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Old 05-20-2021, 08:55 AM   #1
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Eibach sways w/ Bilstein B8, -3.9 camber, -1.25" ride height

Thinking about ordering up Eibach sway bars front and rear.

I think they should fit/install fine but just checking! I'm lowered 1.25" on stock-diameter Swift R-Spec springs, Bilstein B8 struts, -3.9 front camber via Raceseng camber plates.

The Eibach sway bars use the factory end links, right? I'm *very* tight with factory bars and links, I can see where the upper end link has scraped the inside wheelwell due to maxed out camber.

ASSume rear Eibach swaybar should be no problemo?
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Old 05-20-2021, 10:40 AM   #2
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With lowering anything regardless should be using an adjustable endlink to be able to avoid preload on the bar itself.

I ran the 22mm Eibach bar prior and found to be inbetween adjustments (too stiff on the 22mm but too soft on the 20mm).

Personally, I think in today's market anyone who isn't going with Karcept's bar is shooting them in the foot as far as adjustability sake.
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Old 05-20-2021, 12:28 PM   #3
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With lowering anything regardless should be using an adjustable endlink to be able to avoid preload on the bar itself.
Looks like Hotchkiss has 'em for the front that look pretty low-profile...

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I ran the 22mm Eibach bar prior and found to be inbetween adjustments (too stiff on the 22mm but too soft on the 20mm).

Personally, I think in today's market anyone who isn't going with Karcept's bar is shooting them in the foot as far as adjustability sake.
I'm not looking for much adjustability. Looking to augment roll stiffness as I'm fairly undersprung for the track at 4.4 kg/mm front and 5.3 kg/mm rear (Swift R-spec springs). I figure swapping the stock front or rear bar back in is my first stage of adjustability, if aftermarket/stiffer bars come with a couple of adjustment holes, fine, but I don't need a lot here.

Also I don't wanna go too nuts on swaybar stiffness, based on:
1. street car
2. softish springs (for track anyway), don't want to overload support and attachment structures. (less a concern with more track-oriented springs, but more of roll loads go into sways with softer springs...)

Looking at options, though there's conflicting info on stiffness vs. stock...
I'm seeing 376 lb/in P1 setting for Eibach 25mm front bar as "167% stiffer than stock", and 500 lb/in front P1 setting for Hotchkiss 25.4mm front bar as "170% stiffer than stock"...

I'd really like something closer to 100% stiffer than stock (i.e. twice as stiff), what options are out there?
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Old 05-20-2021, 01:17 PM   #4
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I am running Hotchkis 25mm FSB and 19mm RSB; Hotchkis endlinks in the rear; Whiteline endlinks in the front.
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Old 05-20-2021, 02:02 PM   #5
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Sounds not that different from an SSC setup, I know they were having issues with rear swaybar binding and terrible angle with the ~1" lowering and stock endlinks on the Eibach rear bar, full stiff was the only setting a lot of people could make work but other factors might have been at play for taht, this year they are allowing aftermarket/adjustable links to help the problem. I'd budget for adjustable endlinks front and rear.

@M0nk3y any reason you didn't split the holes? stiff on one side, soft on the other?

Edit; big list of swaybar options, if you've got the cash to burn monkey is right, Karcepts has the biggest adjustment range that starts where you're interested in, looks like most are either less then twice as stiff or more, Karcepts page also has good reference for stiffness values when comparing since one companies 100% is the same as another companies 200%.

https://www.ft86club.com/forums/showthread.php?t=49659

http://www.karcepts.com/shop/product.php?id_product=136
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Old 05-20-2021, 03:30 PM   #6
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Sounds not that different from an SSC setup, I know they were having issues with rear swaybar binding and terrible angle with the ~1" lowering and stock endlinks on the Eibach rear bar, full stiff was the only setting a lot of people could make work but other factors might have been at play for taht, this year they are allowing aftermarket/adjustable links to help the problem. I'd budget for adjustable endlinks front and rear.
Will do! Thanks for heads-up.

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@M0nk3y any reason you didn't split the holes? stiff on one side, soft on the other?
God, I cringe every time I see this suggested. Karcepts even shows this on their site!

This is a bad idea. You will get weight/corner-jacking with bump travel! Also one side of the car will see the sway bar as *stiffer* vs. the other side. Not remotely worth it IMO unless you *specifically* want the car's corner weights being jacked around in opposite directions during left-handers vs. right handers. And also to have corner-weights go asymmetrical under straightline braking and acceleration!

Quote:
Edit; big list of swaybar options, if you've got the cash to burn monkey is right, Karcepts has the biggest adjustment range that starts where you're interested in, looks like most are either less then twice as stiff or more, Karcepts page also has good reference for stiffness values when comparing since one companies 100% is the same as another companies 200%.
Yup, looking at their site now!

