Suspension adjustments and how they affect handling

jazz · 05-26-2011, 12:19 PM

i am at neutral plus a bit of power and it just wants to kick out. thats being said any + power is kicking. its almost as its rocking front to back and side to side at the same time?

ChrisSlicks · 05-26-2011, 12:37 PM

Quote:

Originally Posted by jazz

i am at neutral plus a bit of power and it just wants to kick out. thats being said any + power is kicking. its almost as its rocking front to back and side to side at the same time?

The chassis is unsettled, probably from the changing road camber and bumps. You need to get on the power slowly and smoothly and not before the apex. Softening the setup as described above will reduce the "rocking" sensation you are experiencing.

jazz · 05-26-2011, 12:39 PM

it make me so sad! never had any issues with the audi tt

jazz · 05-26-2011, 12:41 PM

some pic of the audi build...

jazz · 05-26-2011, 12:46 PM

i keep running on a new road with a long sweeping right its gets twitchy and then a long but shorter left it starts to kick. not putting that much power down if any when it starts...it only stops after i am back at top dead center?

ChrisSlicks · 05-26-2011, 12:58 PM

Quote:

Originally Posted by jazz

i keep running on a new road with a long sweeping right its gets twitchy and then a long but shorter left it starts to kick. not putting that much power down if any when it starts...it only stops after i am back at top dead center?

Just soften the dampers and try again. It sounds like you are over damped for the spring rate.

MJB · 03-30-2012, 11:43 AM

BUMP!!!

I'm not trying to bash anyone nor is this directed towards anyone in particular .... But it just seems like the lack of knowledge on suspension setups from people is causing tons and tons of alignment headaches on this forum.

I've been seeing a bunch of threads started about people that lower their Z's, but then when they take it in to get an alignment the techs can only do so much with what they are working with, and thus are unable to get a good alignment. A bunch of these same people have no idea what camber, caster, or toe is, they have no idea where the toe is even adjusted at, and they think that just installing after market rear camber arms is the solution for getting everything back within specs.

Why start trying to lower your Z if you do not have a clear understanding of our suspension system and how it works, the parts to it, and what is a 4 wheel alignment and how it affects your handling/tire wear? Doing a little bit of research can go along way. This is a very good thread by the way!

Front and rear camber arms, and eccentric toe bolts installed with the cutouts in the subframe enlarged, shouldn't have a problem with alignment. That is with it being performed by a competent mechanic.

Fishey · 02-18-2015, 03:44 PM

Here is my little guide for track setup.

let me say this guide will help you with a 350z or 370z but there are some differences you need to be aware of between the cars.

The 370Z was built to be more nimble then the 350Z and the way they went about doing this was they decreased the wheelbase by 4 inches. Then on the front suspension Nissan used a few other tricks to change the feel of the car like decreasing the amount of caster from 7.6 to 8.9 degrees to 4.4 to 5.9 degrees for the 370z. This change in Caster reduces steering effort along with the reduced wheelbase makes for a car that feels far more nimble and is likely is a bit more nimble. However, to do this they had to increase the SAI from 4.3 to 5.8 degrees on the 350z to 6.9 to 8.4 degrees since caster will help promote camber gain during cornering. The 370Zs increase in SAI is a more mechanical change to how fast the suspension increases camber as it really is the measurement between the long arm and short arm in the suspension. In a 350Z the top arm is longer so it has less SAI vs the shorter top arm of the 370Z that allows for faster camber gain during compression.

Some of you might know but I do alot of track setup work at my shop and I am also involved in a few professional racing efforts. Let me say that I have done track setup on everything from Grass Roots to Professional racing and unless its a time-attack car setup or AutoX it always has a general profile that will benefit 95% of you but certainly changes on venue/conditions/etc but I want to give a few general guidelines and things I see all the time that keep people from getting that extra edge. This is the way I think about it in my own head when I get a new car to setup.

First, I want to tell you that everything is a compromise and I am talking about generalities here. I could counter my own way of thinking very easily. So to talk about tires and a few general guidelines. The very first being that the grip level of the tires you are using is going to effect setup. So if your running a very sticky compound (Short life) generally speaking your going to be more on a harder setup and if your running on street tires your going to be running a softer setup. I generally error on the side of soft vs hard as when you get to hard in your setup mechanical grip suffers and things like curbs can really start unsettling a car.

