S14 Stock (data from CourtesyParts)Front 27.2mm Rear 15.9mm
Whiteline Adjustables (data from PDMRacing.com)Front 27mm Rear 20mm (22mm available as well)
Suspension Techniques (data from STRacing.com)Front 28.6mm Rear 20.6mm
Cusco (data from Japanparts.com)Front 30mm Rear 21mm
Nismo (data from Japanparts.com) Front 30mm Rear 23mm
Tanabe (data from Tanabe-usa.com)Front 30.4mm Rear 27.5mm
Further Information:Nismo Stabilizer Kit (I thought the spring rate was interesting)Front: Diameter=30.0, Spring Rate=101.2mm(10.3kgf/mm) Rear: Diameter =23.0, Spring Rate=43.1mm(4.4kgf/mm)
Suspension Techniques data (from CourtesyParts.com)The stabilizer bar kits are manufactured by Suspension Techniques and include all mounting hardware and urethane bushings. Torsional rigidity is increased by 22% over the 27.2mm OE front bar and 182% over the 15.9mm OE rear bar (SE model).
S13 Stock ? (data from Japanparts.com) JDM ?Front 24mm Rear 16mm
Suspension Techniques (data from STRacing.com)Front 27mm Rear 20.6mm
Whiteline (data from PDMRacing.com)Front 27mm Rear 20-22mm
Cusco (data from Japanparts.com) Front 28mm Rear 18mm
Tanabe (data from Tanabe-usa.com)Front 30.4mm Rear 22mm
Further Information:For the S13: 24 and 25mm OE front and 15, 17, and 21 mm OE rear bars can be had from CourtesyParts.com
I've seen some data on some other bars but have not confirmed them yet or in some cases determined whether they are S13 or S14.Hicas rear bar for S13: 21 mm ?Largus 31.5mm 27.5mmD'Stage 31mm 23mm
Possible Sources: (have not verified them all yet)Suspension Techniques can be found at Enjukuracing.com, and possibly Nopi.com or Summitracing.comTanabe can be found at ProjectNissan.com, Enjukuracing.com, MVPMotorsports.com Cusco can be found at ProjectNissan.com, CIPmotorsports.com Japanparts.com and Nismo S14 bars can be found at Japanparts.com (brace yourself... pun intended...)
Antiroll Bar Changes (copied here from the Suspension FAQ)Modification - Effect on Suspension
Increase front rate - Front roll resistance increases, increasing understeer or decreasing oversteer. May also reduce camber change, allowing better tire contact patch compliance with the road surface, reducing understeer.
Increase rear rate - Rear roll resistance increases, increasing oversteer or decreasing understeer. On independent rear suspensions, may also reduce camber change, allowing better contact patch compliance with road surface, reducing oversteer.
Decrease front rate - Front roll resistance decreases, decreasing understeer or increasing oversteer. More body roll could reduce tire contact patch area, causing understeer.
Decrease rear rate - Rear roll resistance decreases, decreasing oversteer or increasing understeer. On independent rear suspensions, more body roll could reduce tire contact patch area, causing oversteer. http://store.240sxmotoring.com/swaybars.html
Stabilizer / Anti-Sway bar information for the 240sx
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Kinesthesia
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Q45tech
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Just remember that the rear bar END LINK on J/Q/240 attaches to the middle of the lower suspension arm so the actual wheel stiffness is approximately 1/4 of the actual bar stiffness [a little trig used to calculate the exact wheel stiffness].
Similar situation with rear springs except they are slightly angled from EXACT perpendicular so multiply by 0.95 [5% less wheel rate].
"NISMORear: Diameter =23.0, Spring Rate=43.1mm(4.4kgf/mm)"
4.4 x 2.2 x 25.4= 246 for bar alone but the wheel rate is ~~ 60-62 pounds per inch plus [actually minus] what ever slop is in the end link isolator mounts [rubber vs urethane].
A 23mm rear bar could be over half as stiff as the rear oem springs.........this is getting into a touchy area considering this bar would be 5 times stiffer than oem.
Of course most increase the front bar from 27 [oem] to 30 mm to shift the stiffness ratio back forward.
