number...maybe a 5 or a 6. Without the rear sway..I am at 6 F and 4 R..and my car rotates decently as is. I dont think I need the rear sway change at all...but also remember that I am on a non-staggered track set up...with 235s on all four corners. I will be moving to 245 on all fours on my next R compound purchase.

I am going to Laguna Seca and teaching with Hooked on Driving on Feb 29th..cant wait. It better not rain.

[j28s]

S4to335 - Thanks for the info. I'm on second set of OEM tires (225/255), almost third. I've been on the track with the car a total of 11 days and making adjustments to the car each time to the shocks/swaybar. I was able to get the shocks and tire pressures where I needed them within the first day. Since then just driving the car, playing around with different settings and changing settings between the shocks and swaybars. Prior to the swaybars, I was either running 5f/5r or 6f/4r depending on the track. After the swaybars installed, I went to 5f/6r with the adj swaybars (#2 hole on right, #1 hole on left). Ended up softening the rear to get more traction and same amount of oversteer as the OEM rear bar. After about 9 days of track time (along with two sets of pads and almost two sets of tires), I've reached this point and pretty comfortable with what I've done. In the very near future, I'll be getting an LSD and another set of wheels and probably Toyo RA1 or R888 (245f/265r setup). As I'm sure you'll agree, easier to make primary adjustments on street tires than R-tires. Was lucky that only one day was with rain. That day, softened the rear shocks to 8, #1 hole rear bar, and #3 hole front bar (from #1). Car did handle well in the rain. When the track dried out...it was pretty piggy. Next morning, put the settings back and car was great. Oh, tire temps good and level across the patch in the rear, front was about as good as I could get because of the RFT's.

[S4to335]

I use to have ground control suspension on my old BMW race car and with just me doing the adjusting..of the high speed and low speed rebound settings..I just got confused. Sometimes there are just too many friggin variables to adjust. Compound that to driving style ..and it makes it worse..one set up to one driver is perfect..and to another guy "this is loose as hell".

[j28s]

I know what you're saying. I have friends that own race teams and have been going to the private track days for the last few weeks pretty often. They are using Moton 4ways. After about 45 minutes I came in and they asked what my opinion was on making the car handle better..."which would feel better, high speed rebound, low speed rebound, high speed compression, low speed compression, front sway bar, rear sway bar, stiffer front spring, stiffer rear spring, softer front spring, softer rear spring?" I'm sure my expression was 'a deer in headlights' look.

As of the late, I think I found a mechanical design engineer (in the suspension industry) that is helping me understand my swaybar dilemma. That is, if I can get him to talk English I can understand and shows me some pictures (note: talks in engineering terms I don’t understand). In any case, thanks for the help again…

[S4to335]

Yeah..its one thing if this is your job..and another thing if its your hobby. My brain overloads.

When it ceases to be fun..that is when I go back to when it was.

[sg335]

Hasn't anyone with PSS9's tried running setting #2 in the rear, while 4-6 in the front? This should act similar to adjusting the hole position on a rear bar.

[j28s]

I did try going to #3 w/o swaybar. Problem was with roll and wheelspin. On a tight righthander, the springs control the compression, and on rebound (shock control) the left tire would stick better. But, the right tire (because of roll) would spin like hell which then caused traction break which caused oversteer. Would be great if I had a set of double adjustable Koni 2812's on the car. Easy to adjust and just an awesome shock...but don't have a desire to spend $4k on my streetcar shocks. I'm curious (haven't driven a 335i w/ LSD) how much of a change in handling the car will have (either good or bad). Guess I'll find out in a couple months.

[elbert]

I didn't see you state what exactly you're trying to accomplish.
Please correct me if I'm wrong, but it seems you're just guessing and trying everything.

- Do you have understeer or oversteer? (I'm guessing understeer)
- Corner entry, mid corner, corner exit?
- Fast sweepers or tight turns?
- What alignment are you running? Camber plates?
- What track is this at? Wet or dry? Air temp? Tires? If any of these change, you're just wasting time.

Keep in mind with the limitations of the car and suspension setup, you're probably not going to get the car perfectly dialed in everywhere and will have to make some compromises. What you compromise will depend on what kind of driving you prefer.
Personally, I don't like having the tail hang out and prefer to launch out of the turns. So I will set my car so it is a little slow on turn-in, but accelerates very quickly. Other people prefer a car that turns easily (what I would call unstable) but it won't come out of the turn quite as fast.


About going without a rear sway bar:
For the e46, you need at least 750-800# springs to do that. The PSS9 has something like 300# springs.
I realize that the e90 has a somewhat different rear suspension than the e46 but I'd imagine the spring rates are still too low to be running without a rear bar.

[j28s]

- I do have oversteer, but I prefer oversteer since I can control it with the throttle. The amount of oversteer is slightly higher than desired.
- Oversteer issue is at corner exit. Entry and mid the car handles great. If I have a long straight after a turn, I can trail brake into the turn to further decrease oversteer at corner exit since this increase oversteer in the entry of the turn.
- issue is with tigher turns more than sweepers.
- Alignment is as much as I can get with OEM setup. (no additional camber - slightly more toe out total in front).
- Tracks - VIR, CMP, RA, etc (Southeast) - primarily dry unless otherwise stated - air temp varies since it is winter, but 40s to 60s avg. but track temp more constant in 70s (sunny) - Tire - OEM RFT - Tire temp around 160 to 170. obvious left outside is hotter than outside, right inside hotter than outside since more tighter right hander turns. To compensate for track temp, look at tire pressures and tire temp.
- e90 PSS9 spring rates (as informed by Bilstein) are 400front, 630rear

[j28s]

With some help from a few shock and spring manufacturers, I found the answer about the swaybars I was looking for. Shortening the length (further hole on the swaybar) is reducing the leverage ration which increases rate. if using different hole adjustment, the rate increases overall and the roll stiffness to the side with the shorter length. Next I'll be experimenting with softer/firm RR corner shock setting...hopefully this weekend...

[elbert]

That's interesting. I prefer slight understeer because I can control with the throttle (either romp on the gas a bit to get the tail around or lift).

Not sure why I said temps matter, my mind was probably on lunch.

Anyway, what turn(s) at VIR?
My driving style is obviously different than yours but I give up a bit on turn-in at Turn 1 and Oak Tree to get the car the way I want for the rest
(well, uphill esses too but I either need to run the James Clay line through the grass, or need more aero).

[S4to335]

"James Clay line thru the grass" LOL

what turn?

[elbert]

Originally Posted by S4to335

"James Clay line thru the grass" LOL

what turn?

Uphill esses at VIR
Basically there are two lines:

- you can either drive around the curbs (hitting the curbs tends to upset the car) but need downforce to do this quickly. Daytona Prototypes usually follow this line.

- or you straight-line the turns by putting two wheels off and the curbing goes right in the middle of the car

I like my car, so I drive around the curbs but give up more than a second by doing so.

[j28s]

VIR - T1, T4&5 (left hook), T12 (oaktree). All of the others are fine. Uphill esses really give me no problems unless I just passed someone and to far left and have to pull in too hard hard at T8. As you know there's a bump on the inside of 8 which makes (or the car wants) to drift out far left so the rear end won't come around. I've actually been hit at T8 twice in two different races. T10 is one of my favorites since I tend to get one or two right tires off the track. And every time (if someone is behind me driving my line/car instead of watching the track), they go off the track and end up going down the hill in the grass. Pretty funny. Second turn of Hogpen (going on to straight) can give some problems sometimes (off camber turn) depending on passing, preparing to pass and setting up, or off line. But 98% of the time it's fine.