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Shocks - ?????

What do I do for shocks? I know that with shocks I can change the transitioning and turn in feel of the car. So far, the STi seems to be a little slow and "laggy" on the transition and I could definetly use a quicker and sharper turn in. What I don't want to mess with, is the mid turn and turn out ability of the car, as right now, the car is perfectly balanced on the throttle while pulling out of a turn.

So basically, how should I have the shocks valved to help the turn in and transitional response of the car, but leaving the same mid turn feel and turn out feel? Here are my thoughts, anyone have any opinions? I feel I can get the singles on the front and save some $$.

Front - Leave the compression alone and make them rebound adjustable only. Degass to get the front lowered a tad and have a lower roll center. Set the softest setting to "stock STi shock" rebound and go up from there

Rear - Double adjustable. Do not degass. Have the Rebound and Compression softest settings as "stock STi shock" and go up from there.

Thanks for any input
-Tom

front sway bar?

_________________
Jim Pastorius
2008 Silverado VortecMax
1992 Camaro CMC#92
2002 BMW R1150R

2009 3rd Place CMC Mid-Atlantic Championship
2009 CMC Hyperfest Winner

Already has the biggest front bar I can buy in the US which is a 26mm.

They make a 28mm bar in australia, but with anything bigger I think I might compromise the excellent on throttle on turn out the car has now. I ran a 24mm front bar on the WRX in DS and anything bigger was a "dimisnishing returns" situation between gaining in transitions, but losing front end grip in sweepers. I guess the center diff on the STi makes up for it and lets you run even a bigger front bar, and I would be willing to try the 28mm if I could get one here!

-Tom

How does degassing the shock lower the suspension? I thought the car was supported by the springs, not the shocks...

I've also read that the front LSD will limit the quickness of turn-in on tarmac, so you may be stuck with it regardless of what changes you make. Or you may be able to adjust it out with the center diff? (or I may have no idea what I'm talking about?)

Degassing the shocks while having a high rebound setting will allow the shocks to sort of "ratchet" themselves down during a run thus lowering the car a tad

-Tom

Tom,

AFAIK a lower roll center will allow more roll unless the CG goes down at least as much as the roll center goes down. Roll is heavily influenced by the distance between the CG and the roll center. The greater the distance between the two, the greater the roll for a given spring/bar combination. Whether the lowering associated with degassing will make a significant difference I don't have a clue. I'm not sure shock degassing had been "invented" the last time I ran a stock class car seriously. Note that I did do rather well with a Stock 260Z which was actually raised slightly by Bilsteins but that was a LOOOONG time ago.

If you are going to run large tires on relatively narrow rims (boy have things changed when a 7.5 in rim in Stock is narrow compared to he available tires), then I would be really concerned about doing anything else that could hurt transitions. I'm not sure what cars will be in AS next year but I suspect many of them will be lighter and/or have a lower center of gravity. If so, you will need to be able to change directions really quickly to take advantage of your power/forward bite (I love that Nascar term).

You may want to spend some time looking at http://pub6.ezboard.com/fdsrforumcarbui ... =420.topic

Pay particular attention to posts by Jay Novak (see write up on Jay in recent Sports Car) and Richard Pare. Note Jay's comment regarding ultimate grip being less important than balance. I think he is also an advocate of transition speed being important in autocrossing.

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Dick Rasmussen

FS 50 2018 Mustang GT

A shock with gas pressure is a spring of sorts. That's why the shock rod is normally extended and takes a force to compress it. The gas pressure, however, simply adds a small amount of "lift" to the car compared to the springs. I don't know the correct terminology, etc. but it is "sort of a preload". Gas pressure shocks can be tuned by adjusting the gas pressure.

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Dick Rasmussen

FS 50 2018 Mustang GT

Tom,

I recommend that you contact shock gurus such as GH Sharp, Guy Ankeny, Mark Daddio, etc. to get their input. You may want shocks that allow you to "fool" the stock suspension by doing things like sucking the car onto bump stops or, conversely, keeping the car off the bumpstops. Maybe you can contact Brien Priebe since he is a Subaru guy and is apparently knowledgeable. Don't forget how bumpy many of the National level sites are.

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Dick Rasmussen

FS 50 2018 Mustang GT

Tom, I agree with Dick...contact some shock folks. I'd start with G.H.

Eric

Anyone have GH's email address?

Eric/Jim/Dick - how did you guys figure out what to do on your cars when you were/are setting up the shocks??

-Tom

ghsharp@aol.com

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SPIN or WIN!
there's no glory for going slow.

I think Eric is an expert on this topic. He was in a similar situation, setting up a new car in class.

