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Old 04-23-2014, 09:05 PM   #1
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Got my S back after suspension upgrade

Sourced a lightly used spec box setup
With some KWsports, 500# front and 650# rears

From various folks I picked up
A set of M030 sways, some tarrett rear drop links, tarrett camber plates, and new tarrett monoballs rear strut mounts.

Did a little tower dremmel mods to the front camber mounts.

Just got it back from the alignment shop

Pulling -2.8 degrees front camber and -2.3 rear camber.

New Dirrezza Ii's on rear to go with Dirrezza 1's up front

Installed Underdrive pulley, plumbed for oil pressure gauge (although I have to wire up the gauge still)

Felt really solid on the ride home.

Stiff for sure, but not intolerable.

Can't wait to hit the track and see how the upgrade performs.

Mike

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Old 04-24-2014, 01:21 PM   #2
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Sounds nice...pics?

Running adjustable rear toe arms?
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Old 04-24-2014, 04:09 PM   #3
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Quote:
Originally Posted by jimk04 View Post
Sounds nice...pics?

Running adjustable rear toe arms?
No -- KW sports, M030 sway bar and tarrett drop links with
tarrett mono-ball spring supports.

No after pix yet

Here is a before with my DD and Tow vehicle.



Mike
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Old 05-06-2014, 12:47 PM   #4
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Well crap -- took the Box S to my local track and had to replace 4 fillings and 3 ribs....

Ok it wasn't that bad -- but it was damn near undrivable.

My home track resembled a cow pasture when driving at speed.

I have to source some alternative springs --

Does anyone know what spring rate the original Boxster S is equivalent to?

I don't want to go quite that far -- but I can't drive with the 500/650 I have in there now.

thanks,

Mike
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Old 05-06-2014, 03:08 PM   #5
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Quote:
Originally Posted by seningen View Post
Well crap -- took the Box S to my local track and had to replace 4 fillings and 3 ribs....

I have to source some alternative springs --

Does anyone know what spring rate the original Boxster S is equivalent to?

I don't want to go quite that far -- but I can't drive with the 500/650 I have in there now.

thanks,

Mike
I measured the fronts at about 220 lb/in before I pulled them off the car, Resulting front wheel rate is about 180 lb/in. I didn't measure the stock rear, but would guess they are around 300 lb/in spring. They are progressively wound, so not linear though.

I am running 400 lb/in front / 500 lb/in rear now which works well on smooth race tracks (Barber & Road Atlanta) as well as relatively rough auto-x parking lot course. Good luck.
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Old 05-06-2014, 03:41 PM   #6
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What compression and rebound settings were you using? The Boxster I bought currently has 700/800 front/rear but has Moton shocks with a ton of adjustability. I'll be in it for the first time on track this weekend - looking forward to seeing how it is setup. I have setup notes from the previous owner - but not for the track I'll be on. I'm figuring I've got to start some place. It is also on full race slicks as well.
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Old 05-06-2014, 04:22 PM   #7
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Quote:
Originally Posted by seningen View Post
Does anyone know what spring rate the original Boxster S is equivalent to?
Stock springs are roughly 180F 250R
Stock PSS9 springs are roughly 260F/370R [ My car]
Boxster Spec are 450/500

Personally I think 450/500 is too much spring for a car with an open diff and often results in wheel spin on corner exit. Also way too stiff for street use with PSS9s. A more sophisticated dampener may be able to manage stiffer springs.

The voodoo is getting your tires, running weight, spring rates, dampeners, sway bars and driving style all working together to control your contact patch instead of fighting each other. Getting it exactly right is harder than it seems.
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Last edited by Topless; 05-06-2014 at 04:29 PM.
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Old 05-06-2014, 06:49 PM   #8
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Welcome to the wonderful world of suspension! Your education will start now and end....... uh, never.

My first suggestion is to set the shocks to full soft for compression and rebound. I have found that often the shocks cause a harsh ride rather than the springs. Then adjust from there.

If you look at all of the Spec Boxster setups, you will see a surprisingly wide variety. For example, Topless' suggestion to help put the power down on turn exit is to run a softer spring (which is fine), however I like to run a softer rear roll bar to try to soften the rear end in corners. This not only lets me get the power down on turn exit but also to keep the rear end planted if there are bumps. At the end of my last race, I even had a fellow racer even get down on his hands and knees to see where my rear bar was set because he couldn't believe how well I was able to drive away from him in some corners. The trade off (yes, there is almost always a trade off) is that I give up some roll stiffness and have to account for the additional roll in my driving technique. Same goal, but different approaches for different drivers.

I will admit that I have no experience with the KW's and they might react completely differently than the PSS9's. With that being said, my next best suggestion is to find a local shop that is familiar with racing and have them help set up the car. There is a fine art in balancing shocks, springs, tires, ride height, rake, tire pressures, etc., and one size definitely does not fit all. Paying someone with the right experience to get the car into the ballpark as a starting point might save a lot of trial and error ($$$) in the long run. Then you can work the fine adjustments on your own and always go back to the baseline.
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Last edited by thstone; 05-06-2014 at 06:59 PM.
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Old 05-14-2014, 04:35 PM   #9
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How about calling a few race-shops or placing a wanted ad on here for stock bilstein pSS-9 springs ?
You should be able to get a set as a cheap experiment .
There must be hundreds of spare sets gathering dust seeing as all the spec racers have bilsteins with quarter ton springs ......

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