Thanks for linkies!
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Old 05-20-2021, 03:48 PM   #7
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Anybody have stock 2017 sway bar diameters handy?
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Old 05-20-2021, 04:01 PM   #8
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Anybody have stock 2017 sway bar diameters handy?
Front is the same pre facelift. The rears are 1mm larger at 15mm.
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Old 05-20-2021, 04:20 PM   #9
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Front is the same pre facelift. The rears are 1mm larger at 15mm.
Aright, thanks, so 18mm front/15mm rear
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Old 05-20-2021, 05:29 PM   #10
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@ZDan sway bars rotate freely, splitting holes is not a problem, it's a simple spring as long as endlinks do not preload the bar.
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Old 05-20-2021, 06:42 PM   #11
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@ZDan sway bars rotate freely, splitting holes is not a problem, it's a simple spring as long as endlinks do not preload the bar.
It is a simple torsional spring, with bendy lever-arm ends, *with links at the ends of those lever arms connected to some part of the moving wheel/upright/control arm assembly*. As soon as you have different lever arm lengths on the two ends, *you are putting preload into the bar* with what would ordinarily be symmetric L/R bump and droop.

If you try to compress the front say, 2", under braking, with both ends at same stiffness setting, having the same lever arm length, the swaybar rotates freely in its mounts and does nothing. Even load left/right.

BUT:
Now let's say you have one end set at a the stiffer setting, the lever arm at that end is (guessing) ~8" lever arm. Other end of the bar is at the next-softer setting, say ~9" lever arm.

Now what happens when the front tries to compress that same 2"? If the end with 9" lever arm moves up (relative to the chassis) 2", with a rigid bar, that would mean the end with the 8" lever arm only moves up (8/9)*2" = 1.78". The bar is *trying* to enforce a 0.22" difference at the end links while the car under braking wants both sides to compress the same amount.

0.22" in a stock bar, at 191 lb/in = 42 lb., means you end up UNloading one end by about 21 lb., and loading up the other end by 21 lb.

You're corner jacking the car!

Bad idea, and for 99% of us who track these cars totally unnecessary to get that fine with tuning roll stiffness anyway.


I suspect people got the idea this is OK because it *is* totally OK to disconnect one end link and let the sway bar passively move with the connected end. So they probably concluded that if *that's* ok, surely any asymmetric setup is, right? Nope...
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Old 05-20-2021, 08:05 PM   #12
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@ZDan Alright, I also came out with 21 lbs/axle using your numbers and going after the rotational angle instead of ratio-ing it.

My one contention is no spring is effective from rest at their rated value and the 1.5 degrees of twist induced by 1" long sway bar arm differential is not producing the full 21 lbs/in per wheel of resistive twisting, there's a certain amount of 'slack' in every spring that is not insignificant and <20 lbf on a system dealing with >600lbf is entirely negligible. I will continue to split holes on my swaybars.

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Old 05-20-2021, 08:28 PM   #13
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@ZDan Alright, I also came out with 21 lbs/axle using your numbers and going after the rotational angle instead of ratio-ing it.

My one contention is no spring is effective from rest at their rated value and the 1.5 degrees of twist induced by 1" long sway bar arm differential is not producing the full 21 lbs/in per wheel of resistive twisting, there's a certain amount of 'slack' in every spring that is not insignificant and <20 lbf on a system dealing with >600lbf is entirely negligible.
I wouldn't call 3% negligible. And certainly with stiffer springs and sways (Eibach front sway is 376 lb./in "soft" setting, 488 lb/in "stiff"), and serious setups with slack taken up it will become ever more significant.

It seems to me that *particularly* for a car with a setup apparently so very sensitive to roll stiffness, that you wouldn't want to invite in *any* sort of asymmetric corner-jacking wonkiness that *will* load up the fronts asymmetrically under straight-line braking, not to mention different handling in lefties vs. righties...

Also, consider that your effective swaybar stiffness is going to be *different* at the left wheel vs. right if you do this.

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I will continue to split holes on my swaybars.
Do what you will, but this is *extremely* poor practice! Yeah, on our cars probably not gonna notice any difference. Just like people who work their asses off to corner-weight down to 50.0/50.0 cross-diagonals, they might never know the difference at 53/47... But to go out of your way to *intentionally* induce this asymmetric swaybar weight-jacking wonkiness, just, ewwwwwww....


All that said, if you *insist*, you should try it ONE way first, and then the opposite way, and see what happens at the track. Not many (any) perfectly L/R symmetric tracks out there, one "handedness" should be preferable!

Last edited by ZDan; 05-20-2021 at 09:12 PM.
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Old 05-20-2021, 10:25 PM   #14
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I'd really like something closer to 100% stiffer than stock (i.e. twice as stiff), what options are out there?
I'm not completely sure but see if you can dig up some information on the Tanabe 22 mm hollow front sway bar. I suspect it might be close to what you're looking for.
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