TLLTD Help

Dragvan said:

Id just like to no what the hell you just said? I mean, what does it mean?

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Tire lateral load transfer distribution measures front to rear balance of how lateral load is transferred during cornering maneuvers. It's also used to compare the rate of lateral traction loss between the front and rear tires (Understeer and oversteer).

A TLLTD of greater than 50% means understeer. And 50% TLLTD means that you'll always be at the brink of extreme oversteer. Street friendly, but aggressive TLLTD is at around 58%. Most stock FWD sports cars are tuned to be at around 64% which are prone to mainly understeer. What I want to find out is if the Hotchkis sways will put my TLLTD rate higher or lower than 58%. I don't want to be lower, but I want to be at 58% or a little bit above. I forgot how to calculate this because I lost my paperwork explaining how to figure TLLTD, so I was hoping that someone could refresh my memory.



Here's some information on Hotchkis and the Stock sway bar.

Hotchkis Anti-Sway Bar vs. Stock Anti-Sway Bar [TORSIONAL RIGIDITY]

FRONT: (29^4=707,281) / (24^4=331,776) = 2.131803 = 113% Stiffer than STOCK
REAR: (24^4=331,776) / (17^4=83,521) = 3.972366 = 297% Stiffer than STOCK



Hotchkis Anti-Sway Bar Specs: Front 29 mm/ Rear 24 mm (5mm difference from front to rear)

[Torsional Rigidity Equation] 29^4 / 24^4 = Front Hotchkis sways are 113% stiffer than the rear Hotchkis sways.
-> The front Hotchkis sways are 5mm larger in diameter than stock.
-> The rear Hotchkis Sways are 7mm larger in diameter than stock.
Conclusion: The 2mm extra to the rear will cause more oversteer. But how much oversteer? The TLLTD equation will answer this.



Stock Anti-Sway Bar Specs: Front 24 mm / Rear 17 mm (7mm difference from front to rear)

[Torsional Rigidity Equation]24^4 / 17^4 = Front stock sways are 297% stiffer than the rear stock sways.
Conclusion: How much understeer is caused by the stock sway setup? The TLLTD equation will also answer this question.

stowaway said:

that formula can only give you a general idea, if I'm looking at this right. Spring rates play a huge part in weight shift and tendency to under/oversteer, so just saying that swaybar stiffness ratio of XX% will do this or that.

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The equation measures the amount of understeer that the entire suspension plus the weight of the chassis creates. It does this by measuring what tire slips first (during steady-state maneuvers). Then by reading the percentage, you can change the TLLTD percentage through spring rates, shocks, sway bars, rear to front/ left to right weight distribution. Each individual suspension component will change TLLTD in different ways. Sway bars may make some of the biggest changes to TLLTD while minor weight reduction adjustments may account for the smallest changes to TLLTD.

Say you start with a stock SRT-4. If you add Hotchkis sways, they'll reduce understeer because the rear sways are 1.59 mm larger than the front. TLLTD will measure the amount of understeer reduced. Then say later on you decide to buy springs and shocks. The springs plus the shocks will also change the degree of understeer. But you might never know to what percentage it's reducing or adding understeer. So if you know what percentage of understeer you have, you'll be able to fine-tune your suspension a lot easier and save a lot of money on mods because instead of using trial and error, you'll know exactly what mod you'll need to get the handling characteristics you want.

stowaway said:

htheduck said:

good luck in assigning a number to oversteer and understeer characteristics-by generalizing sway bar proportions.

i'll wait patiently for the additional Osteer/Usteer numbers for:

-size of contact patches and their effect
-coefficient of friction for various street & R compounds; friction circle
-abiment air & ground tempuratures - in my region
-dew point, humidity levels - again, in my region
-comparative track surfaces, specifically watkins glen (portions have been repaved), limerock and NHIS
-sprung & unsprung weight shift characteristics on stock springs

If you can help me with this, I would appreciate it.

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that's what I've been hinting at. I can do something as simple as change tires (within the same size) and the handling characteristics will change drastically.

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lol Didn't I already say that TLLTD doesn't measure understeer based on sway bars alone? It measures how fast lateral load is transferred to the tires. That means everything before the tires: sway bars, springs, shocks, and the weight of the entire vehicle is measured to how fast it transfers load and how much at each tire. That sway bar information uses equations to measure torsional stiffness, not TLLTD. You probably got confused by the sway bar stuff.

And of course TLLTD won't measure temperature because it focuses on how lateral load transfers to each tire. Not how temperature changes understeer. Where does it say temperature or road condition? Additionally, professional drivers really don't need numbers to tell them that their tires are getting hot and are losing traction or that a thin layer of dirt is going to change oversteer by blah blah blah percent. Who does that? Those are all things that the driver should already know from experience. What matters is how the entire vehicle before the tires behaves. Because if you know how your car behaves, you'll know how it behaves at different temperatures or on different terrains. Then you can adjust your driving to accommodate for it. The rest are all things you gauge through your instincts and experience, the driver mod.