Suspension Gurus: Importance of Zero Preload on Sway Bars with lowered suspension?

radiantm3 · 09-25-2014, 01:09 PM

So long story short, my RD Sport rear sway snapped in half a few days ago when I was pulling into my driveway. Because of my front splitter, I'm always going into driveways at an angle and so my sway bars get a good workout. I'm running Ohlin RT suspension, btw. Someone I know asked me if I'm running aftermarket adjustable end links to zero out preload and I am not. He said zero preload is very important for the handling of the car. He knows quite a bit about suspension tuning on E46's, but not E92's.

I did a search for aftermarket adjustable end link options and I was surprised to find that they are only available for the front end and not rear. Does this mean that every E9x on aftermarket suspension is running with rear preload on the bars?

Can some of the suspension guru's enlighten me on this subject as a whole? Is anyone running zero preload on their rear sway on aftermarket suspension? Are you on stock or aftermarket rear sways? How important is this on the E9x?

slicer · 09-25-2014, 04:01 PM

I'm no expert but I think KW Clubsports include front end-links. They are not adjustable but presumably they are a different length than OEM to compensate for lowering.

I am curious about this topic as well. I do sometimes hear a noise when I pull into steep driveways at an angle... I believe mine is my front spring shifting.

RickyBobby · 09-25-2014, 04:27 PM

They are important when really getting into the nitty gritty of fine tuning your suspension. Similar to corner balancing.
I don't think that it would have contributed to breaking your swaybar though. Perhaps the bar is binding on something?
Turner can make end links of any length. I've got them on the front of my e90 and the back of my e36.
Give them a call to see if they can make you some. Food for thought though. That rear bar only excerpts a couple hundred pounds of force (vs the front that is multiple times stiffer) so stronger end links are probably not necessary.

RickyBobby · 09-25-2014, 10:21 PM

Oh and I forgot to add. My stock rear end links don't have any preload (with my stock suspension and with my aftermarket coilovers). Guess the engineers at bmw know what they are doing

radiantm3 · 09-25-2014, 10:37 PM

Quote:

Originally Posted by RickyBobby

Oh and I forgot to add. My stock rear end links don't have any preload (with my stock suspension and with my aftermarket coilovers). Guess the engineers at bmw know what they are doing

Are you suggesting I just switch the rear sway back to stock?

That was my plan anyways.

surlynkid · 09-26-2014, 06:49 AM

I run adjustable sway bar end links on the GT3 with zero pre load. I am surprised about having them broke your sway bar. It is more about fine tuning the overall suspension when lowering and corner balancing. I though I saw adjustable rears at Bimmerworld.

Petros · 09-26-2014, 10:23 AM

how can the sway bar have preload if the ride height is the same between both sides of the car? If the sway bar end links are the same length then there shouldn't be any torsion on the bar itself, right?

surlynkid · 09-26-2014, 10:35 AM

Quote:

Originally Posted by Petros

how can the sway bar have preload if the ride height is the same between both sides of the car? If the sway bar end links are the same length then there shouldn't be any torsion on the bar itself, right?

Lowered car will load them. They are fixed length. Put on adjustable ones and start adjusting the center piece by hand and you will feel the pre load after about a revolution

C-M2 · 09-26-2014, 10:47 AM

I find it strange that it snapped. You aren't slammed to the ground by any means. Could it possibly be a manufacturing defect due to the the RD Sways being hollow?

Do you have a picture of where it snapped?

radiantm3 · 09-26-2014, 11:08 AM

Quote:

Originally Posted by surlynkid

Lowered car will load them. They are fixed length. Put on adjustable ones and start adjusting the center piece by hand and you will feel the pre load after about a revolution

I'm corner balanced too so they aren't the same on each side.

radiantm3 · 09-26-2014, 11:10 AM

Quote:

Originally Posted by C-M2

I find it strange that it snapped. You aren't slammed to the ground by any means. Could it possibly be a manufacturing defect due to the the RD Sways being hollow?

Do you have a picture of where it snapped?

Yea it is strange. The rd sport bars aren't hollow for what I remember seeing. I'm going back to my stock bar just to be safe.

C-M2 · 09-26-2014, 11:16 AM

Quote:

Originally Posted by radiantm3

Yea it is strange. The rd sport bars aren't hollow for what I remember seeing. I'm going back to my stock bar just to be safe.

They are: http://www.rdsport.com/store/e9x-m3-sway-bars.html

The GT4 runs a normal e92 rear sway

radiantm3 · 09-26-2014, 11:36 AM

Quote:

Originally Posted by C-M2

They are: http://www.rdsport.com/store/e9x-m3-sway-bars.html

The GT4 runs a normal e92 rear sway

Ah thanks.

