Splenda_Daddy
Splenda_Daddy New Reader
5/25/18 3:23 p.m.

I own a 2014 Mazda 3 and no experience in suspension tuning but would like to get the car to have a neutral balance.  Considering that the chassis is relatively new, there is no helpful info on the Mazda 3 forums other than plastidip techniques.  I figured by posting here, you guys can guide me in the right direction.

Assuming that a car's weight distribution is 50/50 and a roll stiffness bias of 50/50, does that mean that under a steady state turn with no brake or throttle at the limit that the front and and rear tires would lose traction at the same time?

With this assumption and the goal of a "balanced" car I came up with this: https://i.imgur.com/fJwJD1c.png (swaybar rate has not been included yet but I will be taking measurements this weekend.)

I talked to an old ME friend and he mentioned that I need to know my chassis' torsional rigidity(~27,000 Nm/deg) and that the TLLTD % is what I should be aiming for and that in his experience 54% balance with a hint of understeer (he states that I should aim for a hint for understeer since it provides more usable feedback to the driver.  Is this true?).

How do I learn more about TLLTD and how do I calculate it?  What other variables do I need?

Thanks,

- Splenda_Daddy

Ron_Sutton
Ron_Sutton New Reader
6/14/18 7:09 p.m.

Sorry no one has answered your question.

I don't typically use the term Tire Lateral Load Transfer Distribution or TLLTD.  In my circles we just refer to the front or rear lateral load distribution percentage.  Acronyms are FLLD & RLLD.  Over the years, running hundreds of race cars, I learned a wonderful baseline formula. 

For "most" road courses with the fastest corners being below 100 mph, I set the FLLD at 5.0% above whatever the car's front weight bias is, assuming they have square tire sizes.  So if your car has a 50/50 weight bias, I'd suggest you start with a 55% FLLD percentage.  You will find the car is very neutral, as long as you don't have other "ills" in the car.  For tracks with long sweeping corners, over 100 mph, I'll bump that FFLD percentage up to 5.5 to 6.0% more than the front weight bias.

The correct FLLD percentage is not magic. It won't fix incorrect, or poor, camber, caster, toe, shock valving, setup methods, less than full tire contact patches, nausea, diarrhea, or other issues.  But it is one very important key to your overall handling. 

Best wishes !

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