RSB: Eibach 22 mm vs. OEM 18 mm Si

[bbeem]

One factor is the rear sway bar binding, which momentarily increases rear spring rate and results in oversteer. I have a Type R bar on my SI and for autocross, it’s perfect. For track cross or track work, I swap back to the factory SI bar.

I bring this up because the factory end links don’t really work well for other RSBs. I like the loose rear end for autoX, but it’s too loose. Definitely budget for adjustable end links for you can fully tune the bar.

I thought the adjustable end links are only for the front? I don't mind the eibach front non adjustable bar, running pro kit with it. I don't monkey with the front, it was a pita. I run accord links on the rear and sometimes switch between the 2 holes. With my 255/40 summers the back it isn't as loose.

I haven't experienced any binding with OEM or eibach. The eibach has greese zercs on the bushings, probably helps.

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[sibanez]

I thought the adjustable end links are only for the front? I don't mind the eibach front non adjustable bar, running pro kit with it. I don't monkey with the front, it was a pita. I run accord links on the rear and sometimes switch between the 2 holes. With my 255/40 summers the back it isn't as loose.

I haven't experienced any binding with OEM or eibach. The eibach has greese zercs on the bushings, probably helps.

There's probably less binding with the lower springs, too. When you reduce ride height, you change the geometry of the sway bars.

Aren't the Accord links the same length as the SI ones?

 

[bbeem]

There's probably less binding with the lower springs, too. When you reduce ride height, you change the geometry of the sway bars.

Aren't the Accord links the same length as the SI ones?

They are the same geometry but they are aluminum and beefier. I had the rear sway bar on first. Then FSB the same time I did springs. Then accord end links last.

 

[hobby-man]

Thanks to you also for starting this. I was led deep down the rabbit hole as you can tell.

I'm resurrecting this thread again as the RSB is my next upgrade this week ?

Thought you might like to know that I found a source from the Subaru boys that their Eibach 22mm RSB has a 4.76mm wall thickness. That means the ID of that bar is 12.48mm. At this point I've been cross-shopping the Whiteline 22mm solid RSB and the Eibach 22mm tubular RSB. I'm getting Eibach springs next so my preference is to keep it all Eibach.

Whiteline SF = OD^4 = 22^4 = 234256
Eibach SF = (OD^4) - ID(^4) = 22^4 - ((22-2*4.76)^4) = 209998
Sport hatchback SF = OD^4 = 16.5^4 = 74120

So Whiteline is ~10% stiffer than the Eibach, but they are both significantly stiffer than the OE bar (2.83x for Eibach, 3.16x for Whiteline)

I just emailed Eibach to get the official answer on what the ID is for the Civic bars in case it's different. If that 4.76mm is fairly accurate, I'll probably jump on one of those.

 

[bbeem]

I'm resurrecting this thread again as the RSB is my next upgrade this week ?

Thought you might like to know that I found a source from the Subaru boys that their Eibach 22mm RSB has a 4.76mm wall thickness. That means the ID of that bar is 12.48mm. At this point I've been cross-shopping the Whiteline 22mm solid RSB and the Eibach 22mm tubular RSB. I'm getting Eibach springs next so my preference is to keep it all Eibach.

Whiteline SF = OD^4 = 22^4 = 234256
Eibach SF = (OD^4) - ID(^4) = 22^4 - ((22-2*4.76)^4) = 209998
Sport hatchback SF = OD^4 = 16.5^4 = 74120

So Whiteline is ~10% stiffer than the Eibach, but they are both significantly stiffer than the OE bar (2.83x for Eibach, 3.16x for Whiteline)

I just emailed Eibach to get the official answer on what the ID is for the Civic bars in case it's different. If that 4.76mm is fairly accurate, I'll probably jump on one of those.

Thanks for the math. I've wondered what the eibach 22mm stiffness is. Also keep in mind the mounting distance from the bar to the endlinks will also play into the overall stiffness. With only the rsb installed it was too stiff. Then I did the pro kit and fsb at the same time and its perfect now. Using accord end links on close mounting hole nice and stiff but I'd considering the softer hole if not doing the fsb. The fsb shouldn't be necessary like that but if you go real stiff you might want to up the front.

 

[BS1]

I'm resurrecting this thread again as the RSB is my next upgrade this week ?

Thought you might like to know that I found a source from the Subaru boys that their Eibach 22mm RSB has a 4.76mm wall thickness. That means the ID of that bar is 12.48mm. At this point I've been cross-shopping the Whiteline 22mm solid RSB and the Eibach 22mm tubular RSB. I'm getting Eibach springs next so my preference is to keep it all Eibach.

