Why "Hella Flush" and Over Lowering Your Car Is Dumb...

[2_Liter_Turbo]

A very good read! Especially for those of you who are into the "hella flush/super low/stretched tires" fad...

http://www.motoiq.com/magazine_articles ... r-car.aspx

[youngmoney]

im not one for slamming anything, but that write up sucks. he could have summed it up with something like "over lowering is bad for handling" and it would have been just as informative

[nismoracingsx]

i was never much into the whole hellaflush thing, either. Entertaining article, for sure.

[Didderson]

He forgets to mention center of gravity being lowered. With the right amount of camber, even going extra low can have benefits that outweigh being stock heightish.
This is why we have custum roll center adjustment arms available. Longer LCA's, longer ball joints and outer tie rod bolts, and everything is as close to fine as I can tell without delving too much into it.

Everyone has their opinions. This guy is just butthurt his car probably is a sunken fail.

[Hijacker]

Did anyone read the full article? The last two pages go into roll centers, center of gravity, and ways to lower a car properly by moving the mounting points for the suspension arms.

The best article i ever read about suspension outside of dedicated rac suspension books was done by mike kojima and dave coleman for sport compact car many years ago. It's more in depth and does a better job of explaining how the roll center and center of gravity affect each other and ways to manipulate them.

Motoiq's article is very well written in my opinion. If it lost the snarky attitude, it would impact more people. Instead, the snarkiness is offputting the people it really should be targetting, the super low, tire stretched, wheel tuckers.

[Hijacker]

I knew something was familiar about motoiq's article. It's part of SCC's suspension series from back in 05. I didn't look at motoiq's author at first, but it's Mike Kojima. He's only one of the smartest car engineers you will ever find. Anyone flambasting an article of his would do well to reconsider and take his advice instead. I have never read a thing by Kojima that wasn't well written, very technical, and highly accurate. If anyone wants to read the full suspension series he wrote with Coleman and Jared Holstein for SCC, click this link. You won't be disappointed.

[2_Liter_Turbo]

On every forum, those who bash this article have 2 things in common:

1. They are of the ricer flush crowd
2. They didn't read the entire article

lol

[Hijacker]

I got a little frisky today and went out and measured my suspension just to kind of show what happens when you lower your car.

I've been running Eibach S-tech springs, which are good for about an inch and a half of drop, on some KYB AGX dampers. The s-techs are a progressive spring, which should have a softer initial spring rate, and then as the spring is compressed, begins to ramp up the spring rate. I generally stay off my bump stops, but still incur a lot of body roll when I auto-x. To emphasize this, here's a picture of my friend Jay running the cones in my car. The only difference between this setup and how I run on the street is I turned the dampers stiffer.



Mmm...body roll.

But Bart. You lowered the car, and you're running a stiffer than stock spring.

If you read Kojima's articles, you'll understand that just even a simple 1.5" drop in ride height will effectively kill your roll couple.



If you look at the above picture, my suspension looks like the lowered MacPherson image. I measured the height of the bottom of my LCA near the mounting point to the cross member, and then again at the point before the control arm curves upwards to the ball joint. I measured a 1/4" difference. My control arm is effectively parallel to the ground and makes the angle between my strut axis and my LCA axis very close to 90. My roll center isn't exactly the best as is, but with the degree being less than 90 still, I have some wiggle room. You can only imagine what the suspension arms of a super lowered S chassis can look like. Even with a short bodied damper, they probably ride the bump stop through any half way decent speed turn. Kojima, around page 3 of his motoiq article, mentions lowering the mounting point of the ball joint to give the control arm a better angle. This is what I would have to consider if I wanted to correct my suspension geometry for my mild lowering.

There's a reason why parts like this:

cost money. They are vital to maintaining proper geometry. And heck, with a good welder and the proper measurements, they're not that hard to make. Then it's a fairly easy affair to fix the control arm geometry.

