Suggestions for design undertray

[Just_a_fan]

We are both wrong.

https://robrobinette.com/images/S2000/A ... anual4.jpg

.24 degrees = 1/4 inch of toe which equals 6mm.

Half a degree is 12mm.

And if both tires have the same toe there is zero thrust steer.

If what I say is nonsense then how come I was right about the Mercedes car not being very good?

The 0.24 is not degrees, it's inches. 6mm is 0.24in. There are no degrees in that set up information.

degrees and inches are really close that you can call a quarter degree about a quarter inch. A 1 foot diameter circle has a 3.14 foot radius, 12x3.14 = 37.68 inches 360 degrees in a circle. Off by one golden ratio.

A 1 foot diameter circle will have a 3.14ft circumference, not radius.

And the coincidence of your 1ft circle's circumference to degrees is just that, a coincidence, and of no application to the case in question. A more realistic tyre circumference is not going to enjoy that coincidence.

[PhillipM]

Ah but you just used the downvoting system for 'ignorance and pettiness' without ever refuting any of it, ironic giving the amount of whining you do about downvotes this year


Still, I don't see anyone using a 1ft diameter wheel and tyre on a road car, and regardless of that, do you know just how much 6mm of toe out on each tyre would affect the handling and grip? You'd be snap oversteer in every corner and going through tyres every ten laps, for what, your theoretical 1% better downforce at the diffuser?
Absolutely laughable, just like the last time you brought this up wrt F1 cars.

If the guy takes your advice on this he'll end up in a barrier at the side of the track. Put your money where your mouth is and go have 6mm of toe out put on each rear wheel of your S2000 and lets see how it affects your track times. Even on road tyres with 4x the slip before peak, never mind racing slicks.

[PhillipM]

it doesn't matter, the proportion is the same. 2/1 is the same if you have 16/8 or 512/256.

The proportion is, the absolute distance isn't, suddenly your 1/4 inch is 1/2 inch

[godlameroso]

it doesn't matter, the proportion is the same. 2/1 is the same if you have 16/8 or 512/256.

The proportion is, the absolute distance isn't, suddenly your 1/4 inch is 1/2 inch

Even better with a taller wheel then, yaw aero, and aero forces have more surface area to act. Even then, things are relative, you can increase the vortex on the side of the tire by aiming airflow at it at an angle. Like my downvoted picture shows, you can aim airflow at an angle you don't necessarily have to depend on the static toe.



The regulations give you plenty of furniture to take advantage of the aero forces on the tire. With a toe out wheel, or angled airflow, that area will get more airflow. The same with the rear end of the car, if you toe out the wheel the furniture on the rear wheels will have a more direct stream of air interacting with it. The flow will be cleaner, and more energetic.

If you toe in the rear wheels you're effectively blocking airflow to the furniture and reducing its effectivness.

Don't take my word for it though, you can try it out for yourself, it's easy to just load up a simulator, crank the toe out and doing some laps. Take your pick, every single simulator you use will show an improvement with rear toe out. You'll think that's just a limitation of the sim physics, but what if it works in the real world?

[godlameroso]

Think about this then, if you have your wheel furniture perfectly working in a straight line, what happens when the car is under yaw? With toe out you ensure the wheel furniture always has airflow even under yaw.

[godlameroso]

The 0.24 is not degrees, it's inches. 6mm is 0.24in. There are no degrees in that set up information.

degrees and inches are really close that you can call a quarter degree about a quarter inch. A 1 foot diameter circle has a 3.14 foot radius, 12x3.14 = 37.68 inches 360 degrees in a circle. Off by one golden ratio.

A 1 foot diameter circle will have a 3.14ft circumference, not radius.

And the coincidence of your 1ft circle's circumference to degrees is just that, a coincidence, and of no application to the case in question. A more realistic tyre circumference is not going to enjoy that coincidence.

Yes you are correct, I had a lapse in terminology, that happens to me often and I end up confusing people. F1 diameter is ~28" wheel/tire assembly.

https://robrobinette.com/ConvertToeDegreesToInches.htm

With a 28" tire diameter .5 degrees of toe amounts to .499 inches of toe, or about 12 mill so yeah not perfect, but close nuff'.

