Input requested: S14, Koni/GC...shock settings?

[orion]

Hey guys...

Recently upgraded to a Koni 8611 (front and rear) and ground control setup...my old(er) Tein HE's served me well, but it was time to upgrade.

With the old setup, the car was VERY neutral, and very predictable. Slight hint of oversteer, but just a great level of grip (on smooth surfaces, at least).

With the new setup, it's "twitchy", I'd say. Too tail happy. I've done one autocross (just to test it out), and one open track event (small track, Gainesville Raceway)...and I'd say the car exhibited the same behavior at both (especially before making changes).

Pertinent details:

OLD: Tein HE's, 448lbs/in(F), 336lbs/in(R). Whiteline front anti-roll bar, stock S14-SE rear anti-roll bar.

NEW: Koni 8611's (F&R), 500lbs/in(F), 350lbs/in(R). Whiteline front anti-roll bar, stock S14-SE rear anti-roll bar.

Identical ride height and alignment.

Same wheels/tires (255/40-17 Kumho XS's, on 17x9, +18 RPF1's).

S14, weighs a little less than 2700...KA-T making ~320rwhp.

Notice that I went up in spring rate significantly more up front, as compared to the rear.

SO...

What I've tried:

Remove rear anti-roll bar...no significant change. That leads me to believe it's all shock setting related.

I have added 2 clicks of compression damping in the front (making it 7 clicks off of full soft), and dialed out almost all of the rebound (it was almost full stiff, F&R...with respect to rebound...when I installed the shocks). Koni install sheet has you start there...that's why I made that change.

That netted a positive change, but has not cured the issue.

One thing I have not touched - Rear compression damping. I have no idea where it's set, as the rear housings modified do not allow a quick and easy way to access the adjuster. They do work with stock S14 rear knuckles, however .

...

SO - Baseline settings, or input would be great.

Thanks...

- Brian

[josh18_2k]

see hwo this goes..

Front: rebound in the middle somewhere (1.5 turns?), 4 clicks compression (from soft)
Rear: rebound full soft, 4 clicks of compression

With a front heavy car, sprung softer in the rear, you dont want F/R rebound the same. that'll make for an ass happy car in transitions. I'd leave the rear rebound on full soft and just play with the front.

[orion]

^^^ EDIT: posted at the same time as this reply ^^^

After some reading, I will dial in some rebound (maybe halfway) F&R...and dial out all the rear compression (unless it already is, as I said - No idea of the setting now).

That was my plan, and some research backs it up.

Good place to start? Anyone with a similar situation, and what helped?

- Brian

[orion]

see hwo this goes..

Front: rebound in the middle somewhere (1.5 turns?), 4 clicks compression (from soft)
Rear: rebound full soft, 4 clicks of compression

With a front heavy car, sprung softer in the rear, you dont want F/R rebound the same. that'll make for an ass happy car in transitions. I'd leave the rear rebound on full soft and just play with the front.

Great input, thanks!

Could be the root cause...it's not horrible as-is...but it's worse (read: harder to go as fast) than before with crappy dampers.

- Brian

[josh18_2k]

rear rebound should definately be on full soft. damping ratio is already at .65, only reason to go higher is for better transitioning (which it sounds like you dont need).
you want as much compressions as you can get away with (without being harsh/skittish), and minimal rebound. Same thing in Koni's tuning instructions, they just don't really word it that way.

[CodyAce]

I run 8611front/8610 rear 550/450 springs Whiteline Sway Bars F+R (full soft) Full Weight s14

I personally like the front at about 1.5 turns, 4 or 5 clicks (can't recall), for the rear I have them at about 1/2 turn and that's it. Seems to work best for me. I too initially had them turned up even and didn't like it so much. Softened the rear and was totally happy.

[Matt93SE]

Essentially the same damping settings on my KTS setup.. I'm running about 3/4 stiff up front and full soft in the rear to help keep the inside rear tire on the ground.

Keep in mind that with that much suspension change, you might need to change your alignment settings somewhat too. i.e. with these shocks there's going to be more/less body roll, so your static camber may need adjusted to compensate for your proper camber during cornering.

[orion]

UPDATE:

So, after dialing out the 3 clicks of rear compression...I'm at 5-6 clicks of compression up front, none in the rear. Rebound is 3/4 turn up front, none in the rear.

Car felt better at a recent autocross...but was HORRIBLE at a track event a couple weeks ago.

Hard to drive, still twitchy...and about a second off pace.

IMO, it just feels too soft.

Further evidence - Ever since the Koni/GC "upgrade", I've had several people ask what's different after seeing me on course...and state it looks like the car has a ton more body roll.

So, I'm going stiffer.

OLD: Tein HE's, 448lbs/in(F), 336lbs/in(R). Whiteline front anti-roll bar, stock S14-SE rear anti-roll bar.

