Porpoise effect and three wheelin 6+" in the air *Paging Hollis

[Erv]

So I ran this weekend at huntsville ended third in pax, but the car was raising the tires over 6" in the air, not an exaggeration. Also the front end had a habit of bouncing, like the spring rates were WAAAAAAY to soft. It was basically gripping hopping gripping hopping. Corner Balancing this week and lightening the front end, so hopefully the hopping will be lessened. Hoping to have intake and Exhaust done, unfortunately headers won't be done yet.

Anyone else had this issue? Hollis, Andres, FAM?

 

[Andy Hollis]

So I ran this weekend at huntsville ended third in pax, but the car was raising the tires over 6" in the air, not an exaggeration. Also the front end had a habit of bouncing, like the spring rates were WAAAAAAY to soft. It was basically gripping hopping gripping hopping. Corner Balancing this week and lightening the front end, so hopefully the hopping will be lessened. Hoping to have intake and Exhaust done, unfortunately headers won't be done yet.

Anyone else had this issue? Hollis, Andres, FAM?

You are probably bottoming out the front.

To see if this is the case, put a zip tie on the shock shaft before a run. Push it down against the shock body. Take a run. Now look and see where it ended up. If it's jammed up against the upper spring perch, you bottomed.

The K Sport setup will allow you to lower the car far enough that you bottom fairly consistently with the given spring rates. That's why I went double the rate.

What are you doing for an intake?

The exhaust will help a bunch, once you get the stock mid-pipe/resonator/cat#2 out of there.

 

[Erv]

CAI running into the splash guard like the Injen. Was going to go SRI, but I like the CAI. Def need more rate on springs I was thinking 500f/550r.

 

[genericmoniker]

Sounds like my FC. I know for a fact that thing bottoms out, bad APEX lowering springs lmao.

 

[TAftonomos]

I just ordered the pss coilovers as I've never had good luck with lowering springs and stock shocks...I don't have the funds to duplicate Andy's setup, but I hope they will let me have some local cone weaving fun...

 

[Andy Hollis]

More on this...

At Packwood, I had this happen on a couple of runs. I am convinced that it comes from the extremely limited bump damping in the K=Sports, which causes bottoming out of the front under hard braking and then turning. From there, the bump stop bounces the car back up and there isn't enough rebound damping to control the spring rate of the bumpstop. This causes an oscillation.

The Bilsteins should have decent bump damping so you should be fine so long as you don't go too low on ride height.

 

[TAftonomos]

Thanks Andy! I didn't order them to drop the car into the weeds. Do you have a suggestion as to what height I should pick as a starting point? I'll be using a 15x7" 35mm offset wheel and plan on using 190/50/15 tire.

 

[Gravity]

I was thinking between the Bilsteins and the K-Sport... I'm running H&R on stock dampers now... I suppose Bilsteins are the way to go

 

[CRG Racer24]

Depends what you're looking for.. K-Sports will be perfect for being low, daily driving, backroads and the occasional track day. The Bilsteins I'm fairly certain don't go as low, but the dampers/shocks are much better than that of the K-Sports, so they will handle better.

From there, it's now up to you.

 

[Gravity]

See I'm far more interested in 'good' than 'low'

I've got about 1.5" drop on the H&R's and i'm quite happy with the look. What I want is not a 'softer' ride but a more controlled 'tight' ride. I like the ride as it is now, but i want the control.

 

[CRG Racer24]

Yeah fair enough.. go for the Bilstein's my friend. You can drop the Bilstein's to your current ride height and have a MUCH better handling car.