Kojima goes into the motoiq article starting off with how people who are hellaflush are killing their suspension geometry. And it's true. Hellaflush cars not only have tires that look like they can barely hold their beads to the rim, but have nasty negative camber, so they barely have any contact patch. Then you top it off with the super long roll couple. I will give the super low crowd one thing; they generally use some form of coil over to obtain the lowered stance. This at least eliminates the issue of lowering a stock Nissan damper and keeps the car from riding its bump stop all the time.

So before people scoff the article because it goes against the grain of what they aesthetically like, think about what the article really means. Kojima is talking about functional suspensions, not aesthetic suspensions. There's nothing wrong with lowering your car, tucking the tires, and showing off to your friends and the car shows. Just don't expect to go win auto-crosses or even drift competitions with your suspension in that state.

He forgets to mention center of gravity being lowered. With the right amount of camber, even going extra low can have benefits that outweigh being stock heightish.
This is why we have custum roll center adjustment arms available. Longer LCA's, longer ball joints and outer tie rod bolts, and everything is as close to fine as I can tell without delving too much into it.

Everyone has their opinions. This guy is just butthurt his car probably is a sunken fail.

Read what I've posted above about Kojima, and then you might want to retract that last statement.

Center of gravity is generally gonna be in the same place in a car, no matter how high or low you take it. As the SCC article states (and most of my race books back up), the CoG for the front should line up around the crank shaft of your car. So going super low, doesn't exactly lower your CoG that much. Not like it does your roll center, and the roll couple that ties the two together. Also, remember that the article was satirical in nature and targets the average joe who drops his car 2-3 inches and then tries to go Vin Diesel on everyone out on the streets.

[2_Liter_Turbo]

^^^ +1

Thanks for typing all that up, I didn't want to! Ha ha

[Didderson]

My 'statement' was me typing before I left for work. I hardly had time to read. If you remember me you'd know my car has plenty of wheel gap because I care about proper function. I care less now more than ever just because I want it to be hellaflush. haha. I don't give a f*** anymore until I get track wheels.
I don't expect to win autocrosses when I go. I go for fun of releasing adrenaline and getting smoother with my driving style. Fitted tires blow for autox. Esp my 8" wide federals up front.

I'm glad you're shedding new light on the subject for me though. Honestly. Everyone needs to over this again including myself. in time I will finish reading.

[Didderson]

It's easy to understand how stock suspension gets increased camber with compression, and how a car with parallel-to-road LCA's (especially up front) will get decreased camber with compression of the suspension. This is where bad and unpredictable handling comes from. Still, without increased length of the LCA, original geometry is still not met because the strut pulls the wheels closer to the center of the car with lowering..

[Hijacker]

It's no problem, Didd. I was taken aback that you would say something negative about the article since I've been following your car for a while.

But I'm gonna reinforce some suspension geometry. I wish I had some measurements of a car on stock springs to compare this against, but I did some quick scale drawings. On my graph, 1 square = 2 inches. The meaningful measurements are:
ball joint height = 8.5"
LCA mounting point height = 7-3/16"
LCA length from mid bolt point to mid ball joint = 13.5"
Strut tower height = 29.5" (to get the center point, I lined my tape measure up to the center of the top hat, got it perpendicular to the ground, and then measured where my tape crossed the LCA from my ball joint to get 5" away from the joint)
Front cross-member length, LCA bolt to bolt = 27"
Tire width = 9" (to get a reference of tire relation to the suspension, I put a straight edge across the inside rim resting on the LCA, and then measured from the ball joint to get 2.75")
Tire height 24"
Center of Gravity (assuming it is crankshaft) = 12.5"



The bottom picture is how my suspension sits currently. My roll center is 2" above ground, and my roll couple is 10.5" long. Not bad, but I don't have stock geometry to compare against.

The top picture is if I used a spacer on the ball joint to move it's pivot plane down 1". For that 1" I changed it, my roll center goes to 3.5" off the ground and my roll couple is 9".

