Rear-end wanders at speed Help please

oscargarza88

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!

Spooler

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.

oscargarza88

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

Spooler

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.

Rusty

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.

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GSS138

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?

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Rusty

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.

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oscargarza88

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!

oscargarza88

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!

FL 4Motion

Track/street alignment for our car:

Front:
camber - 2.1

Caster + 6

Toe 0.0

Rear:

Camber - 1.70

Toe 0.10

GSS138

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.

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oscargarza88

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

GSS138

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.

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oscargarza88

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.

Jordo!

Too much toe in the rear.

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