Fixing corner grip on bumpy surfaces?
 

The Z seems to hate bumpy surfaces, even more so on corners - a great example would be highway interchanges.

Seems there's always a bumpy interchange ramp, at least in Tulsa, that if you corner even at the posted speed for the ramp, will still toss your car around - where you can feel it lose traction and move outward a few inches at least.

I know my truck used to have a problem with this, but that was due to blown out shocks and worn out tires. Replacing both of those, fixed that problem.

My Civic and my Truck (and definately my motorcycle (not a crotch-rocket)) handle uneven cornering surfaces better than that Z...which is unexpected, to say the least.


So, how does one go about fixing this?

Maybe you have too much toe in the rear. That can cause the rear to get really sloppy, especially on bumps. Also too much tire pressure could cause that issue also.

Tire pressure is good. Rear Alignment toe is something like .01 according to the alignment paper I had.

I've misplaced it so I don't know the other info right off...

KW V3's have fixed that problem for me. ;-)

This is generally the result of shock tuning..

I combat my issues with different lines and throttle modulation ;) I found that with a lol more gas the backend settles out. Or should I say steps out a slight bit :D but it's very smooth when it does.

Anti-bump steer kit
 

I had the same problem with my S2000. It was due to suspension geometry. A couple of aftermarket manufacturer came out with an anti-bump steer kit. Hopefully someone will have one for our Z.

I will say this much for it, you definately FEEL the G-forces more in this car than anything else I drive...it's odd and I can't explain it - but when you corner in this car, you feel yourself being thrown harder...

At least I know it's not uncommon.

This is all bound and rebound + spring stiffness and how they work together. Get a set of good coilovers and voila.

Any recommendations?

I like the stock height, with Tulsa roads I damn near need a lift kit...lol

It'd be for street use too...

Disregard previous post :)

Found a relevant thread...

What you are feeling is a car with sticky tires and a relatively soft suspension. The car leans and rolls into the corners because the suspension isnt stiff enough to counter the load. That lean makes you feel like you are building higher g-forces when you aren't.

You also can't just throw a stiff spring in there with the stock dampeners because they arent designed to work with it. The car will become uncomfortable to drive and very skittish and nervous over bumps.

Depending on what you do with the car...you can opt to get a full coilover system...If you are looking for something comfortable and good, get the KW V3's.

Will do and glad you searched for your answer.

Yeah, KW V3's are what I was thinking.

Then I saw the price, and figure that's a "later" item. Exhaust is next...originally exhaust was first, but then Stillen had a sale and I snatched the G3 intake ;)

As for aftermarket adjustables...is that something someone who doesn't know a whole lot about it can do? I mean, I've got adjustable progressive shocks on my bike, but I turn that up/down depending on if I'm riding alone or not.

I figure with a car it'd be more complex (to a 4th!)

Also, how difficult would it be to DIY a coilover swap? I imagine the (rear) springs aren't going to be easy. I know when I swapped shocks on my truck, I cheated and used my car jack to compress them to where they'd bolt up. With the Z being as low as it is, I figure that won't be very likely.

Hmm... first off, When you are ready...I can get you a pretty good price on the KW's.

Second..you may not really need to go so crazy as getting coilovers, check out some of the available options for lowering springs. Otherwise, they arent complicated to play around with. They give you parameters to stay between, however if I were you I would just use the settings they put on the V3's from the factory, they are perfect.

Don't forget also that you will NEED camber adjustable control arms so you can add another bunch of money to your estimate.

As far as how hard everything is to install... Its pretty straight forward, but if you do it in your garage it will take you a good amount of time...specially if you are doing the control arms too.

Sway bars did wonders on the bumps for me. Allows much less bound and so the re-bound doesn't kick the rear out.

Thanks, I'll keep that in mind on KW's - it'll probably be around tax-return season :)

Also, I'm not really after lowering - so would camber arms still be needed? Granted, I know they'll allow for more adjustability, but, will it be nessicary?

Good to know on factory settings being right :)

Installation is the only concern of mine - I mean, if you jack the car all the way up, is it a matter of popping them off where they're not under a lot of pressure, or, is it something where I'd have to find a way to compress the springs to get them in? If it's the later, it'd be easier to have someone else (with more tools, proper facilities, experience) to do it.


Thanks for the info!

I've heard those are easy to install as well. Did it change the balance of the car much, or mostly just help with body-roll?


Also, which sway bars did you go with?

I went with the Hotchkis, which are perhaps a little too aggressive for street use. The Stillen is probably a better street setup.

The sway bars detrimentally affected low speed aggressive turn in until I increased front camber (using the SPC camber arms). I think this was because there was less roll induced camber. For higher speed cornering it improved the car wonderfully.

It's most likely due to the hard suspension setup in the Z. Check you tire pressures. Then the alignment. If the alignment is true, and the camber is < -5 degrees then you should be at the optimum for reducing these types of effects. If you still feel as if you are getting pitched around and at the edge of losing traction the only other option I can think of with stock suspension is to reduce the unsprung weight IE tires, wheels, brakes, suspension. (which could be quite expensive). If you already have adjustable coilovers, then you could soften the bump dampening, allowing the suspension to react quicker and smoother to the changes in pavement height. Other than that your pretty much on your own.

Hmm...? :(

Whats a "true" alignment? You mean stock?

I understand you mean ">" not "<", but man, if your camber is anywhere near -5 degrees then something is extremely wrong...specially since you can't go much past -1.5 on the stock setup...and because -5 degrees is an insane and detrimental amount of camber for a street car. Also...camber adjustments are part of an alignment so its not an "alignment AND camber".

:ugh2:

He doesnt.

