Back end feels super loose.

[furochan]

I have like, zero clue why it's doing this, but ever since I switched rims and tires, the back end of my car feels almost dangerously loose at speeds of above about 55-60 mph. At lower speeds, handles wonderfully as far as I can tell. No looseness at all.


Any ideas on why it's acting like this?

[Gimp]

What is your suspension setup?
Alignment?
Tire pressure?

[furochan]

Tire pressure is 40 psi front and back, on 17 inch rims. (was hoping for 16, but none that would fit my car. x.x). The front was aligned and should be nearly zero camber and toe, although the caster on the right front is off by a bit.
The rear, the toe was corrected, but the camber is just within tollerances, on the + side, I think.

Suspension is ksport coilovers, set softest, front and back. Sway bar is stock, as is everything else.

[skierd]

Tire pressures are WAY too high. Hell, I dont even run that high for autocrossing and I still have plenty of oversteer. Drop the pressures to like 33-35psi front and 30-33psi rear. Also, even a slightly fubar'd alignment will wreak havoc on the best suspended car, get the damn thing aligned properly and with you+you're average load of stuff in the car in it when its done.

[Gimp]

Since you are on K-Sports, and I regret saying this even as I type it, but you could stiffen up the front shocks -- just a little -- to promote understeer.

But Skierd is right - get the pressures down, and get the car on an alignment rack. Who knows, maybe when you installed the K-Sports something didn't get tightened down properly, you hit a bump, and now the slotted upper bolt holes have come loose and allow for some change.

[qb2k5]

Originally posted by skierd
[body]
Tire pressures are WAY too high. Hell, I dont even run that high for autocrossing and I still have plenty of oversteer. Drop the pressures to like 33-35psi front and 30-33psi rear. Also, even a slightly fubar'd alignment will wreak havoc on the best suspended car, get the damn thing aligned properly and with you+you're average load of stuff in the car in it when its done.
[/body]

Yup hes right!

Drop that pressure to 30-33! If you open your glove box and look inside, there would be a sticker that shows that.

[furochan]

Ah, will do. Back when I was using larger tires, having the pressure at a higher amount made for a better feel, as at the recommended 32 it felt like it was a barge, and understeered really badly a lot. I upped the tire pressure back then and it actually handled quite well. I'll drop it down to about 35 tomorow and see what happens.

Would the front becoming unaligned mess up the rear end much? Or should I just be looking at the rear and how it's set?

I've heard that you can adjust the camber in the rear without camber bolts, but I'm not sure what they were talking about. Should I just get a set of those, install them, and mess with it that way?

And, as I said, at low and mid speeds, it feels grippy as anything, front and back. Just at speed it gets weird.

Gimp: I had them set to highest on all four corners for a bit to see what it was like. It rode..weirdly. :??: Felt like it had a mind of it's own. I softened it up and it feels more non-possessed now. Havn't adjusted it at all since though.

Thanks for your help all!

[Gimp]

The part of the K-Sports I was talking about was not the pillow ball mount, but on the front and rear coilovers where it mounts to the spindle. The upper bolt holes are slotted to allow for minimal camber adjustment.

I race on these coilovers and I think they are great, but I would never run full stiff all the way around, on the street or on the course, and I would never run anything but full soft on the street. Double check your alignments before you try to fix it any other way.

[Elantra_99]

With aftermarket rims and tires you wouldn't use the recommended tire pressure for a set of stock 195/60-14's would you????????? Cause like furochan I always run 40psi in front and 38psi in back. :??:

[furochan]

I lowered the pressure down to 35, front and back. It feels safe now! No problems with looseness at the moment. Although, I only went up to 80 on the way home tonight, so I couldn't say it's stable at all speeds any more.

Gimp: Oh, those slots. I think I had to widen the fronts to get the bolts through. The backs though, havn't checked. And Full hard was out of curiousity more than anything. Full soft is hard enough as it is. x.x

My tires are currently... *checks*
205/40-17

Back when I was using the stock ones still, I usually went up to as high as the tires permitted me to, as at the recommended 32, it was a mooshey blunted steering experience. I would take an onramp at 45 and there would be tire screeching and understeer. At the higher presure, there was no screeching, and it handled nicely.

But my two cents. ^^;