Necessity of lowering car?

[Mercury_Hg]

My flamesuit is on.

Let's say I have 240sx with all the essential suspension modifications (coilovers, new bushings, control arms, etc).

Would the difference in handling be significant between stock height and a 2" drop? I know the center of gravity would be lowered, but how much of a real effect will this have on drivability (drifting and autocross)?

[SX APPEAL]

In all honesty, 99% of the lowering we do is just for looks. The car's suspension was engineered to work properly at stock ride height and all the mismatched aftermarket parts in the world probably wont improve the handling much without major structural modification to the suspension mounting points and such. Roll center and camber arcs are your major considerations there. I'm not saying that some performance can't be gained through stiffer spring settings and lowered center of gravity, but if these modifications come at the expense of the tires' contact patch as the suspension moves through its travel, then whatever gains you might have seen have been nullified. IMHO there's there's more performance to be gained from $800 worth of sticky rubber than $3000 worth of shiny suspension pieces.

[Mercury_Hg]

Thanks man, that's all I needed to know.

[240hatchsx]

All though SX APPEAL is correct I look at it this way
Wheel gap is like vagina the more fingers you get in there the worse it is ...

[alms24sebring]

Well you can fit more in there.

Anyways, altho its probly true that its mostly looks, you do definantly gain some better stability at the cost of tire durability. But if you spend a good amount on it, It pays off IMO especially if your buying it for function and a purpose.

[Mercury_Hg]

All though SX APPEAL is correct I look at it this way
Wheel gap is like vagina the more fingers you get in there the worse it is ...

I prefer having a minimal equal length gap around the entire wheel well. I don't like overlap on top with gaps on the sides.

Well you can fit more in there.

Anyways, altho its probly true that its mostly looks, you do definantly gain some better stability at the cost of tire durability. But if you spend a good amount on it, It pays off IMO especially if your buying it for function and a purpose.

That's what I'm going for. I want to stuff bigger wheels in there. 17s or 18s, with decently sized tires (not a fan of the stretched look).

Honestly I want to keep my car around stock height for the wrong reasons (the same reasons most people want to lower their car).

Could I not compensate for the difference as a driver?

[Razi]

Once your lower control arms go past the point of being parallel to the road and start pointing up, your roll center will be below the car, and the car will try to roll more. (But you won't notice since you're on stiffer springs.)
And the way your wheels gain or lose camber and toe will be different and messes with your traction.

Your car won't be undriveable, but it won't be performing it's best. There's a reason why pro drifters started raising their cars.

Also, you won't be losing tire durability like ALMS said. That'll only happen if your toe alignment is off and you don't correct it.

[MellowZ32]

ooo00000ffffff!!!!!
calling out ALMS like a boss!

the OP will end up buying godspeeds or megans anyways
so it won't matter

[danshaz82]

and, there are parts companies that do make knuckles and other parts to correct rods pointing upward. so you can go pretty low while still maintaining a factory geometry set up

[Mercury_Hg]

and, there are parts companies that do make knuckles and other parts to correct rods pointing upward. so you can go pretty low while still maintaining a factory geometry set up

Can you elaborate on this?

What companies? What other parts besides knuckles?

[Razi]

Parts Shop Max, GKTech, and Trackday Performance (TDP).

PSM knuckles are the best bang for the buck. GKTech and TDP aren't producing drop knuckles for the rears at the moment, though.

[Mercury_Hg]

PSM knuckles say they're $400 to modify your own. Do you know if it's $400 per knuckle or $400 for the front pair?

[mechanicalmoron]

Once your lower control arms go past the point of being parallel to the road and start pointing up, your roll center will be below the car, and the car will try to roll more. (But you won't notice since you're on stiffer springs.)
And the way your wheels gain or lose camber and toe will be different and messes with your traction.

Your car won't be undriveable, but it won't be performing it's best. There's a reason why pro drifters started raising their cars.

Also, you won't be losing tire durability like ALMS said. That'll only happen if your toe alignment is off and you don't correct it.

The car will want to roll more, but if it can't roll because of the springs, it will still be more stable, with a lower center of gravity.

Also, the suspension travel and how it effects alignment/contact patch should be pretty negligible, with stiffer springs. I don't think mine are stiff at all for aftermarket stuff, and with factory sway bars and a drop to where the wheels are just centered nicely instead of monster-truck-lookin', my car doesn't really lean at all compared to stock, the sprung weight seems to be all but stuck to unsprung stuff.

I'm not saying a huge drop will make the car perform much better, past a point. And I realize a 240 is not going to be prone to rolling over in the first place. But if the car's lower, it would still be harder to actually flip it or to lose traction or contact on one side. Probably more important to circut racing, so, probably pretty unimportant for most 240 owners.

[Razi]

PSM knuckles say they're $400 to modify your own. Do you know if it's $400 per knuckle or $400 for the front pair?

Pair

Once your lower control arms go past the point of being parallel to the road and start pointing up, your roll center will be below the car, and the car will try to roll more. (But you won't notice since you're on stiffer springs.)
And the way your wheels gain or lose camber and toe will be different and messes with your traction.

Your car won't be undriveable, but it won't be performing it's best. There's a reason why pro drifters started raising their cars.

Also, you won't be losing tire durability like ALMS said. That'll only happen if your toe alignment is off and you don't correct it.

The car will want to roll more, but if it can't roll because of the springs, it will still be more stable, with a lower center of gravity.

