[mwahlert]

orb - found this post of yours in another thread..

Originally Posted by Orb

I would not be fooled that the KW v3, v2 are better systems. They street comfort springs are linear and stiffer than the v3 or v2 kits. The difference is the street comfort compression dampening is much softer than v2 since the car can’t be dropped no near as much. In short, you car will handle better and less under steer than a KW v2 system under any setup.

The spring rate are:

Street comfort:

285 lb/in front
625 lb/in rear


Kw vv1, v2, v3:

190 lb/in to 256 lb/in (Progressive average) front
545 lb/in to 570 lb/in (Progressive average) rear

It is the only KW system i would recommned unelss you change the "V" sereis springs.

Orb

these springs (kw street comfort) appear to be 48% stiffer up front and only 5% stiffer out back compared to the stock e92 sport package springs - what effect will this have on handling?

[Orb]

Originally Posted by mwahlert

orb - found this post of yours in another thread..



these springs (kw street comfort) appear to be 48% stiffer up front and only 5% stiffer out back compared to the stock e92 sport package springs - what effect will this have on handling?

On a stock car it will add a bit more under steer but not too much. On a stock car that had H&R roll bar installed it will create a lot more understeer. The car has so much front weight bias it will under steer when pushed. At some point does it matter if the car goes into terminal understeer at .50 G or .55 G.

The only setup with balanced car is stock spring and H&R or M3 roll bars.

Orb

[Chowbow]

Originally Posted by mwahlert

i wish someone would make a spring that is about the same rate as the stock ZSP springs - but didn't lower the car so damn much....i basically like the ZSP stance but wish it had a slight forward rake - i hate how the car looks like its squatting when it is standing still

Check out the Vorshlag / AST build your own coilover... You can utilize your stock springs, and they made spring perches that were adjustable in height I believe. I don't see it on their site but I've seen it on their forums and I know they sometimes can do custom stuff like that for people.

[scollins]

Found this while doing a search on "motion ratio":
http://eibach.com/eibach/img/ers-14s...nworksheet.pdf

I haven't read through it closely enough to digest it all. From Orb's posts, it would seem that spring rates should be selected that maintain the same frequency ratio as the factory setup?

[Orb]

Originally Posted by scollins

Found this while doing a search on "motion ratio":
http://eibach.com/eibach/img/ers-14s...nworksheet.pdf

I haven't read through it closely enough to digest it all. From Orb's posts, it would seem that spring rates should be selected that maintain the same frequency ratio as the factory setup?

If want the front load transfer to stay the same then keeping to the same suspension frequency biasing is what you want to do. Here are few numbers to plug into the formula.


Front sprung mass: 889 lbs
Front unsprung mass: 105 lbs
Rear sprung mass: 782 lbs
Rear unsprung mass: 135 lbs


Most BMW have the rear frequency at 10%-15% higher than the front for a flat ride so when you hit bump on the freeway the both front and rear suspension settle at the same time. However, as we go with a more of performance setup this will shift so that the front and rear frequencies are equal or up 8% higher on the front than the rear. KW is the exception and will have much higher frequencies in the front than the rear.

What do I have for biasing …equal frequencies front and rear at 2Hz. Just enough to get R compound tires working well.

It is much better to look as suspension frequencies than spring rates as it is more meaningful and tells you something by looking at the biasing.

The next step is load transfer which determine over/under steer in a corner. The stock car is a big understeering pig at 67% front weight transfer and we like it about 56% (an M3 is at 56.5%). The other option is to go the other way with a big front bar and be a proud owner of a 3 wheel wonder which i have no time for.

Orb

[HP Autosport]

Originally Posted by Orb

The other option is to go the other way with a big front bar and be a proud owner a 3 wheel wonder.

Orb

Hmmm....I have seen air underneath a 335i's inside front tire during cornering more than a few times!

[mwahlert]

Originally Posted by HP Autowerks

Hmmm....I have seen air underneath a 335i's inside front tire during cornering more than a few times!

i think orb is saying that isn't a good thing!