09-25-2014, 01:09 PM	#1
radiantm3 Apex Everything! 979 Rep 4,378 Posts Drives: 2007 Honda S2000, 2017 GT350 Join Date: Sep 2008 Location: Cedar Park, TX iTrader: (6) Garage List 2011 E92 M3 [9.35] 2014 BMW i3 [10.00]	Suspension Gurus: Importance of Zero Preload on Sway Bars with lowered suspension? So long story short, my RD Sport rear sway snapped in half a few days ago when I was pulling into my driveway. Because of my front splitter, I'm always going into driveways at an angle and so my sway bars get a good workout. I'm running Ohlin RT suspension, btw. Someone I know asked me if I'm running aftermarket adjustable end links to zero out preload and I am not. He said zero preload is very important for the handling of the car. He knows quite a bit about suspension tuning on E46's, but not E92's. I did a search for aftermarket adjustable end link options and I was surprised to find that they are only available for the front end and not rear. Does this mean that every E9x on aftermarket suspension is running with rear preload on the bars? Can some of the suspension guru's enlighten me on this subject as a whole? Is anyone running zero preload on their rear sway on aftermarket suspension? Are you on stock or aftermarket rear sways? How important is this on the E9x? __________________ 2011 E92 M3(Sold). 2007 Honda S2000 (Track Car). 2016 Cayman GT4 (Sold). 2017 Shelby GT350 (AKA Crowd Killer). My pet project: https://stickershift.com
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09-25-2014, 04:01 PM	#2
slicer Major General 2746 Rep 6,734 Posts Drives: 'E46 M3 Race Car, '23 X7 Join Date: Jan 2009 Location: Wisconsin - Instagram - @slicer_m iTrader: (39)	I'm no expert but I think KW Clubsports include front end-links. They are not adjustable but presumably they are a different length than OEM to compensate for lowering. I am curious about this topic as well. I do sometimes hear a noise when I pull into steep driveways at an angle... I believe mine is my front spring shifting. __________________ '23 X7 '04 M3 - Fall Line Motorsports Built Race Car - S65 swap, Dry Sump, Bosch Stand-Alone ECU, Drenth Sequential Trans, MCS 3-Way, Flossmann Wide Body, Brembo Motorsports Brakes, Drexler LSD, BBS E88 Etc. INSTAGRAM - @Slicer_M Last edited by slicer; 09-25-2014 at 04:12 PM..
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09-25-2014, 04:27 PM	#3
RickyBobby Captain 108 Rep 697 Posts Drives: M3 Join Date: Mar 2008 Location: NorCal iTrader: (3)	They are important when really getting into the nitty gritty of fine tuning your suspension. Similar to corner balancing. I don't think that it would have contributed to breaking your swaybar though. Perhaps the bar is binding on something? Turner can make end links of any length. I've got them on the front of my e90 and the back of my e36. Give them a call to see if they can make you some. Food for thought though. That rear bar only excerpts a couple hundred pounds of force (vs the front that is multiple times stiffer) so stronger end links are probably not necessary.
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09-25-2014, 10:21 PM	#4
RickyBobby Captain 108 Rep 697 Posts Drives: M3 Join Date: Mar 2008 Location: NorCal iTrader: (3)	Oh and I forgot to add. My stock rear end links don't have any preload (with my stock suspension and with my aftermarket coilovers). Guess the engineers at bmw know what they are doing
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09-26-2014, 06:49 AM	#6
surlynkid Major 115 Rep 1,470 Posts Drives: 2013 E92 M3 Join Date: Apr 2012 Location: League City, TX iTrader: (1) Garage List 2010 Porsche GT3 [0.00] 1988 Toyota 4Runner [0.00] 1995 Toyota T-100 4x4 [0.00] 2013 BMW M3 [0.00]	I run adjustable sway bar end links on the GT3 with zero pre load. I am surprised about having them broke your sway bar. It is more about fine tuning the overall suspension when lowering and corner balancing. I though I saw adjustable rears at Bimmerworld. __________________ Stoptech 380mm/355mm \| PFC08 / Pagid RS-29 \| Akrapovic EVO - CF tips \| Benvo Tune \| MS UDP \| AA air filter \| MCS 2-way with 700/1000lb springs \| Solid bushings and adjustable links \| RD front swaybar \| Apex EC-7 18x10 square 275/35-18 NT01 \| Turner Race Studs \| GT4 Brake Cooling \| GT4 Power Steering Cooling \| Alekshop Oil Cooler \| Performance Steering Wheel \| \| CF Spoiler \| Varis System 1 Full CF Diffuser \| Extended Paddle Shifters \| Schroth Quick Fit Pro \| Turner Steering Rack Stops \| Vorshlag Camber Plates
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09-26-2014, 10:23 AM	#7
Petros Banned 62 Rep 1,381 Posts Drives: M3 Join Date: Jan 2014 Location: Canada iTrader: (1)	how can the sway bar have preload if the ride height is the same between both sides of the car? If the sway bar end links are the same length then there shouldn't be any torsion on the bar itself, right?
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09-26-2014, 10:47 AM	#9
C-M2 First Lieutenant 41 Rep 318 Posts Drives: 09 E92 SG M3 Join Date: Oct 2007 Location: Chicago iTrader: (2)	I find it strange that it snapped. You aren't slammed to the ground by any means. Could it possibly be a manufacturing defect due to the the RD Sways being hollow? Do you have a picture of where it snapped? __________________ Current: 2009 Space Gray e92 M3 - Mod list too long to list Gone: 2004 Jet Black/Black SMG M3
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