Suspension Geometry

SON240sx Automotive
1

Hey guys. I recently went to a HADA autocross event and had one of the instructors drove and looked over my car. He said the car was much too low (and I also need an alignment). According to him, the max you can lower most cars without screwing up the suspension is around 2 inches. I would say my car is lowered about 3-4inches.

My car has Tein Flex coilovers on it but all of the control arms are stock. I would like to find the optimal ride height for performance with my setup before I go in for an alignment. Does anyone have any suggestions?

2

optimal ride height for performance is a big debate

dont quote me on any of this but I believe this all to be true to the best of my knowledge

im not going to get too much in to detail because i’m not qualified to do so

but someone like sasha would tell you that the lower you can go the better to keep your CG down (to a point, obviously - i dont think anyone can debate that lowering your s13 4 inches will negatively affect your performance and possibly cause some binding issues)

Adam Hutchinson on the other hand is very fast on the race track also and he runs stock ride height on his Tein RA coilovers and R-comps in order to keep his geometry working the way nissan intended for it to be working.

3

what I know is that if you lower your car till the control arms are parallel with the ground thats about as low as you can go with out negativly effecting you suspention inless you get role center adjusters.

Mael

4

you will need fully adjustable LCAs and tie rods to combat the mishaps of lowering the car.

Lowering the car also makes you have less dampner stroke, meaning you’ll hit those bump stops or fender frame faster…

Low to the ground race cars tend to have inboard, designed to be low suspensions…

Lower = lower cg, but your roll center will be way off… causing you less suspension efficiency, less ride comfort, less grip, requiring stiffer springs to combat the added roll, etc…

Adjustable LCAs front and rear will run you about 1200$… check SPL for adjustable tie rods.

You would definetely want them being 3-4 inches lower heh… I’m 1.5" all around and have bumpsteer… i do need an alignment however… spl unfortunately has the tie rods on backorder since june :-/

5

Ramesh, there’s a pretty good alignment shop called “Can-Alignment”, if you go there, he would be able to tell you what height would make your suspension work best, etc. But I think he charges to change the ride height. However, the guy that works there seems to really know his shit. He did the alignment on Zee’s car and I was very impressed. They are located in Milton.

I’d probably go back there next.

Whatever you do, don’t take advice from Ahmed. =\

He’s going to tell you that you need ford taurus brakes if you plan on autocrossing your car more.

6

Actually you dont NEED any of that. infact for a dialy driven car that would be just stupid to invest in.

if you REALLY wish you car to be ideal for track and autocross use the raise it up 2 inches and sacrafice the “looks”.

even if you were to get the lowercontrolarmsbushingstirerodsnrca’s blah blah you will still be putting an awkward load on a suspension setup that wasnt supposed to be like that from the factory.

The 240sx race cars that run that low have been totally re-engineered to allow the car to sit that low. MOstly by way of rebuilding subframes with inner control arm mounts that have been moved to allow full suspenion movment with no binding.

Also lowering your car to that level will not allow the shocks to use their full stroke as they were intended. You need to allow the car to rebound and compress in order to actually gain traction, hence why you see many cars bouncing around corners due to the fact that the shock/spring is at its maximum limits and really is doing nothing but keeping your frame off the ground.

By no means am i some sort of engineer or guru of suspension holyness, however im an enthusiast of it because my car is slow :slight_smile: so i have make up in the corners. (i read teh books and test the theories)

raise your car, get an alignment and go have fun. itll cost you a 100 bucks and you love it.

Greg

7

a_hamed explain to me how roll center adjusters will change your control arms in the rear from looking like this \ / instead of __ __ like they should? You better know what your doing when you start to play with roll center adjustment.

I lowered my car until my rear arms were parallel with ground. It isn’t very low. The gains from lower CG arn’t wroth the losses in suspension characteristics. Raise your car, and get a proper alignment. Noone looks at what your car looks like, its lap times.

If you really wanted to combat suspension geometry being screwed at lower ride heights, it requires development of raising the spindles. Company in Japan as accomplished this, however it isn’t perfect. Essentially, start engineering new suspension for the 240…however is it really worth it?

Also, with a coilover that has 2 collar adjustment, you can lower the car as much as you want and maintain the same stroke length of your damper design.

Andrew.

8

it all depends on how much suspension travel you have really

if you have stiff springs and sways, slam the car

to be honest, the car will work exactly teh same slammed as it will a few inches up, on the one hand you have more peak grip but a skittery hard to drive car (WHICH IS AWESOME) on the other hand you have a car that is easier to drive but has a bit less peak grip.

at the end of the day after adding aero into the equation I find that raising the car and having the geometry working for you is good for tighter tracks like dunnville, toronto, shannonville etc.

and a lower car works at faster downforce relevent tracks like mosport

9

let me add that my car will always be as slammed as is legal because its awesome

and over the winter i am going to try and design zero bump steer into the rear suspension

10

edit

fuck it i deleted two posts in a row, so not worth arguing with idiots.

Conclusion gt you just reworded what i said in a stupid way and attacked me.

3-4" is not a ‘daily driver’ oriented thing either.

Sasha knows what he’s talking about each time i read his posts… prob is compensating for introduced roll with stiffer springs and crappy valved jdm tyte coilovers will result in drum roll…a shitty ‘DAILY DRIVER’S’ ride quality.