[mwahlert]

street comfort
285F *.96^2 = 263
625R *.563^2 = 198

263F appears to be 33% stiffer than 198R

stock e92 sport suspension
145lb/in * 0.96^2 = 134 lb/in
460 lb/in * 0.563^2 = 146 lb/in

where with the stock setup the front is about 8% softer than the rear

i would imagine the car would feel completely different w/ the KW setup - for the good or the bad i'm not sure....

why are suspension tuning options for this car ALL over the place? some are stiffer in the front, some are stiffer in the rear, some as about as stiff as stock but much lower..... its like suspension tuning companies are not tuning - just picking numbers out of a hat and saying its good to go...

orb - do you have any comments regarding my car w/o the sport package sedan? how much different are the roll bars on my car compared to the stock sport package? what does this change regarding overall balance, etc.....

like i mentioned to you i am not looking to track the car - i just want it to be fun on the street but well balanced - do not want to make it snap oversteer etc...

[HP Autosport]

Originally Posted by mwahlert

i think orb is saying that isn't a good thing!

I know it's not a good thing!

[HP Autosport]

[QUOTE=mwahlert;3929583] i'm not sure....

why are suspension tuning options for this car ALL over the place? some are stiffer in the front, some are stiffer in the rear, some as about as stiff as stock but much lower..... its like suspension tuning companies are not tuning - just picking numbers out of a hat and saying its good to go...

[QUOTE]

And I have know some suspension tuners relying on what they know on the E46 chassis tuning results to tune the E9X!!!! Since they were in such of a hurry to release the kits, they had to rely on customer feedbacks trying to correct what was wrong, so the next kit is supplied with a closer to correct spring rates.

From some of the data I have collected and working closely with "Orb", there is only one suspension tuning company who got it very close from the start, where everyone else is still in the infant stage and guessing what spring rates to use.

[Orb]

Originally Posted by mwahlert

street comfort
285F *.96^2 = 263
625R *.563^2 = 198

263F appears to be 33% stiffer than 198R

stock e92 sport suspension
145lb/in * 0.96^2 = 134 lb/in
460 lb/in * 0.563^2 = 146 lb/in

where with the stock setup the front is about 8% softer than the rear

i would imagine the car would feel completely different w/ the KW setup - for the good or the bad i'm not sure....

why are suspension tuning options for this car ALL over the place? some are stiffer in the front, some are stiffer in the rear, some as about as stiff as stock but much lower..... its like suspension tuning companies are not tuning - just picking numbers out of a hat and saying its good to go...

orb - do you have any comments regarding my car w/o the sport package sedan? how much different are the roll bars on my car compared to the stock sport package? what does this change regarding overall balance, etc.....

like i mentioned to you i am not looking to track the car - i just want it to be fun on the street but well balanced - do not want to make it snap oversteer etc...

I am not sure if the suspension companies have a clear objective what they are tiring to achieve so you see all sorts of setups. Do you know what you want would be a better question.

It is better to look at this as suspension frequencies at the very least to understand pitch. You can see the frequencies on OEM setup are higher in the rear so when you go over bump both the front and rear settle down at the same time with very little dampening. As we move to performance setup will see equal frequencies front and rear or front frequencies increase up to 10% more than the rear. One of the difference these two setup will change is the KW setup will take set in corner late with the rear taking set first. The opposite is true with the OEM setup. Since we change the frequencies biasing we see some change in balance but it subjective and based on your existing roll bar sizes and spring stiffness. The rule is that the stiffer end losses traction first no matter how little when we make a single change like springs.

There is not a setup I know other than stock spring and H&R rear bar only that will cause oversteer as it front weight biased 2% towards over steer…not good. The sock suspension H&R bars are still biased more than ideal towards understeer by a very safe margin. My old KW with H&R roll bar setup terminally understeer. Regardless of the comments on this forum true oversteer is not going to happen unless you go to some effort to make it this way.

Getting a balanced setup is very hard to do. The reason it we are tiring to get weight transfer with 2-3% range so were are dealing with only a 300 lb load. It not something you can guess at. It has to be calculated and then validating through testing to you understand what is going on.

