No front anti-sway bar=a better ride

[KoolBRZ]

Originally Posted by RJasonKlein

I'm quite fascinated by your problem solving abilities - may I ask what it is that you do in your 'daily work'?

Residential computer repair. That just taught me to question everything. I learned the do-it-wrong then do-it-right method as a homeowner. I've been working on my own cars since I was 16. That taught me that manufacturers make compromises.

[wparsons]

Originally Posted by KoolBRZ

For example, I thought I would get a better ride with softer dampening and softer springs. I found out, by making this change, that that is wrong. The heavy wheels/tires shake the whole car when they move very far up and down because the car was designed for lighter weight 16" wheels/tires. (Little-known-fact that.)

The stock 17's are very light for OEM wheels, and if you look at the weight of most 16" packages you'll see the weight difference is essentially negligible.

There's only about 2.5" of bump travel, so I don't know how much extra movement you think you're getting. Plus, the shocks are dampening the movement of the body vs the wheels, not just the wheels against the road. The sprung weight is WAY bigger than the unsprung weight, so a lb or so per wheel isn't going to make a big difference in damping.

What you will get from 16's is taller sidewalls (assuming same overall diameter) which will soften the ride from the tires being squishier.

Originally Posted by KoolBRZ

The sway bars are what actually communicates that shaking to the rest of the car. By keeping the front sway bar and removing the rear one I keep the ability to corner the car, but I've reduced the shaking transmitted by the sway bars by 50%.

Not one bit of that makes any sense. The sway bars are less connected to the body than the shocks/control arms are, so they're much more likely to transmit any vibrations to the body than the sway bars.

Like I said before, sway bars only have an affect on anything if only one wheel is moving. Over a bump that both wheels hit (ripple in the pavement, etc), the sway bars just pivot freely.

So even if you were correct, the only time you've eliminated shaking is when only one of the rear wheels hits a bump (highly unlikely).

Originally Posted by KoolBRZ

I'm trained in my daily work to question everything. But, just because I question things about these cars, doesn't mean I don't love them. It means I believe there are things the factory could have done better.

The compromise from the factory is being almost too soft for great handling. They definitely didn't compromise it towards stiffer.

[Captain Snooze]

Originally Posted by KoolBRZ

That taught me that manufacturers make compromises.

Of course they do. As I have said 4.2x10^5 times everything's a compromise. They are unavoidable. Pick a spring rate, any spring rate. Go on, think of a spring rate. Have you chosen one? Ok, that spring rate you have chosen is a compromise.

[Kostamojen]

Originally Posted by Captain Snooze

I do not know about the oem 16" wheels but when I was considering 16" wheels I found there wasn't much difference in weight between 16 & 17 inch wheels.
RPF1 17x8 + Yoko AD08 17x8 18 kgs
RPF1 16x8 + Yoko AD08 16x8 17 kgs

T66-F 17x8 + Kumho V710 16.8 kgs
T66-F 16x7 + Kumho V710 15.8 kgs

Ya there are a lot of light 17's out there. My 16x7's are 13.5lbs so they are very much on the low end of the weight spectrum, and the 16" tires potentially can be lighter as well.

[TougeSlug]

Quit wasting money and time. I think your "tuning" time and money would be better spent on a simulation. Sure it isnt as complex as real life... but why should it be. buy a machine that can play Gt6 (probably a ps3) and tune it to your hearts content. I feel its pretty spot on for what it is.

[8R6]

Originally Posted by KoolBRZ

... I learned the do-it-wrong then do-it-right method as a homeowner...

i totally understand this method is sometimes necessary for some people but dood... if that's your default method... holy shit. that's the most intentionally inefficient method ever! LOL!

[aagun]

i balanced my 86 by removing front and rear sway bars
but i run it with high spring rate
12.5kg rate front
10.2kg rate rear

with 36 stiffing ways.


daily drive and drift weekend

[wparsons]

Why do people keep running stiffer springs up front? Do they even look at the geometry before making decisions?

The effective wheel rates put that as incredibly front biased, it must understeer like crazy at turn in.

12.5 * 0.95^2 = 11.3kg/mm at the front wheel
10.2 * 0.75^2 = 5.7kg/mm at the rear wheel

if you flipped the springs front to rear it's still front biased, but not nearly as bad:

10.2 * 0..95^2 = 9.2kg/mm at the front wheel
12.5 * 0.75^2 = 7.0kg/mm at the rear wheel

[Shankenstein]

Originally Posted by wparsons

Why do people keep running stiffer springs up front? Do they even look at the geometry before making decisions?

The effective wheel rates put that as incredibly front biased, it must understeer like crazy at turn in.

12.5 * 0.95^2 = 11.3kg/mm at the front wheel
10.2 * 0.75^2 = 5.7kg/mm at the rear wheel

if you flipped the springs front to rear it's still front biased, but not nearly as bad:

10.2 * 0..95^2 = 9.2kg/mm at the front wheel
12.5 * 0.75^2 = 7.0kg/mm at the rear wheel

While it's clear to us, most of the coilovers from Taiwan (and some from Japan) coilovers come setup with a significant front bias.

This is how I imagine their R&D teams:

[wparsons]

I think it's pretty clear some companies just throw rates they use on other platforms at it and don't even test, or do math.

[wparsons]

Originally Posted by Kostamojen

Ya there are a lot of light 17's out there. My 16x7's are 13.5lbs so they are very much on the low end of the weight spectrum, and the 16" tires potentially can be lighter as well.

For the same width and overall diameter, a 16" tire will be heavier than a 17". More rubber, and more sidewall reinforcement.

[Racecomp Engineering]

Originally Posted by wparsons

I think it's pretty clear some companies just throw rates they use on other platforms at it and don't even test, or do math.

99% of "R&D" at some companies is simply getting an existing system to physically fit the car (i.e. making new lower mounts).

- Andy

[DGM33]

I'm loving this thread for the sheer entertainment value. And while I would never bother with all the effort the OP is putting into his car, I must applaud his ability to stay on track and not get all defensive with all the flaming that is going on here. Well done. Do what makes you happy, just don't hurt anyone else and all will be well.

[wparsons]

Originally Posted by Racecomp Engineering

99% of "R&D" at some companies is simply getting an existing system to physically fit the car (i.e. making new lower mounts).

- Andy

Wait, that isn't what you guys do too???