A sway bar link question for the experts please

[raygreenwood]

So....I just changed the front sway bar links on my 2012 Golf. They were shot at 88k miles. They rattled. Very easy......and the key to this before I come to the question.....is that changing them....not only restored the minor amount of roll control I had lost (they were worn and loose.....not snapped or broken). .....but restored quite a bit of shock absorber control I had not noticed I lost.

The point: looking at how these are attached....I am not really surprised they also restored some straight line shock absorber function in driving. I am just struggling to find the right way to explain how this newer more modern method of end link attachment is that much different than the method used in my VW 412.

I will post some pictures of each in the next day but the text explanation:
On the 412 with McPherson struts.....the swaybar is mounted forward on the body with the ends trailing aft. At each end of the swaybar.....you have a block of rubber cast into a steel hoop with a 10mm stud on the bottom. That stud with the block attached bolts into the control arm on each side of the car....about 2" from the ball joint at the bottom of the strut.
As you can visualize....any vertical motion of the end of the control arm twists on the sway bar. The rubber block in the hoop has a hole in it that the end of the sway bar fits in. Anti-vibration bushing.

Ok.....the Golf....has roughly the same shaped sway bar but its mounted aft of the suspension subframe. I don't see this as a difference.....its simply necessity as the drivetrain is whats in the way of mounting it forward with arms trailing aft.
The difference is that the end link on each side......is a rod about 16" long with a fixed tie rod/ball joint on each end. These are a spherical ball stud within a solid nylon packing....no spring inside......and a rubber boot. The bottom end of each link bolts to the end of the sway bar...and the top bolts to the strut body tube about 1.5" below the lower spring perch. As the strut rotates while you turn.....the ball joint at each end rotates in opposite directions so twist is not applied to the rod.

Now....in my mind.....the golf sway bar links should be doing the exact same thing as my 412 sway bar links. On both.....as the control arm moves up and down.....the lower strut body below the spring moves up and down with it at the same rate. Theoretically.....attaching the end link to EITHER the control arm or the strut body SHOULD have the same action/effect on the sway bar.

But......I have actually driven my 412 for a short period without the sway bar when I was sourcing new bushings. It had poor roll control. ....but no noticable difference to shock/ride control action.

The golf on the other hand......the sway bar exhibits significant shock/ride control action.
One more note....neither sway bar is pre-loaded by the end links .....ooooh.....wait.....the Golf is not loading the sway bar....when the wheel is off the ground....meaning I did not have to compress anything to remove and install the links. Just lift one side....remove wheel.....loosen upper and lower nuts on the ends of the links....and swap in the new ones......so I am assuming the golf links are not preloading the sway bar.

So....why are the Golf sway bar links exhibiting so much more effective ride control that the old style of end link my 412....and for that matter....super beetle and other cars?

I am speculating that if the sway bar on the Golf is getting pre-load by lifting one end and dropping the other as the wheel turns....which does move the sway bar link in an arc at the top....which probably lifts that end of the swaybar upward....even though the control arm is only moving a slight amount. I am speculating that this method of attachment makes the sway bar sensitive to not only the vertical axis of motion caused by the strut compressing and moving the control arm in the vertical....but also to rotational movement of the strut.....and castor change.

And....I am wondering if I could improve my 412 handling by installing swaybar links like this.

Sorry for the narrative. If it gets you thinking I will post some pics. Ray

[Piledriver]

Pictures... might need to measure things and draw it out.
If jacking up one side doesn't load it, its not working like a sway bar should.
Somethings missing from the model.
Maybe its a "Z" bar?

Note the Golf weight distribution is ~backwards from the ACVWs, so both the springing/damping and likely sway bar logically are much stiffer.

[raygreenwood]

Yes....when its on the ground....both wheels...there is some swaybar loading. With one wheel on the ground and the other off the ground...there is no pre-load on the side off the ground which is not surprising as the strut is at full extension....but there would have to be pre-loading on the side that is on the ground.

If both wheels were off the ground and both struts at full extension....because the bar rotates 1:1 on both sides...there would be no pre-loading on the Golf.

I think I kind of answered my own question last night. I will post pics by tomorrow.

As I noted....the Golf sway bar links are not just sensitive to up and down motion of the control arm like the bar in my 412. Because the top joint of the link moves fore and aft as the strut body turns through its arc...because they are attached to the strut body instead of just the control arm......they lift/load the end of the sway bar.

Also....and this is also the key.....these tie rod ends on each end of the Golf centerlink...are solid with respect to lateral motion. in line with the connecting rod. They are essentially working in the same function as using heim joint outer links like the Porsche track guys and high performance water cooled guys use. They are that solid....and that responsive.....but they are just more weatherproof for the street. I had to dig back in modifications notebook to remember this....

Back in the 90's.....while trying to get better control of the rear end of my 412....before I cooked up the double sway bar mod that solved it....I took one of my spare sway bars and drilled the ends for heim joints.

The control/sensitivity effect of no longer having a rubber joint on the bar end and a rubber joint on the trailing wishbone end....was outstanding. However...heims don't live long on the street. Constant dust, rain etc....and even with monthly greasing and cleaning....they get to chattering and sieze. I busted about 6 of them over a year living in Dallas. It was still a lot of miles...but a lot of work. These were chromolly heim joints made just for suspension.

The outer links many of the watercooled modern cars are using....work just like a heim joint in the fact that they change axis for sensitivity...but have no flex or play in them.
This is the aftermarket Whiteline brand links http://www.whitelinesuspensionparts.com ... aQodtZYHIA

You should see the outer links my sisters 2009 Audi A4 has....they are cast aluminum monsters.
Like these http://www.ebay.com/sch/Audi-A8-Quattro ... 927/i.html

Ray