Cure for high speed nervousness?
 

What are people doing to cure the high speed nervousness of the Z34?I was doing about 65 at highway speed and someone suddenly were hard on their brakes ahead of me to avoid a fridge that fell off of a pickup truck. :shakes head:

When I went hard on the brakes I quickly reacted because it looked like I wasn't going to stop in time to avoid a rear end collision when pressing the brakes and changed lanes because I didn't see a car next to me just 20 seconds earlier. I felt a lot of vibrating in the steering wheel and in the car so I assume I overloaded the front tires so much that I was losing grip, the car also seem to dart uncontrollably for a split second and regained composer.

I figured with the tires and new shocks and sway bars (I know they only come into play in hard cornering), this might cure the Z34 nervousness but it felt the same as it did when it went over road imperfections at high speed.

Has anyone tamed this for the street and track? It scares the crap out of me and my 350Z never did this, it always felt flat and stable at high speeds even in stock form. Do I need to soften my front struts? I'm running full soft in the rear and full stiff in the front with brand new tires with only 100 miles on them. I know I need coilovers in the future but who's solved this nervousness at high speed issue? If it's doing this in emergency situations on the street, I feel like it's going to do this at Willow Springs if I'm hard on the brakes and then trying to change direction quickly after getting off of them. Will making the front full soft fix this?

sounds like you need an alignment

I had an alignment after I got the brand new tires. The sway bars and shock+struts came after

Sounds like your rotors are warped.

You shouldn't have any vibrations while braking.

You may also have a brake caliper slow to react and can also lead to pulling to one side IF your alignment is good.

If you darted when you stomped on the brakes it was more than likely due to brake pad buildup on the rotors. This is also why you had some brake pedal shudder. That is why I don't care for the stock brake pads. They are bad about brake pad build up on the rotors. I would suggest you re-bed the pads in and see how it goes. It will clear of the brake pad deposits off the rotors. Your braking should come back to normal.

Did you trigger the ABS ?? as well as Stability/Yaw Control when switching lanes ........

Can be freaky if you are not expecting it

I have no problems with the Z34 platform on the track.

The ABS light never came on, I didn't jam on them that hard to trigger it but when I switched lanes quickly I wasn't on them at all and it almost made a noise like those Front wheel drive cars that understeer. I have about 23k miles and had a check up on the suspension, brakes and any chassis bracing and only found that the stock front passenger strut was leaking and nothing else. Everything was basically all stock. Would the stock brake pads be that bad to cause this? Or the rotors?

Did you talk to Alex about the issue when you took it in to him?

You got an alignment BEFORE you installed shocks/springs that lowered the car?

You realize those parts affect your alignment?

I didn't, I've had this before if I was cornering too hard with some crappy Goodyear's that were on it when I got the car. No braking involved at all in that situation and that went away after I switched tires. I didn't have this until I braked hard yesterday and then switched lanes.

My car is stock height, I just have sport dampers and shocks with stock springs

If you have sport dampers. Are they oem? How do you adjust them? :confused:

I have Koni Yellows that are adjustable with stock springs. I can adjust how how stiff or how soft the front or rear can be similar to coilovers that adjust dampening but I can't raise or lower my ride height.

I know about Koni's. But the way you worded it sounded kind of confusing. You said the way you have the dampers adjusted, then said you have the sport dampers. Meaning you have the stock sport dampers.

since you changed from oem to Koni's after you had an alignment. I would get it aligned again. The Koni's will lower the front by at least a 1/4". The lower spring perch is lower on the Koni's. Also the toe setting is most likely off. If the setting is zero to toe out. The car becomes less stable.

Sorry for the wording, they just call them Koni sport dampers in the video I was watching lol. I did try jamming on the brakes in a straight line today and that vibrating didn't show up but it still felt unstable when suddenly at a high speed and then going to a complete stop. It felt uneasy like the tires were just about ready to lose grip. So I think you may be right that it's the alignment, the shop that installed them said I won't need an alignment. I think he was full a crap.

an alignment is maybe a hundred bucks
most places will actually check your tires for balance and inspect your brakes for free, or a minimal cost

i'd do that before buying stuff

but eventually

coilovers and adjustable everything and sticky tires will solve alot

I have the sticky tires already, I'm going to check the alignment tomorrow at the shop

After an alignment and slightly softening up the front dampeners, that high speed skittishness went away. My Alignment when I went to the shop wasn't off that much but I tried driving and doing the same thing afterwards and it's definitely less nervous now. I was thinking it was a combo of things. Maybe the front dampers were too stiff up front and the alignment being a tiny bit off combined with me slamming on the brakes (all the weight going up front) then asking those same tires that are already at their breaking point to switch lanes quickly caused this?

Either way it feels a lot better. Learned my lesson, will be saving up for the Greddy KW Coilovers or the Bilstein B16 PSS9/10 if I'm impatient or wait to get the KW V3's.

Just my 2 cents, I had an 09 Sport Package before my current 14 Nismo, and it never felt unsteady at any speed under any circumstance. But after just a week of driving my Nismo I noticed exactly what you described, under hard braking it would quickly pull one way or the other and the back would feel loose. So I got rid of the 245s on the front and went to 275s and my problem pretty much diminished. 2 different solutions to the same problem? I don't know, but just a thought for anyone else reading this.

Interesting. That would make a lot of sense since the contact patch is larger. This may be a necessary upgrade for people going to the track or are going to be exploring the limits of their car? Even though I did the alignment and adjusted the dampers, I don't know if I'll see the same thing when I go to the track.

Doesn't take much of an alignment difference to totally change the feeling of a car.

On my R33 skyline I went from 0 rear toe to 1mm rear toe in and it totally killed the liveliness of the rear end, it was BORING to drive. On my R34 I told them to toe out 1mm at the back and it was beautiful (factory spec is 0 to Out 5.2mm!).

I have noticed some skittishness on the Z34, braking from highway speed. The car was almost new and maybe the brakes hadn't bedded in yet. Hasn't happened since but it's in the back of my mind.