285F *.96^2 = 263 lb/in @ 1.70 Hz
625R *.563^2 = 198 lb/in @ 1.57 Hz

145lb/in * 0.96^2 = 134 lb/in @ 1.20 Hz
460 lb/in * 0.563^2 = 146 lb/in @ 1.34 Hz

I would take KW v3 and run M3 roll bars with these spring rates. You will need camber plates.

230 F
635 R


Orb

[scollins]

Originally Posted by HP Autowerks

From some of the data I have collected and working closely with "Orb", there is only one suspension tuning company who got it very close from the start, where everyone else is still in the infant stage and guessing what spring rates to use.

Which company is that? I've been deciding what parts to pull the trigger on, but after the wife's reaction to the AE exhaust, I'm leaning more towards an easily adjustable system (from the cabin) so I can try to make it floaty-bloaty when she drives, but taut when I drive.....


This is where it pays off to be a "late adopter" vs. an "early adopter"!! Besides, the majority of guys here on the forum buy coilovers striclty to lower the car and don't really care about performance (as long as it is as smooth or smoother than stock.) Some of the guys hanging out in this sub-forum are a little more serious.....

[Chowbow]

Originally Posted by Orb

I am not sure if the suspension companies have a clear objective what they are tiring to achieve so you see all sorts of setups. Do you know what you want would be a better question.

It is better to look at this as suspension frequencies at the very least to understand pitch. You can see the frequencies on OEM setup are higher in the rear so when you go over bump both the front and rear settle down at the same time with very little dampening. As we move to performance setup will see equal frequencies front and rear or front frequencies increase up to 10% more than the rear. One of the difference these two setup will change is the KW setup will take set in corner late with the rear taking set first. The opposite is true with the OEM setup. Since we change the frequencies biasing we see some change in balance but it subjective and based on your existing roll bar sizes and spring stiffness. The rule is that the stiffer end losses traction first no matter how little when we make a single change like springs.

There is not a setup I know other than stock spring and H&R rear bar only that will cause oversteer as it front weight biased 2% towards over steer…not good. The sock suspension H&R bars are still biased more than ideal towards understeer by a very safe margin. My old KW with H&R roll bar setup terminally understeer. Regardless of the comments on this forum true oversteer is not going to happen unless you go to some effort to make this way.

Getting a balanced setup is very hard. The reason it we are tiring to get weight transfer with 2-3% range so were are dealing with only a 300 lb. It not something you can guess at. It has to be calculated and then validating through testing to you understand what is going on.

285F *.96^2 = 263 lb/in @ 1.70 Hz
625R *.563^2 = 198 lb/in @ 1.57 Hz

145lb/in * 0.96^2 = 134 lb/in @ 1.20 Hz
460 lb/in * 0.563^2 = 146 lb/in @ 1.34 Hz

I would take KW v3 and run M3 roll bars with these spring rates. You will need camber plates.

230 F
635 R


Orb

Maybe something that Vorshlag or TCK can set people up with?

[scollins]

Originally Posted by Orb

If want the front load transfer to stay the same then keeping to the same suspension frequency biasing is what you want to do. Here are few numbers to plug into the formula.


Front sprung mass: 889 lbs
Front unsprung mass: 105 lbs
Rear sprung mass: 782 lbs
Rear unsprung mass: 135 lbs

Orb

Which car are those numbers for? What I mean is, E90 335i ZSP with 18" 162's, E92 335i with 189's, etc. So changes to wheels, tires and brakes would have an effect on those numbers, correct? Or is the change fairly neglible and can be ignored? I've dumped about 12 lbs per corner by changing my wheels.....

Edited to add:
I've done a bunch of math and I come up with the following:

Tein SS-P Coils (392F/671R)
Front WR = 361 @ 2.00 Hz
Rear WR = 213 @ 1.63 Hz

JIC Cross Coils (450F/674R)
Front WR = 415 @ 2.14 Hz
Rear WR = 214 @ 1.64 Hz

TC Kline Coils (350F/700R)
Front WR = 323 @ 1.89Hz
Rear WR = 222 @ 1.67Hz

[Orb]

Originally Posted by scollins

Which car are those numbers for? What I mean is, E90 335i ZSP with 18" 162's, E92 335i with 189's, etc. So changes to wheels, tires and brakes would have an effect on those numbers, correct? Or is the change fairly neglible and can be ignored? I've dumped about 12 lbs per corner by changing my wheels.....

