Handling with 10.5 rear?
10-06-2016, 08:34 AM
#21
While I haven't been on a track for any real high speed stuff other than a few ride-alongs at MLSIR and in Vegas in years, the way I always looked at it was, "The track is the great equalizer. Spending time on same is where the driver's flaws show up and tell me what I need to work on....
....Oh, then I'll get around to worrying about the stuff on the car."
....Oh, then I'll get around to worrying about the stuff on the car."
So I wanna get out there. I also wanna have a good time and not be causing traffic and sliding out every 5ft due to lack or supporting mods to keep it planted and suitable for the track.
But still have fun with it and learn better driving skills at the same time with our starting with a full fledged $50k cup car haha
Not sure if anyone is familiar with one take but Mr.Farrah said he's really interested in driving my roadster once I get some FI and suspension set up on it. So when I get that sorted I can probably let Matt take a run in my Z for one of his episodes. I mostly want his feed back on the set up and performance lackings from someone with experience such as him.
10-06-2016, 01:52 PM
#22
350Z/370Z Tech Moderator
MY350Z.COM
MY350Z.COM
I'm still somewhat confused. Let's say my car currently understeers, and for the sake of argument let's assume that:
at 0.7 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose
If I wanted my car to be neutral, I'd want the front and rear to break loose at the same lateral G force. Increasing front tire size could then make my car look like this:
at 0.9 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose
But now if I were to adjust the sway bar in the rear to reduce understeer instead of increasing front tire size, we know the front will break loose roughly at the same G force as when I started. So assuming we stiffen the rear enough to attain neutral handling, my car will look something like:
at 0.7 lateral G's = front breaks loose
at 0.7 lateral G's = rear breaks loose
So if that's all logically sound, it seems (to me at least) that stiffening one end (ie making it less grippy) only makes that end crappier in order to match up with the crappy front. They'll be roughly even and neutral, but what good is neutral if they're both crappy? On the other hand, rather than bring the grippy side down to match the crappy side, you can bring the crappy side up to match the grippy side. That way it'll be neutral and grippy all around.
That's the theory aspect of it that I'm hung up on. Am I making sense?
at 0.7 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose
If I wanted my car to be neutral, I'd want the front and rear to break loose at the same lateral G force. Increasing front tire size could then make my car look like this:
at 0.9 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose
But now if I were to adjust the sway bar in the rear to reduce understeer instead of increasing front tire size, we know the front will break loose roughly at the same G force as when I started. So assuming we stiffen the rear enough to attain neutral handling, my car will look something like:
at 0.7 lateral G's = front breaks loose
at 0.7 lateral G's = rear breaks loose
So if that's all logically sound, it seems (to me at least) that stiffening one end (ie making it less grippy) only makes that end crappier in order to match up with the crappy front. They'll be roughly even and neutral, but what good is neutral if they're both crappy? On the other hand, rather than bring the grippy side down to match the crappy side, you can bring the crappy side up to match the grippy side. That way it'll be neutral and grippy all around.
That's the theory aspect of it that I'm hung up on. Am I making sense?
What you are modifying through tire sizing and/or chassis roll stiffness is the timing of when one end's TIRES reach their maximum slip angles; that is, the maximum angle of tire deflection prior to loss of traction, NOT when the tire begins to "slip" or actually lose traction resulting in the car sliding, as many people think when this terminology is used.
These changes/tweaks apply to STEERING CHARACTERISTICS ONLY (over, under, neutral steering), not lateral grip necessarily, even though they ARE related.
Lateral grip has even more factors influenced into the equation.... tire size, tire compound, tire weight, temperature, vehicle weight transfer, circumference, angle, and radius of the turn used to measure the lateral grip, just to name a few.
