Dinan Swaybar adjustment strategies - The Unofficial BMW M5 Messageboard (m5board.com)

Lscman · 21st December 2007, 16:00

As I discussed Dinan swaybar settings at Mid Ohio with Irish m5 something occurred to me....

Anyone ever consider using an uneven left and right position setting on the rear adjustable bar? This is effectively done all the time in Pro SCCA Racing thru one cockpit tuneable end arm on the right or left. The bar ends do not need to be balanced for any reason, so this works great. The swaybar torque spring applies equal and opposing force to both control arms under all conditions, even if the ends are different lengths (rxF). This is because a swaybar is free-floating (swivels freely on the frame mounts).

This would seem to effectively offer a 1.5 and 2.5 setting which folks occasionally mention they wish they had:

1 to 1
2 to 2
3 to 3
1 to 2 = 1.5
2 to 3 = 2.5

E55AMG2 · 21st December 2007, 18:44

I leave mine on the middle setting, any tighter and my car is undrivable, but that is due to my having coilovers

iconoclast · 21st December 2007, 18:56

Redshift · 21st December 2007, 22:24

Interesting idea. I have both cars (540 and M5) set to max oversteer, but lately have been considering going back to the middle setting, to see how it would affect the feel. Let us know if you try this uneven setup and if it works for you.

drallen · 22nd December 2007, 04:07

Quote:

Originally Posted by Redshift

Interesting idea. I have both cars (540 and M5) set to max oversteer, but lately have been considering going back to the middle setting, to see how it would affect the feel. Let us know if you try this uneven setup and if it works for you.

You have not been happy with the inside hole?...IIRC you and I were the early adapters on our GC shocks...I am now running the #430s up front and the #280s (pain in the arse to change them) in the back (14.5" F/14"R)...am I wrong in thinking that if I add more bar to my rear end that it will help me more in my lateral stability in the turns?...Sometimes I bottom out on the bumpstops and get a little squirrelly...I was thinking of adding more bar to help this with out changing the springs...any thoughts on this?

Thanks,

Mark

khiroshima · 22nd December 2007, 05:32

I guess this might make sense if I only made right (or left) hand turns, seems you would want to optimize for a variety of conditions rather than just one since this is a road vehicle-- JMO, KH

E55AMG2 · 22nd December 2007, 06:24

more bar in the rear = more bump steer in the rear. More stability = understeer.

mottati · 23rd December 2007, 06:37

Quote:

Originally Posted by khiroshima

I guess this might make sense if I only made right (or left) hand turns, seems you would want to optimize for a variety of conditions rather than just one since this is a road vehicle-- JMO, KH

You can have uneven settings and it will have the same effect on any turn. All you are doing, essentially, is adjusting the torsional stiffness of the bar. they don't have to be even.

I'm pretty pleased with them at the middle setting on both, but haven't been to the track in a while. Used to run 275/285, with the slight stagger, the middle hole was good for me. Now running 275 x4, so maybe i'll back one side off to the softer setting, if the car feels twitchy or loose at the next track event. It's fine as is on the street.

mottati · 23rd December 2007, 06:39

Quote:

Originally Posted by drallen

You have not been happy with the inside hole?...IIRC you and I were the early adapters on our GC shocks...I am now running the #430s up front and the #280s (pain in the arse to change them) in the back (14.5" F/14"R)...am I wrong in thinking that if I add more bar to my rear end that it will help me more in my lateral stability in the turns?...Sometimes I bottom out on the bumpstops and get a little squirrelly...I was thinking of adding more bar to help this with out changing the springs...any thoughts on this?

Thanks,

Mark

Mark, are you thinking if you add more torsional stiffness to the bar, it will be like increasing the effective spring rate at the rear? Not sure if that will work, would think it would just make the rear looser, as if you made the rear shocks stiffer.

Lscman · 23rd December 2007, 07:32

Quote:

Originally Posted by khiroshima

I guess this might make sense if I only made right (or left) hand turns, seems you would want to optimize for a variety of conditions rather than just one since this is a road vehicle-- JMO, KH

As was explained, uneven setting on right and left swaybar link connection does not result in uneven torque or force applied for right and left turns. The car will behave EXACTLY the same making right and left turns under any conditions. A swaybar does not behave like a torsion bar spring attached to the chassis, where the right and left side must be precisely matched for balanced handling. Don't confuse a spring with a swaybar. A swaybar does not need to be symmetrical R->L to perform properly. This unconventional swaybar adjustment strategy simply offers two extra (perfectly balanced) settings for fine tuning, in addition to the standard 3.