[PhillipM]

You realise 12mm of toe out is an insanely huge amount, right?
Like single seaters are usually set to an accuracy of +-0.05mm, and maybe a couple of mm either way

[godlameroso]

You realise 12mm of toe out is an insanely huge amount, right?
Like single seaters are usually set to an accuracy of +-0.05mm, and maybe a couple of mm either way

Yeah it's a little on the high side. IIRC the Caterham setup sheet that was floating around showed they ran that much up front. My $74,000 USD when I bought it Hunter alignment rack is about that accurate.

*Nope I was wrong, according to this they ran 6mm toe out total which is 3mm on each wheel, so about 1/8th of an inch.

[godlameroso]

I’m sorry, but as fun as they are, they are just video games. I wouldn’t use any of them to set up a real car. Even F1 teams, which are so far more advanced still have to look at tires and everything else at the track, and adjust there.

If you want to learn this stuff in real life buy a vintage Formula Ford, they are “affordable” enough.

I have an s2000 I track regularly, I run .3 degrees of toe out in the rear, I've only grazed the wall in turn 1 of Sebring.

[godlameroso]

I’m sorry, but as fun as they are, they are just video games. I wouldn’t use any of them to set up a real car. Even F1 teams, which are so far more advanced still have to look at tires and everything else at the track, and adjust there.

If you want to learn this stuff in real life buy a vintage Formula Ford, they are “affordable” enough.

I have an s2000 I track regularly, I run .3 degrees of toe out in the rear, I've only grazed the wall in turn 1 of Sebring.

So track days… what kind if lap times are you turning and what mods? You can graze the inside of T1 at Sebring going very slowly too..

Do you believe you doing that for aero purposes?

I have home made aero made of alumilite that I bolt on. Mods are, brakes, shocks, springs, bushings, tires, sway bar, subframe tie bar, and aero. No aero, I'm in the 36's with aero 29's. I'm not that fast. I lack power, but I don't care, I want to keep the car cheap. Yes, my diffuser was made to exploit the tire flow field.

[dren]

Does "with aero" signify running a lot of toe up front for that vortex benefit?

[Tommy Cookers]

Half a degree of toe is roughly 50mm that you've moved the trailing edge of the tire closer to the car. Stick your hand out the window of a moving car and turn your hand 50mm is the aero force significant? What if your hand was the size of the wheel assembly?

nonsense !
half a degree of toe is roughly 5mm

We are both wrong
.24 degrees = 1/4 inch of toe which equals 6mm.
Half a degree is 12mm.

no you are wrong

what is toe ?
(AFAIK) it's the difference between the track at the front of the tyres and the track at the rear of the tyres
ie the manual's .24 inches 1/4 inch of toe means 1/8 inch on the left tyre and 1/8 inch on the right tyre

half a degree (on the 24 inch /600mm tyre dia that I used) is roughly 5mm (each tyre)
half a degree (on eg a 29 inch/720mm tyre) is roughly 6mm (each tyre)
not your 12mm

[godlameroso]

Just a FYI, the Spec Miata lap record is a 2:28.7 with 120whp (plus drafting). I don’t believe your 6” is from the aero because you are under driving the car by a lot and it would be hard to discern what changes really would work.

But if you are having fun then that’s all that matters.

LMAO no, just no, the Miata cup is 180whp I've seen the dyno sheets. It's also 900kg, or about what the F1 car weighs, it also runs slicks. Comparing a full race car to something I'm tinkering with is as silly as it gets, I'm sorry, I just find your p****** contest hilarious.

My car is like 1340kg with me in it and the extra stuff and I'm only pushing ~205whp, you really think I'm supposed to smoke a race car? LMAO

[godlameroso]

Does "with aero" signify running a lot of toe up front for that vortex benefit?

I run it front and back and I use those settings on the road, stock settings is a quarter inch of positive toe in the rear I run the opposite of that.

[godlameroso]

nonsense !
half a degree of toe is roughly 5mm

We are both wrong
.24 degrees = 1/4 inch of toe which equals 6mm.
Half a degree is 12mm.

no you are wrong

what is toe ?
(AFAIK) it's the difference between the track at the front of the tyres and the track at the rear of the tyres
ie the manual's .24 inches 1/4 inch of toe means 1/8 inch on the left tyre and 1/8 inch on the right tyre

half a degree (on the 24 inch /600mm tyre dia that I used) is roughly 5mm (each tyre)
half a degree (on eg a 29 inch/720mm tyre) is roughly 6mm (each tyre)
not your 12mm

You're wrong, deal with it. You can't say I'm wrong if you yourself are questioning what toe is. It's very simple look at your feet, toes pointed out? That's toe out, toes pointed in, that's toe in.