[Hijacker]

The issue isn't increasing the length of the LCA. It's spacing the pivot point of the ball joint down. That in turn shifts the plane between the joint and the mounting point, which will change your roll center and geometry.

[upsdude]

speaking of suspension tuning...when i lower my car i want to get it properly aligned-i'm going with the full line of pbm suspension links and fortune auto coils. my biggest question is if i need to get corner balancing. i'm only lowering my car enough to get rid of wheel gap, and i highly doubt i'll track the car....maybe just some weekend cruises in the mountains (not drifting just enjoying a spirited drive). so would corner balancing even be necessary on top of the tuning of the susp. links?

[2_Liter_Turbo]

Personally, I don't think you'll need it unless you auto-x or road race.

[Sugar]

speaking of suspension tuning...when i lower my car i want to get it properly aligned-i'm going with the full line of pbm suspension links and fortune auto coils. my biggest question is if i need to get corner balancing. i'm only lowering my car enough to get rid of wheel gap, and i highly doubt i'll track the car....maybe just some weekend cruises in the mountains (not drifting just enjoying a spirited drive). so would corner balancing even be necessary on top of the tuning of the susp. links?

No.

[Didderson]

The issue isn't increasing the length of the LCA. It's spacing the pivot point of the ball joint down. That in turn shifts the plane between the joint and the mounting point, which will change your roll center and geometry.

Right Ok good I'm with you on this. I wanted to make some longer ball joints for my car this year, but senior projects are in groups so it's a no go. Looks like I shoulda bought megan replacements or something

[youngmoney]

Did anyone read the full article? The last two pages go into roll centers, center of gravity, and ways to lower a car properly by moving the mounting points for the suspension arms.

The best article i ever read about suspension outside of dedicated rac suspension books was done by mike kojima and dave coleman for sport compact car many years ago. It's more in depth and does a better job of explaining how the roll center and center of gravity affect each other and ways to manipulate them.

Motoiq's article is very well written in my opinion. If it lost the snarky attitude, it would impact more people. Instead, the snarkiness is offputting the people it really should be targetting, the super low, tire stretched, wheel tuckers.

i thought it was only 1 page

[Hijacker]

The issue isn't increasing the length of the LCA. It's spacing the pivot point of the ball joint down. That in turn shifts the plane between the joint and the mounting point, which will change your roll center and geometry.

Right Ok good I'm with you on this. I wanted to make some longer ball joints for my car this year, but senior projects are in groups so it's a no go. Looks like I shoulda bought megan replacements or something

If i was serious into auto-x again, i'd consider fabbing up some LCAs since SPL doesn't carry them anymore (although I do wonder if you can still have them made, or if they have left over stock from when they used to actively carry them). Hell, I might fab some up just for s*** and giggles when I have the time, money, and a welder.

This whole discussion kind of has me wanting to design a spreadsheet or something that you can plug in numbers like your ride height, and it would spit out what your roll center and couple would be. I'm waiting on some rear subframe measurements from a local who has his dropped, and then I can try to make something work.

[novocaine]

I knew something was familiar about motoiq's article. It's part of SCC's suspension series from back in 05. I didn't look at motoiq's author at first, but it's Mike Kojima. He's only one of the smartest car engineers you will ever find. Anyone flambasting an article of his would do well to reconsider and take his advice instead. I have never read a thing by Kojima that wasn't well written, very technical, and highly accurate. If anyone wants to read the full suspension series he wrote with Coleman and Jared Holstein for SCC, click this link. You won't be disappointed.

I vouch for mike! he's an awesome dude and knows his stuff man. i remember him having a meet at his house with his nicely built 200sx and his white twin turbo 300zx. haha i was driving a 1991 sentra se at the time (1.6) auto and he didnt once make fun of me lol! he even let me use his garage to put on my kyb/agx combo at the time. great dude...anyone read his article on clutches?

[Flatline1121]

what i dont like about it is he assumes that most people running 6* of negative camber and have 1" of ground/frame clearance are on s*** cut springs and stock shocks that have no idea how to lower a car.

most of that knowledge he goes into is known to the community of people that do it and pretty basic.

