sayanything

iTrader: (1)

Car is a 01 GSR, with Illuminas/gc. 450F 400R. Stock GSR rear sway bar, stock front tower.

so i am slightly tucking tire in the front, about 1 finger gap in the rear (no homo comments please).

so my question is what is the ideal ride height for great handling? would raising my car another inch or 2 or 4 give me better handling? Im planning on going to the track soon, and just want my car to be prepared. Thanks.

ejprimo

my current ride is height 5inches in the front and 5.5inches in the rear from the jacking tabs on all four corners. when my ride height was lower, it would understeer more.

meb58

The elements you can change in the order of fundamental to fine tuning

Ride height
Track width
Spring rate
damper
alignment settings
swaybar

Throw tires in there somewhere

Ride height affects the path and forces that eventually find their way to the contact patch. Center of gravity, instant centers and roll centers are all at work here. anyone interested in good dynamics will at least think of these three elements...even if you don't know how to draw or calculate some of the forces you can be pretty sure that lowering more than 1" - 1.5" may prove to be counter productive in many instances.

You have to actually think backwards at some level...a tire can only perform so much work and you want to preserve as much of that potential as possible...you shouldn't widdle it away by making ride height changes that lead to aggressive weight transfer...because then you need higher spruing and damping rates and these potentially compound the problem.

So, the physical linkages - their orientation/position determine first order weight transfer...okay, thr center of gravity plays a big part but every movenment begins at the roll centers then migrates to the center of gravity then through the suspension linkages...but the suspension links are link little lever arms...the fulcrums determine how fast and how much weight moves through them.

In reality, and this will read as very simple but it is not, all you have to do is make sure the camber curves are where they are supposed to be...that there is enough camber compensation...not too much and not too little. The camber compensation curves are in reality defined by ride height. Camber correction may or may not be necessary...I can almost guarantee a Mac Strut will require more static neg camber. Then you need to pay attention to tire temps across the tread to fine tune.

98civdx

My friend was about that low when he hit the track and he just played around with the ride height a little bit.

i think when he finaly was happy the jacking tabs were 6.5 off in front and 6 in rear.

racebum

it really depends on the track. smooth and fast will be lower than autocross. on the street you'll benefit from a higher ride height.

these measurements will only mean something in the front since my rear tabs are bent somewhat {this is on a dc2 and equates to roughly a tight 2 finger gap}

front driver 5-7/16
front pass 5-1/4


driver rear rail 8-1/4
pass rear rail 8-7/32nd

i also measured from the fenders and from any other solid point i could find to try and get an idea of where the body actually was for weight balance. this has been a pretty good setup for street and autocross since there is enough travel to prevent wrecking the car when you hit a wow in the road at speed. i remember last year a slammed jetta was following me on a back road, one of the corners had a dip in it, something like a marked 35mph corner i went around something like 60-65, nothing too extreme. anyway, in my rearview i see the front end throw sparks in the ground then the back come right out from under him. that jetta wound up in the bank and did so because it bounced right off the road. so little travel let the tires come out of touch with the road.

ChokolAwt

iTrader: (1)

dudewat?

do you have any links that go into detail more on the math involved in tuning a suspension setup? you used alot of fancy words, but im not seeing any continuity between senteces/paragraphs. perhaps this is some copypasta? and if so, where'd you get it from?

meb58

You should not use jack tabs or fenders to measure ride height...perhaps the rear fenders but certainly not the front.

Inner lower control arm bolts will always yield very accurate measurments...you can also use these to verify that the chassis is square.

Pay attention to the details in my #3 above...those are fundamental to good handling.

Re the Jetta...probably lowered with aftermarket springs while utilizing stock shocks...a disaster just waiting to happen.

meb58

Define copy pasta?