Edited to add:
I've done a bunch of math and I come up with the following:

Tein SS-P Coils (392F/671R)
Front WR = 361 @ 2.00 Hz
Rear WR = 213 @ 1.63 Hz

JIC Cross Coils (450F/674R)
Front WR = 415 @ 2.14 Hz
Rear WR = 214 @ 1.64 Hz

TC Kline Coils (350F/700R)
Front WR = 323 @ 1.89Hz
Rear WR = 222 @ 1.67Hz

I wouldn’t worry about the numbers to much as it just good to get a general idea and they are close enough. The mass calc are for e92 with me in the car. You can PM with the detail and I can refine this for you.

No you can select a setup for how you want the car to run in ect but it is dependant on your goals so let me know this and we can narrow it down one parameter at time.

If you did not know you can also upgrade KW v3 to selectable spring rate coilovers. They actually have a very good adjustable range up to 75 lb/in at the wheel. The numbers look good for v3 with KW camber plates and linear springs. This will be close to balanced with M3 roll bars. The M3 bar will work well will equal frequency to 5% higher front frequency.

280 lb/in @ 1.69 Hz
672 lb/in @ 1.63 Hz

The most important thing is to have a goal in mind then the data will help you pick the right system or slightly customize a off the self one.

Orb

[YvesD]

Originally Posted by Orb

If want the front load transfer to stay the same then keeping to the same suspension frequency biasing is what you want to do. Here are few numbers to plug into the formula.Orb

Orb,

Does this explain why the Eibach pro-kit seems to work well with stock shocks ?

ie Eibachs spring rates are very similar to stock ?

Regards

Yves

[jah29]

After reading this thread I've gone and done a lot of suspension theory reading so I now agree with Orb, and would like to keep the same spring ratio front and rear as comes stock from bmw.

I have a 135i. Notice my car has the lowest rates listed so far 120/350!! It seems like I could swap in the springs from a 335i, from a m3 (non-edc car) or from tein. I'm hoping all these springs are interchangeable across the 3-series and 1-series range since the suspensions are virtually the same. Maybe each car has different mounts, anybody know?

I'd also like to upgrade the swaybars in a similar manner too, M3 front and rear. It seems like that can be done no problem.

thanks,
justin

[seccsc]

Anybody know the spring rates for the BMW Performance Suspesion? I was curious and thought it might add to the thread....

[HP Autosport]

Originally Posted by jah29

After reading this thread I've gone and done a lot of suspension theory reading so I now agree with Orb, and would like to keep the same spring ratio front and rear as comes stock from bmw.

I have a 135i. Notice my car has the lowest rates listed so far 120/350!! It seems like I could swap in the springs from a 335i, from a m3 (non-edc car) or from tein. I'm hoping all these springs are interchangeable across the 3-series and 1-series range since the suspensions are virtually the same. Maybe each car has different mounts, anybody know?

I'd also like to upgrade the swaybars in a similar manner too, M3 front and rear. It seems like that can be done no problem.

thanks,
justin

Hi Justin,

Yes, you can use springs from 335 or M3. The M3 front and rear anti roll bars do fit as well and will give you a very balanced car.

Harold

[jah29]

Harold-

thanks for the reply.

I'll be contacting you soon about buying some stuff. I can't decide between the lsd or m3 suspension parts first. One of those is certainly less painful to the wallet, but maybe not as fun...

justin

[LaYzEe]

Originally Posted by HP Autowerks

Hi Justin,

Yes, you can use springs from 335 or M3. The M3 front and rear anti roll bars do fit as well and will give you a very balanced car.

Harold

Does that also mean you can use the bmw performance springs from the 135s and fit them in the 335s?

[tscdennab]

Ohlins Road & Track for e90:

Front: 400lb/in
Rear: 343lb/in

But you can order any rates you want with this suspension, free of charge (almost).

Edit: the rates may be the other way around (front 343, rear 400).