lshenretty

Was just reading the C&D article on the new TL, and Honda claims the new TL is 24% more rigid than the current model.

Those of us who read the car mags have seen this many times, with each of the 2nd, 3rd, 4th, 5th iteration of a model having upwards of 15-20% more tortional rigidity than the model it replaces.

Maybe one of the engineers here can talk a little about how we experience tortional rigidity. I'm assuming it's the biggest factor in a car feeling solid and "all of a piece."

But here's the question - how is it that a model can improve at dramatic levels like 24% several times? It would seem that at some point the car would have to be hollowed out from a single ingot. The improvements claimed begin to sound like a comedy skit. ("The body of our new model is made of solid rock!, and is 100% more rigid than our old model, which was made only of layers of carbon fiber. And we don't even hollow it out! To keep it as rigid as possible, we just put the wheels on, hang the engine underneath, and strap a seat on the top. It can evidence a little brittleness when driven at speed, but that's a small price to pay for the literally rock solid ride. And wait 'til you see how it.........")

kenbiddulph

Torsional, refers to twisting. Torsional rigidity is therefore resistance to twisting, this helps the ride, reduces squeaks, noise and improves handling (the suspension has to do less work if the body is more rigid)

New metallurgical techniques, reduced glass area (compare it to an older Accord, like the 86-89, 90-93 Accords) and you'll notice there is less glass, meaning more surface area of metal. Smarter shaping of the metal, strategically locating strong points and the increasing demand for safety all mean a stronger body.

lshenretty

That's helpful information. Thanks.

But it leaves unanswered the issue of compounding improvement rates. If the current TL has a stiffness measured at 1.00, then this new one has a stiffness rate of 1.24. And if the next model is improved another 20%, then that model is 1.488 as stiff as last year's model, almost 50% more rigid than last year's model. I guess what I'm wrestling with is that it seems you'd run into a wall pretty quickly, beyond which you couldn't improve it. And yet over the years, models have made seemingly great stiffness improvements year after year.

kenbiddulph

You make a good point, but drive a Honda from 20 years ago and you notice a huge improvement in how "solid" the car feels. Eventually the gains will be much smaller unless car manufacturers come up with some radical innovations (silksteel alloys, exotic metals)

swami

If anyone is familiar with Honda motorcycles, particularly their sportbikes, that utilize aluminum frames. They've taken a radical approach that has the other manufacturers scrambling to catch up. Honda calls it "Tuned Flex" which involves making portions of the frame ultra stiff and others less stiff. In a nutshell, there are certain areas you want to flex a little for traction purposes, others you want zero flex in. I'm sure there's some crossover to the car division and vice versa.

fdl

LOL, well obviously there is a trade off of weight with your rock example.

Materials like aluminum are very stiff for its weight. I believe Audi uses and all aluminim laser welded chassis which works very well. Basically you want the car to flex as little as possible, allowing your suspension to be tuned to provide better and more consistant handling.

swami

Exactly...One thing Honda discovered with their first aluminum framed dirt bike in 97 was, they made the frame super stiff and the suspension ultra soft...Bad move, as the hot ticket with the bike that year was to stiffen the suspension. Since then they've tweaked the design 3 times and have it almost perfect now. There's a fine line between chassis rigidity and suspension compliance that's being closed in on. If they get in nailed as I'm sure they will, maybe they can build them for our climates. The fair weathered peeps get the firmer suspension and the colder climates{us pothole dodgers} get a little more cush.