Second, I want to talk about Camber and how it is going to change depending on situation. I can tell you right now that an acceptable range is from -3.5 to -2.2 front and -2.5 to -1.5 rear. Your spring rate and your tire compound will be primary factors in your camber levels. I have yet to come across a situation yet that has required a higher rear camber then front camber.

Third, Caster because it goes hand in hand with camber.

Since camber changes to negative on the loaded wheel and positive on the unloaded wheel. I tend to keep Caster consistent until I can get good tire data. Also, if your one of those guys running crazy amounts of camber because that is what your seeing right now from data. It might be time to think about making a drastic caster change to reduce the need for crazy camber numbers. I have also noticed if you are seeing increased front grip with larger front sway bars its highly likely its time to increase front caster.

This is one area I think the 370Z can really be improved. I have not done alot of testing and being late to the setup party I don't really know what B.J. and the guys have tried. However, there could simply a limitation where it no longer helps as camber gain gets to dramatic on the outside/loaded tire and reduces grip. In that case take B.J.'s advice and add more front bar! I do not think the 350z suffers the same problems as a result of different geometry.

Fourth, lets talk about toe as its one of the best ways to make changes to your car. Rear toe is going to depend some on parts you have in your car. Front toe on a race car generally going to keep it pretty close to zero but some drivers prefer a toe out for more turn in. The rear toe we always leave some toe in to keep the rear stable under braking and under acceleration off the corner. A zero toe with soft bushings can turn into toe out on acceleration and make for some very interesting dynamics.

Fifth, Shocks! If you are running a full remote res setup with the ability to adjust pressures do me a favor and please buy yourself a nitrogen bottle/reg and a dry-break or whatever it is called tool. Keeping shock pressures at a constant pressure from weekend to weekend will help you. I can't tell you how many times I have seen very nice aftermarket shocks that were way uneven or way low on pressure. I always keep an eye on the pressure inside the shocks before the start of a weekend.

Sixth, Corner weighting your car. I always suggest this be the very last thing you worry about in your setup and I would only start to mess with it after you get a general handle on your car. If you do decide to get a corner balance then remember that you need to have at a minimum. adjustable ride height with coilovers and adjustable swaybar endlinks. When I do corner weighting the individual numbers are not important. The important numbers to me are the cross weights so what is the split from RF/LR or LF/RR

I hope that helps.
Also, remember if you have any questions about your setup feel free to E-mail me at shop@metricgarage.net. You also can always reply to this thread and like us on our facebook page www.facebook.com/metricgarage.net

kenchan · 02-18-2015, 04:55 PM

re11, front kangaroo bar for me.

Kraken370 · 01-21-2016, 12:41 AM

So it's not possible to put lets say ark gts springs on the z and not do anything else? Are camber arms and toe bolts absolutely necessary otherwise the wheels just wear faster or make the car uncontrollable? Still confused after reading the whole sticky.

Kraken370 · 01-21-2016, 12:49 AM

Ark's website says the GT-S springs work with OEM suspension and comes with instructions how to put them on.

EJ30157 · 05-25-2022, 05:53 PM

A good read about sway bars specially for 370z from Stillen.

https://blog.stillen.com/2018/04/sti...ide-sway-bars/

filip00 · 07-09-2024, 07:19 AM

Bringing this up from the ashes to ask an adjustment question I couldn't find:

If I want to adjust rear coilovers, I should remove the trim. Did anyone maybe make a trim cutout that would allow quick rear shocks adjustment? Like cutting out a hole on the top, that would be covered with a quick-removal rubber cap or something?

Averying · 07-09-2024, 08:43 AM

Quote:

Originally Posted by filip00

Bringing this up from the ashes to ask an adjustment question I couldn't find:

If I want to adjust rear coilovers, I should remove the trim. Did anyone maybe make a trim cutout that would allow quick rear shocks adjustment? Like cutting out a hole on the top, that would be covered with a quick-removal rubber cap or something?

My car has a couple ~1” holes in the trim above the coilovers to allow the extension adjuster to pass through. Those adjusters live there permanently. I’ll get a pic for you later.

Sent from my iPhone using Tapatalk

filip00 · 07-09-2024, 09:03 AM

Quote:

Originally Posted by Averying

My car has a couple ~1” holes in the trim above the coilovers to allow the extension adjuster to pass through. Those adjusters live there permanently. I’ll get a pic for you later.