10-06-2016, 07:42 PM
#23
Super Moderator
MY350Z.COM
MY350Z.COM
iTrader: (8)
I'm still somewhat confused. Let's say my car currently understeers, and for the sake of argument let's assume that:
at 0.7 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose
If I wanted my car to be neutral, I'd want the front and rear to break loose at the same lateral G force. Increasing front tire size could then make my car look like this:
at 0.9 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose
But now if I were to adjust the sway bar in the rear to reduce understeer instead of increasing front tire size, we know the front will break loose roughly at the same G force as when I started. So assuming we stiffen the rear enough to attain neutral handling, my car will look something like:
at 0.7 lateral G's = front breaks loose
at 0.7 lateral G's = rear breaks loose
So if that's all logically sound, it seems (to me at least) that stiffening one end (ie making it less grippy) only makes that end crappier in order to match up with the crappy front. They'll be roughly even and neutral, but what good is neutral if they're both crappy? On the other hand, rather than bring the grippy side down to match the crappy side, you can bring the crappy side up to match the grippy side. That way it'll be neutral and grippy all around.
That's the theory aspect of it that I'm hung up on. Am I making sense?
at 0.7 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose
If I wanted my car to be neutral, I'd want the front and rear to break loose at the same lateral G force. Increasing front tire size could then make my car look like this:
at 0.9 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose
But now if I were to adjust the sway bar in the rear to reduce understeer instead of increasing front tire size, we know the front will break loose roughly at the same G force as when I started. So assuming we stiffen the rear enough to attain neutral handling, my car will look something like:
at 0.7 lateral G's = front breaks loose
at 0.7 lateral G's = rear breaks loose
So if that's all logically sound, it seems (to me at least) that stiffening one end (ie making it less grippy) only makes that end crappier in order to match up with the crappy front. They'll be roughly even and neutral, but what good is neutral if they're both crappy? On the other hand, rather than bring the grippy side down to match the crappy side, you can bring the crappy side up to match the grippy side. That way it'll be neutral and grippy all around.
That's the theory aspect of it that I'm hung up on. Am I making sense?
I will say, for track use 275/35-18 all around is considered the standard for the Z
10-07-2016, 06:50 AM
#24
there any loss in running 19's?
Also I was watching a time attack and some dudes were running 17 fronts and 18 rears but the same profile tire. So basically the front had more meat while the rear had more rim.
Does that have a significant improvement? I figure that would introduce more underwater due to tire flex being greater up front.
Also I was watching a time attack and some dudes were running 17 fronts and 18 rears but the same profile tire. So basically the front had more meat while the rear had more rim.
Does that have a significant improvement? I figure that would introduce more underwater due to tire flex being greater up front.
10-07-2016, 07:06 AM
#25
350Z/370Z Tech Moderator
MY350Z.COM
MY350Z.COM
there any loss in running 19's?
Also I was watching a time attack and some dudes were running 17 fronts and 18 rears but the same profile tire. So basically the front had more meat while the rear had more rim.
Does that have a significant improvement? I figure that would introduce more underwater due to tire flex being greater up front.
Also I was watching a time attack and some dudes were running 17 fronts and 18 rears but the same profile tire. So basically the front had more meat while the rear had more rim.
Does that have a significant improvement? I figure that would introduce more underwater due to tire flex being greater up front.
Generally speaking, grip/adhesion will remain relatively unchanged (if any, a little gain in overall traction) given the tire's width being unchanged. A 275 is a 275mm width no matter the wheel diameter.
What may change (positively) is you'll get a slight gain in the amount of steering response (turn-in and return to center) due to the shorter, stiffer sidewalls of the 19" tire when maintaining the same overall tire diameter (again, depends on tire choice).
But in reality, with the state of tire technology today, a good 18" tire will respond just as well as a good 19" tire and the difference will be negligible in real world application.
10-07-2016, 03:01 PM
#26
there any loss in running 19's?
Also I was watching a time attack and some dudes were running 17 fronts and 18 rears but the same profile tire. So basically the front had more meat while the rear had more rim.
Does that have a significant improvement? I figure that would introduce more underwater due to tire flex being greater up front.
Also I was watching a time attack and some dudes were running 17 fronts and 18 rears but the same profile tire. So basically the front had more meat while the rear had more rim.
Does that have a significant improvement? I figure that would introduce more underwater due to tire flex being greater up front.
They run the same profile so it maintains a staggering but its the 1 inch of the wheel. The tire profile is the same, and the same amount of meat on each corner...
Im assuming it's 275/40/17 front and 275/40/18 rears...
From what ive heard its a nice set-up... I thought about getting that but never did...
Terrasmak has run that before though, and he is the 350z track master...
Thread
Thread Starter
Forum
Replies
Last Post