Also, the suspension travel and how it effects alignment/contact patch should be pretty negligible, with stiffer springs. I don't think mine are stiff at all for aftermarket stuff, and with factory sway bars and a drop to where the wheels are just centered nicely instead of monster-truck-lookin', my car doesn't really lean at all compared to stock, the sprung weight seems to be all but stuck to unsprung stuff.

I'm not saying a huge drop will make the car perform much better, past a point. And I realize a 240 is not going to be prone to rolling over in the first place. But if the car's lower, it would still be harder to actually flip it or to lose traction or contact on one side. Probably more important to circut racing, so, probably pretty unimportant for most 240 owners.

You should call up every race team in the world and tell them this new ground breaking theory on suspension.

[Hijacker]

I'm not saying a huge drop will make the car perform much better, past a point. And I realize a 240 is not going to be prone to rolling over in the first place. But if the car's lower, it would still be harder to actually flip it or to lose traction or contact on one side. Probably more important to circut racing, so, probably pretty unimportant for most 240 owners.

240s are highly prone to rolling. My car on a set of KYB AGX's and Tein S-Tech springs had a horrible time with roll control at an autocross. I was getting better lap times out of another 240 I raced with stiffer linear springs and roll bars.

And it is very easy to lose traction on a car that's lowered. Improper roll control, poor camber arc, poor toe arc, improper tuning of the scrub radius, softly damped suspension, the list goes on. Lowering the car only gives you the added benefit of lowering CG, but unfortunately with most production cars, you throw so much else out of whack that it's almost not worth it. Once the car's lowered, you need camber correction, increased need for bump steer correction, RC correction, sway bars, and someone who knows how to dial all that in.

[mechanicalmoron]

It's just a fact of physics.... lower car means it won't flip over as easily. I don't mean roll as in handle, that's obviously going to be compromised. And yes, it is going to slide more easily if perfect factory suspension geometry is not preserved. And no, I'm not saying it will be preserved, unless you happen to be nismo personified.

Just saying, it's common sense that if you put weight lower to the ground, it will take a lot more force to actually flip it over. Go try some fast turns in a big truck.

Again: I'm talking flipping and firey death, not the type of roll that a sway bar fixes. Wether or not you keep traction, actually flipping a lower car will be much harder.

[Razi]

Nobody is talking about flipping cars here, except you.

[mechanicalmoron]

....maybe I should invest in my own flamesuit.

my point was that lowering could have a side other than the cosmetic, in circut racing or other things that involve high speed turns with grip. So, as I said, very few 240s.

A small side, but a side.

[Razi]

I'm not flaming anybody, I just don't know what you're talking about.
I don't know why you started bringing up flipping cars on the subject of roll center and what not.

When we talk about roll, we're talking about body roll, not a car rolling over and tumbling.

[mechanicalmoron]

My point was simply, building on that, that a car courd withstand more sideways force if it's lower to the ground, before bad things start happening.

Not trying to attack anyone or anything. But as the topic is about what can be gained by lowering a car, I think it's a fair thing to mention.

[Hijacker]

It's just a fact of physics.... lower car means it won't flip over as easily. I don't mean roll as in handle, that's obviously going to be compromised. And yes, it is going to slide more easily if perfect factory suspension geometry is not preserved. And no, I'm not saying it will be preserved, unless you happen to be nismo personified.

Just saying, it's common sense that if you put weight lower to the ground, it will take a lot more force to actually flip it over. Go try some fast turns in a big truck.

Again: I'm talking flipping and firey death, not the type of roll that a sway bar fixes. Wether or not you keep traction, actually flipping a lower car will be much harder.

A not top heavy car won't flip. Go stick a roofrack and a few bikes on top of your 240, and she'll feel more like a truck than you'd realize. But as Razi stated, we're talking roll center, not physically rolling the car on its top. In anything smaller than a crossover, you gotta be doing something stupid to flip a car (ie, off road down a hill, hit a curb at excessive speed, etc), so I think the argument of rolling the car over is a moot point in the discussion.

And in all honesty, Nismo doesn't do much to correct roll center and preserve suspension geometry. All of their bits are non-adjustable and designed for the car to stay at factory ride height.

[mechanicalmoron]

Curbs happen.... obviously hopefully not, but still, if going all out, the lower the car, the more it will take before flipping.

I was thinking about roll-center, and I COULD be wrong, but I think that it shouldn't lean more easily, because you won't be able to lower the center of gravity below the roll center. It will obiously screw the geometry, but until the center of gravity is just inches off the ground, it won't be putting more torque on the arms, no matter which direction they're pointing, it will be putting less torque on them, because it starts out above them.

[Hijacker]

the issue is not if the CG is lower than the RC. RC drops quicker than the CG when you lower a car. The problem is that there's an invisible lever arm, the roll couple, linked between the two. The longer that arm, the more tendency the car will have to roll. That's why over lowered cars handle poorly if they're not designed to go that low. If you correct the RC so it's closer to the CG, the roll couple gets smaller, keeping the car from rolling easier. Also, it will help keep the car off the bump stops. A lot of overlowered car owners think that the car's not rolling, which it technically isn't, because the car hits the bump stops, which keeps the dampers from doing their jobs. Mike Kojima has a great article about it over on motoIQ. And good luck getting your CG a few inches off the ground. On most production cars, front CG is best guestimated to be around the height of the crankshaft. If it were a few inches off the ground, you wouldn't have an oil pan in a 240.