Sent from my iPhone using Tapatalk

That's EXACTLY what I need!!! Please do several pics, open/closed and from a few angles, so that I can just go to cutting without removing the trim first.

Thanks a lot!!

05-26-2011, 12:19 PM	#46 (permalink)
jazz Track Member Join Date: Feb 2011 Location: barrie ON Posts: 910 Drives: 11Zcab/12venzaV6awd Rep Power: 15	i am at neutral plus a bit of power and it just wants to kick out. thats being said any + power is kicking. its almost as its rocking front to back and side to side at the same time? __________________ One part rubber, three parts Krazy Glue.

05-26-2011, 12:46 PM	#50 (permalink)
jazz Track Member Join Date: Feb 2011 Location: barrie ON Posts: 910 Drives: 11Zcab/12venzaV6awd Rep Power: 15	i keep running on a new road with a long sweeping right its gets twitchy and then a long but shorter left it starts to kick. not putting that much power down if any when it starts...it only stops after i am back at top dead center? __________________ One part rubber, three parts Krazy Glue.

03-30-2012, 11:43 AM	#52 (permalink)
MJB A True Z Fanatic Join Date: Aug 2011 Location: Tacoma, WA Age: 41 Posts: 1,498 Drives: a POS truck Rep Power: 496	BUMP!!! I'm not trying to bash anyone nor is this directed towards anyone in particular .... But it just seems like the lack of knowledge on suspension setups from people is causing tons and tons of alignment headaches on this forum. I've been seeing a bunch of threads started about people that lower their Z's, but then when they take it in to get an alignment the techs can only do so much with what they are working with, and thus are unable to get a good alignment. A bunch of these same people have no idea what camber, caster, or toe is, they have no idea where the toe is even adjusted at, and they think that just installing after market rear camber arms is the solution for getting everything back within specs. Why start trying to lower your Z if you do not have a clear understanding of our suspension system and how it works, the parts to it, and what is a 4 wheel alignment and how it affects your handling/tire wear? Doing a little bit of research can go along way. This is a very good thread by the way! Front and rear camber arms, and eccentric toe bolts installed with the cutouts in the subframe enlarged, shouldn't have a problem with alignment. That is with it being performed by a competent mechanic. KraTToR, MaysEffect and Sharad909 like this. Last edited by MJB; 03-30-2012 at 11:51 AM.

