Honey Badger's Completely Off-the-Rails Race Car Build and Track Adventure Thread

[honeybadger]

What are your alignment settings?

I'm currently running -2.7 up front and -2.4 in the rear. I didn't get a chance to take temps at the track day since my pyrometer was dead , but the care felt absolutely fantastic. The fronts definitely wore great. The rears looked like they would have liked a bit less camber. BUT, I have found the car to handle a bit better with more rear camber than required per the tire temps. It rotates on track out much better. But this could just be my driving style.

I'll probably back it down to -2.5 and -2 for the first on the R7s and work my way up/down as I play with pressures and get up to speed. Very curious to see what pyrometer says come COTA time!

 

[Austinj427]

I'm currently running -2.7 up front and -2.4 in the rear. I didn't get a chance to take temps at the track day since my pyrometer was dead , but the care felt absolutely fantastic. The fronts definitely wore great. The rears looked like they would have liked a bit less camber. BUT, I have found the car to handle a bit better with more rear camber than required per the tire temps. It rotates on track out much better. But this could just be my driving style.

I'll probably back it down to -2.5 and -2 for the first on the R7s and work my way up/down as I play with pressures and get up to speed. Very curious to see what pyrometer says come COTA time!

Toe settings?

 

[tracktardicus]

Curious as to why your front camber is not -3 or greater?

 

[honeybadger]

Toe settings?

0 in front and 1/8in in rear (OEM recommendation). Haven't played with toe much on this car.

Curious as to why your front camber is not -3 or greater?

I was running -3.5-3.7 on the Cup2s, but did experience some rubbing on the strut due to my need for the camber bolts. I mostly backed off because of the MPSS I was running for the past few events don't need the same amount of camber. I presume I'll work my way back up with the Hoosiers!

 

[Hack]

Fix? nothing I am pissing money into the wind like most car guys. I wanted the R splitter got it for a good price and down the rabbit hole we go!!

The only real issue i have with the cars handling is turn in could be a little better but I think thats a front sway bar.

I'd like to clarify this to make sure I understand. A stiffer front bar will cause more understeer, I believe. Is that correct? So I think you are considering a softer front bar in order to improve turn in through reduced understeer?

I could see a front splitter helping with turn in on high speed corners. A larger splitter should reduce lift.

 

[firestarter2]

I'd like to clarify this to make sure I understand. A stiffer front bar will cause more understeer, I believe. Is that correct? So I think you are considering a softer front bar in order to improve turn in through reduced understeer?

I could see a front splitter helping with turn in on high speed corners. A larger splitter should reduce lift.

I "think" a stiffer front bar does not let the car roll as much as or as fast so when you initially turn the force is on the outside tire? I think if the sway bar is soft the car rolls reducing the initial transfer???

Someone smarter than me chime in.

 

[Hack]

I "think" a stiffer front bar does not let the car roll as much as or as fast so when you initially turn the force is on the outside tire? I think if the sway bar is soft the car rolls reducing the initial transfer???

Someone smarter than me chime in.

That's why I was asking (I want someone that knows more about this than I to respond). It's been long enough that I'm not sure, but I think if you want more front grip, you need to soften the front bar. This causes the rear bar to do more of the work of preventing roll (of course that change will reduce the amount of grip in the rear).

I believe a stiffer bar will tend to lift the inner tire more, thus reducing traction from that set of tires. Yes a stiff bar puts more weight on the outer tire, but I believe that it's better to have more balanced force on both inside and outside tires if you want the most traction possible. That is why wider tires are used rather than skinny tires (a larger contact patch is better than higher pressure for absolute grip).

 

[oldbmwfan]

I "think" a stiffer front bar does not let the car roll as much as or as fast so when you initially turn the force is on the outside tire? I think if the sway bar is soft the car rolls reducing the initial transfer???

Someone smarter than me chime in.

Not quite.

Hack is theoretically correct that a softer front bar can increase transient cornering grip by allowing more weight transfer onto the outside tire that's doing the work.

But, on a Macpherson strut suspension, too much roll (and, therefore, too much compression on the outside corner) moves into a positive camber gain curve, so in practice, as tires get stickier you want to limit roll more. That's why Mapherson strut cars benefit from stiffer springs and bigger sway bars up front. A softer rear bar can allow better hookup through mid-corner and exit, as long as your roll couple doesn't get really out of whack relative to the front.