Whiteline SF = OD^4 = 22^4 = 234256
Eibach SF = (OD^4) - ID(^4) = 22^4 - ((22-2*4.76)^4) = 209998
Sport hatchback SF = OD^4 = 16.5^4 = 74120

So Whiteline is ~10% stiffer than the Eibach, but they are both significantly stiffer than the OE bar (2.83x for Eibach, 3.16x for Whiteline)

I just emailed Eibach to get the official answer on what the ID is for the Civic bars in case it's different. If that 4.76mm is fairly accurate, I'll probably jump on one of those.

Please report back on the Eibach wall thickness, Thanks! Just did a track day with a stock car, but had 275s on the front and 245s on the rear (with not great Firestone Indy 500 340 TW tires; but came with the wheels). Brakes were worthless after a lap or two, will try some Carbotech or EBC pads and a high-temp fluid. It really needed some more rear roll stiffness. With better balance and brakes, it might not be like my old Type R, but not too bad.

 

[LampRod]

What kind of supporting mods are you going to need with upgrading the sway bars? I play to lower the car soon and already have wheels are tires. I read people like to switch to accord end links but I haven't really seen why. Thanks

 

[Bunhyung]

Which do you guys think is best for a daily driver who has opportunities for more "spirited" bits along his commute? I'm leaning towards the Eibach but wondering if it's too aggressive for daily driving (I'd use the soft setting).

I also plan to install Eibach pro springs along side the RSB upgrade.

Some if your decision needs to be based on the climate in which you live. If you only see three seasons, go as big as you can stand. If you drive in snow or icy conditions stay at 20mm and under (my opinion only).
Personally, I think Ultra racing's 19mm bar is ideal for a four season daily.

 

[NixChixFix]

What kind of supporting mods are you going to need with upgrading the sway bars? I play to lower the car soon and already have wheels are tires. I read people like to switch to accord end links but I haven't really seen why. Thanks

The stock Si end links are plastic, as opposed to the Accord end links which are metal. I've read stories about the plastic ones cracking after a while, or under hard tracking. The accord links cost me less than $40, which is definitely worth the peace of mind IMO.

 

[BS1]

What kind of supporting mods are you going to need with upgrading the sway bars? I play to lower the car soon and already have wheels are tires. I read people like to switch to accord end links but I haven't really seen why. Thanks

Being a front drive car with a pronounced front weight bias, the goal is to reduce understeer...which is what more rear roll stiffness does.

 

[2018 Sport]

The stock Si end links are plastic, as opposed to the Accord end links which are metal. I've read stories about the plastic ones cracking after a while, or under hard tracking. The accord links cost me less than $40, which is definitely worth the peace of mind IMO.

Could you please link the accord end links.

I am also looking at getting a RSB to stiffen everything up a little more. I installed a front strut brace about a year ago and that was an awesome improvement. Anyone know if a front sway bar is worth it if I already have the front strut brace?

 

[hobby-man]

Could you please link the accord end links.

I am also looking at getting a RSB to stiffen everything up a little more. I installed a front strut brace about a year ago and that was an awesome improvement. Anyone know if a front sway bar is worth it if I already have the front strut brace?

A thicker front sway is just going go introduce even more understeer on a FWD car. Unless you're tracking and know exactly what you're trying to correct for a think a front strut brace and bigger rear sway is all you need.

 

[bbeem]

 

[WF19]

OK guys...math time. Found this info on another forum combined with a sway bar thread here. I think I have this right.

To find the stiffness factor (SF) of a solid swaybar you take the 4th power of the outer diameter of the bar. This means the SF of the Si bar (19mm)^4 = 130321 and SF of the hatchback bar (16.5mm)^4 = 74120.

Simple ratios tell us that the Si bar is therefore 76% stiffer than the hatchback bar.

Now, the Eibach is a 22mm tubular bar. With these, the SF is the bar's inner diameter (ID) to the fourth power subtracted from the bar's outer diameter (OD) to the fourth power. To do this you need the thickness measurement of the bar wall. We'll guess it at 1 mm, 1.5 mm, and 2 mm. Because I have no idea. The ID is simply the OD - 2*wall thickness.

This gives us OD = 22 mm and potential IDs of 20mm, 19mm, and 18 mm.

So the SF range for the Eibach would be (OD)^4 - (ID)^4 = (22^4) - (18^4) and (22^4) - (20^4) = 74256 - 129280.

At the low end (1 mm wall), it is pretty much exactly as stiff as the stock hatchback bar. This is unlikely. At the high end (2 mm wall), it is 74% stiffer than the hatchback bar and actually 1% less stiff than the Si bar.

All this being said, it seems like there's very little difference between a 19 mm solid bar and a 22 mm tubular bar, depending on the thickness of the tubular bar's wall. I'd like to find out what the wall thickness is from Eibach. The OEM Si bar may just be the safer choice then rather than all this guessing

I was told there'd be no math.

 

[KYRGYZ]

those are direct fitment?