It's not totally [or even all about the biggest bars] what counts is the ratio between the bars. Not getting in a situation where the rear total stiffness [springs and bar] is not equal [ 3-4% less is ideal] to the weight distribution ratio.
Similar situation with rear springs except they are slightly angled from EXACT perpendicular so multiply by 0.95 [5% less wheel rate].
"NISMORear: Diameter =23.0, Spring Rate=43.1mm(4.4kgf/mm)"
4.4 x 2.2 x 25.4= 246 for bar alone but the wheel rate is ~~ 60-62 pounds per inch plus [actually minus] what ever slop is in the end link isolator mounts [rubber vs urethane].
A 23mm rear bar could be over half as stiff as the rear oem springs.........this is getting into a touchy area considering this bar would be 5 times stiffer than oem.
Of course most increase the front bar from 27 [oem] to 30 mm to shift the stiffness ratio back forward.
It's not totally [or even all about the biggest bars] what counts is the ratio between the bars. Not getting in a situation where the rear total stiffness [springs and bar] is not equal [ 3-4% less is ideal] to the weight distribution ratio.
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Kinesthesia
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Dennis,I was hoping to attract you to this post. I was hoping you could pull out some of that high dollar math and estimate the increase of stiffness relative to the increase in diameter. I do realize there are some jumbo assumptions to be made, including but certainly not limited to materials, shape, connectivity, etc.
But I think some general estimates would be handy. Like ... "all things being equal a 30mm front bar would be x percent (or times) stiffer than the stock 27mm bar".
But I think some general estimates would be handy. Like ... "all things being equal a 30mm front bar would be x percent (or times) stiffer than the stock 27mm bar".
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Q45tech
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What you really want to know is a starting point ACCURATELY. I took a 15.9 mm rear Q bar and built a jig to measure its stiffness as the formulas don't work with all the convolutions necessary to clear exhaust.
Assume that the 15.9 mm rear bar is 50 pounds per inch [on the Q45] then you can multiply the 4th power factor to come close to what a 20mm or 30 mm is IF the designs are exactly the same unfortunately the wall thickness might vary the true readings by +- 10%.
Then there is the coupling error which can only be estimated.
You could use 1000 pound electronic scales and jacks to compress the tires and measure the forces. Or just remove one link and put a BIG bathroom scale under a screw jack and move the bar 1.0" inch upward and watch the forces.
Lots of my numbers are educated guesses.
The front bars are so stiff that you cannot accurately measure them so easily.......outside the lab.
The engineers that design Nissans bars have done so many that their brain does it almost automatically.
I'm sure lots of aftermarket is seat of the pants engineering or what ever bar stock/tubing stock diameters is easily available.
Only the factory orders 100,000 at a run so they can get anything they want made to perfection.
My basic rule of thumb is to find the largest oem rear bar and guess that an extra 2mm wouldn't be excessive.
20mm>22mm = 22/20=1.1^4th power = 1.4641=146% stiffer more or less depending on tubing wall thickness.
When you look at the front bars it seems most go 27mm>30mm roughly 50% stiffer on the front.........which increases total front stiffness by 25% [springs didn't change].
Note that S13 oem bars are available at 21mm and the largest aftermarket is 22 mm [maybe 20% stiffer].......a 1mm bump up....not my 2mm rule of thumb.......but most use urethane vs oem rubber so that would make the 21mm act like a 22-22.5 mm with rubber bushing.
With progressive rear springs the springs going from 120>150>175 > 200 make the 21mm rear bar at say 50 pounds per inch flat somwhat immaterial at full [3.5' roll].
150 pound per inch increasing to 250 pounds per inch. IF 400 pounds is the max force from x speed at y G rate the rear never rolls but 2.5" instead of 3.5" with no rear bar.
Obviously the rear feels safer with less roll so you push it harder [speed up in curve] and the G forces increase till the tire can't hold it any longer, so at 3" roll the rear spins out instead of 3.5" with no rear bar.
Some rear roll is very good, the trick is not to reduce it too much till the tires let go without warning.
BMW 's new active rear roll bar decouples as the G forces get close to 0.65G so the tires in light wet don't lose it suddenly.