NEW: Koni 8611's (F&R), 500lbs/in(F), 350lbs/in(R). Whiteline front anti-roll bar, stock S14-SE rear anti-roll bar.

Reposting that, from above - As you can see, I've upped the rates already as compared to the old setup...but it's clearly not enough.

I have 600/450 springs in the mail right now. (Anyone need a set of 500/350...???...haha)

I'll update once they are on the car.

- Brian

[veilside180sx]

Most of the "track" geared cars we've been running 550-600 lb springs up front as well. I think you'll be happy with your switch.

[240sxTTC]

OLD: Tein HE's, 448lbs/in(F), 336lbs/in(R). Whiteline front anti-roll bar, stock S14-SE rear anti-roll bar.

NEW: Koni 8611's (F&R), 500lbs/in(F), 350lbs/in(R). Whiteline front anti-roll bar, stock S14-SE rear anti-roll bar.

Same wheels/tires (255/40-17 Kumho XS's, on 17x9, +18 RPF1's).

That's interesting cause I have:

Tein HE's, 650lbs/in(F), 500lbs/in(R). Whiteline front anti-roll bar (stiffest setting), Whiteline rear anti-roll bar (softer setting).

I do run 245 Hoosiers (on 17x9 RPF1's) and aero, which will make a difference. However I still need more spring F&R. I'm surprised you didn't feel like it needed more spring with the Tein HE's. What setting did you run the HE's F&R at?

[Def]

I have 500/380 rates and the car is awesomely neutral at the track. Maybe just a hint of understeer at the limit, but its nice and easy to drive it close to 10/10ths like that.

What are your alignment specs? Also, what have you done with the rear traction arm? With mine 1/4" less than stock (8"?) It was SUPER loose as the car rolled over. Same alignment later with the traction rod 1/4" longer than stock really mellowed out the car's behavior. The bumpsteer graphs so lots of toe out I think with the shorter trac arm.

Have you also ensured you have plenty of shock travel? Do the zip tie test. You might be surprised to learn you're using up your travel since you have damping that's much closer to critically damped.

[orion]

Most of the "track" geared cars we've been running 550-600 lb springs up front as well. I think you'll be happy with your switch.

I hope so.

By the numbers, I thought I was going up in rate a fair amount when I put the Koni's on...but in the real world, it seems so much softer.

That's interesting cause I have: Tein HE's, 650lbs/in(F), 500lbs/in(R).

...I'm surprised you didn't feel like it needed more spring with the Tein HE's. What setting did you run the HE's F&R at?

I had the front springs pre-loaded to clear my wheels...and they were set all the way soft, front and rear.

I REALLY liked the way the car handled with that setup. Never felt the need for stiffer springs.

???

What are your alignment specs?

IIRC:

FRONT: -2.7 camber, 7.5 degrees caster, no toe.

REAR: -2.1 camber, and basically no toe.

Also, what have you done with the rear traction arm? With mine 1/4" less than stock (8"?) It was SUPER loose as the car rolled over. Same alignment later with the traction rod 1/4" longer than stock really mellowed out the car's behavior.

Dunno, but I will check it. Interesting.

Have you also ensured you have plenty of shock travel?

I have not. Stiffer spring should solve that, if it is an issue.

- Brian

[240sxTTC]

.....I run -4.0 camber in the front. Hoosiers love camber.

[Matt93SE]

Moooore camber. Glad to hear TTC runs as much as I do. I run -3.5 usually but the car seems to want more based on handling. havent' checked tire temps though cause I'm a cheapass SOB.

[Def]

I run -3.6 deg right now, the Toyos are REALLY telling me they want more. The outer tread blocks are destroyed up front. I should have rotated them frt/rear, but the rears wear nice and even with -1.6ish deg camber so it's not like it's going to wear the insides much or anything like that by rotating them back there.


As for your alignment orion, put in at least 1/8" total in the rear. I run that now, and honestly it's better in some corners than 3/16" total, but I feel the 3/16" total also let me put the power down easier in some really loaded up "sweeper" type corners(but this is not at autox, so we're talking like 3rd gear, 60-70 mph WOT while pulling just less than max lateral Gs). No toe I imagine makes the car just unstable under power, especially at higher speed.

Stiffer rates will help some, but I feel like if you've got the car a hair low you might be just having the travel get eaten up by bumps. Stiffer rates net you a little safety margin, but minute bumps still need how much travel they need (i.e. a 1/2" bump still needs 1/2" more travel at your dynamic ride height on the outside). I've thought about going up in rates on my car too, as I feel it's a little sluggish to change directions up front. The rear feels pretty solid, but some people run higher rear rates, and some run them with even more frt/rear stagger than I have.