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Stiff Front Sway Bar Thoughts

I always come back to this thread when trying to understand sway bar stiffness on the Z. I found this today that seems directly related to the conversation. From the

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Old 05-25-2022, 07:39 PM   #46 (permalink)
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I always come back to this thread when trying to understand sway bar stiffness on the Z.

I found this today that seems directly related to the conversation.


From the pages of High Performance Handling Handbook by Don Alexander:

"There are situations where increasing the stiffness of an anti-roll bar will have the opposite effect. Most stock vehicles have excessive understeer because it is easier to control and provides more stability for the average driver than a vehicle that oversteers. A big part of this comes from excessive body roll, which induces too much camber change, and a good portion of the front tire contact patches loses contact with the road.
In this instance, adding a stiffer front anti-roll bar, which would typically increase the extreme understeer, actually reduces the understeer by reducing the body roll-induced camber change. The front tires now stay in better contact with the road surface, creating more traction and reducing understeer."
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Old 05-25-2022, 08:22 PM   #47 (permalink)
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Good find!! I’m a nerd for learning more about suspension geometry and race car chassis setups so I love this stuff.

Found the post that explains this well. j-rho explains it better than me. See his post here: Auto-X street - no rear sway

It’s not that a front bar gives more grip… a stiffer bar actually asks MORE of the outside loaded tires… but the tire is kept in a better range of the camber curve which outweighs the increased load, and therefore more grip!
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Old 08-26-2022, 03:27 AM   #48 (permalink)
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Originally Posted by MaysEffect View Post
The Z is not the only exception. Almost every car with a greater front weight bias has a larger front bar. The wrong information has been spread over the past decade that the rear bar should be enlarged for a plethora of wrong reasons. In reality the only reason the bars should be increased is if you have a significant increase in torque or increase in weight and or spring rate.

Most cars understeer from either having too much weight on the nose, or not enough at speed, this is why a 50/50 weight balance is ideal or slightly rearward (48f/52r). Under braking and lateral forces, weight shifts forward and outward increasing load on the front tires. Too much load and you overload the tires and lose traction, too little and the tires won't grip. This balancing act is the most critical aspect of design.

The Z has more weight on the front axle, no where near the levels of a Subaru or VW. But combined with smaller tires, you get a loss of traction from tire overload. There isn't anything funky about the suspension design or alignment that would cause additional understeer.

Increasing sway bar size is rather compromising unless you're increasing the spring rate or the amount of lateral load (increased g forces from bigger, stickier tires). Adding a larger bar with the same factory tires will just increase the load on the outter tire and reduce the contact patch on the inner tire. This is no bueno, thus the plethora of complaints of understeer.

Adding a larger front bar will reduce roll as intended with increased lateral load or additional weight (downforce). Increasing the rear bar causes a cross weighting effect that will transfer additional load to the inner front wheel, sharpening steering response and tire grip. The downside being increased instability and increased load on the outter rear tire. The trade offs are vast if you aren't actually increasing tire grip and load capacity.
This, I think is the crucial thing to consider when upgrading sway bars. If you have a Z with a staggered setup, everything stock, car will be prone to understeer, that's how it's setup. To reduce it, you could either go with a square setup which will definitely help with the understeer, or you could stiffen up the rear ARB, which will do just as you said - cross weighting effect, transferring the load from the read outer wheel to the inner front wheel, where all of a sudden, most of the understeer is just completely gone.

Also, driving a simulator nearly daily, I fiddled around with various setups and if there isn't any change to the spring rates and dampers, if you leave everything stock, and if the car is understeer prone, the easiest way to remedy it quickly is to stiffen the rear ARB.
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Old 08-26-2022, 07:17 PM   #49 (permalink)
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Originally Posted by filip00 View Post
If you have a Z with a staggered setup, everything stock, car will be prone to understeer, that's how it's setup.
I was under the impression that our cars were more prone to oversteer.
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Old 08-26-2022, 08:52 PM   #50 (permalink)
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Originally Posted by geeteezee View Post
I was under the impression that our cars were more prone to oversteer.
Undertsteer is correct unless you have a Nismo. They are pretty darn neutral out of the box. The V1 Nismo's. I have never driven a V2 Nismo.
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Old 08-26-2022, 11:04 PM   #51 (permalink)
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Hotchkiss sway bar on the front. If you are square. You can eliminate the rear bar. If stagger, use a rear bar.
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Old 08-27-2022, 08:06 AM   #52 (permalink)
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Quote:
Originally Posted by geeteezee View Post
I was under the impression that our cars were more prone to oversteer.
Actually not at all. Best example is if you try to do a slalom in slower/moderate speeds. The car will understeer quite a lot way before the rear will snap out. If you put a rear sway bar, suddently the nose feels pointy and precise and no more understeer. I was quite amazed at the difference it made, immediately reminded me of most sporty versions of bmw (saying this because I have most experience with them).
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Old 08-29-2022, 03:34 AM   #53 (permalink)
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I fitted a front whiteline sway bar with 2 settings, swift springs oem shocks oem 19" tyre sizes and Michelin Piot 4S tyres.