Rain sensitive sway rear bars?
Assume that the 15.9 mm rear bar is 50 pounds per inch [on the Q45] then you can multiply the 4th power factor to come close to what a 20mm or 30 mm is IF the designs are exactly the same unfortunately the wall thickness might vary the true readings by +- 10%.
Then there is the coupling error which can only be estimated.
You could use 1000 pound electronic scales and jacks to compress the tires and measure the forces. Or just remove one link and put a BIG bathroom scale under a screw jack and move the bar 1.0" inch upward and watch the forces.
Lots of my numbers are educated guesses.
The front bars are so stiff that you cannot accurately measure them so easily.......outside the lab.
The engineers that design Nissans bars have done so many that their brain does it almost automatically.
I'm sure lots of aftermarket is seat of the pants engineering or what ever bar stock/tubing stock diameters is easily available.
Only the factory orders 100,000 at a run so they can get anything they want made to perfection.
My basic rule of thumb is to find the largest oem rear bar and guess that an extra 2mm wouldn't be excessive.
20mm>22mm = 22/20=1.1^4th power = 1.4641=146% stiffer more or less depending on tubing wall thickness.
When you look at the front bars it seems most go 27mm>30mm roughly 50% stiffer on the front.........which increases total front stiffness by 25% [springs didn't change].
Note that S13 oem bars are available at 21mm and the largest aftermarket is 22 mm [maybe 20% stiffer].......a 1mm bump up....not my 2mm rule of thumb.......but most use urethane vs oem rubber so that would make the 21mm act like a 22-22.5 mm with rubber bushing.
With progressive rear springs the springs going from 120>150>175 > 200 make the 21mm rear bar at say 50 pounds per inch flat somwhat immaterial at full [3.5' roll].
150 pound per inch increasing to 250 pounds per inch. IF 400 pounds is the max force from x speed at y G rate the rear never rolls but 2.5" instead of 3.5" with no rear bar.
Obviously the rear feels safer with less roll so you push it harder [speed up in curve] and the G forces increase till the tire can't hold it any longer, so at 3" roll the rear spins out instead of 3.5" with no rear bar.
Some rear roll is very good, the trick is not to reduce it too much till the tires let go without warning.
BMW 's new active rear roll bar decouples as the G forces get close to 0.65G so the tires in light wet don't lose it suddenly.
Rain sensitive sway rear bars?
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Kinesthesia
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NateDogg wrote:http://www.whiteline.com.au (I fixed your link) You can find the swaybar stiffness chart there.
Thanks for pointing me in the right direction... here's the direct link
http://www.whiteline.com.au/do...p.pdf
And thanks Dennis for all your input, I'm very glad that we have someone as technical as you around for this stuff.
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Q45tech
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Unfortunately percentage stiffer doesn't help much till you know the basic stiffness. Because the bars are always less stiff than springs.
If a 16mm bar is 12 or 17 pounds after the reduction of mounting trig, how do you know if 30 or 42 pounds is the desirable end result on 120 pound springs.
All those convolutions to clear exhaust can change a straight bar by 30-40%
If a 16mm bar is 12 or 17 pounds after the reduction of mounting trig, how do you know if 30 or 42 pounds is the desirable end result on 120 pound springs.
All those convolutions to clear exhaust can change a straight bar by 30-40%
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Kinesthesia
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I realize that these are wild estimates. But without better information from the manufacturers, or buying one of each kind of bar, what else can be done ?
I still think it's very helpful to have some sort of guideline, it still tells us more than we knew before. I realize it will never be 100% accurate but I think it's a step in the right direction.
Picking someone at random, let's take Tanabe. A good manufacturer who probably stayed close to the oem design, as I haven't heard of any fitment problems.
With the typical assumptions, similiar material, shape, etc... going from a 27mm stock front bar to a 30mm front bar is about 52% increase in stiffness... while going from a 15mm rear bar to a 27mm rear bar is a 950% increase !
That's a much more significant difference than I originally thought of when I saw "30mm/27mm".
