Rear-end wanders at speed Help please
 

Hello,

So I have 2014 Z with 18k miles. nismo shocks and swift springs and spl rear camber arms.

Alignment was all out of wack and got an alignment and its as follows:

http://i.imgur.com/ueqUKFtl.jpg?1


The rear in certain roads acts like it wants to change lanes with no input from the front. When wet the effects are way greater. To the point of not feeling safe at anything over 60mph.

in perfect smooth surfaces its fine but when the road crowns or has imperfections it causes the rear end to wander.

Im guessing it must be the toe/camber but cant really explain it.

Any help as to how to fix this would be greatly appreciated since this feeling is very very unpleasant.

I found this thread and seems to be the same symptoms.
Wandering, floating, queasy feeling at high speed - Nissan 350Z Forum, Nissan 370Z Tech Forums
his issue was fixed with an alignment which he did not post.

thanks for the help.

Have you look at some of the other standard stuff, tire ware and pressure?

What condition are the tires in and do they all match? Mismatched tires front and rear and/or heavily worn rear tires could cause this. The post-alignment numbers don't really look off to me.

Tires are worn but still above the wear bars. And yes all matching.

And yes even tire pressure as well.

I wish i could get someone to drive it and better explain it.

Thanks

well, if your tires were worn at the old geometry then you will need to get new tires and break the new tires in to your new setting.

if that still dont help get some koni's and tighten the dampers down.

Tire can cause this. I had funky warn fronts due to the shipping spacers being left on the front springs for 19k miles. I just got them replaced and the car is mucho better in the handling department.

I wish tires would fix this problem. If tires woudnt fix this im afraid i would probably go back to stock suspension which i know didnt have that issue.


Were what you mean funky the same symptoms im talking about?

Oh and i forgot to mention i also have 20mm spacers all around.

thanks

Sounds like your tires. Uneven wear, especially in the rear will cause this sensation. Get under the rear of your car and check the inner edge of your tires. I bet, at least the passenger rear inner edge will have visible wear. Just my two cents.

Yes, the fronts were worn uneven on the outside due to + camber. The trembling was terrible. I would hooks ruts and they would drag me ever where all over the road. Probably looked like I was texting or drunk.

there are plenty of people with lowered z's that dont have this issue, so try the tires, then the dampers. GL

Your initial Toe settings were pretty horrible, I am not clear if you were having the problem with the initial toe settings or on the final toe settings. Your front camber although not bad, could be a lot tighter than -1.3 and -1.8 on the final.

Toe settings will definitely make the car "dartier".

I would try 0 toe in the rear.
back some rear camber out to about -1.1
and get both front wheels to -1.8

Also: Rear sway setting?

Two things:
1: The rear end alignment needs to be squared with the front end. Sometimes the rear wheels can be aligned square with each other, but not square with the front. This can create "dog walking", which can give this feeling.
2: you may have a blown bushing on your lower control arms or elsewhere within the suspension unit that appears visually ok, but when load hits it, it shifts.

I know the exact feeling you're talking about and it's very scary.

his after shows 0.0 degrees thrust angle.

One other thing could be (I know this sounds dumb)...you didn't tighten down the lug nuts 100%

With the initial toe setting was indeed very bad. That was right after I installed the camber arm so it was all out of wack. I drove the car with the initial settings to the alignment shop and it quite horrible. And now that you mention it it was doing th same effect I am talking about but way way exaggerated to the point I was only able to go 40mph.
After the alignment it felt good but really only get the effect I'm talking about in the rain. Today was pouring rain and the car handled worse than ever, coudnt go past 45 mph without it feeling unsafe.
Another way to explain is pulling sled on ice with a rope. The sled will wander around as you pull.


The guy said there was no camber adjustment for the front so he didn't even attempt to match them better. The front feels solid though. I van tell it'd definitely coming from the back

Yes. Just cause you bring it up I'll check them again in the am. Also the spacers while I'm at it.

I'm looking into replacing th tires on Wednesday and will report back with effects if I get around to it.

Thanjs for all the feedback!

Rain issues ehh, sounds like you do not have much tread left or the car is what I call, plowing due to the toe being out of whack. It will make it an ill handling piece of crap in the rain. Get a thread depth gauge and read from the inside to the outside of the thread on the rear tires. That will give us all an idea of what may be going on.