Perhaps you should ask a specific question...the entire piece has continuity if you know where to look and understand how forces migrate through a car. There is plenty, in this admittedly quick piece, to feed from.

sayanything

iTrader: (1)

thats pretty in depth. thanks for your time. That really sounds like hardcore racer talk, i was just asking for a general "2 finger gap is good, or 3 finger gap is good"

but i do understand that you have to measure each corner and treat each respectively. My car definitely has a drivers side "lean" which might mess up my handling left and right. i do have a basic alignment with some -camber in the front. well ill just see how it goes.

racebum

ohh this is a good idea with the control arms. i noticed what you mean with the tabs. i had to use 3 different places along with the body, then split the difference to even get a remote idea of where i was. the tabs i found and as you point out are just not accurate

meb58

lean is normal...a car leans because the car's sprung mass center fo gravity is above the road and because centrifugal force is resisted by the tire's alignment torque.

Controlling how much of that sprung moves over the two outside tires is affected by ride height because ride height determines the location of instant centers, roll centers and camber curves. The length of the instant center swing arm determines camber curves and roll center location - static for the purpose of this reply. Since roll center location is coupled to the center of gravity it affects weight transfer. If the distance between the RC and CofG increases, weight transfer increases. This is so because the virtual lever arm connecting the RC to the CofG is longer...and almost always gets longer when a car is lowered too much. A longer lever arm means more potential weight transfer. A longer lever arm, or a lower RC may actually reduce initial transient weight transfer but will increase steady state. On the other hand a higher RC will load tires faster but with less steady state distribution. The hint here is you can aid turn-in oversteer by adding a little rear rake to your set up - but these notes are not gospel, you have to work some of the geometry out. The key here is that RC location affects weight transfer and RC location is affected by ride height. The transition characteristics between transient and steady state cannot really be predicted...you have apply some geometry, common sense and go for a drive. Suspesnion engineers devote a fair amount of time to development...meaning, affirmations and corrections after the paper work is done.

So what do we do when we lower a car? We add stiffer springs and shocks...to avoid running out of suspension travel and to control what may be more weight transfer. But, we have now increased weight transfer through increasing roll couple - a geometric change - and this increase in weight transfer falls directly onto the outside tires. In addition we have increased spring and damping rates and these also transfer load to the contact patch faster...all leading up to more work for the the outside tires - higher wheel rate.

And, adding to all of the above, if the camber curve is not ideal, the tire may likely be cornering on its inside edge...not optimal.

Basically you have to employ a number of geometric systems to fefine the path of weight tranfer and knowing the exact location of the center of gravity is vital...and all calculations assume that there is no torsional bending in the chassis. Earth-fixed axis system, vehicle axis system, moment analysis, steady state cornering and control are but a few.

Perhaps this satisfies ChokolAwt...regarding the math you asked for there are perhaps 120 symbols used in these calculations and most are not available on a normal key board.

I thought I would add...increasing spring and dampng rates help give a driver more control but sometimes and often at the expense of grip. Driver control is always important but you have to recognize that there are compromises to consider and many of those are at odds with the notions we believe to be true. Sticky tires, a little more roll camber, reduced weight and reduced weight transfer - proper ride height- help cornering power. Heavier spring rates can take some of that grip away...and this is acceptable so long as the car goes where you point it, doesn't have any dark corners, and is faster by the clock, not the fanny dyno.

Finally, well, not finally, lowering the center of gravity is the single best thing we can do for performance BUT!!!! We are not designing our cars from scratch...we have to live with the fact that most of our cars are production based intended for daily driving. As such there are some elements or characteristics that cannot be changed. You have to decide if you want to go fast or look fast...and be honest with yourself so your expectations lead you down the path you intend. I don't care for cars lowered too far because I don't care about looks...that's my choice. I don't drive your car...but if a question is asked about handling, you'll likely get the above...

racebum

i think you went right over the head of most of the guys on here. i actually follow what you're saying but it may be useful to get into ride height on an example car with spring and dampers then speak on effects of adjustment on either.

Natural Aspirations

I am a complete beginner at understanding suspension dynamics. I was under the impression that a good starting point for a moderately (400lb) sprung honda was setting the height on a flat surface with the front and rear control arms a little higher than parallel with the floor.

meb58

Spring rates for a very sporting ride/handling compromise should be in the 2.2 - 2.5 hz. How much does your car weigh and what are the corner weights? This is how you determine spring selction on paper and then modify in the field.