Honestly it seems ‘track only’ is a substitute for “i can not afford it don’t know how to do it, can not do it properly and i don’t have it and probably won’t have it, and will never do it properly only half way, so neither should you cause I’m jealous”.

Newest trend on son240: Instead of being a douchebag elitist for having ‘jdm tyte’ parts (eg; parts that can be had for cheap in japan or at a japanese junkyard but you buy or sell it at ultra inflated pricings to ignorant kids just as every other ‘i wana be gangster’ mtv kid), now it’s going to the track and bragging about it while telling everyone else whatever they’re doing is not necessary and for ‘track use only’.

Mind you many new sports cars you can buy at dealerships from some distinguished brands such as bmw, honda, nissan, etc… have cars that can probably handle better and grip better and feel better (eg; comfortable) than most of your idiotically setup ‘tracked’ and/or ‘daily driven’ street wanabe race cars. They cost alot, but hey, probably because they were not designed and engineered with a son240 mindset but by actual engineers who did not want to be jdm tyte, with stretched tires flush wheels, and running badly valved made in china/taiwan dampner’d rust bucket cars.

The irony in all of this is as usual, if you can’t do it, you haven’t done it, and its so ever so ‘holy’ of a setup (eg; not alot of people have it, and its expensive) on a 240, its automatically track only (even if it improves the car and is just a small step in improvment to a MORE expensive ‘off the shelf’ new properly enginered much more expensive sports car.)

Honestly the smarter thing to do when on son is to hang around the sales section for low balling and not sharing knowledge or ideas with idiots… as it returns no benefits, it’s better that ever son car handles like shit and feels like shit (not comfortable) in order to compensate for your own car, while everyone thinks that everything is track only if they can’t afford it and will never get it… and and… lol, its mad hardcore jdm tyte and so holy.

While you don’t NEED all that, go also cut your springs because you don’t NEED that spring that is made to be proper length, coils and rate.

11

lol i see all your editing.

and it makes no sence.

and i didnt reword what you said. i said something totally different.

untill you have actual experience dont talk.

no one said they cant afford anything. its making what you have work best for what you are intending to do with it.

you ramble on like a child and take other peoples insight as asshattery so i dont think ill have much luck speaking to you like a normal person would.

in the end.

car guys are fags. everyone knows everything.

ill go hang around the old hotrod guys… they dont talk out their asses. and if they get called on the ass talking that might occur… they shut the fuck up and listen to someone who actually knows.

12

hot rod guys are boring

all they do is talk about the old days and how they used to have (insert random engine displacement here) and used to be able to snap their necks back in 4th.

no body cares

plus they drive slow

13

Just for kicks, when it comes to ‘experience’ in this case. Simple example of how f’ed up this is. Driving a stock 240, vs a 240 with 1.5" drop and same valving resulted in a massive roll (same swaybars, including rear hicas bar, hicas removed, slightly slightly higher spring rates, but poly bushings, but stock dampening). So I run now higher dampening to compensate, which sucks, as the valving sucks and the ride is shaky and bouncy (not blown, always was since new). Also of course bumpsteer, again sorry I notice it, if you consider it ‘track only issue’ again, well… whatever.

Further drop = higher spring rate + more dampening otherwise more roll. Woopie do.

True story. Guess what a shitty 3-4" drop would do, imho worse.

Anyways.

If those parts were unecessary they shouldn’t exist at all. Buy them, don’t buy them, do stupid things or right things. Whatever floats everyone’s boat.

14

When you mature you’ll see that it was advice from experience. It may not be “right” but at least it’s advice from someone who went there and did that.

Newest trend on son240: … now it’s going to the track and bragging about it while telling everyone else whatever they’re doing is not necessary and for ‘track use only’.

a_ahmed, you sound like a spoiled brat who didn’t get what he wanted. Maybe what you wanted was to goto the track with the rest of us. Sorry dude, there’s always next year.

While you don’t NEED all that, go also cut your springs because you don’t NEED that spring that is made to be proper length, coils and rate.

No one has ever advocated this modification. I can’t believe you would even suggest that someone on SON would suggest this.

15

Actually i have everything i want, and know what i want next and how ill get it. Sorry dude, next time. What I want and can’t get is a douchebagless son240 and any money i spend won’t make that happen on here.

I still think your agreement in thinking that adjusting roll is ‘unecessary and stupid’ for a 3-4" drop is stupid in itself. As is such a massive drop but hey.

16

Locked.

17

haha amazing.

all im going to say… is the hotrod guys that i hang with are way cooler than the “i used to have crowd” cus the STILL have. and WILL snap necks in 4th… well some of them… 460 bigblocks… are BIG. hehe

18

Unlocked.

Jammin1911, Brandon, I deleted your posts.

19

lowering your car is not bad… however you want to make sure your suspension has enough travel for the type of driving you will be doing(ie rally, solo 2 or road racing and solo 1)…or you will get into bump steer or binding issues…and then you might as well not have the fancy coilovers since you are defeating its purpose.

and once you corner weigh your car…all the corners will be different hieghts anyway…so there is really no “set” height…

if you can get your suspension to work in your application…then the lowest you can go is the best…since your CG will be lower…

if you are on the street and want the car to look cool…then who cares what its set at…slam it down…its not like you are racing around anyway like on the track…

20

Honestly, the easiest way about how to maximize the suspension performance of just about any car, is to pick up a well written book (something endorsed by a trusted builder, racer, or whatever) and start reading.

Then apply those theories to your own car. You will learn more, in less time, and with far less misinformation…