Lower Control Arm Pivot Bushing
This is a prime example of why you use stock replacement parts instead of the “trick of the day” Bullshit aftermarket “upgrade” Parts.
in my opinion of course.
Why do my urethane bushings squeak
they don’t fit right
they ride too hard
they squeak I’ve speed bumps
they didn’t last
The press fit of the bushing holds it in there. The strut rod provides the triangulation to keep it in alignment while driving. The strut rod connects to the opposite end from the bushing, that’s not what holds it together.
Polyurethane LCA bushings do not work the same as the OE rubber bushings. You have to understand that
before you decide to use them. The OE rubber bushings are friction fit into and onto the inner and outer shells. That friction fit does not allow them to slide, assuming the strength of the rubber is not exceeded. If that happens they just tear, rubber isn't very strong. What that means is that the entire motion of the lower control arm depends on the flex in the rubber. Which is why with OE rubber LCA bushings the pivot nuts must be tightened at ride height, because the rubber can only flex so far. The LCA has to be in the middle of the range of travel when the pivot nut is tightened, so, half the motion is flex up in the bushing and half the motion is flex down. Otherwise, the bushing tears, because rubber has very little shear strength.
With poly, or Delrin LCA bushings the material of the bushing is harder. It does not flex like rubber, and so the motion of the LCA can not depend on the material flexing. Instead, with a poly or Delrin LCA bushing the bushing itself has to spin when the LCA moves up and down. That motion should happen at the LCA pivot, the bushing spins on the pivot itself. This is unlike the OE bushings, and because there is motion of the bushing on the pivot pin there must be lubrication. If a poly bushing is squeaking, it is improperly lubricated. Period. This means it was improperly installed, and if it's driven like that for any length of time it will fail prematurely. That's not the bushings fault, that's poor installation and maintenance. There are aftermarket LCA pivots that are greaseable for this reason, you can add grease to the bushing and keep the poly lubricated. That keeps it from failing.
Poly bushings are not maintenance free. Properly maintained and lubricated, poly bushings will far outlast rubber bushings. Especially the low quality rubber bushings being made today.
And yes, the fit of the poly bushing in the shell and onto the pin is important. If you buy the kind of poly bushings that come without inner and outer shells, you must assure that they fit tightly. The OE bushing shells are not all identical, the thickness varies, and if the rubber is damaged the shells can be damaged. So you can't just slap poly bushings into the old shells, you have to make sure that they fit with a TIGHT slip fit. As in, they should require lubrication and some effort to put them into the shells. If they just loosely fall into the shells, the shells need to be replaced.
The "problem" with poly bushings is that guys that don't understand that they function differently than the OE rubber bushings they're replacing. They're installed differently, and they must be maintained differently. Instead people think it's a shortcut to get around removing the old inner and outer shells, so they don't need a press. But that only works if the bushings fit tightly in the shells. Like any aftermarket part, you have to check the fit!!! If the fit isn't right, you have to fix it. And poly bushings MUST be lubricated. They should NEVER squeak. If they do, it means they've dried out and must be re-lubricated.
It's no different than anything else. The factory used non-adjustable rockers and hydraulic lifters (mostly). Well, if you upgrade to adjustable rockers and solid lifters, you have to adjust them properly and maintain them. If you do that, you get better performance. But you have to understand how they work differently. If you don't understand that, then you should probably stick with the lower performance original stuff that doesn't require maintenance.