I am finding this discussion very interesting. In the quoted article, the author notes that his model assumes that the tire loading is equal at all times. Which means that the weight transfer effect on the tires Billy described is not factored in. As speeds increase, weight transfer increases and there would be continual transition of "optimal" toe setting from out to in. So it seems to me that you would select a nominal toe setting based on intended tracking (toe-out for autocross, toe in for road course) and then tune the turn in response using shock adjustments to control the weight transfer characteristics of your car. I'm thinking that the sway bar is primarily for controlling the amount weight transfer, not the rate of weight transfer (though as it is a type of spring it will affect that too). Continuing my line of thought, stiffening the front end of a car would increase weight transfer and push the car toward the "happier with toe-in" end of the scale perhaps?
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Sway bars - why do so many people recommend stiff front, loose rear?
- Thread starter DAYTA
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Increasing weight transfer with a stiffer bar, higher ride height (&CG), higher roll center, etc... Reduces the total tractive effort of a pair of tires. =reduces grip.
Agreed. Regarding the "turn-in" aspect, I was picturing the cars on the track that lift the inside tire completely off the track, in which case it obviously has no effect on the turning. But it appears that point is reached sometime after the turn-in phase of the corner. I suppose with a stiff enough bar you could lift the inside tire off during turn in. So what are some guidelines for deciding how stiff your front bar should be?
Not really at turn-in unless you turn in on throttle. Most cars lift the inside front tire when they are on throttle and weight is shifted to the rear, so the inside front is the least loaded and with a soft enough rear and stiff enough front bar, the combination can lead to the inside front tire coming off the ground and not contributing to any lateral force.
Suspension is an interconnected and complex system and you can set a car up in many different ways to achieve a similar performance but can vary greatly in feel. A stiffer front bar typically reduces roll, controls the cars platform and stability at the cost of total front grip. However if there is very little negative camber up front, a stiffer front bar (to a degree) CAN do the opposite and improve front grip by keeping the outer loaded tire flatter on the ground. There's a lot to it and you have to look at the big picture.
Suspension is an interconnected and complex system and you can set a car up in many different ways to achieve a similar performance but can vary greatly in feel. A stiffer front bar typically reduces roll, controls the cars platform and stability at the cost of total front grip. However if there is very little negative camber up front, a stiffer front bar (to a degree) CAN do the opposite and improve front grip by keeping the outer loaded tire flatter on the ground. There's a lot to it and you have to look at the big picture.
It makes sense to me that you need to find a balance between body control and tire grip, but isn't there also a point where your settings can be too stiff up front and you'd ultimately tune the car to lose steering response and understeer?
I understand everyone is discussing the pros/cons of anti-roll bars front and rear, but I don't know if anyone is running the same bar/brace set up as me. To that point, is it possible that the LoveFab chassis brace I added is making the car toostiff up front? To confirm, the brace I'm referring to that was added after the anti-roll bars is in the link below:
https://www.lovefab.com/Store/Product-Detail/ProductID/42
I quickly scanned through this thread, Dayta I am not sure how you are making a link between the chassis and the suspension. A chassis bar stiffens the chassis. Suspension parts can stiffen only the suspension. The suspension NEEDS the chassis to work right. Think of the chassis as the body's skeleton and the suspension like the ligaments and tendons. They attach to the bone but if the bone is to flex, the suspension simply won't work right. It makes no sense to me to ask if the chassis is "too stiff", because as far as I am concerned it may as well be a solid block of billet steel. The stiffer the better. If you are trying to resolve an issue, I wouldn't try to bring chassis stiffness into the picture. The only time that you want the chassis to not be stuff, is in certain areas that involve crash protection. And that is something that worries me with all the untested chassis bars. It is easy to tie two parts of a frame together, but I don't know how that changes the behavior of the car in a partial front crash. You have essentially change the behavior of the car. Anyway, that is another subject. I don't think you need to worry about having made the front chassis "too stiff".
