SAI and caster

[poshatch]

so ive been looking into alot of alignment articles to try to dial in the suspension of my car properly, recently installing some lcas to make EVERY arm adjustable, this only has to do with the front BTW

specs before were:

camber -2.5 adjusted from the camber plates at the top
caster: OEM spec
toe: OEM spec

now the camber plates are at roughly 0 and the LCAS are adjusted to give me:

-3.5 camber (my spec just as an experiment)
OEM caster + 1 additional degree (so i dont hit the tie rods)
OEM toe

i know the SAI is different now since the strut is know more vert than it was before yet running more camber due to the lcas

how i noticed a slight bit more grip in heavy turning, but may be cambering too much since i feel slight more understeer while before i almost never had any

the steering is alot heavier and the "straightening up" affect seems more slughish than before

i have read that both caster and sai affect the straigheting up affect

i would like to know an answer for sure since i cant find the correct definitive answer online anywhere, im trying to dial the straigtening up to be as fast as possible (so switch backs while drifting are quicker and require less of a throw) i have p.s. so it being heavy isnt really an issue, when i know what affects what i will compensate one for another to give the best feel for me

can anybody answer this question for me?

[poshatch]

nobody can answer this?

[OM3GA]

Try setting your camber at -2.5 you really need to weight transfer to the front wheels when you have that amount of camber up there usually.(at least thats what i have noticed) You also should run your caster at around +7 degrees. There is also a way to set caster up to assist in counter steering and it basically entails setting up the caster different for each side. I forgot exactly what the specs are but im sure you could find it somewhere. Basically one of the best things to do is to not run a front strut bar( i am keeping mine but it does help) Also keep the stock front sway bar and upgrade the rear one. You definitely need a special machine to adjust SAI most of them do not have stock specs on what the SAI should be at. I assume it would be best to try and get the SAI back to stock no matter what your cars height is at.

[poshatch]

yeah ill probably try that then, i had told the guy at firestone to max out my top camber plates then adjust the rest of the camber as needed from the lca, he didnt listen to me, and im pretty sure that messed up the sai, i have a feeling that it is the sai that is responcible for the turning back since when the struts are nearly vert now it like almost completely went away, so im gonna put them back all the way in and stand there and watch them adjust it from the lca

i had really needed this answered for suree since i needed to know which controls that aspect so i can better dial it in, so i guess caster = straight line tracking and sai = countersteering so ill adjust my specs accordingly

since firestone isnt a performance alignment shop its hard to get the desired spec's you want, i got to learn it all and micromanage the hell out of them

but thanks for the 7 caster spec and i will probably dial my camber back down as well to 3 or 2.5 again ill probably have them set it to that and hopefully my tie rod wont hit the lca i took out the blocker plates so that would help a bit

i already dont have a front sway bar and im running a stock rear

thanks for the info

[egitan]

OK let me begin by saying I'm in no way an expert, just trying to sort out my own settings and been reading about it a bit, here is what I have found maybe it will help:

this applies to FR cars of course
please remember that adjusting camber will affect toe setting
FRONT
should be set with a bit of toe out to avoid understeer how much depends on the setting aggressiveness you desire 2 much toe out and you will kill your tires and your car will always be trying to turn, caster should be set dead on at 6, as for camber I don't know how much to set but I've heard guys go do track and street that are running over 3.

REAR
should be set with a bit of toe in to avoid overstear how much depends on how much you wish your tail to swing out on turns find the setting best suited for your driving but keep in mind that the higher toe-in will give you more straight line stability while less will give you more rear swing, too much and you will kill your tires 2 quickly. Caster (no idea I've been trying to find out what the rear caster should be. Camber, by what I've seen around for other car settings the camber on rear of the car should be 1 less than your front or somewhere close to it at least

Keep in mind that this is for an s13 240sx which tends to understear and are tail happy dont know what you are running but by your pic I assume it is

Now taking my foot outside my mouth I will post some settings that some guys who are pretty good are running, one for autox and one for autocross (just to give you an idea)

Re: Autocross Alignment (240sx AutoXer)
by j-rho » Tue Feb 27, 2007 12:36 pm

Front
Camber: -4.5 degrees
Caster: 6 degrees
Toe: 1/8" toe out (would set to zero if car sees much street driving)

Rear
Camber: -2.5 degrees
Toe: 1/4" toe-in

That's what I ran on my STS car anyway, with 225/45-17 all the way around. I would try running the 235/40-17 tire instead of your current setup - it'll help gearing and CG, and the 235's from Falken or Yokohama are as wide as most 245's.



Re: Autocross Alignment (j-rho)
by nismoautoxr » Tue Feb 27, 2007 5:48 pm

if youre running in stock class like me you can run what I run:

camber-3.5 degrees front
toe 1/8 " toe out front
I have never seen gain from castor change
Rear already has -2degees
toe @0-1/16" out .I like to loosen the rear up a little since my S-14 tends to plow abit , so I toe it out a bit for autox.
Thats already plenty if your running on the street too.

[poshatch]

lol thanks for the help! i found a good setting for me threw some trial and error

the set up is for drift though not so much for grip and it drifts nice so this is what just works for me, id have to tweek it to get it to grip because this set up wants to drift and stay there

front
camber = -3.5 - 4
toe = 0 (ackerman cut in half so i wouldnt need the toe out or in thing until i test)
caster = (i thought caster settings were plus..) 7.5

rear
camber = (was -2.5 going to try - 1.5)
toe = (im measuring in degrees) - 0.2 - 0.3 not alot
thrust angle = unknown, shortened my tension rod so reduced it?

just to recap if anybody is looking on here for info, i think that SAI is directly correlated to the camber on the McPherson strut assembly, ive seen something online for the purch on the coilovers that are slotted so you can adjust camber at the purch and the sai at the coilover itself, idono how much they are

i just took the little play i had in the knuckle and moved it outward as much as possible (reduced) then put the coilover max in on upper camber plates and then my FLCA is set to about 14"s which i think is around the same as s14's i rough measured my friends

my camber curve in the back is a little more aggressive than it used to be in order to put tyre on fender and clear it on compression but im sure it will be fine with the reduction in camber

going to run 215 40's, no front sway bar, stock rear with poly bushings

[RustspecS13]

Check out Nissanroadracing if you want to learn more about suspension setup.

