Alignment settings for time attack

[VS15]

Hi guys ,

Wish there is a track section for discussion . Am having some headaches related to my car behavior as am setting it up for time attack , the tail is too wiggly powering out from a corner and it doesn't feel stable on high speed transitions.

Below is the car setup and hope to get the veteran trackies recommendation on what's a better setting to go for

Front:
Camber : -3.5 degrees
Toe: 0
Caster: 7 degrees

Rear
Camber: -3degrees
Toe: 0

Suspension:
custom valve rebound rate
Front spring rate : 13k
Rear spring rate: 12k

Wheel size: 255/40/R18 front and 255/40/R18 rear with Federal Semi slicks

Running a 2" front splitter with a 1500mm rear wing bolted to the trunk.

Car is currently putting down 490hp and 450Nm Tq

Any advise to make the car more stable powering out from mid corner to corner exit will be appreciated. I know it depends on much more variables on car setup but hope to get a general idea how am i doing thanks.

 

[spoonman]

im not veteran track person but if this helps

if anything make the rear toe in a bit so when you put the power down they will sit straight instead of trying to toe out, which might, i say might help your exit traction, this will only be effective with the hard acceleration you get at lower gears, on a hard right hand corner your rears with a setting of 0 will be doing this \\ || instead of || ||

 

[Fasthands]

Contact SXDevelopments they are running an S15 in time attack right now and have been helpful to me with just general advice with fast road handling.
Google them plus they are on Facebook..

 

[Auss15]

Ok I'm a bit of a track hack and from what I can see you have way to much neg camber in the rear if you are -3 degs each side.

My car is ver well balanced and I run track specs of

Front, 7.8 degs of castor
Camber, 3.5 neg
Toe, 1 degree out each side

Rear,
1.7 degrees neg each side
Toe, 1 degree in on each side

 

[VS15]

Thanks guys .

why would you run less negative camber in the rear?

fasthands: thanks for the tip , will they respond to external queries ? or u have a contact i can get through with?

spoonman: i dont quite get what you mean on a hard right corner how the car toe out on the current 0 toe rear .

thanks

 

[Auss15]

You will run less neg in the rear because you have less weight, you are putting the power down via the diff giving you traction and you are not steering or braking the rear wheels like the front where the G forces are greater.

Similar reason why your spring rates a softer in the rear then the front



BTW I'm personal friends with the SX Developments guys and attend track days with them through the same club.....NSCC

 

[VS15]

Auss15: Thanks a lot for your advise . what kind of camber setting would you recommend on the rear ? am running a 2 way kaaz lsd as well ...... Do you know what alignemnt settings does the 200sx in sx development runs?

the track i am running is as below , doing clockwise runs . I am not so good in technical stuff like suspension settings , with the setup i have my front grip is excellent . just the rear is all over the place..... and hope to sort that out but my driving skills cannot adapt to it hence need more opinions on alignment settings.

 

[Auss15]

Iv'e sent him a Msg and will let you know when he responds. You must remember he is running a wide body with a wider track and on the rears he is using 295's with Advans AO48's.

 

[VS15]

Thanks for the help Auss15 , it if helps to dianose my problem as well i run wheel offset of +18 front and +18 rear both 9.5jj .

Would you recommend i run the same rear camber as you which is -1.7 on each side ?

 

[Auss15]

Ok so he's come back to me and he's running -3 on the front and -2.5 0n the rear but as I said he has a wider track.

What type of sway bars are you running? Those rear spring rates are pretty stiff as well.

I would maybe start at that -1.7 especially with your two way and see how it feels

 

[S15_SAM]

Auss settings are bang on for track work! I would get it set to that and try it! Playing with it is the only way to find out what makes it work better. may cost you abit to have it adjusted and re adjusted but it's worth it!

 

[VS15]

do you know what kind of castor and toe settings he has?

Am using 29mm front and 25mm rear sway bars .......

Will try slight toe in and less rear camber in the rear , hopefully it will aid the stability of the FR platform =) . so when u say start at -1.7 and slowly going higher ( -2.0 and above? )

if there is any materials online that i could read on ( with layman terms) would appreciate it hahaha , aint so technical .

