Cal Club Autocross Forums

Reconnecting the sway bars after corner balancing. In order to re-attach the rear end links to that there is no pre-load, I find that on the Right hand side I get binding unless I bottom mount the top of the end link. I'm thinking this might change the leverage on the bar and in this case slightly reduce the sway bar force? Yes ... No ?

Could your bar have shifted (slid) left to right/right to left a tad? Otherwise, I think the endlinks should be installed as if the car is on a level surface, which you can do by putting the same height of blocks, etc. under the wheels to get it up in the air but have the wheels, shocks, etc. as if on the ground. No?

Yup, car is sitting on ramps with all of it's weight present. Could try shifting bar to the left ... so that the angle works better on the right, so I can go back to top (outside) mounting it on top.

Thanks Ed ... that did it. Both endlinks are now mounted to the outside with no binding.

Think it's time to stop ...

I can't really see the geometry of the bar ends from the picture, but it seems like the way you mount the endlinks would change the leverage for twisting the bar. As a rough estimate of how much, measure the distance from the center of the endlink bushing to the axis of the actual swaybar. If this changes between the two configurations then you're changing the leverage on the bar.

Seems like you want the same leverage on both sides. Otherwise, when you go over a bump with both wheels, it will twist the bar and transfer some suspension force from one side of the car to the other. Normally, on a both-wheel bump, the bar should MOVE, but not TWIST.

sc

Seems like you want the same leverage on both sides. Otherwise, when you go over a bump with both wheels, it will twist the bar and transfer some suspension force from one side of the car to the other. Normally, on a both-wheel bump, the bar should MOVE, but not TWIST.

Years ago I spent an hour on the phone with Carroll Smith discussing exactly this. His opinion was that it doesn't matter on a race car. You will never hit the exact same size bump at the exact same time with both front or rear wheels on a race track at a place on the track that matters. And even if you did, the rate delta between the sides would be insignificant.

John Coffey wrote:

Seems like you want the same leverage on both sides. Otherwise, when you go over a bump with both wheels, it will twist the bar and transfer some suspension force from one side of the car to the other. Normally, on a both-wheel bump, the bar should MOVE, but not TWIST.

Years ago I spent an hour on the phone with Carroll Smith discussing exactly this. His opinion was that it doesn't matter on a race car. You will never hit the exact same size bump at the exact same time with both front or rear wheels on a race track at a place on the track that matters. And even if you did, the rate delta between the sides would be insignificant.

You've got one critical flaw with you reasoning. Under braking you will get substantial parallel wheel travel and get diagonal weight transfer with non equal sway bar arms usually right at turn in. Whether its significant or not is a different question.

You've got one critical flaw with you reasoning. Under braking you will get substantial parallel wheel travel and get diagonal weight transfer with non equal sway bar arms usually right at turn in. Whether its significant or not is a different question.

We discussed that and came to the conclusion that, unless the sway bar ends are a locating link in the suspension or you get bind, the bar is just a spring with the load spread (mostly) evenly on both sides. In my discussion with Carroll we were using a total suspension travel of 2" as the basis. The bind issue would be my big concern with end links that are not in the same plane or angles.

Marshall is right in the case of an asymmetric arm length or motion ratio between the two sides. For an asymmetric endlink mounting angle but using symmetric holes, I'd say that you will end up with the same motion ratio on both sides if the bar end and mounting hole on the arm don't move relative to one another in the same direction as the offset in the position of the endlink joints. Or looking at it another way, if the endlink's two ends move in parallel planes, and the projection of the endlink onto those planes is the same for both sides of the car, then the spring behavior of the swaybar will be the same as if the endlinks were really symmetric. But they do likely produce an asymmetric thrust in the directions that those components are not supposed to move in -- such as the swaybar sliding to one side. You can constrain the bar with a collar next to each bushing, but that will transmit the load onto whatever the bar is mounted to. On a Miata, the stock mounting point is pretty weak to begin with and isn't shaped to resist lateral loads effectively.

Best thing you can do is throw away those RB links and get yourself something with proper rod ends. Those give you all kinds of stiction and binding issues, adding a lot of hysteresis and unpredictability to it's action.

Thanks Steve ... that's what was on the car ... I might actually have some better end links

Steve Lepper wrote:stiction

I thought you just made this up, but I just looked it up and it's legit.

Yeah, th RB links might be an improvement over the stock NA rubber links, but they are a downgrade from stock NB. Too long, and the joints are so stiff it's like they aren't really jointed.

Yeah. Marshall was right.