Braking and car moves strangely.

kannibul · 09-15-2009, 10:03 AM

I don't know if this conditions, braking, suspesion...

I've noticed under some braking conditions that the car feels like it'll bite harder on one wheel, then shift to another wheel, then another, then another...almost in a circular motion.

The result is that it doesn't feel "happy"...and like you should fight the wheel a bit.

What causes this? What can fix this?

To a point, I had this happen with other cars too, but, it wasn't as noticable.

Division · 09-15-2009, 10:04 AM

Does your VDC indicator come on when your braking? This may be the VDC kicking in.

kannibul · 09-15-2009, 11:19 AM

Quote:

Originally Posted by Division

Does your VDC indicator come on when your braking? This may be the VDC kicking in.

I've not noticed it coming on.

corbin09 · 09-15-2009, 11:26 AM

Mine does this too, I thought it was the VDC, and played with it a little, Then got sways and springs, and new tires... It is no longer an issue. Mine felt like for lack of better words "skittish" almost. Its more stable now. I have a base though.

G35guy84 · 09-15-2009, 12:47 PM

I've got a base also and it happens to me every time I brake hard. I definitely have to grab the wheel with both hands and hold on for dear life. It almost feels like the car skids from side to side. Not a good feeling.

shabarivas · 09-15-2009, 01:00 PM

Interesting ... I have base + sport and I brake really hard sometimes... I could almost let off the wheel and brake if i am going straight...

Modshack · 09-15-2009, 01:33 PM

Quote:

Originally Posted by G35guy84

I've got a base also and it happens to me every time I brake hard. I definitely have to grab the wheel with both hands and hold on for dear life. It almost feels like the car skids from side to side. Not a good feeling.

Typically that's the result of "tramlining". Cars with wide tires are particularly susceptible to this. Generally caused by slight road irregularities on heavily trafficed roads. Often you cannot see the road level difference. The tire track areas gradually sink a bit especially where there is heavy truck traffic. The tires nibble and fight side to side in this "groove". Some tires make this more noticeable.

Tirerack tech explanation here: Tire Tech Information - Tramlining: Coping with the Ruts in the Road

shabarivas · 09-15-2009, 02:10 PM

Nice read - thanks MS

kdo2milger · 09-15-2009, 02:25 PM

Quote:

Originally Posted by Modshack

Typically that's the result of "tramlining". Cars with wide tires are particularly susceptible to this. Generally caused by slight road irregularities on heavily trafficed roads. Often you cannot see the road level difference. The tire track areas gradually sink a bit especially where there is heavy truck traffic. The tires nibble and fight side to side in this "groove". Some tires make this more noticeable.

Tirerack tech explanation here: Tire Tech Information - Tramlining: Coping with the Ruts in the Road

had this (tracking) problem in the stang...felt like the front ires always wanted to jump rails so to speak...even worse when braking...

Modshack · 09-15-2009, 03:20 PM

Quote:

Originally Posted by kdo2milger

had this (tracking) problem in the stang...felt like the front ires always wanted to jump rails so to speak...even worse when braking...

The problem becomes exaggerated on Sports (or sporty) cars where the suspension settings are a skewed toward handling response, rather than a hands off boulevard ride. YOu can dumb down the settings (lol...the Corvette guys do this all the time), buy different tires, or just choose to live on the edge...

G35guy84 · 09-15-2009, 04:15 PM

Quote:

Originally Posted by Modshack

Typically that's the result of "tramlining". Cars with wide tires are particularly susceptible to this. Generally caused by slight road irregularities on heavily trafficed roads. Often you cannot see the road level difference. The tire track areas gradually sink a bit especially where there is heavy truck traffic. The tires nibble and fight side to side in this "groove". Some tires make this more noticeable.

Tirerack tech explanation here: Tire Tech Information - Tramlining: Coping with the Ruts in the Road

That makes a lot of sense. Thanks so much for the info!

bullitt5897 · 09-15-2009, 04:19 PM

Modshack is completely right. Great Post Modshack! Another option is to notice these indifferences on the road and to drive a different line (shade a lil to the left or right) this will keep your tires out of the trouble areas and give you better more stable braking. I do it all the time and in racing terms your just using a different line to approach a turn entrance.

Boy in GA we have some bad ones thanks to MARTA and their heavy buses on every road... its like jumping a canyon wall in some places. Thats where taking a completley different approach to a turn really helps the dynamics of the car and allows you to enjoy the car on crappy roads.

RCZ · 09-15-2009, 06:21 PM

How hard were you braking? I remember the stock suspension kinda got squirly under hard braking when the rear was getting a little light. But you have to be braking really hard for that to happen...

kannibul · 09-15-2009, 10:25 PM

Quote:

Originally Posted by RCZ

How hard were you braking? I remember the stock suspension kinda got squirly under hard braking when the rear was getting a little light. But you have to be braking really hard for that to happen...