Just out of curiousity, why make the front swap bars non-adjustable, and the rear's adjustable?

Also, would installing (stillen) swaybars cause other potential issues? I guess what I'm saying is, are they any negatives to installing them?

You can argue a few points to why, but its always beneficial to be able to adjust balance front and rear. Arguably, you can still do that by just changing the rear, however some people will be left unhappy even if they set the rear to softest. I've always thought balance should be alignment induced and then you can change the tendencies of that setup using adjustable swaybars. Doing swaybars first is backwards.

There arent really negatives to installing sways. Specially milder ones like the Stillen bars. Remember that going extreme in either direction (hard or soft) is not good. You should pick the swaybar by the suspension setup you will be running. If you are running soft street springs, get the not-so-aggressive bars, they will work together. If you are running 8k spring coilovers then get the stiffer bars.

Stiffer isnt automatically better. Better = what works with your car + produces the desired balance.

There shouldn't be any negatives. You might start tripoding around when you go into driveways sideways and you might hear a little more noise, but its nothing to worry about...unless your bar is walking. Thats the thing with adjustable bars, you have to tighten them down like crazy or they will start shifting around under load, causing a very distinct clank. Its very annoying, so I for one, don't have much of a problem with a non-adjustable front on my non-racecar.

I'll probably go with the coilovers mentioned earlier (KW V3) since a number of people have said they have had good results (I might wait until the 370z specific version comes out) - with that, would you say the Stillen sway bars would be a good match? Would the Stillen bars be fine to swap out now (and still show an improvement, but, not overkill?)

I'm perfectly happy with this car never seeing a track, but, I think it'd be fun to someday (if I could find a road course near here...)

after reading this tread i took my Z to my usual predetermined crappy exit ramp with an offcamber turn + dip then a bump, followed by series of cracks on the road with patching. this is
where i usually do my sus tuning and testing.

car handled it beautifully. it might be that since this is your first
MFR platform you are just not use to how the car absorbs the
bumps and dips.

aim the car and just keep the steering wheel steady, dont try to
counter the bumps when your steering feedbacks with a slight tug.
for street driving, i think nissan got it right this time.

now ive driven through tulsa before and you guys have some
massive cracks between the concrete patches...

Will I need adj. camber arms if I'm keeping the ride height the same?

The Stillen would be a good match for you. The hotchkis may be a little more than you need if you are going to keep it on the street. Yes, you would be perfectly fine swapping sways for the stillen right now.

If you are keeping the height the same...you probably won't need camber arms. You can probably get away with the stock bolts...they had some adjustability that would be about enough for you. If you have to run a little more negative...well as long as its not less than -2 deg...then you should be fine. So If you can get them and keep your setup between 0 and -2 then you should be fine. Im running -2 all around right now and its nice. Going to do -2.25 up front and -2 rear when I get it aligned tomorrow though.

Do you have any links/articles on effects of camber and so on and suspension mods in general? Just looking to get rid of my ignorance on the subject and learn more :)

I understand you mean ">" not "<", but man, if your camber is anywhere near -5 degrees then something is extremely wrong...specially since you can't go much past -1.5 on the stock setup...and because -5 degrees is an insane and detrimental amount of camber for a street car. Also...camber adjustments are part of an alignment so its not an "alignment AND camber".

Sorry I meant to put -.5 i guess the decimal ran away. As for the Alignment and camber being the same thing, I always see them as different cuz of the last 11 years I've been go-carting, by alignment I meant toe-in/out and camber as a separate adjustment, and castor as another separate adjustment. I have never adjusted the alignment on a car before so yeah.

Kann, you ride, don't you?

One of the nice surprises when I upgraded my K1200RS with F&R Ohlins was how it handled bumpy surfaces. I was expecting it to be more firm, but the compliance of the Ohlins was a revelation. There is an Ohlins suspension for the 370Z...but it costs between $4254 and $5059 yowza might not be within your budget.

Pro Stock Racing Spec Ohlins Suspension for 370z | 370zblog.com

Completely agree on ride height, no way would I lower this thing on the street with the roads the way they are around here.

I think part of it has been getting used to the Z. I don't notice the issue as much now...

I'll probably go with KW Variant3's and their lift deally, so I can handle steeper driveways and such....

I have this same problem and it is NOT normal. I feel that it is unacceptable for a car to behave like this. The car handles great in all other aspects, but this is downright unsafe. I've also driven many different cars with various suspension setups and I have never experienced this until I got the Z.

I have to agree to some extent. I am hoping the KWs will fix the problem when I can afford them. The effect for me is that the car feels much heavier than it is when canyoning.

i know what the OP is talking about first hand. my BC coilsovers can be set hard enough where it skids over the bumps..... great for a smooth track/street, but terrible otherwise. i keep it in the middle.....

sway bars made the confidence skyrocket. no more unsettled rear end, or body roll.

i do need the camber i think now.....with the hotchkis. at 90% they are great. but when i push the car hard, it slightly understeers on turn in, which quickly goes into snap oversteer if im not careful (rear sway on full stiff, which is too much, but helps the understeer on turn in).

i need to order the arms, but dont have the $$ right now.

all in all, id still say the oem set up is a GREAT compromise of the above.

SPL rear traction arms
 

Would the SPL rear traction arms help?

SPL RTR Z34

yes

Inexperience taught me to get aftermarket springs with stock shocks. Now i am feeling this effect very drastically (unstable on bumpy surfaces). I have the Eibach pro kit with stock shocks. Now instead of wasting money on those springs, ive read that you can order koni yellows and get them to valve them according to spring rates you give them. Is this true?

Yes, Koni offers custom valving, both fixed rates and adjustable.