Hi all,

I've been having a small issue with my steering ever since I made some changes to my car. Once I get above 45-50 mph the steering gets very light and vague. There's no freeplay when stationary, but it's driving me crazy on the back roads, it's far less precise than it used to be. Current suspension/tire settings below. Any help is appreciated.

Sumitomo HTR ZIII - 2k miles on them
245/40/17 on 17x8.5
255/40/17 on 17x9.5

Alignment:
Front
-2.2 Camber
Stock Toe
6 degrees Caster

Rear
-2.2 Camber
Stock Toe

Suspension:
Spoon Dampers
14k/12k Springs
4 Clicks in the Front
2 Clicks in the Rear

Stock 06/07 Sway Bars

Thanks!

 

Do you have exact toe readings?

Does it feel dead on center or just not as precise through a turn? How is initial turn in?

Tire pressures set at stock? What size tires did you have before?

Caster looks good. Does the wheel return to center evenly left to right after turns?

 

I want to say .01 in the front and .26 in the rear,

Steering wheel is centered, while in a corner I'd describe the steering as "floaty" initial turn in is fine at lower speeds, but if I take a corner at about 40-50 it's just not very precise.

Set the tires to 32 psi when they were mounted two weeks ago. I was running 225/255 before.

Steering centers fine, it does seem to be a bit lethargic and doesn't "snap" back to center.

 

How are your ride heights? What wheel offsets are you using?

Sometimes even though caster is good, low ride height suspension angles increase friction and decrease caster effect (in addition to change in bump steer, but that sounds different than what you're noting is off) - but usually that makes steering more sensitive and/or twitchy (not smooth). 3mm toe-in for the rear should be ok. I wonder if you took some load off the front and the steering is slightly over-assisted now, just a thought.

How is the steering over bumps?

 

I'm pretty low in the front, 12.5" from the wheel cap to fender. Running 8.5 +53 in the front and 9.5 +63 in the rear.

I'm definitely not getting bump steer, I have yet to hit the bump stops on the suspension. The steering just feels very loose and light, doesn't take any effort to move it side to side. So I paid really close attention while driving today and the wheel doesn't fully center when turning, I need to turn the wheel about 1/4 turn back to center once out of a turn. It also seems to get tighter the further from center I get, steering is far heavier near full lock.

On bad roads it does seem to tramline quite a bit, but I chalk that up to road conditions and wider tires up front, doesn't happen on smooth roads and bumps themselves don't seem to affect steering.

One thing I notice is that when Sport Compact did the suspension shootout the Spoon car had 7.5 degrees of camber vs 6 degrees for everyone else. Is there a way the suspension could inherently need more caster due to the way it's valved?

 

LOL.

 

I can look at those graphs and see what the low speed compression/rebound damping looks like compared to stock.

Bump steer doesn't necessarily come from hitting the bump stops. It just means that the arc of the tie rod is different than the arc of the suspension movements, which comes from moving the gearbox down relative to the suspension points. Bump steer correctors use longer bolts and spacers between the front subframe and the gearbox to get the arc back to stock. There are some good illustrations of it online if you google it.

what you're describing with steering feel and centering could just be changes in feel due to lower ride height.

 

Gotcha, I always assumed it just due to hitting the bump stops. Is there anyway to tighten up steering other than raising the car?

Thanks

 

To confirm that's the issue you can raise it up temporarily. Roll center adjusters and bump steer kits will help to correct the geometry and restore the original steering arc to some degree at the lowered ride height.

I'd try raising it first to see if it helps.

 

Alright, I'll raise it up and see how it does. Never thought about ride height affecting steering feel, but it does make sense.