Since we last worked on the suspension of our IS-F project, we noted that Sikky Manufacturing, our rear sway bar manufacturer, had since come out with a new adjustable front sway bar. Since we would take the front suspension apart to replace the lower control arm bushings with new parts from Figs Engineering, we figured why not change the front swaybar with the new Sikky. One of the things we had noted with a bigger rear bar and a stock front car is that the car was slightly loose or more biased toward oversteer unless we had the rear bar adjusted fully soft. We wanted a stiffer front bar so we could dial up the rear bar add some more roll stiffness and keep the car neutral. An IS-F is still a luxury sedan and we wanted to get rid of more body roll.
The front Sikky bar is 28mm in diameter which is actually the same diameter as the stock bar. However, both the Sikky bar and stock bars are tubular and the Sikky has a thicker wall. We can tell because it is much heavier than stock.
The Sikky bar is 3-way adjustable which is very useful when it comes to tuning the suspension to your liking. The soft position is about where it is on the stock bar, the middle position is about where we had modded the stock bar end links to pick up and the inner stiff position is almost 1″ forward of that. That gives about a 15% increase of bar roll resistance over how we had it and about 27-32% stiffer than the stock bar just by endlink positioning alone. That does not count the gain from the increase in wall thickness.
Like the stock front bar, the Sikky bar has these bushing stops to keep the bar from moving from side to side.
3 comments
It’s strange to me how endlinks are never in double shear on both sides. I imagine this is to prevent binding, but couldn’t you just design it with a clevis on the swaybar end?
Seems like it would improve the response of the bar.
The heim jointed end links used (above pic) have no give when loaded, and offer the same response as a double shear link would.
Some manufacturers rate their bars, in lb/in, usually done on a test rig with no bushings, one end pinned and loaded on the other end.
On a custom application with a 1.13″ dia bar with long arms, we found that the rate based on the Puhn formula was almost twice the rate measured rate with poly bushings. We determined the difference was due to rigid body deflection of the bar, that only needed a few mils of deflection at the bushings.