I asked whiteline how much stiffer over oem and soft is approx 30% and hard is 65% I tried the hard setting and the car just wanted to understeer too much. Simple test was perform quick U turn, hit the gas trying to spin the car around and it just understeered.

I simply cannot understand how some run the much stiffer bars up front 100-130% stiffer whatever it is. Just tells me majority simply do not drive the cars hard enough (which is fine) so all they are feeling is the stiffer setup and less roll, but if actually drove the car agressivly they would end up pushing.
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Old 08-29-2022, 03:38 AM   #54 (permalink)
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Quote:
Originally Posted by AH370Z View Post
I fitted a front whiteline sway bar with 2 settings, swift springs oem shocks oem 19" tyre sizes and Michelin Piot 4S tyres.

I asked whiteline how much stiffer over oem and soft is approx 30% and hard is 65% I tried the hard setting and the car just wanted to understeer too much. Simple test was perform quick U turn, hit the gas trying to spin the car around and it just understeered.

I simply cannot understand how some run the much stiffer bars up front 100-130% stiffer whatever it is. Just tells me majority simply do not drive the cars hard enough (which is fine) so all they are feeling is the stiffer setup and less roll, but if actually drove the car agressivly they would end up pushing.

Spot on. If you do the same test you mentioned with a stiff rear sway, your *** will be overtaking you immediately.
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Old 08-29-2022, 04:43 AM   #55 (permalink)
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The stiff front sway bar was tested by Doren Racing. When they ran a 370RC in the Pirelli Cup. Their race driver was a member on here. Dwnshift, pro driver. And others have proven that it works. I, for one. I'm a Class C driver.
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Old 08-29-2022, 06:16 AM   #56 (permalink)
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Quote:
Originally Posted by Rusty View Post
The stiff front sway bar was tested by Doren Racing. When they ran a 370RC in the Pirelli Cup. Their race driver was a member on here. Dwnshift, pro driver. And others have proven that it works. I, for one. I'm a Class C driver.
Maybe so for a track setup on R compounds and square setup tyres. Front stiff bar on street setup is not ideal.
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Old 08-29-2022, 06:40 AM   #57 (permalink)
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This is probably the best explanation of sway bar impact on a normal car:

https://www.youtube.com/watch?v=NFGkZNrNTIE&t=12m16s
(annotated to the main point at 12min 16sec, no need to watch it all, but I recommend)
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Old 08-29-2022, 06:33 PM   #58 (permalink)
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I always love when this topic comes up from an entertainment standpoint although this time, I'll just sit back and not feed the trolls.
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Old 08-29-2022, 07:07 PM   #59 (permalink)
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Quote:
Originally Posted by gomer_110 View Post
I always love when this topic comes up from an entertainment standpoint although this time, I'll just sit back and not feed the trolls.
Quote:
Originally Posted by gomer_110 View Post
The 370's need the stiffest front sway bar you can find to improve the handling. The Hotchkis is just a stiffer bar than the Eibach.

There is no sway bar offered for our car that will make the ride quality so bad you wouldn't drive it on the street. The only reason mine doesn't see more street driving is the custom front splitter that would get damaged by many of the roads in my area.
I'm not going to enter into a debate I'm simply highlighting that in my real world experience with one of the best street tyres you can run, a street setup suspension with oem stagger. I have proven that with a whiteline bar on stiffest setting which is no where near as stiff as hotchkis, understeers like a pig. I will go as far as to say if anyone who actually attempted to go around a tight corner in the wet with some speed would surly be off into the ditch or oncoming traffic. Unfortunatly what I see on forums is too much advise that is just regurgitated from what they have read from others and very little from real world experience. I'm not saying you dont have any but if we just focus on the above scenario and setups which most are running it's not ideal in my opinion
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Old 08-29-2022, 07:55 PM   #60 (permalink)
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https://youtu.be/H7uALgGvXvw?t=692
https://youtu.be/H7uALgGvXvw?t=824
he's running 14k 6k(true)
he was running hotchkiss front and rear, going back to oem rear.
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