You have to look at many parts of the car when asking about good handling...you have to make intelligent compromises but there are critical choices that determine the path you should take.

The reason we like LCA parallel with the ground - and parallel is only a reasonable beginning point for a discussion - is because we hope that toe and camber are relatively the same in bump and compression. This means we do not get one tire toeing out while the other is toeing in as one hits a bump and the other a pot hole. Also, when look at a car from above, the camber curve determines track changes as the wheel moves through the suspension stroke - at full droop or compression the track is more narrow. So, there is also a sideways scrubing action that takes place as a tire moves through this curve. The degree to which this scrubing action begins to tug at the wheel and cause a very unsettled ride is determined by camber curve - and therefore ride height.

Most LCA are typical parallel or angled down toward the tire a little bit.

idrivesideways,

This is a crude but effect method - using tools we might have in our garage, nothing fancy.

Lets use the driver's side front wheel. Make sure the car is on perfectly level ground, tire pressure is correct. The best way to begin...measure the angle of the lower control arm. Next, jack up that corner and remove the tire, spring and swaybar endlink. Now, place another jack under the lower ball joint and lower the other jack until the control arm angle equals your previous measurement. Next, place a piece of plywood in front of the wheel inside the fender well. Make sure it is on axis with the car's center line and is perfectly plumb - up and down. Now, using the jack under the ball joint you can raise and lower the suspension and plot its curve on the plywood. You have to use something that attaches to the face of the hub/brake rotor ( not the brake rotor surface) that can extend to the plywood and plot the curve. If you have a camber guage you can use that to determine the stock position of the hub in lieu of measuring the LCA angle. You can refer to this camber guage as you raise and lower the control arm to determine camber and toe curves...and you should look at the curve in compression and droop.

You have to consider your spring rate/wheel rate at some point because those will determine the effect range of suspension stroke your car operates in.

EDIT : I forgot to add...you can and should, but with great care, jack up the cross corner - pasenger side rear - to simulate 5 degrees of roll and this will also tell you something about the camber angle in roll...the two jacks remain in place car at stock height to being with.

MAKE SURE YOU REMOVE THE SPRING BEFORE PERFORMING THIS TEST OR THE CAR WILL FALL OFF THE JACK!!!

kili

LOL. What if you have fat fingers? I keed...what kind of suspesion setup are you running? simple dampers and lowering springs or coilovers?

Conventionally, I would say whatever setup that lets your turn at speed without anything rubbing would constitute to your best right height. if you have coilovers where the height adjustment is apart from the spring adjustment...you adjust the spring upwards towards the pillow mount giving more preload. it's not that kind of coilover, then crank up the preload. if you have springs..your spring rates are too low.

meb58

...well, that's a fairly simplistic and unscientific advice. You have to set ride height based upon other factors, then select the proper spring...proper spring length, spring rate and block height. There should only be enough spring load at ride height to hold the spring in place at full droop. Higher spring rates ahve shorter block heights because the coils are thicker.

If you race, you may be able to get away with shorter springs - fall out of the perches at full droop. Shorter springs save unsprung weight...and a shoprter spring is less apt to buckle in the middle.

slammed_93_hatch

meb-

Sounds like most of what you are talking about is RE Mac-Strut.. Which doesn't have anything to do with 90% of honda/acura, nor the original posters car in question.

Things like "lowering more then 1 to 1.5" will not be benifical" and "control arms should be parallel" are statements that come from the mac-strut world and have ZERO bearing on the DWB honda's.

To answer the question... though the general idea he presents is correct. That being,

There is NO blanket statement for what the best ride height is.


With that being said, for a DWB honda here is what i follow, and what i learned from a Professional Chassis Engineer.

You want to be as low as you can with out bottoming out your shocks/UCA. But it is ok to bottom out in a corner or two, sacrifice one or two corners for a better handling car on all the other corners.