As Turbo said, there's a difference between stiffening the chassis and stiffening the body motion/suspension. You almost always want the stiffest chassis possible so the suspension does its job and is sensitive to changes. If you have a flimsy chassis, the car will not react as precisely or accurately to changes. A driver may be able to feel a 50lb spring change in a stiff chassis while not feeling a 2-300lb change in a flimsy chassis. This is why performance cars are typically coupes, and why the NSX-R was a coupe.
I'm surprised to hear that LoveFab front chassis brace made such a huge difference for you. I don't think the SOS bars are stiffer than the NSX-R front bar...? So it's not as stiff as the Dali 1" bar.
Try the damper settings in post #17 and get back to us.
Appreciate the responses from both of you and I do recognize that there is no such thing as too stiff of a chassis. I will also try adjusting my damper settings and revert.
Again, maybe my post wasn't clear but is it possible that adding more chassis stiffness to one side or end can cause the chassis to be unbalanced? I've added tons of stiffness towards the front of the chassis (3 separate braces by my count) but not nearly as much at the back (only the rear targa brace). Could that potentially upset the handling characteristics from OEM if the front is substantially more stiff than the rear? If this is true, I'd imagine that it would be even more pronounced in a targa than a coupe.
Again, maybe my post wasn't clear but is it possible that adding more chassis stiffness to one side or end can cause the chassis to be unbalanced? I've added tons of stiffness towards the front of the chassis (3 separate braces by my count) but not nearly as much at the back (only the rear targa brace). Could that potentially upset the handling characteristics from OEM if the front is substantially more stiff than the rear? If this is true, I'd imagine that it would be even more pronounced in a targa than a coupe.
Id say no since targas flex in the center of the car where the roof is missing. How does your handling change when your roof is on vs off? (That would make a greater difference than the bars you added.
Far too many posts here for me to read, but let me share my experience.
I have the NSX-R Front bar, and the Zanardi rear.
17x7 on front, 18x9 on the back
Stock springs, Bilsteins on lower perch.
With my setup the way it is, I do feel the front is far too stiff in roll. Why? Because we do have backroads here in Illinois with speed limits around 40 and at high degrees of wheel angle and slow speeds the front end of my car does not roll. Is this bad? Most would say no, but remember we have something like 9 degrees of caster so the camber gain when you turn the wheel tighly is very pronouced. The A-arm geometry is set so that when the car rolls you lose camber (to counteract the bunch you just gained by turned the wheel) which maintains the entire contact patch on the road.
In my case, my car is too stiff and I lose that contact patch. I will be changing swaybars soon to Comptech adjustables and I hope to dial it in just to my liking.
Now, that is for lower speed corners with high levels of wheel angle. At high speed corners (like on/off highway at high speeds) the car feels great within normal speed limits but still understeers safely as higher speeds.
I think once I tune the bars I'll be neutral at high speed and much closer to neutral at low speed corners but still biased to understeer.
I have the NSX-R Front bar, and the Zanardi rear.
17x7 on front, 18x9 on the back
Stock springs, Bilsteins on lower perch.
With my setup the way it is, I do feel the front is far too stiff in roll. Why? Because we do have backroads here in Illinois with speed limits around 40 and at high degrees of wheel angle and slow speeds the front end of my car does not roll. Is this bad? Most would say no, but remember we have something like 9 degrees of caster so the camber gain when you turn the wheel tighly is very pronouced. The A-arm geometry is set so that when the car rolls you lose camber (to counteract the bunch you just gained by turned the wheel) which maintains the entire contact patch on the road.
In my case, my car is too stiff and I lose that contact patch. I will be changing swaybars soon to Comptech adjustables and I hope to dial it in just to my liking.
Now, that is for lower speed corners with high levels of wheel angle. At high speed corners (like on/off highway at high speeds) the car feels great within normal speed limits but still understeers safely as higher speeds.