It's not uncommon in BMW race cars (like my E36) to run very stiff springs all around, with a giant front sway bar and a small or no rear sway bar.

 

[oldbmwfan]

That is why wider tires are used rather than skinny tires (a larger contact patch is better than higher pressure for absolute grip).

Contact patch size is a function of tire pressure and vehicle weight. The benefit of a wider tire is not a larger contact patch; it's the shape of the contact patch (wide and thin vs long and narrow). High performance tires also have stiffer sidewalls for two reasons:
1) can reduce pressure without damaging the tire and distorting the contact patch (this DOES increase contact patch size)
2) less distortion under lateral load makes the contact patch more consistent through corners

The lower profile tire also permits less slip angle, as the "twisting" of the wheel within the tire is reduced.

 

[firestarter2]

Not quite.

Hack is theoretically correct that a softer front bar can increase transient cornering grip by allowing more weight transfer onto the outside tire that's doing the work.

But, on a Macpherson strut suspension, too much roll (and, therefore, too much compression on the outside corner) moves into a positive camber gain curve, so in practice, as tires get stickier you want to limit roll more. That's why Mapherson strut cars benefit from stiffer springs and bigger sway bars up front. A softer rear bar can allow better hookup through mid-corner and exit, as long as your roll couple doesn't get really out of whack relative to the front.

It's not uncommon in BMW race cars (like my E36) to run very stiff springs all around, with a giant front sway bar and a small or no rear sway bar.

Not to be dense (I am) is grip and initial turn in the same? I was talking more about the later.

 

[honeybadger]

Not to be dense (I am) is grip and initial turn in the same? I was talking more about the later.

Nope .a stiff bar will give great steering response, but can lead to understeer as oldbmwfan said .My bar on full stiff at COTA was this way. Great initial steering response, but a bit too much mid corner understeer.

Moving to the softer hole backed the directness off a bit (because the car can now "roll" a bit more), which is giving me better mid corner grip.

To make things more complicated, as oldbmwfan said, springs, tire contact patch, sidewall stiffness and camber also all come into effect.

 

[Austinj427]

0 in front and 1/8in in rear (OEM recommendation). Haven't played with toe much on this car.

Well, that was all I had.

I'm no more help on this thread discussion. All I know is from what I have learned dialing in cars on Forza lol.

 

[honeybadger]

Well, that was all I had.

I'm no more help on this thread discussion. All I know is from what I have learned dialing in cars on Forza lol.

Have you played Project Cars 2? The "mechanic" in the game is very good at help you dial in the car. You can tell it you're understeering, then it'll ask you where (corner entry, mid-corner, high speed, etc.), and finally recommend a change while giving you an explanation of why.

I'd be lying if I didn't use that to diagnose some track out understeer in GT4 car at COTA

 

[Austinj427]

Have you played Project Cars 2? The "mechanic" in the game is very good at help you dial in the car. You can tell it you're understeering, then it'll ask you where (corner entry, mid-corner, high speed, etc.), and finally recommend a change while giving you an explanation of why.

I'd be lying if I didn't use that to diagnose some track out understeer in GT4 car at COTA

Haha no but that sounds bad ass.

I may have to look into it, sounds fun.

 

[oldbmwfan]

Not to be dense (I am) is grip and initial turn in the same? I was talking more about the later.

Echoing HB a bit, but ...

Not exactly the same thing.

Overall - if you maintain the tire in a healthy part of the camber curve and reduce the time the suspension takes to settle when you change direction (steering input), your turn-in response will increase. This is largely a function of spring rate, with contributions from springs and roll bars. But tire sidewall height, alignment, and aero matter too.

Once into the corner and the car is "set," max grip can be higher with softer settings, to a point. It's like you want the softest setting that is stiff enough to maintain camber and use both inside and outside tires.

Because of the inherent weakness of a Macpherson strut, specifically that camber curve goes into positive after a certain level of suspension compression - it is usually a matter of compromising on the "too stiff" side. Too soft can hurt both turn-in and mid-corner grip by giving up negative camber (tire camber goes positive under constant lateral load). Too stiff and you "skate" because you don't transfer enough weight to fully maximize the tire grip - which usually shows up as corner entry and mid-corner understeer. But too-stiff gives better transitions and better braking, relative to too soft.

In the wet, it all changes again ...