Sway bar bind / Polyurethane bushings HELP!
Posted: Wed Sep 03, 2014 7:14 pm
Hey guys, so I was just reading an article for an STS miata build and skimmed across the following:
"While sizing the bars is important, mounting them for optimal performance is critical. Particular attention must be paid to removing any tendency for bind. This is especially important when urethane frame mount bushings are used. These typically are sized too tight. In almost every off-the-shelf aftermarket application I’ve ever seen, these required some modification to facilitate smooth movement. Lubing the inside of the bushing will provide some temporary relief, but under pressure, the lube will just be forced out over a very short period of time. Once that happens, the bar will act a lot stiffer than it is or it will be erratic. It will also start to fatigue the frame attaching hardware or the frame itself. It is common to see either the saddle bracket or frame extension on a Miata cracking from improper front bar installation.
To fix this problem, there are two easy solutions. One is to grind away some of the material from the flat outside part of the D_shaped bushing. Alternatively, you can put a washer or two under the saddle mount to shim it up. I prefer the former method. Ultimately, you are looking to be able to smoothly move the bar arms up and down when the end links are disconnected."
Does this have any merit? My car is currently having all bushings converted to polyurethane and the sway bars front and rear are stock. If my mechanic installs the urethane bushings on a stock bar will I experience any of this binding? Please let me know if anyone has experience with this or can offer hands on advice. Thanks as always!
-Chris
"While sizing the bars is important, mounting them for optimal performance is critical. Particular attention must be paid to removing any tendency for bind. This is especially important when urethane frame mount bushings are used. These typically are sized too tight. In almost every off-the-shelf aftermarket application I’ve ever seen, these required some modification to facilitate smooth movement. Lubing the inside of the bushing will provide some temporary relief, but under pressure, the lube will just be forced out over a very short period of time. Once that happens, the bar will act a lot stiffer than it is or it will be erratic. It will also start to fatigue the frame attaching hardware or the frame itself. It is common to see either the saddle bracket or frame extension on a Miata cracking from improper front bar installation.
To fix this problem, there are two easy solutions. One is to grind away some of the material from the flat outside part of the D_shaped bushing. Alternatively, you can put a washer or two under the saddle mount to shim it up. I prefer the former method. Ultimately, you are looking to be able to smoothly move the bar arms up and down when the end links are disconnected."
Does this have any merit? My car is currently having all bushings converted to polyurethane and the sway bars front and rear are stock. If my mechanic installs the urethane bushings on a stock bar will I experience any of this binding? Please let me know if anyone has experience with this or can offer hands on advice. Thanks as always!
-Chris