Advanced Suspension Setup; (Toe? Camber? Spring Rates?) Learn here!

[theflatlander]

Front spring rate increase:
More under steer; increase in proportional weight transfer to the front when rear wheel rate is not increased; reduces front traction when rear rate is not changed.
Usable adjustment: 150-600 lbs/in
Symptoms of too much adjustment: terminal under steer; front of car hops in corners; excessive wheel spin on inside front tire on FF cars.

Front spring rate decrease:
Less under steer; decreases proportional weight transfer to the front when rear wheel rate is not increased; increases front traction when rear rate is not changed.
Usable adjustment: 150-600 lbs/in
Symptoms of to much adjustment: Too much over steer; over steer then under steer if spring is so soft that the car bottoms out on lean, car bottoms out excessively with a jolting ride.

Rear spring rate increase:
More over steer; increase in proportional weight transfer to the rear when front wheel rate is not increased; increases rear traction when front rate is not changed.
Usable range: 100-600 lbs/in
Symptoms of too much adjustment: too much over steer; sidestep hop in corners; twitchy; pretty scary.

Rear spring rate decrease:
Less over steer: decreases proportional weight transfer to the rear when front wheel rate is not changed; increases rear traction when front rate is not changed
Usable range: 100-600 lbs/in
Symptoms of too much adjustment: car under steers; if way to soft car under steers then over steers as car bottoms out on lean; car bottoms out excessively with a jolting ride.

Front anti-roll bar stiffer: more under steer
Usable range: none to 1.25 inches in diameter
Symptoms of to much adjustment: terminal under steer; lifts inside front tire off the ground witch can cause massive wheel spin on FF cars; also not good for most effective tire usage as inside tire is now doing nothing.

Front anti-roll bar softer: less under steer
Usable range: none to 1.25 inches in diameter
Symptoms of to much adjustment: overstate scary; more like fun

Rear anti-roll bar stiffer: more over steer
Usable range: none to 1 inch in diameter
Symptoms of too much adjustment: Big-time over steer. Can cause inside rear tire to lift off the ground.

Rear anti-roll bar softer: less over steer
Usable range: none to 1 inch in diameter
Symptoms of to much adjustment: under steer; slow and boring

Front tire pressure higher: less under steer by reducing slip angels on most tires
Usable adjustment: up to 55psi hot
Symptoms of too much adjustment: no traction- tire crowned so more under steer; adds wheel spin in FF cars; jarring ride; center of tire wears out

Front tire pressure lower: more under steer by increasing slip angles on most tires
Usable adjustment: not less then 20psi
Symptoms of too much adjustment: edges of tire wear quickly because tire is folding over; feels mushy; tires chunk because low pressure means heat build up.

Rear tire pressure higher: less over steer by reducing slip angles on most tires
Usable range: up to 45psi hot
Symptoms of too much adjustment: no traction—tire is crowned so more over steer; bad wheel spin on FR cars; jarring ride; center of tire wears out.

Rear tire pressure lower: more over steer by incresing slip angles on most tires.
Usable range: not less then 20psi
Symptoms of too much adjustment: edges of tire wear quickly because tire is folding over; feels mushy; tires chunk because low pressure means heat build up

More negative camber front: less under steer because of better lateral traction as tread is flatter on the ground under side load.
Usable range: up to 3.5 degrees negative
Symptoms of too much adjustment: poor braking; car is road crown sensitive; twitchy; front tires wear on inside edge

More negative camber rear: less over steer because of better lateral traction as tread is flatter on the ground under side load. More rear grip
Usable range: up to 2.5 degrees negative
Symptoms of too much adjustment: more over steer; car feels twitchy in back; tires wear out on inside edge; less breakaway warning when limit is exceeded.

Ride height to low (typical beginner mistake): car is twitchy with unpredictable dynamics. Bump steer make you life miserable.
Usable range: usually 1.5-2.0 inches lower then stock unless car has been modified to go lower.
Symptoms of too much adjustment: everything that could possibly go wrong: sudden over/under steer; twitchy due to bump steer; very harsh ride; premature tire wear.