I still think it's very helpful to have some sort of guideline, it still tells us more than we knew before. I realize it will never be 100% accurate but I think it's a step in the right direction.
Picking someone at random, let's take Tanabe. A good manufacturer who probably stayed close to the oem design, as I haven't heard of any fitment problems.
With the typical assumptions, similiar material, shape, etc... going from a 27mm stock front bar to a 30mm front bar is about 52% increase in stiffness... while going from a 15mm rear bar to a 27mm rear bar is a 950% increase !
That's a much more significant difference than I originally thought of when I saw "30mm/27mm".
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Q45tech
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A 20mm rear bar is 35-45 pounds per inch AT the WHEEL if it fits a 240sx or a 300zx/J30 or a Q 45..........same design rear suspension only the track and thus the bar width changes an 1" or so [why I used the range] the narrower bar is stiffer.
UNLESS you are willing to measure a bars stiffness as installed you have to accept a potential 25% variation. But that gets divided by 2 or more as the bars are less stiff than the springs.
There is a reason why most aftermarket rear bars are between 20 and 23mm...........that is the RIGHT {CORRECT} range [40 to 70 pounds of wheel rate +- 10%]..........18% difference in rear roll stiffness with the same springs...................which means a fore/aft shift in couple ratio of half that or 9% [20mm >23mm] and a 25%/2= 12.5% from no bar to 23mm.
Don't worry about sway instead redesign for the coupling ratio you want.
UNLESS you are willing to measure a bars stiffness as installed you have to accept a potential 25% variation. But that gets divided by 2 or more as the bars are less stiff than the springs.
There is a reason why most aftermarket rear bars are between 20 and 23mm...........that is the RIGHT {CORRECT} range [40 to 70 pounds of wheel rate +- 10%]..........18% difference in rear roll stiffness with the same springs...................which means a fore/aft shift in couple ratio of half that or 9% [20mm >23mm] and a 25%/2= 12.5% from no bar to 23mm.
Don't worry about sway instead redesign for the coupling ratio you want.
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Q45tech
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Since rear bars remove compliance [make it less independent], one would need to study the REAR tires and wheels to know the ABSOLUTE BEST answer.
Since both these brands have the same relative stiffness [20-22]as the oem 21mm rear bar...........why not just try the oem 21mm rear bar first [with rubber oem bushings, then step up to urethane if you want a little more, after you learn to handle the 21mm bar.
Don't mess with the front suspension just yet [other than new shocks] as a stiffer front bar will defeat the stiffer rear.
Since both these brands have the same relative stiffness [20-22]as the oem 21mm rear bar...........why not just try the oem 21mm rear bar first [with rubber oem bushings, then step up to urethane if you want a little more, after you learn to handle the 21mm bar.
Don't mess with the front suspension just yet [other than new shocks] as a stiffer front bar will defeat the stiffer rear.
I've been looking at sway bars as well. I'm looking to get more grip in the rear as it likes to come around quite easily, especially on wet roads. I currently have H&R springs with Tokico blues and Tanabe rear camber arms. So, trying a larger bar in the rear with the stock front bar or going with ST or Whiteline setup should help that problem.
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s13sr20chris
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yep, you're right. I wasn't thinking straight....lol. Actually I was.....I was thinking of drag racing. Let me rephrase that, I need a bigger bar up front. Hmmm, anyone using the same springs/struts as me with one of these sway bar sets?? My car is pretty annoying to drive in the rain, especially around the clover leaf highway ramps in the rain.
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Kinesthesia
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Well, I finally decided on Suspension Techniques (or maybe I should say ExarKun talked me into it, either way....) I thought I would take a minute to detail my experience.
First of all... sway bars rock ! I wish I had put them on long ago, long before springs, dampers, etc, etc. Bang for the buck, they've made the biggest change in my S14.
Now a bit about Suspension Techniques. First let me say that these are well made, seriously heavy biatches. Relative to the money invested (note disclaimer) I don't think I could have made a better choice (see above about it barely being *my* choice). The fact that they come with hardware and poly bushings is extra added gravy on top.
Now for the downside... installation, while it could have been a breeze, was not. The rear bar took me about an hour by myself mostly due to getting one striped nut off in a tricky place. If it had not been for that, it would have been minutes.