 

[VS15]

THanks for input Sam , yea suspension settings is like a black art. will try it out by one just want to know a baseline on what to set for my rear =)

 

[VS15]

couple of shots of the car =)

 

[Auss15]

I think he is running 1.5 toe on each corner out in front in in rear. Not sure of castor but I think near 9 degrees. He's running Whiteline adjustable sway bars with solid links which I run. Ive run them at hard front and rear but have taken the back one back to soft which helped with a little oversteer I had because the rear was to stiff.

 

[VS15]

on a non elevated track , wouldnt a stiff suspension be better ?

I run solid sub-frame mounts as well as hard race pillow ball mounts suspension arms if that have any influence on the suspension geometry.

 

[Fasthands]

Thanks guys .

why would you run less negative camber in the rear?

fasthands: thanks for the tip , will they respond to external queries ? or u have a contact i can get through with?

spoonman: i dont quite get what you mean on a hard right corner how the car toe out on the current 0 toe rear .

thanks

Just bung them an email and ask away, I did they seem a good bunch.. Mention the forum they may join up and help a lot more.. Good luck with your 15..

 

[spoonman]

Ive played around with my alignment settings to see how much affect you get by slightly adjusting this and that, and the toe adjustment gave the most horrible response when not toed in

Under hard acceleration the rears don't stay in there exact spot that you align them to, especially if you have rubber bushing and even with solid bushes the metal will still move a bit, this is where good quality caster camber toe and traction arms with solid bushes come in.
The reason for a little toe in on the rear is so that when you are booting it in second or third your rears will sit straight

i.e. when your car is standing still your rears with a little toe in will sit like this / / \ \ (just not that much toe, only symbols on the keyboard) once you boot it they move a little to this position | | | | so you have the best grip, pretty much every RWD car is aligned this way from the factory for this reason if you run 0 toe your rears will sit | | | | this way when you are stationary but under hard acceleration they will move a bit like this \ \ / / which will make the rear as unstable as hell when powering out of a corner, the more solid your rear sub-frame is the less this will happen but it will always happen.

And for time attack i would put the helical LSD back in or maybe a 1way but that part is more to suit your driving style. 2ways are for drift cars. I also sold one a while ago to a guy who runs a targa/circuit car and his words were that hes run most types of LSDs but the helical gives him the most traction, he also said that hes yet to break a nissan one..... running a 500hp V8 upfront

 

[VS15]

Thanks fasthands , will email them to see what do they have to say .


spoonman , thanks for your feedback on this. stock lsd for track driving eh , what's the logic behind this one as maybe i have not been exposed enough but most guys around south east asia runs a 1.5 way or 2 way for time attack . Would definitely like to know more as this is the first time im hearing this =)

cause the article below says otherwise
http://www.cusco.co.jp/en/movie/lsd_limited_slip_differential.html



Will try toe-ing in a little to see if i can get some stability as you guys mentioned in the next 3 weeks as the care is under-going some aerodynamic mods in the body shop

Cheers

 

[spoonman]

keep in mind that anyone trying to sell a product will always tell you that there option is best or simply the option which will make them money sometimes what they say is tru but you cant always bank on it, isn't that why you asked on here? we aren't trying to endorse any products.

The slight toe in will make alot of difference, and that may be all you need, however about the LSD options...

Im not saying slap in a helical and you will be quicker, as your driving style with have alot to so with it, but the main difference between a 50/50 locked drive and a drive that is continually varying the power is the correct amount of power is being applied to either wheel depending on the power you are demanding to be applied and cornering force, the helical will always give you power to both wheels, but it just wont be 50/50 it could be 60/40 70/30 80/20 all depends on the corner. It gives you better traction on corner exits, which is where you said your car is the hardest to control.
When going around a corner if a both wheels are locked to 50/50 one will have to skid a little to keep up with the other one, which is why its perfect for drifting, and some circuit racers prefer this as this suits them as they can corner faster with a little bit of slip, where a helical will move the power more to one of the wheels to compensate for the difference in wheel speed, it wont act like a open and put all the power to one wheel, this is why you get better traction when trying to grip instead of slide.

Why do you think nissan put them some of the GTRs rear ends?
Even Ferrari have used this type of lsd from time to time, just they dont call it helical/torsen