I think once I tune the bars I'll be neutral at high speed and much closer to neutral at low speed corners but still biased to understeer.
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To be honest, I've only spiritedly driven the car with the roof on 2-3 times so I can't really comment on handling changes. I vaguely remember having to make more midcorner steering adjustments but I haven't driven it enough times to be sure.
My steering feels the same as you're describing - great at mid-high speed corners (i.e. greater than 50MPH), but lacking turn-in response and understeering (possibly due to losing front grip?) in corners at speeds less than 40MPH.
Yep, you have too much front bar. I'm going to tune mine when I put my Comptechs on (adjustable) and I'll report back and tell you what feels good. I assume softest setting on front and softest on rear (perhaps medium on rear).
If I stick with the Zanardi on the rear I will just put the Comptech front on and put to the softest setting (compared to my NSX-R bar) that way I will get a good A-B.
Then if it still understeers, then I need more rear bar and I'll put the Comptech on the rear as well (softest setting) then compare, then move up the rear until I get it good.
NSXs don't like much rear bar. Also NSX-Rs have stiffer front springs than you're running and they are great handling cars. Try trailbraking to reduce understeer when entering corners.
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Due to the NSX's really low front geometric roll center (especially when the car is lowered), it really needs a lot of front roll resistance to control the body's roll and to get the correct front to rear roll distribution. This is why track NSXs (and even the NSX-R) have stiffer front springs than rear, and much stiffer front swaybars than the OEM NSX.
I caution you from making the front too soft so it turns better in condition where your driving inputs are telling the car to understeer (like being on throttle) because when you are in a situation where you need to brake and turn to avoid hitting something or if you entered a corner too fast and are trying to make the turn while slowing down (inputs which make the car turn better/oversteer), your compromised setup could make the car snap oversteer and put you in a really bad situation.
I'd recommend taking a good driving school and learning a bit of vehicle dynamics and practicing trailbraking before setting your car up in such a manner.
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Due to the NSX's really low front geometric roll center (especially when the car is lowered), it really needs a lot of front roll resistance to control the body's roll and to get the correct front to rear roll distribution. This is why track NSXs (and even the NSX-R) have stiffer front springs than rear, and much stiffer front swaybars than the OEM NSX.
I caution you from making the front too soft so it turns better in condition where your driving inputs are telling the car to understeer (like being on throttle) because when you are in a situation where you need to brake and turn to avoid hitting something or if you entered a corner too fast and are trying to make the turn while slowing down (inputs which make the car turn better/oversteer), your compromised setup could make the car snap oversteer and put you in a really bad situation.
I'd recommend taking a good driving school and learning a bit of vehicle dynamics and practicing trailbraking before setting your car up in such a manner.
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How could I find a bar softer than stock? I don't think they exist. The comptech (which I have on now) is still much stiffer than stock at the softest setting, just slightly softer than the NSX-R bar, which I have now sold.
Works okay so far.
Bringing this semi old thread back from the dead instead of starting a new one.
I have an 04 on stock springs, bilstein shocks on lower perch, 15/20 F/R H&R spacers, stock wheels and oem sized tires.
Was thinking of a front NSX-R front sway bar for betting cornering and leave the rear as is.
Used only on the street with semi spirited driving. No track.
Is it still beneficial to add the bar with this set up, and do you need a new alignment done? After the shocks/spacers I had the alignment set back to oem.
I have an 04 on stock springs, bilstein shocks on lower perch, 15/20 F/R H&R spacers, stock wheels and oem sized tires.
Was thinking of a front NSX-R front sway bar for betting cornering and leave the rear as is.
Used only on the street with semi spirited driving. No track.
Is it still beneficial to add the bar with this set up, and do you need a new alignment done? After the shocks/spacers I had the alignment set back to oem.
It will reduce body roll for sure. If that is what you're after, then the bar is good for you. No alignment needed as swaybars don't change ride height.
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