As for the front however, I'm still recovering from wrestling with that thing for about three hours simply because the brackets as the come simply would not go on. The endlinks were a snap (and btw probably a better design than stock) but the two brackets in the middle were another story... It could be my lack of experience that took so long to realize that while the stock brackets were open on one side (notched rather than a hole) and the ST's were not. Two minutes with a dremel tool and the bar went right on after that. The hours I spent convinced that surely they were supposed to fit the way they shipped I guess could be my own naivete.
Having said that... for a brief moment I toyed with the idea of using the original hardware and realized this would have been even harder. So while I have no experience with bars designed to use the stock hardware, it seems really difficult to me now and I'm glad that I bought a "complete solution".
So... in retrospect... I love them and they were worth the trouble and well worth the money. My S14 is much, much, much more balanced now. But if anyone reads this before purchasing/installing, just notch one side of each front bracket from the start and you'll be done in no time !
First of all... sway bars rock ! I wish I had put them on long ago, long before springs, dampers, etc, etc. Bang for the buck, they've made the biggest change in my S14.
Now a bit about Suspension Techniques. First let me say that these are well made, seriously heavy biatches. Relative to the money invested (note disclaimer) I don't think I could have made a better choice (see above about it barely being *my* choice). The fact that they come with hardware and poly bushings is extra added gravy on top.
Now for the downside... installation, while it could have been a breeze, was not. The rear bar took me about an hour by myself mostly due to getting one striped nut off in a tricky place. If it had not been for that, it would have been minutes.
As for the front however, I'm still recovering from wrestling with that thing for about three hours simply because the brackets as the come simply would not go on. The endlinks were a snap (and btw probably a better design than stock) but the two brackets in the middle were another story... It could be my lack of experience that took so long to realize that while the stock brackets were open on one side (notched rather than a hole) and the ST's were not. Two minutes with a dremel tool and the bar went right on after that. The hours I spent convinced that surely they were supposed to fit the way they shipped I guess could be my own naivete.
Having said that... for a brief moment I toyed with the idea of using the original hardware and realized this would have been even harder. So while I have no experience with bars designed to use the stock hardware, it seems really difficult to me now and I'm glad that I bought a "complete solution".
So... in retrospect... I love them and they were worth the trouble and well worth the money. My S14 is much, much, much more balanced now. But if anyone reads this before purchasing/installing, just notch one side of each front bracket from the start and you'll be done in no time !
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Kinesthesia
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A little bit more info on the ST sways.
After a short time, they've started to creak a bit, most noticably while slowly easing off from a stop at a light, etc. and speed bumps that I take at an angle.
I called Suspension Techniques and they suggested that I remove the bars, wrap the bars with teflon tape under the bushings and repack with white lithium grease.
Removing and reinstalling the front bar was about as much fun as it was the first time.
In the end, I see that the rear bar is rubbing (hard) against the heat shield that's over the LSD. All the wrapping and greasing did not solve the problem, I assume the noise I hear is apparently from where it rubs on the heat shield.
So as it stands, I'm just trying to get used to the noise. I've got other things to worry about for now.
After a short time, they've started to creak a bit, most noticably while slowly easing off from a stop at a light, etc. and speed bumps that I take at an angle.
I called Suspension Techniques and they suggested that I remove the bars, wrap the bars with teflon tape under the bushings and repack with white lithium grease.
Removing and reinstalling the front bar was about as much fun as it was the first time.
In the end, I see that the rear bar is rubbing (hard) against the heat shield that's over the LSD. All the wrapping and greasing did not solve the problem, I assume the noise I hear is apparently from where it rubs on the heat shield.
So as it stands, I'm just trying to get used to the noise. I've got other things to worry about for now.
Just bend that heat shield out of the way a bit. The 240 has about 100 of those darn things all over the place. The one over the muffler in the rear of my S14 started rattling one day, turns out it was vibrating against the bottom side of the trunk, I just bent it away....problem solved 
Damn heat shields!!
Damn heat shields!!
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sleepyRPS13
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s13sr20chris
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