So upon further inspection yes the tires I'm the back are definitely in the Wear bar. So essentially the rear was hydroplaning everywhere... That was scary, and im used to Autox and sliding around but this was different.

As far as the alignment. I've heard some people go zero toe In the back. Is this recommended? Also is - 2 camber too much in the back for a dd?

Thanks

You autoX and the rain bothers you? I love it when it rains. Good wipers and some rainx go a long way. Tires, the less the funner it is, LOL
The 370z actually does really well in the rain.

For track and DD. I have my camber at -1.5, and a hair toed in. Zero toe to toed out will give you snap oversteer at times.

How in the hell does a shop make this mistake. Don't ever go to that shop again lol.

@OP the problem you are describing does indeed sound a bit more sinister than simply a bad alignment, your current alignment isn't track day tweaked and tuned, but it should do fine for 45 miles per hour.

I suspect something like a cracked/broken bushing or maybe even a loose control arm/midlink that is allowing the wheel to steer on its own. Do you hear any vibration noise like it could be a wheel? Something is very not correct and you should take it to a real Nissan/alignment shop.

@Rusty, I have taken temps at track for last few months at -2.0 rear camber, and there is no reason to run that much. I will probably bring it back down to about a -1.6 to -1.7. Even for a full track spec running slicks I doubt you would ever need more than -2.0 if you are sprung decently in the rear.

Thanks for the pointer on rear toe as well, I have been having snap oversteer issues for months and will definitely try your suggestion of adding just a tad of toe in, do you suggest like .10?

I ran -1.75 rear camber last year. Which wore the inside edges of the tires pretty good. This year I changed to -1.5 rear camber. Zero toe on my Z makes the rear feel squirrelly in a straight line under power. Mid-turn, was I was always on guard for it to step out. The Hotchkis rear bar added to that. For a spec to set the toe. I feel that close to zero without being zero is fine.

I agree with you, i love the rain and yes more fun. I have a SC miata i use as my track car and my All season tires (street setup) are very worn to the wear bars and i love driving it in the rain.
This feeling in the Z is nothing like what i enjoy and is unpredictable going in a straight line at 45mph. Like i said i wish someone else would drive the car to more accurately describe the feeling. It requires 10-2 and focus while just trying to cruise.
Ive been autoxing for almost 10 years now so no stranger to getting sideways and all that fun stuff.

Thanks i will get the camber brought in a bit after i get new tires. As far as a "hair" towed in. how much is that exactly in numbers?
thanks

So consencus -1.5 camber in the back and what about toe?

Also i didnt answer earlier i have stock sways so no adjust ability there.

thanks!

I have not heard any vibrations.
I would agree with you with the possible bushing or such damaged but woudnt that mean it would handle like that all the time? not just in the rain? With under 20k miles and no accidents and such the likelihood of that happening is also minor im sure.
Im finally off work tomorrow so i will get down there and make sure everything is tight and solid. When you tracked your Z what were your alignment specs?

As stated before i hope tires will fix this which i should have some by tomorrow hopefully.

Thanks!

Track/street alignment for our car:

Front:
camber - 2.1

Caster + 6

Toe 0.0

Rear:

Camber - 1.70

Toe 0.10

Well my track day spec has varied quite a bit for the last few months because I have been fighting some issues, been changing springs, sways ride height a lot trying to trouble shoot the weird snap over steer problem. Without going into too much detail:

In the front, I am thinking but can't prove yet that -4.0 camber is out of the question, I ran it for two weeks and it felt great, but it's still a DD so that will kill your street tires fast and my "track spec" was -3.2 on both fronts.

-2.0 camber in the rear for street or track is too much. Our rear end likes to camber out-too much. Even when pushing hard on track with a rear end that was dangerous, I could never even come close to heating up the outside of the tire like the inside at -2.0 static camber. 1.6-1.8 is probably ideal even for a pretty hardcore track setup.

I went too low on front ride height and too soft for my initial spring rate up front (and too stiff in rear) and I started to have problems with suspension bottoming and throwing weight around-not to mention the rear end trying to show off at the same time.


The rear toe I left at 0, with a little toe out in front.

I removed the rear bar, it was much better, but then would still snap oversteer at really weird times, not in high speed corners and sweepers, but at 60-80 MPH and at really weird times, but mainly on exit when I was pushing hard on entry.