Toe in – front: car is stable going straight. Turn in is average
Usable range: 0-1/8th inch
Symptoms of too much adjustment: car has slow twitchiness under braking; feels odd; kills outside edge of tires

Toe out – front: Car turns in well; works pretty well on FF car as they tend to toe-in under load.
Usable range: 0-1/4 inch
Symptoms of too much adjustment: Car is really twitchy under braking; car wanders on straight road; kills inside edge of tire

Toe in – rear: car is less likely to over steer when the throttle is lifted
Usable range: 0-1/8th inch
Symptoms of too much adjustment: weird, slow, rocking movement in back; feels slow but still unstable; wears outside edge of tires.

Toe out – rear: Helps car rotate useful in low speed and slalom courses; very common on FF pro rally cars.
Usable range: 0-1/8th inch
Symptoms of too much adjustment: not to good for street driving; causes lift throttle over steer; makes violent side to side rocking motions in the rear; tie wears on inside more.

Positive front caster: helps stability; suspension will get more negative camber when turning; reducing positive caster reduces steering effort. (Negative caster is not usable)
Usable range: 4-9 degrees positive
Symptoms of too much adjustment: can increase under steer especially in cars with wide low-profile tires. Can increase steering effort.

Single adjustable shock stiffer: Better turn in; better transient response; causes slower onset of over/under steer by slowing weight transfer depending on what end of the car is adjusted.
Symptoms of too much adjustment: suspension becomes unresponsive; ride gets harsh; car skips over bumps, loosing traction; Causes a big delay in weight transfer resulting in strange handling like under steer then late corner stage over steer.

Single adjustable shock softer: slower transient response; quicker onset of over/under steer
Symptoms of too much adjustment: car oscillates due to under dampened spring motion, like a boat. Car gets twitchy in turns. Feels unstable.




Have fun tuning your suspention. Use Toe and Camber to your advantage! Even Tire pressure helps.

[nissanguy_24]

Good job man should be stickied... i knew the basics but this really helped and gave me some more ideas and a better understanding.

[theflatlander]

glad i could help.

[Menchi]

Car and Driver as a decient spoco magazine called Boost, without all of the BS, it has an artical, about tire tuning that resembles this, but isn't as good, but I recommend it

[CrazyHawaiian]

Is this from a book or something or personal experience?

[theflatlander]

^sorry i thought i put that on there, guess not. The author of this is driftaholic from nopistons.com

[marshun]

interesting.

[ACDSupra7]

Excellent. Someone sticky this thread

[phinko]

good info, bumpity bump

[chuaboi36]

nice article. kinda got lost a little bit though. some pretty complicated stuff for noobs like me

[prodigy]

Originally posted by theflatlander
^sorry i thought i put that on there, guess not. The author of this is driftaholic from nopistons.com

Haha. I wonder if that is Jacob. No, he owns three 240sx's and no sevens. Must just be a same name coincidence.

[Vinsanity]

this may be a dumb question, but is there any difference between 'reducing understeer' and 'increasing oversteer'?

[OH240SE]

Thanks Flatlander, that really breaks down difficult suspension setup nicely. Good post

but those are for FR setups not FF, right??

[theflatlander]

Originally posted by OH240SE
Thanks Flatlander, that really breaks down difficult suspension setup nicely. Good post

but those are for FR setups not FF, right??

it's for all cars in general.

[BENJO]

i found the actual site of this information! after reading this i went on google and searched "suspension tuning" and this was the first thing that poped up

http://www.se-r.net/car_info/suspension_tuning.html

have fun

nice thread it really helped I always needed guidance with toe adjustments.

[soblade]

hmm, so does tha tmean it's nto that good of a idea to put lower springs...but some other good coilovers and springs that will give u better performance?


oh hmm, btw, if you JSUT put lowering springs to all 4 wheels, does it affect the previous suspension? like when it was first bought with suspension?

[GRiDRaceTech]

If you do get lowering springs, match them with the appropriate shocks. If you just cut the springs and leave the stock, blown shocks, I will slap you across the back of the head.