02-18-2015, 03:44 PM	#53 (permalink)
Fishey Base Member Join Date: Sep 2012 Location: Lebanon Posts: 159 Drives: Volvo T5-R Rep Power: 13	Here is my little guide for track setup. let me say this guide will help you with a 350z or 370z but there are some differences you need to be aware of between the cars. The 370Z was built to be more nimble then the 350Z and the way they went about doing this was they decreased the wheelbase by 4 inches. Then on the front suspension Nissan used a few other tricks to change the feel of the car like decreasing the amount of caster from 7.6 to 8.9 degrees to 4.4 to 5.9 degrees for the 370z. This change in Caster reduces steering effort along with the reduced wheelbase makes for a car that feels far more nimble and is likely is a bit more nimble. However, to do this they had to increase the SAI from 4.3 to 5.8 degrees on the 350z to 6.9 to 8.4 degrees since caster will help promote camber gain during cornering. The 370Zs increase in SAI is a more mechanical change to how fast the suspension increases camber as it really is the measurement between the long arm and short arm in the suspension. In a 350Z the top arm is longer so it has less SAI vs the shorter top arm of the 370Z that allows for faster camber gain during compression. Some of you might know but I do alot of track setup work at my shop and I am also involved in a few professional racing efforts. Let me say that I have done track setup on everything from Grass Roots to Professional racing and unless its a time-attack car setup or AutoX it always has a general profile that will benefit 95% of you but certainly changes on venue/conditions/etc but I want to give a few general guidelines and things I see all the time that keep people from getting that extra edge. This is the way I think about it in my own head when I get a new car to setup. First, I want to tell you that everything is a compromise and I am talking about generalities here. I could counter my own way of thinking very easily. So to talk about tires and a few general guidelines. The very first being that the grip level of the tires you are using is going to effect setup. So if your running a very sticky compound (Short life) generally speaking your going to be more on a harder setup and if your running on street tires your going to be running a softer setup. I generally error on the side of soft vs hard as when you get to hard in your setup mechanical grip suffers and things like curbs can really start unsettling a car. Second, I want to talk about Camber and how it is going to change depending on situation. I can tell you right now that an acceptable range is from -3.5 to -2.2 front and -2.5 to -1.5 rear. Your spring rate and your tire compound will be primary factors in your camber levels. I have yet to come across a situation yet that has required a higher rear camber then front camber. Third, Caster because it goes hand in hand with camber. Since camber changes to negative on the loaded wheel and positive on the unloaded wheel. I tend to keep Caster consistent until I can get good tire data. Also, if your one of those guys running crazy amounts of camber because that is what your seeing right now from data. It might be time to think about making a drastic caster change to reduce the need for crazy camber numbers. I have also noticed if you are seeing increased front grip with larger front sway bars its highly likely its time to increase front caster. This is one area I think the 370Z can really be improved. I have not done alot of testing and being late to the setup party I don't really know what B.J. and the guys have tried. However, there could simply a limitation where it no longer helps as camber gain gets to dramatic on the outside/loaded tire and reduces grip. In that case take B.J.'s advice and add more front bar! I do not think the 350z suffers the same problems as a result of different geometry. Fourth, lets talk about toe as its one of the best ways to make changes to your car. Rear toe is going to depend some on parts you have in your car. Front toe on a race car generally going to keep it pretty close to zero but some drivers prefer a toe out for more turn in. The rear toe we always leave some toe in to keep the rear stable under braking and under acceleration off the corner. A zero toe with soft bushings can turn into toe out on acceleration and make for some very interesting dynamics. Fifth, Shocks! If you are running a full remote res setup with the ability to adjust pressures do me a favor and please buy yourself a nitrogen bottle/reg and a dry-break or whatever it is called tool. Keeping shock pressures at a constant pressure from weekend to weekend will help you. I can't tell you how many times I have seen very nice aftermarket shocks that were way uneven or way low on pressure. I always keep an eye on the pressure inside the shocks before the start of a weekend. Sixth, Corner weighting your car. I always suggest this be the very last thing you worry about in your setup and I would only start to mess with it after you get a general handle on your car. If you do decide to get a corner balance then remember that you need to have at a minimum. adjustable ride height with coilovers and adjustable swaybar endlinks. When I do corner weighting the individual numbers are not important. The important numbers to me are the cross weights so what is the split from RF/LR or LF/RR I hope that helps. Also, remember if you have any questions about your setup feel free to E-mail me at shop@metricgarage.net. You also can always reply to this thread and like us on our facebook page www.facebook.com/metricgarage.net BGTV8, Presto, pbs370z and 7 others like this. Last edited by Fishey; 02-18-2015 at 03:46 PM.

05-25-2022, 05:53 PM	#57 (permalink)
EJ30157 Base Member Join Date: Sep 2016 Location: Dallas, GA Posts: 6 Drives: 2009 370z Sport Rep Power: 9	A good read about sway bars specially for 370z from Stillen. https://blog.stillen.com/2018/04/sti...ide-sway-bars/ Last edited by EJ30157; 06-13-2022 at 04:33 AM.

02-18-2015, 04:55 PM	#54 (permalink)
kenchan A True Z Fanatic Join Date: Aug 2009 Location: N/A Posts: 76,801 Drives: N/A Rep Power: 141521	re11, front kangaroo bar for me.

01-21-2016, 12:41 AM	#55 (permalink)
Kraken370 Base Member Join Date: Dec 2015 Location: CT Posts: 33 Drives: 2009 370Z Rep Power: 9	So it's not possible to put lets say ark gts springs on the z and not do anything else? Are camber arms and toe bolts absolutely necessary otherwise the wheels just wear faster or make the car uncontrollable? Still confused after reading the whole sticky.

01-21-2016, 12:49 AM	#56 (permalink)
Kraken370 Base Member Join Date: Dec 2015 Location: CT Posts: 33 Drives: 2009 370Z Rep Power: 9	Ark's website says the GT-S springs work with OEM suspension and comes with instructions how to put them on.

07-09-2024, 07:19 AM	#58 (permalink)
filip00 Track Member Join Date: May 2021 Location: slovenia Posts: 557 Drives: 370z pack Rep Power: 125427	Bringing this up from the ashes to ask an adjustment question I couldn't find: If I want to adjust rear coilovers, I should remove the trim. Did anyone maybe make a trim cutout that would allow quick rear shocks adjustment? Like cutting out a hole on the top, that would be covered with a quick-removal rubber cap or something? __________________ ride epic drive epic

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