My Toe settings were close to 0 and 0. I have since dropped spring rates on the rear and have no idea what my current alignment settings are but will get them next week. The car currently feels very good for the first time since aug/sept.

In regards to your situation, there is nothing in a basic alignmentclose to factory spec that could be creating the situation you are describing. I ran my RS3's with 30+ track days and 15 K total DD miles with 1/16th of tread and cords showing at Big Willow in the rain in Dec and the car still did fine.

Basically, I can not see how even really f-ed up street tires and a so so alignment like yours could be creating a semi dangerous situation.

Those were my thoughts exactly before I was semi convinced by you guys on purely tires haha.
I'll go under there and triple check all the arms just in case something is loose. Once again weird that it's only in the rain not in the dry if it was a alignment/suspension issue you know.

Thanks

I really don't think it's tires at all, but change them if you know they are bad and if you have the same problem then it is something more serious.

I ran my last set of tires into the damn dirt before I swapped them 3 weeks ago because my race shop guy told me explicitly "Do not go to the track again on these tires!"

If you have OEM sways, and low mileage like you are talking about, then something is wrong back there and needs to have someone professional look at it. If the tires don't fix it, then you have something loose in the back end that needs a real suspension tech that knows the 370z. If the tires make a vast improvement, then you need to take your rear camber down to like 1.3 and stop buying sh`tty tires.

I got stock tires. So thy are good just worn.

And thanks for all your help. I will report back after changes.

and btw here is quick bad picture of one of my rear tires.
http://i.imgur.com/xc69ZIml.jpg

Too much toe in the rear.

With too much toe. You usually see the edge of the tread blocks start to feather.

oscar- u need new tires. you're down to the wear bars. :icon17:

still going with this, or maybe a broken CV

http://i.imgur.com/RIeUVZzl.jpg
good news! new tires in the back!

The fronts still look good so im going to hold off for a while.

Still have an alignment due, didnt have time to do it today.
Once i got home after a couple hard corners i realized im at lease 1+ inches from the sidewall so as you guys confirmed way too much camber in the back.

Came to the conclusion of -1.4 camber in the rear with -.03 and go from there.

Seems good but will not know for sure until it rains again.

Until further notice thanks for all the feedback and will report back once i can get a alignment again.

Thanks!

RE 760 Sports?

Hankook v12 2.
So early update Is he car still feels a bit off. It hasn't rained so haven't tested it fully. Hopefully this plus alignment will fix the issue completelly.

As far as grip they feel a bit more than the stock tires when they were starting to go out. Kind of what I expected for the price. For a dd I think it should be enough dry ad wet grip.

Hmm -- so just tires?

Glad it turned out to be a relatively simple fix :tup:

Not quite. I'm thinking after I re do my alignment it will be back to normal fingers crossed

I have the same issues it sounds like with the rear feeling like it wants to go its own direction, esp in rain and on bumps. I got new tires and aligned that helped nothing. I have now bought new rear koni's and that did not help at all either. I'm kinda lost now since i have literally checked everything like 1000 times. Let me know what you come up with and if you decide to go with new shock's I have a basically new set of rear kyb's and rear adjustable koni's i would sell ya.

so update...:

ITS FIXED!!!:ughdance:

So I had new rear tires replaced and still did not fix the issue even though it did get better. I didnt get around to aligning it yet since my guy was busy this week but i did find the bolt that holds the camber arm in the hub area in the passenger side was loose. Loose like the nut was flush with the end of the screw



Thinking about this being loose doesnt make sense in my head how it would have cause such an issue since i have the SPL camber arms and even if the bolt was loose the movement up and down would have been the same and the way the arm is in place does not allow side to side movement.

Regardless of explanations (which i hope someone can chime in) i no longer get that wandering feeling and the rear following the grooves of the road. Its pouring rain right now and can confidently drive at whatever speed without this issue. It feels like the first day i picked it up.

Unfortunately i cannot explain what the issue was exactly but i did 1:replace the tires and 2: tighten the camber arm bolt that was loose.
Still plan on dialing back the camber but in the meantime very happy with the fact that my car is back to normal, i was worried for a minute there.

For you that said oh its just the camber and don't be scared of the rain, haha it was definitely something more.

Thanks for all the feedback, much appreciated and anyone with further questions please ask.

Thanks!