See what a lot of people get wrong is that they put lowering spings on their stock shocks. Thats a big mistake. Stock shocks cant take the pressure and the way the car behaves under lowered conditions. Cutting springs is even worse because you can almost never cut the springs to a point were all four will have an even ballance and cutting them causes really bad tire wear and is deadly to the whole car suspension.

[SaintDrift]

http://www.niagarapca.com/autocross/ax_doanddonts.html
I always used this as a quick and brief guide.

[Simon Danhoff]

Good article, Very informative.

Thanks,

[mranlet]

Mr. Anlet approved :thumbup:

Lowering springs like arospeed and knock off crap will lower the car but won't improve performance. if a low-slung look is important to you, a spring that has an increased rate like H&R or something would help, and unless you want to drive around with blown shocks then you'll need to swap them out for something tougher.

Even good entry-level aftermarket shocks don't like to be lowered all that much more than 1 to 2 inches. This is because all of the forces that occur when the car goes over bumps are now compressed into a much shorter motion since the suspension stroke is closer to bottoming out at neutral than it was from the factory. If you have KYB AGXs or some kind of adjustable dampening suspension (Tockico and Koni also make good inexpensive shocks) you will need to increase the dampening as the ride height is lowered.

Unless it is some sort of emergency, don't try to use a oem shock with a stiffer spring - when I took apart my CRX's suspension for the first time since buying it, I was amazed at how horrable the shocks were operating. An owner a few exchanges ago had installed some fairly decent springs front and rear but had used the stock dampening units - when I compressed the removed shock by hand, it simply stayed there...

Something else to note is that different suspension geometries have different limitations. Honda double wishbone suspensions can be lowered farther than macphearson strut types before adverse effects start to mess things up. Lighter cars (especially with lightened unsprung weight) will also give the impression of stiffer dampening since there is less mass for the suspension to support. It is this reason that sometimes you see some hardcore grassroots'ers use truck leaf springs in the back of their muscle cars or springs from much larger and heavier cars on their smaller and lighter cars.

Excellent post.

[theflatlander]

Originally posted by mranlet
Mr. Anlet approved :thumbup:

Lowering springs like arospeed and knock off crap will lower the car but won't improve performance. if a low-slung look is important to you, a spring that has an increased rate like H&R or something would help, and unless you want to drive around with blown shocks then you'll need to swap them out for something tougher.

Even good entry-level aftermarket shocks don't like to be lowered all that much more than 1 to 2 inches. This is because all of the forces that occur when the car goes over bumps are now compressed into a much shorter motion since the suspension stroke is closer to bottoming out at neutral than it was from the factory. If you have KYB AGXs or some kind of adjustable dampening suspension (Tockico and Koni also make good inexpensive shocks) you will need to increase the dampening as the ride height is lowered.

Unless it is some sort of emergency, don't try to use a oem shock with a stiffer spring - when I took apart my CRX's suspension for the first time since buying it, I was amazed at how horrable the shocks were operating. An owner a few exchanges ago had installed some fairly decent springs front and rear but had used the stock dampening units - when I compressed the removed shock by hand, it simply stayed there...

Something else to note is that different suspension geometries have different limitations. Honda double wishbone suspensions can be lowered farther than macphearson strut types before adverse effects start to mess things up. Lighter cars (especially with lightened unsprung weight) will also give the impression of stiffer dampening since there is less mass for the suspension to support. It is this reason that sometimes you see some hardcore grassroots'ers use truck leaf springs in the back of their muscle cars or springs from much larger and heavier cars on their smaller and lighter cars.

Excellent post.

I try,
i'm very pleased to know that you appreciate it, thank you.

[mechaniac]

after learning all that was posted, and then stepping away from it, after actually adjusting, modifying, and driving your own car, you will soon come to realize that the aforementioned information is not an "all ending guide" but more of a "general starting point" because the mentioned adjustments don't always play out exactly as they do in every car with every playing field.

can someone go over tie rods, cv bearings etc?
ya nm that pushrod...i was spacing out