When installing Bilstein PSS9s what

[Johnny Danger]

Originally Posted by thstone

Yes, I called them end links. Sorry if this caused any confusion.

TMan,

I have PSS9's installed on my vehicle, however, the "race prep" shop felt confident that they were able to accomplish an excellent "street" set-up without the need for adjustable control arms or link ends (drop links). Although, my vehicle felt transformed after installing the PSS9's, Ive wonder all of these years if my set-up is optimal ? Also, the shop claims to have corner balanced my vehicle, along with the height adjustment and alignment, however, in hindsight, I find it difficult to imagine that they were able to properly corner balance my vehicle without using adjustable drop links. Correct ?

[thstone]

Originally Posted by Johnny Danger

TMan,

I have PSS9's installed on my vehicle, however, the "race prep" shop felt confident that they were able to accomplish an excellent "street" set-up without the need for adjustable control arms or link ends (drop links). Although, my vehicle felt transformed after installing the PSS9's, Ive wonder all of these years if my set-up is optimal ? Also, the shop claims to have corner balanced my vehicle, along with the height adjustment and alignment, however, in hindsight, I find it difficult to imagine that they were able to properly corner balance my vehicle without using adjustable drop links. Correct ?

Well, mostly yes (they could corner balance the car) but a little bit no (without adj end links the corner balance could be biased).

First, corner balancing is done through the adjustment of the springs so adjustable drop links are not necessarily required. Of course, this can only be done on cars with coil over suspension. Adjusting the springs will either lighten or load the weight on a particular wheel. Of course, adjusting the springs also changes the ride height (how much depends on the stiffness of the spring and how out of balance the car is).

The magic in corner balancing is getting the ride height correct (including front to rear rake) and at the same matching the diagonal weight pairs (LF/RR to RF/LR). This is a somewhat iterative process (this is why it costs several hours of shop time to perform).

Corner balancing is best done with the sways unattached to avoid any pre-load that they might impart to the suspension/springs. However, if you have stock sways, then most often the car is corner balanced with the sways attached so any preload from the sways can be taken into account/compensated by the corner balance. However, some shops will corner balance with the stock sways unattached and then re-attach and measure the effect (load) added by the sways. If its not too much, then they will leave it at that.

Adjustable drop links allow the tuner to go that one small step further and re-attach the sway bars after the corner balance making sure that the sways don't add any preload to the suspension.

So, is having non-adjustable end links a big deal? Does the difference really matter? Hard to say, because it depends on the amount of load that the stock sways add to the suspension. And even though its there, the corner balance did compensate/account for it. But its not as precise or pure as the corner balance using adjustable end links.

As for simply setting the ride height equally and leaving it at that, this is readily acceptable for a regular street car. This is done all of the time. But understand that you're not going to get the most out of the suspension. And why install an expensive coil over suspension if you're not trying to get the very best out of it?

[Johnny Danger]

Originally Posted by thstone

Well, mostly yes (they could corner balance the car) but a little bit no (without adj end links the corner balance could be biased).

First, corner balancing is done through the adjustment of the springs so adjustable drop links are not necessarily required. Of course, this can only be done on cars with coil over suspension. Adjusting the springs will either lighten or load the weight on a particular wheel. Of course, adjusting the springs also changes the ride height (how much depends on the stiffness of the spring and how out of balance the car is).

The magic in corner balancing is getting the ride height correct (including front to rear rake) and at the same matching the diagonal weight pairs (LF/RR to RF/LR). This is a somewhat iterative process (this is why it costs several hours of shop time to perform).

Corner balancing is best done with the sways unattached to avoid any pre-load that they might impart to the suspension/springs. However, if you have stock sways, then most often the car is corner balanced with the sways attached so any preload from the sways can be taken into account/compensated by the corner balance. However, some shops will corner balance with the stock sways unattached and then re-attach and measure the affect (load) added by the sways. If its not too much, then they will leave it at that.

Adjustable drop links allow the tuner to go that one small step further and re-attach the sway bars after the corner balance making sure that the sways don't add any preload to the suspension.

So, is having non-adjustable end links a big deal? Does the difference really matter? Hard to say, because it depends on the amount of load that the stock sways add to the suspension. And even though its there, the corner balance did compensate/account for it. But its not as precise or pure as the corner balance using adjustable end links.

As for simply setting the ride height equally and leaving it at that, this is readily acceptable for a regular street car. This is done all of the time. But understand that you're not going to get the most out of the suspension. And why install an expensive coil over suspension if you're not trying to get the very best out of it?

TMan,
Thanks for the excellent and thorough explanation !

[jaykay]

Great we are going through a lot detail here...

Have another train of thought ..question

As Topless indicated front LCAs will become necessary to save and optimize R-compound tires. What exact tread ware threshold are we speaking about? Is there a tread ware number range where the arms are essential. If so what is it? Currently I plan to be in the 140 to 200 range.

Lets say one puts front LCAs in on PS2s and corner balance and set up is done. Then you change to R1Rs or some more sticky R comp. Will a completely new set up have to be done for each tire change? Have you wasted money setting up on PS2s?

Would be it be true to say that unless LCA installation is included with strut time you are wasting money because a complete setup must done for different tire compounds/styles anyway, and you should install them during one of these iterations to be cost effective?
(considering LCA installation labour is discrete/separate)

[Topless]

Running street compound tires and a good setup you should be fine without GT3 control arms. As you move towards softer compound tires, they generate a lot more lateral grip and require more negative camber. I like to make tire and setup choices once per year and run the same comp tire all season.

A rough guide for track days:

140 TW -1.5deg F camber
100 TW -2.0 deg F camber
40 TW -3 deg F camber
Racing slicks -3-4deg F camber

This is variable depending on specific tire choice and driving style but gets you in the ballpark. Final adjustments should be made after checking tire temps and wear patterns. Getting your setup just right means tires achieve max grip, wear evenly, and last a lot longer. Setup costs pale in comparison to shredding soft compound tire shoulders and eating a set of tires in one weekend. A $1600 set of Hoosier R6 might last 4 track days. Shredding a $1600 set of R6 comp tires in one day due to a lousy setup is painful.

[jaykay]

Nice information. So I should be able to get -1.5 with the stock arms?

[Topless]

Yep, my car is close to -2 degrees with stock arms and the front end significantly lowered. This is just enough for NT-01 tires and a bit too much for Hankook RS3s.