[SX APPEAL]

Dammit, I read this whole thread hoping to find a huge flame war between the hellaflush fanbois and the sensible racers and what do I get? Nothing but a bunch of well thought out, informative posts with hardly any foul language or even excessive use of emoticons!

[2_Liter_Turbo]

Ha ha, read the same thread on northwestnissans Plenty of fan boi flame wars there!

[the converted]

Great article. One thing that I think he left out is that roll center stability can become an issue when you lower a car. It can cause some really interesting handling when it is shifting left and right as you go through corners.

Here's a link to a simpler suspension analysis program that I have used before with good results and the an explanation of how to use it. http://locostusa.com/forums/viewtopic.php?f=5&t=1438

[DR F33LG0OD]

cool story bro

[Sugar]

How many of us can really utilize the benefits of perfectly set suspension geometry...?

Low cars look good, they respond well. Threads like this make me .

[c-hood240sx]

A very good read! Especially for those of you who are into the "hella flush/super low/stretched tires" fad...

http://www.motoiq.com/magazine_articles ... r-car.aspx

yo dat s*** is clean as a mofo

[SX APPEAL]

It's no problem, Didd. I was taken aback that you would say something negative about the article since I've been following your car for a while.

But I'm gonna reinforce some suspension geometry. I wish I had some measurements of a car on stock springs to compare this against, but I did some quick scale drawings. On my graph, 1 square = 2 inches. The meaningful measurements are:
ball joint height = 8.5"
LCA mounting point height = 7-3/16"
LCA length from mid bolt point to mid ball joint = 13.5"
Strut tower height = 29.5" (to get the center point, I lined my tape measure up to the center of the top hat, got it perpendicular to the ground, and then measured where my tape crossed the LCA from my ball joint to get 5" away from the joint)
Front cross-member length, LCA bolt to bolt = 27"
Tire width = 9" (to get a reference of tire relation to the suspension, I put a straight edge across the inside rim resting on the LCA, and then measured from the ball joint to get 2.75")
Tire height 24"
Center of Gravity (assuming it is crankshaft) = 12.5"



The bottom picture is how my suspension sits currently. My roll center is 2" above ground, and my roll couple is 10.5" long. Not bad, but I don't have stock geometry to compare against.

The top picture is if I used a spacer on the ball joint to move it's pivot plane down 1". For that 1" I changed it, my roll center goes to 3.5" off the ground and my roll couple is 9".

Hijacker, I used your drawing to estimate what the roll couple would be on a stock height 240sx, and the news is not good.... I think I'm correct in assuming that the only measurements that will change between a lowered car and stock height one are the LCA mounting point height, the strut tower height and the CoG height, correct? So I simply added your 1.5" drop back onto these figures and redrew the diagram. Now this is very rough but according to my diagram the CoG of a stock height 240 should be at 14" above the ground, and the roll center would be roughly 7.5" above the ground, giving you a roll couple of 6.5". Thats a far cry from the 10.5" you've got now with a simple 1.5" drop, even with the extended ball joints we're still not getting anywhere close. But the thing is, you can combat the effects of increased roll couple with heavier springs, not a big deal. Although I have absolutely no idea how to calculate the increase in spring rate required for a said increase in roll couple (any engineers in the house?) My major concern is the affect lowering has on the camber arcs of the tires, I definitely don't want my tires going into positive camber around hard corners. Does anyone have any input on what can be done about this?

[the converted]

Bart, I just threw your numbers into Solid works to make a quick guestimate. I had to guess on the top hat center to center, but if I was anywhere near close, your roll center is actually .75" BELOW the ground. Bumping the height up 1.5" brings it up to 3.24" above ground, which is a pretty good number.

Lowered 1.5"


Stock height

[SX APPEAL]

I know this thread is a bit old but I though you guys might find this interesting: part of my build thread, scroll to the last post, or look at the whole thing for that matter lol.