Eibach Sway-Bars Review
11-10-2010, 11:31 AM
#21
Rob and/or any Eibach rep:
Do you know, or can you find out, the thickness of each bar? That's the best way to compare these bars apples-to-apples with the OEM parts.
The reason I ask is that in my thread on the OE spring rates I document some adjustments that need to be made to the typical swaybar stiffness equation in order to account for the shape of the OEM bars. (Eibach's bars are identical in shape to OEM so the same adjustments would apply.)
In particular, the OEM swaybar rates in the first post are from Swift Springs' thread, and I know Swift used a simplified formula for their calculations.
Just trying to help.
FWIW, I saw these bars at HC2 (and had a nice chat with Eibach's sales rep) and they really do look like nice, well-made parts.
Do you know, or can you find out, the thickness of each bar? That's the best way to compare these bars apples-to-apples with the OEM parts.
The reason I ask is that in my thread on the OE spring rates I document some adjustments that need to be made to the typical swaybar stiffness equation in order to account for the shape of the OEM bars. (Eibach's bars are identical in shape to OEM so the same adjustments would apply.)
In particular, the OEM swaybar rates in the first post are from Swift Springs' thread, and I know Swift used a simplified formula for their calculations.
Just trying to help.
FWIW, I saw these bars at HC2 (and had a nice chat with Eibach's sales rep) and they really do look like nice, well-made parts.
any upgrades for the end links?
01-20-2011, 01:05 PM
#24
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Re the debate on spring rates. I called Eibach to get the wall thickness:
Front: 4.76mm
Rear: 6.35mm
Using twohoo's sway bar spring rate formula I get these spring rates:
Front: 596 lb/in
Rear: 576 lb/in
This assumes that the geometry of the Eibach bars matches the Honda bars and does not account for the adjustability the bar provides. I don't know if these rates correspond to the stiff setting, soft setting or in somewhere between.
Hope this is useful.
Front: 4.76mm
Rear: 6.35mm
Using twohoo's sway bar spring rate formula I get these spring rates:
Front: 596 lb/in
Rear: 576 lb/in
This assumes that the geometry of the Eibach bars matches the Honda bars and does not account for the adjustability the bar provides. I don't know if these rates correspond to the stiff setting, soft setting or in somewhere between.
Hope this is useful.
01-20-2011, 05:13 PM
#26
tbakker, thanks for the research. 
It certainly seems like these bars don't quite fit my model, huh? 
Actually this data doesn't mean either my equations or the OP's stiffness ratings are wrong. With some reverse engineering, I can get back to the values quoted by the OP by assuming somewhat longer arms for the Eibach bars. In the front, the arms must be about a inch longer than stock to achieve the lower stiffness rating. In the rear, it's only about a half inch longer. In both cases, the adjustment holes must be about 0.7in apart, which looks about right from the photos.
What's absolutely certain is this: that's a seriously stiff rear bar!
It certainly seems like these bars don't quite fit my model, huh? Actually this data doesn't mean either my equations or the OP's stiffness ratings are wrong. With some reverse engineering, I can get back to the values quoted by the OP by assuming somewhat longer arms for the Eibach bars. In the front, the arms must be about a inch longer than stock to achieve the lower stiffness rating. In the rear, it's only about a half inch longer. In both cases, the adjustment holes must be about 0.7in apart, which looks about right from the photos.
What's absolutely certain is this: that's a seriously stiff rear bar!
01-21-2011, 08:49 AM
#27
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twohoos - I wasn't trying to imply that these bars don't fit your model or that the OP was wrong. I didn't have all the data to put into the model so I had to make some assumptions. I didn't realize how dramatic an effect they would have though!
I would be interested to hear any feedback from folks that have tried these bars on otherwise stock AP2 suspensions, especially on track.
I would be interested to hear any feedback from folks that have tried these bars on otherwise stock AP2 suspensions, especially on track.
01-21-2011, 11:12 AM
#28
^Yeah I just don't want people to think there's some science-guy out there casting doubt on Eibach's numbers. (And I should have said "my model doesn't fit these bars," not the other way around.) It's all good.
Regarding swaybars for the track: Most track guys would stongly advise against anything stiffer than a stock AP2 bar in the rear; some have gone so far as to fit a thin Miata bar at the rear, and many of us have abandoned rear bars altogether. Reason is that a big bar tends to cause inside rear wheelspin at turn exit, which is not only slow, but can be harmful to the diff.
For the street, there's no inherent disadvantage to a big rear bar, as long as you get the overall balance you want when combined with springs and the front bar.
Regarding swaybars for the track: Most track guys would stongly advise against anything stiffer than a stock AP2 bar in the rear; some have gone so far as to fit a thin Miata bar at the rear, and many of us have abandoned rear bars altogether. Reason is that a big bar tends to cause inside rear wheelspin at turn exit, which is not only slow, but can be harmful to the diff.
For the street, there's no inherent disadvantage to a big rear bar, as long as you get the overall balance you want when combined with springs and the front bar.
01-24-2011, 11:45 AM
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Originally Posted by twohoos,Jan 21 2011, 03:12 PM
^Yeah I just don't want people to think there's some science-guy out there casting doubt on Eibach's numbers. (And I should have said "my model doesn't fit these bars," not the other way around.) It's all good.
Regarding swaybars for the track: Most track guys would stongly advise against anything stiffer than a stock AP2 bar in the rear; some have gone so far as to fit a thin Miata bar at the rear, and many of us have abandoned rear bars altogether. Reason is that a big bar tends to cause inside rear wheelspin at turn exit, which is not only slow, but can be harmful to the diff.
For the street, there's no inherent disadvantage to a big rear bar, as long as you get the overall balance you want when combined with springs and the front bar.
Regarding swaybars for the track: Most track guys would stongly advise against anything stiffer than a stock AP2 bar in the rear; some have gone so far as to fit a thin Miata bar at the rear, and many of us have abandoned rear bars altogether. Reason is that a big bar tends to cause inside rear wheelspin at turn exit, which is not only slow, but can be harmful to the diff.
For the street, there's no inherent disadvantage to a big rear bar, as long as you get the overall balance you want when combined with springs and the front bar.
thanks!