Rear-end wanders at speed Help please

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!

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.