Fairly hard, maybe 70% max or a bit more?

It was when I was "stop testing" the car. I found out the car stops fast enough it's nearly an out of body experience.

RCZ · 09-16-2009, 08:44 AM

Yeah, it kinda tends to feel like it wants to "squirl" out to the sides a little? Its a combination of the road, the staggered setup and the suspension. If your alignment is off, breaking is where you will feel it most too...

09-15-2009, 10:03 AM	#1 (permalink)
kannibul A True Z Fanatic Join Date: Jun 2009 Location: Jenks, OK Posts: 2,281 Drives: 370z Touring/Sport Rep Power: 267	Braking and car moves strangely. I don't know if this conditions, braking, suspesion... I've noticed under some braking conditions that the car feels like it'll bite harder on one wheel, then shift to another wheel, then another, then another...almost in a circular motion. The result is that it doesn't feel "happy"...and like you should fight the wheel a bit. What causes this? What can fix this? To a point, I had this happen with other cars too, but, it wasn't as noticable.

09-15-2009, 12:47 PM	#5 (permalink)
G35guy84 Enthusiast Member Join Date: Aug 2009 Location: New York Posts: 305 Drives: '09 370Z 7AT Sprt PW Rep Power: 16	I've got a base also and it happens to me every time I brake hard. I definitely have to grab the wheel with both hands and hold on for dear life. It almost feels like the car skids from side to side. Not a good feeling. __________________ '09 Nissan 370Z Base 7AT - Sport Package - Pearl White \| Performance Mods: Stillen G3 CAI \| F.I. HFC \| F.I. TDX CBE w/ 18" resonators \| Megan Racing coilover kit \| Ichiba rear camber kit \| 20mm front / 25mm rear H&R spacers \| Aesthetic Mods: White interior/license plate LEDs \| 6000K bulbs \| 20% tint

09-15-2009, 04:19 PM	#12 (permalink)
bullitt5897 Premium Member Join Date: Jan 2009 Location: North GA Posts: 6,831 Drives: Twin Turbo Z34 Rep Power: 3682	Modshack is completely right. Great Post Modshack! Another option is to notice these indifferences on the road and to drive a different line (shade a lil to the left or right) this will keep your tires out of the trouble areas and give you better more stable braking. I do it all the time and in racing terms your just using a different line to approach a turn entrance. Boy in GA we have some bad ones thanks to MARTA and their heavy buses on every road... its like jumping a canyon wall in some places. Thats where taking a completley different approach to a turn really helps the dynamics of the car and allows you to enjoy the car on crappy roads. __________________ *Shop Cars: 2013 318whp Nismo VspecII 370z SOLD, 2009 1000hp+ 93oct 4.0L TT 370z Fast Intentions STAGE 4 #054*

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09-15-2009, 10:04 AM	#2 (permalink)
Division Base Member Join Date: Jul 2009 Location: Central FL Posts: 199 Drives: 2009 370Z Sport Rep Power: 16	Does your VDC indicator come on when your braking? This may be the VDC kicking in.

09-15-2009, 11:26 AM	#4 (permalink)
corbin09 Track Member Join Date: Jun 2009 Location: Dallas tx Posts: 665 Drives: 370z Rep Power: 280	Mine does this too, I thought it was the VDC, and played with it a little, Then got sways and springs, and new tires... It is no longer an issue. Mine felt like for lack of better words "skittish" almost. Its more stable now. I have a base though.

09-15-2009, 01:00 PM	#6 (permalink)
shabarivas A True Z Fanatic Join Date: Apr 2009 Location: Sacramento, CA Posts: 2,188 Drives: 370z MB 6mt Rep Power: 914	Interesting ... I have base + sport and I brake really hard sometimes... I could almost let off the wheel and brake if i am going straight...

09-15-2009, 02:10 PM	#8 (permalink)
shabarivas A True Z Fanatic Join Date: Apr 2009 Location: Sacramento, CA Posts: 2,188 Drives: 370z MB 6mt Rep Power: 914	Nice read - thanks MS

09-15-2009, 06:21 PM	#13 (permalink)
RCZ A True Z Fanatic Join Date: Nov 2008 Location: Miami Posts: 6,403 Drives: '09 370Z Rep Power: 1119	How hard were you braking? I remember the stock suspension kinda got squirly under hard braking when the rear was getting a little light. But you have to be braking really hard for that to happen...

09-16-2009, 08:44 AM	#15 (permalink)
RCZ A True Z Fanatic Join Date: Nov 2008 Location: Miami Posts: 6,403 Drives: '09 370Z Rep Power: 1119	Yeah, it kinda tends to feel like it wants to "squirl" out to the sides a little? Its a combination of the road, the staggered setup and the suspension. If your alignment is off, breaking is where you will feel it most too...