Sparetire

So as the title states, would having a lighter rotational assembly lessen, worsen, or not affect a cars tendency to transition into oversteer if the drivers lifts a bit mid-corner? Would the transition be more gradual one way or another?

My thinking is this: When you lift mid-corner, you are taking weight off the rears because the car will naturally want to decelerate. On top of that, you are probably at relatively high RPM, and the engine is going to naturally want to decrease revs. You are more or less doing a bit of engine breaking similar to down shifting though not as powerful. So less weight on the rears coupled with engine breaking means they cont hold traction since they are already working for grip to keep the *** end of the car from just plowing ahead.

So if you lower the mass of the rotational assembly (with a lighter flywheel or a cut crank or rods/pistons etc) then you have an engine that will change RPM quicker when free reving, but also be less of a drag in things like down shifting. I noticed on my last car that going from stock 19Lb or so flywheel to a 11Lb unit meant that I did not get quite so much deceleration from down shifting.

So I suspect that this lower inertia means that the engine will actually be less likely to hold revs up against aero and rolling friction forces with 0% throttle. Basically a 30Lb weight spinning will store more energy than a 10Lber. So the 30Lber will hold speed longer against a friction force than the 10Lber.

So (breathes) the car with the lighter rotational assembly will actually decelerate harder without maitenance throttle mid corner and that might actually result in less weight on the rears/more transfer to the fronts.

Does a lighter flywheel make lift-off oversteer more likely as a result?

This is why I shoudl not wake up at 3:30 and drink strong coffee.

dstn2bdoa

iTrader: (18)

I love waking up to this kind of question.

From my highly unscientific mind, this sounds entirely logical. But how much of an affect? Dunno. Do you have a dataloger, skid pad near your home, and tons of time on your hands?

Doppelgänger

iTrader: (12)

Yeah I don't think it'll make much of a difference.

shlammed

iTrader: (8)

it could be my tune, but i have a bit of a bump in the driving when going from 0 to 5% or the inverse of that when cruising... it seems to be less noticable when driving hard, but its still there.

Everything is tight and new except my trans.

JGard

With a lightweight flywheel the engine will be able to change speeds more quickly than before thanks to rotational inertia.

So in theory, the car's deceleration should be greater with a lightened flywheel and thus bring more weight forward upon complete release of the gas pedal.

In theory... I can't say one way or another if there's a real-world difference. I have a lightweight flywheel and the only time I notice it is if I'm shifting lackadaisically and the engine revs drop further than is needed for the next gear

Full_Tilt_Boogie

iTrader: (1)

Lightweight flywheel causes insane oversteer because it takes weight off the front.
Just like a turbo kit causes INSANE understeer because it puts weight on the front.

/Hyper logic

Sparetire

Time? Check.
Place to test? Check.
Car? Not so check. Hence the time.

Iz true! oh noes!

JasonC SBB

I think the closed-throttle engine compression has a far stronger braking effect than the lighter flywheel, so the effect on lift-throttle oversteer will be negligible. Maybe in 1st gear it might be noticeable, in the same way acceleration may be noticeably better in 1st.

shlammed

iTrader: (8)

Jason, would the effects of engine compression not be more noticable in extreme cases?

I know my car in 3rd and even 4th you can feel the transition quite clearly.

Efini~FC3S

iTrader: (4)

Non-issue because you shouldn't be lifting off of the throttle mid-corner.

shlammed

iTrader: (8)

but its fun to oversteer.

Sparetire

You are probably right. And too true that liftoff should not be happening anyway. I know I will be getting a lighter flywheel when I do a clutch, so really its more intelectual than anything.

Jfornachon

iTrader: (23)

I don't agree there are sometimes when you actually need to do so. This is called throttle stearing my friend. If and when done correctly it is quite a valuable tool to haev in your bag. Although you don't want to get out 100%. Just a little.

Have a great day,
Jared

hustler

iTrader: (6)

If it oversteers too much on corner entry either put a smaller sway bar on or talk to your doctor about testosterone gel.

Sparetire

The non-***** mod is the most important without a doubt. Not a problem anyway, my natural tendency is to try to mash the throttle to get out of anything bad anyway. Which is how I wheel hopped my way to driving a 100 and nothing HP pickup right now.

Efini~FC3S

iTrader: (4)

Thank you for that, how enlightening. I know what throttle steering is. I also know that if you're lifting mid-corner you have already blown the corner because you suck. There's a big difference between making slight throttle corrections throughout the corner to change slip angles and completely lifting off the throttle and inducing oversteer.

JGard

unless you're an an AutoX, where I've found throttle steering to be the majority of how I make my way around a course...especially some of the tighter sections.

Full_Tilt_Boogie

iTrader: (1)

*facepalm*

You never let out of the throttle all at once, thats not "throttle steering", that is called being a *****, and it makes this happen: