Odd driving characteristics

[Bumnah]

So I had a bit of an off road excursion with my car. Nothing major at all.

I checked it out at home and nothing looked bent or out of place. So I had it aligned.

Alignment specs:

Front:
Camber -2.5
caster 8.0
toe 0

Rear:
Camber -1.5
Toe 0

The car tracks just fine for the most part, but it doesn't feel as neutral as it did before my off road excursion.

I only had time to drive it some on the street this weekend. I'm noticing the steering wheel isn't rotating straight when I come out of a corner and let up on the steering wheel. It seems to hold the position I set it at. If I have it cranked slightly to the right it'll stay there.

I'm not sure if I'm describing it properly, but the driving feel isn't as inspiring as before.

What would be the best way to diagnose this further? Could it be binding in the suspension? The inner and outer tie rods looked fine when I checked 'em out.

[Tower240sx]

I looked through "competition car suspension" for a blurb i knew i had read...found on page 84 (2006 edition) Caster angle....states that the characteristic of a self centering steering system is a result of caster angle.

so if your caster is 8.0 and it is in the correct direction and not "positive camber" (borrowing another term from the aforementioned book) I would have to ask if your steering feels heavier and if so you may look at the rack and pinion for some sort of binding, or possibly a bad ball joint in the lower knuckle.

Good luck please keep us posted

Mike

[stewiefied]

yes, more caster will cause more centering action(think bicycle front wheel). Cars do not use positive caster though since that would cause the opposite of this centering action. Also, i don't think this is the case though, if one side has less caster your car will pull to that side.
My guess is that the different feeling you get is from the increase in caster along with the camber. when the steering wheel is off center the tire is flat one the surface and is resisting rolling back up on it's inside edge. Or the camber could possibly be unequal. Hope i explained that well enough.

[Bumnah]

Steering feels the same as before. I did increase the caster from 7.0 to 8.0. I also notice the car feels more stable at higher speeds than before ( I thought it was in my head). There is no weird effect from going over bumps and uneven roads. Perhaps it is just going to take me a bit to get use to the driving feel.

I'll be honest, right now I'm liking the 7.0 caster more. What does everyone else run?

a_ahmed you're the only person I know running 8.0 of caster. Do you have a similar issue/experience?

[McCoy]

I'm running about 8.5 of caster and I didn't notice that much of a difference on the road from 7 degrees of caster.

[Tower240sx]

8.0 caster would increase centering not reduce it as you are describing (regardless of camber increase I "think")

Cars do not use positive caster though since that would cause the opposite of this centering action.

hence the quotes surrounding the words and the reference to that being a term used in the book

(positive caster was used in cars "in the eighties and ground effect era" as it makes heavier turning easier)

Mike

[Bumnah]

Hmmm. Obviously I read it wrong.

Would a binding sway bar be a culprit in anyway? Or should I focus primarily on the steering rack? I did disconnect the outer tie rods and they all looked fine.

[Def]

Do you have urethane bushings up front?

[Bumnah]

Indeed I do. Superpro poly bushings.

[stewiefied]

8.0 caster would increase centering not reduce it as you are describing (regardless of camber increase I "think")

yes, it would increase centering because in order for the wheel to turn, it would have to be lifted up on the edge of the tire. Which you know, but now think if the tire is already up on its inside edge due to camber. Turning the wheel slightly would put that tire flat and would actually have to be lifted back up onto it's inside edge to center the steering.

hence the quotes surrounding the words and the reference to that being a term used in the book

(positive caster was used in cars "in the eighties and ground effect era" as it makes heavier turning easier)

Mike

did not know that, but i did understand that you knew positive caster isn't ideal. Sorry if it seemed like i was correcting you in any way.

[logr]

Adding a little toe in on the front will make it self center better. 0 toe is more of an autox alignment.

[Tower240sx]

did not know that, but i did understand that you knew positive caster isn't ideal. Sorry if it seemed like i was correcting you in any way.

No worries bro,
You are correct that positive caster is, for all intents and purposes, of no use in the automotive world. That's why I showed the text just so everyone didn't think I was a babbling idiot (at least not this time)

I see your point about the camber, my first thought was that any force applied by one tire would be exactly offset by the opposite reaction by the other tire, However I can see now that that is incorrect, more-so with wide front tires or offsets that place the inside edge of the tire far inboard.

Bumnah,
Rim and tire size???
Offset???

Forgive me if i missed that info already.

Mike

[Bumnah]

16x8 + 15 rpf1s
225/50/16 A048R is the setup.

I've always kept the toe at 0 to save my tires.

I should take into account I'm driving my R compounds in sub 50F temps, I'm sure that may be an issue as well.

[Tower240sx]

Based on Info provided i would have to say, as stewiefied suggested that the camber would be the culprit, were you running that extreme camber previous to the off-roading?

Mike

[Bumnah]

Yes. It's been -2.5 since I put the suspension together.