I was able to cheat a little. I had help from Pat Salerno and Sam Strano on setting mine up. They gave me a good baseline to work from. Especially whenI went to the ST bar. ES drivers used to exchange information freely. That has changed over the past 18 months though. It might be due to the fact I have become more competitive with them

Then it comes down to testing, testing and testing. Do to a limited budget, I am behind in the testing. Now I know how some of those NASCAR teams feel.

Pat told me all you need is a third gear, 8 cones slamon to test. I believe that.

_________________
Jim Pastorius
2008 Silverado VortecMax
1992 Camaro CMC#92
2002 BMW R1150R

2009 3rd Place CMC Mid-Atlantic Championship
2009 CMC Hyperfest Winner

Tom,

As you know, after three seasons I was still learning setup tips about the Spyder. This means two things: 1) I am a dumbass, and 2) Figuring out how to max the setup on a car is not always easy.

The short answer is a lot of R&D. I bought 7 different sway bar sizes for the car and went through several re-valve jobs in the first two seasons. Though, don't get too scared, that was likely a worst case scenario...plus Tim actually won the Pro Championship the first year we had my Spyder, so it was not too bad the first year.

More specifically...

Step #1 is find a competent shock person to work with you on firguring out how to valve the shocks. Important: You do not have to have all the answers. Any good shock person should be able to give you something that's in the ballpark.

Step #2 - Go test the shocks and test them with a competent co-driver, the extra feedback is critical. This will give you enough info on what you're next step is. Such as...do I need a front bar, tire size, or alignment change? You'll be able to factor that stuff in with how the car is handling and translate that into the decision of whether or not you need to get the shocks re-valved. I like to know that I have adjustability left in my shocks. For example, if I'm testing on concrete...have shocks set full stiff front, full soft rear, toe-in rear, a big front bar, and the car is still oversteering a lot....then, it's time to send the shocks back. The first time Tim and I tested our shocks the car was undriveable since it was way too stiff, the worst handling car I've ever driven. So we sent the shocks back, gave them feedback, and they were pretty good upon their return.

So, talk to someone competent (G.H. is a good start), put those suckers on the car and start testing. Really not much else to do, except for Step 3, which is win the Tim Aro autographed flag of Finland on eBay so you can put it on your car

Good luck,
Eric

Tom,

I haven't set up a Stock class car with modern shocks. As far as my FF, I took a simplistic approach (probably overly simplistic). I had Mark Ball at Koni valve some high quality shocks for my car assuming planned spring rates, tested a bunch of runs to see what the various settings did, and then picked settings that had no bad habits. Then I decided to DOUBLE my spring rates! Fortunately the shock valving could handle the increase just fine (high pressure Koni 30 series race shocks). I made sure the adjustments had no bad habits and forgot about it. When I get back to autocrossing the CM car again, I may experiment again to see if response time can be improved even further from what the stiff springs did. Plus the tire design has changed and that may force some shock adjustment changes once I relearn how to drive.

Keep in mind that a CM car doesn't need shocks to make the car responsive or to fool it into being balanced. I can change all sorts of other stuff (and get really confused).

Edit to add: Improving a stiffly sprung (my wheel rates equal the corner weights) car with a low center of gravity, etc. with shock adjustments is probably a much more subtle and site specific effort than it is with a stock class car where you are trying to do with shocks what you cannot do with springs, bars, ride height, etc. Plus the "real race tires" change characteristics with temperature even more than the "R" tires or the "almost R" tires do. This complicates testing. Besides, I'm almost always on a "learning curve" for each run and there is much more time in the driver than in the shock adjustment. Makes it hard to "worry" about adjusting shocks between runs to make the car faster. I adjust the driver instead.

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Dick Rasmussen

FS 50 2018 Mustang GT

Thanks for the advice....

I figured a bunch of R&D would be involved, but I really can't afford to have the shocks done and then revalved....That would be a ton more $$.

I shot an email to brian priebe and mark daddio so far. I would feel kinda bad calling GH and asking about shocks since I won't be buying them through him but going straight to truechoice.



I was trying to avoid the "too stiff" thing, which is why I was going to leave the softest setting at pretty much the stock setting. The STi has pretty stiff shocks stock already. I guess the next question is, how did you determine that first shock valving? How did you get it too stiff? Was it something you guys guessed on? I was thinking about sending in the stockers to get dynoed and then base the konis off that...



Well I've gotten outbid twice on it now!



That right there is a great point though. I know I will be on the learning curve for a bit and honestly, unlike the WRX in STX, I don't plan to be fast right away. I think it will take me some time to learn the car. I would hate to be held back by the car, but I don't think that is likely to happen at *all* so I could just hold off on the shocks until I stop getting faster with the stockers....

-Tom