The trick is going from philosophy to reality

This is the exact comment left on a forum after our last event; the poster drives an S2000 btw

The event was 2 days, I posted fastest time of the day on the first day

 

go-kart for sure hahha

 

I actually went on a long road trip recently for 2 weeks & we took the Hummer; once we got back and I got into the Fit to drive to work it felt exactly like a go-cart, so close to the ground and quick around corners. lol, so much fun to drive! It feels like I am falling in love with it all over again

 

^^ditto

I drove my fiance's Ford Escape around for a weekend and when I got back in the Fit, the thing felt like a roller coaster. I love it. Stiffer, more responsive, lower, better.

 

Its worse. not only do we test on a 100 ft circle, we also test on back to back 200 ft circles in a figure 8 pattern to evaluate transitions as well, exceedingly important, then we takei it to the track for track laps. (one of which is the "Fit leading a lap at VIR" on you tube). Stopwatch analyses of section to sections gives us a good comparison. For the time being, we have not lowered although 2 others using this set up have mild lowerering (1") with equally good results. The guy with the HOOSIERS HAS IT HANDS DOWN ON ANY LAP TIME.
For my Fit, we removed the front antisway bar altogether and substituted HD shocks (actually AirLifts) on the rear. So far it has the best lap times on 205/50x15 tires or 195/40x17 tires on 42 mm offset wheels but then we're not through. May have to lower and get Hoosiers. Don't like being that far behind. Not at my office so I don't want to say which lowering kits used but I do remember they are two different ones. Doesnt seem to be that different in performance but I do rember fudging the ride heights a little bit to get 1" drop.
Handling is very crisp and definitely near neutral which is what we wanted. Now if I could get my SiR 175 hp engine and LSD in it it might be really fun. Hoosiers might not be necessary.
Hope that helps.

PS good eye. We start with 50 ft radius to keep errors from resulting in really bad endings so we get our base in safe settings that we can work on. The fact there are a couple of A/Xers involved might be another reason. They don't have many 100 ft radius corners.

And thanks for the complement. It is the congregate view of several suspension designers and racers, all of whom had csuccessful careers. Hate to say it but this is one case where a committee was useful.

 

Well i was gonna go with the T1r dampers & swift springs, & I guess just some bars, i don't know what though, but I will.

 

Wow mahout - no sway bars at all! That could only mean that you have a very stiff suspension in very torsionaly weak chassis. This is all relatively speaking…of course. I would think that you would concentrate your efforts on stiffening the body first. Too bad there is no such thing as Viagra for car chassis.

 

The reason for no sway bars at all is that the Fit chassis is pretty stiff and the standard weight distribution is so front loaded that removing the front antisway bar, or simply disengaging, which is zero cost, makes the balance good (lawyers however will tell you that American drivers MUST have lots of understeer or they can't drive). remember we're not talking about a NASCAR racer. Especially with only 1500cc and 120 hp.

You are correct that adding some spring stiffness is beneficial. The trick is adding enough without too much. Based on this AM's comments from the guys pretty much all the lowering kits are pretty much equal if the drop doesn't exceed 1.25" all around. They said they've driven each other's cars and couldn't tell the difference.

 

did you do any chassis "stiffening" things to your car? ie front lower brace, rear lower brace, X-braces, etc.

 

The Fit is not cornering at 1.0 G much less 1.5 on street tires so the lateral loads are not very high; certainly not enough to be a problem with suspension geometry. No chassis stiffening needed or done. In a Fit its mostly cosmetic Highest g loading measured was .93 and only over a short time, virtually instantaneous..
The best we wanted to get with our Fits was not absolute feeling but absolute stopwatch cornering. as low as the balance is good (pretty much absence of understeer or oversteer) with relatively high cornering g is the goal.
The bottom line is if your Fit drives balanced in corners with relatively high g force (limited by the tires and body configuration, such as CG, weight to power, etc), the driver can extract all the performance his tires can offer because of the control over the Fit. Balance will be altered as needed to fit the competition course but street is straight up balanced.
Thats pretty much what happens in any driving setup. Karts to NASCAR to F!.

 

Now this is the first time we disagree…
Feeling is needed for the driver so he has the confidence and control to keep it on the limit. A stiffer chassis gives the driver much better feedback, needed for control to keep it on the limit. And body stiffness is what gets it for him/her. Otherwise, like you said, you get spot peaks of lateral g’s that you can’t hold or control – as well!

 

Sure you need seat-of-britches feel to get the car around fast; however, it is necessary that feel is accurate. If its fuzzy by unbalance the feeling is not precise enough to corner accurately - or fast - enough. I suspect we still agree. I just didn't describe enough.
Do you do anything inparticular to make sure your butt is directly connected to the car?

 

If you head back to my previous post (#78) this is in line with what I was saying as well, with the philosophy Mahout is talking about, if you are going to do the RSB you can remove the stock FSB as well.

I went with a different approch and I actually rely on the rear wheels being looser and more independent to help move weight around better in corners. When you approch a corner with a stiff front if the rear wheels are more independent it allows the rear outside wheel to shift and rotate around the corner and thus take more weight than if the front was not stiffened up. By taking some of that weight going to the front outside wheel and moving it to teh back it lets you hit the corner faster and put down more power when accelerating out. Another reason I like having the front stiffer is it keeps both wheels flat and equal meaning I don't smoke the inside tire when I start accelerating, I constantly see the mini's and VW's doing this on the course.

With the other philosophy (Mahout) you are basically letting the front navigate freely while relying on the chasis to take the stress and distribute it more evenly accross the tires.

I think both ways do have merit, just a matter of which one is more comfortable for the driver... the driver skill is 80% of going fast through a corner!

 

subscribed!!!!!!

 

Being engineers, we both understand that there are many way to skin a cat…And that everything (in real life) is a compromise. The engineer with the best combination of compromises wins…the race in this case. We measure results with a stopwatch on the racetrack. That is why we say that, “When the green flag drops, the BS stops!” What we are doing now is BSing/philosophizing.

By going with the torsionally weaker chassis and stiffer springs, you may be getting the same result as I would with a much stiffer chassis with roll bars and softer springs. Yours is the much cheaper rout – more bang-for-the-buck approach than mine, but I could (theoretically) dial everything in individually. I therefore have more control over each aspect of the handling characteristic of the car. By saying that you don’t need a rear roll bar, is not accurate enough…and therefore, not necessarily true…for the aforementioned reasons. Neither one of us are wrong, just a different approach.

 

When you take things from paper to form, results may vary lol

Interesting pics from the same corner; you can see the body roll comparisons. The only car that beat my raw time was the Lotus btw

 

If you’re a good engineer…not always.

If you’re not an engineer at all, all you can do is test and re-test your successive approximations.

 

...engineers are so full of it sometimes; I can say this because I work in an EPC firm as a lead designer

 

that is why I said good...

 

Oh...by the way...nice shots!

thanks for posting them.