Remember SAI is basically the camber of the strut. As in viewed from the front. You can adjust it seperately or together with wheel camber as you found out.

Castor is also the angle the strut, but viewed from the side of the car. Positive castor is the top of the strut leaning to the back of the car, and negative is tilted to the front of the car. You'll never want or need neg castor.

Trust angle is the difference in rear toe left/right. This makes the car go down the road crooked. Like if you were to park next to a straight line like a building, or painted line, there would be a distance difference at the f/r wheels. Like the front wheel would touch the line, and the rear would be an inch off the line, but you drive "straight" down the road like that.

For consistency you want everything even left/right.

~Alex

[flohtingPoint]

First off, 3.5 degrees IS WAY too much. If you want to be able to settle the front of the vehicle, back that off first and foremost as right now you're eliminating contact patch. Also put more meat on the front of the car.

[poshatch]

Trust angle is the difference in rear toe left/right. This makes the car go down the road crooked. Like if you were to park next to a straight line like a building, or painted line, there would be a distance difference at the f/r wheels. Like the front wheel would touch the line, and the rear would be an inch off the line, but you drive "straight" down the road like that.

thanks, totally messed that one up

[poshatch]

First off, 3.5 degrees IS WAY too much. If you want to be able to settle the front of the vehicle, back that off first and foremost as right now you're eliminating contact patch. Also put more meat on the front of the car.

lol it works for me

i would like to know what happens to the camber of the car when the wheel is turned though if anybody wants to drop some knowledge about that it seems to me it gets reduced some?

[ScrapnSidwayz]

This post isnt very helpful lol but Im curious what length do you have your rear traction rods adjusted to?

[poshatch]

SORRY! started out as a question and then this happened

my rear traction rods i adjusted soo long ago, but if i remember correctly, i set them to stock, then did that for awhile, then shortened them about 10mm thats what i read anyway online would be a good base setting

basically, i ran as little camber as i could in the back...then adjusted the traction rods to keep my tyre from getting all up in my frender

[ScrapnSidwayz]

I want to adjust mine back to stock length but I dont remember what stock length was. Do you know what the stock length was?

[RustspecS13]

3.5deg is not too much. Depends on the over all setup. Stiffness, lowness, tires, etc etc. My old white hatch i ran 3.5deg at the track otherwise the out side of the tire would wear a LOT in one pass.

http://www.nissanroadracing.com/showthr ... rod+length

http://www.nissanroadracing.com/showthr ... rod+length

Check those out for traction rod length info.

~Alex

[ScrapnSidwayz]

Thanks Alex!! I actually shortened mine back to 8.25" earlier and even though my cars lowered a lot it feels better at the stock length.

[flohtingPoint]

3.5deg is not too much. Depends on the over all setup. Stiffness, lowness, tires, etc etc. My old white hatch i ran 3.5deg at the track otherwise the out side of the tire would wear a LOT in one pass.

Then you:
-Didn't inflate your tires properly
-Had crappy tires with weak sidewalls
-C) All the above

I'm going with C.

You also cannot compare what you do at a track with drifting. At a track your front tires are doing what your suspension geometry is intending them to do, where as with drifting your tire is pointing in a totally different direction. He needs to back the camber down and apply as much contact patch if he's having issues with front end stability.

[RustspecS13]

D- Its not my first time drifting and I know how to setup a car.

3.5deg got me good tire wear AT THE TRACK. As soon as I headed home I dialed it back to 3deg.

Seriously do you even own or track an S13? I have been for a long time now and have autox'd and drifted quite often. I know your a good auto crosser and have an 86 but they are very different cars.

Riddle me this. If Im getting a lot of out side tire wear, and I'm driving hard (at the track), does that not mean the contact patch is not correct?

~Alex

[flohtingPoint]

Seriously do you even own or track an S13? I have been for a long time now and have autox'd and drifted quite often. I know your a good auto crosser and have an 86 but they are very different cars.

Riddle me this. If Im getting a lot of out side tire wear, and I'm driving hard (at the track), does that not mean the contact patch is not correct?

Th 86 is a very different car from a S13? You dont say... Yea, I used to drive my S13 around a few little known tracks like Spa, Hockenheim, Nurburgring, etc. I wouldn't expect you to know them, they only host Formula 1 Grand Prix's there.


http://sidepodcast.com/post/a-first-fly ... enheimring

I just told you that if you're getting too much outside tire wear, you're probably under-inflated and using s*** tires that roll too much. Using a proper tire with a proper shoulder would help that.

[poshatch]

ayyyy there shouldnt be any crazy back and forth's in here, not trying to out do eachother just trying to have a conversation about the suspension...

now i dont think -3.5 front was all that bad, it did me fine, however im always upen to fine tuning setups, i didnt get understeer at all when i used it but i had a fairly soft compound tyre up front and i didnt notice any excess outer ware or heat it was pretty even, 55-60 psi and they were yoko prada spec II, i thought they were decent 205 45 on 8"

flohtingPoint

maybe you could answer my question about the camber of the front s13 set up when it turns, most people probably wont agree but i think the worst thing in the front for drifting is SCRUB!