Pivot shaft problems
I don't have aftermarket pivot shafts, just 2 sets of stock pivot shafts with stock nuts.
@72bluNblu I've seen your posts about tightening them without them being loaded by suspension and have actually tightened most of the suspension components except for the LCA's (due to this problem). You said you use an impact- do you use an air or electric impact? I have both but the strength of them is totally different, or does it not matter.
I always use greaseable pivot shafts, but I have not used the polygraphite bushings that PST sells, just regular poly. I know that the polygraphite is supposed to be self lubricating, so in theory it should not require greaseable pivots. But as I haven’t personally used them myself, I don’t know if they’re truly 100% self lubricating in actual practice, and if that holds up for their entire life.
I use an electric impact, and it’s a 3/8” drive not a 1/2” so it isn’t a massive amount of torque. I don’t use it to final torque the pivots, I use it to spin the pivot nuts fast enough that they grab and exert pressure on the pivot before the pivot spins. Here’s the other thing, you don’t have to be that careful with the torque. The greaseable pivots I use spec a 100 ft-lb final torque on pivot nuts. That’s A LOT. I forget that exact spec in for the stock pivots, but it’s 75 or 90 ft lbs. As in, you need a long handled 1/2” drive torque wrench and some muscle to get to that. It’s not easy. So I wouldn’t worry about using the impact, you’re very unlikely to over torque those pivot nuts.
Also, as pointed out already those nuts are usually lock nuts of some kind. The factory version are usually the type that have an eccentric lock thread, so they don’t thread on smoothly. Once you get more than a few threads on you’ll hit the “lock” threads and it will take effort. Which will spin the pivots if you have poly bushings. Hence the impact to spin the nut fast enough to override the tendency of the pivot to spin.
The factory procedure of torquing them at ride height is for the factory style rubber bushings. The factory rubber bushings are friction fit to the inner and outer shells, meaning, nothing spins. So the entire suspension travel comes out of the flex in the rubber bushings. So they have to be torqued in the middle of the range of travel of the suspension, half the travel is flex up, half the travel is flex down. The rubber doesn’t have enough flex to cover the whole travel. Which means if you tighten the pivots with the suspension hanging, the rubber tears after it gets a bit more than halfway through the travel. It will usually flex enough to sit down to ride height, but the next big suspension compression tears the bushings.
With poly bushings the bushing can spin in the outer shell or on the pivot. The travel is not dependent on the poly flexing, because it doesn’t flex much at all. So instead the suspension travel spins the LCA on the bushing or the bushing on the pivot. That’s why lubrication is important for poly bushings, and also why it doesn’t matter where you torque them. If the poly bushing isn’t lubricated, heat builds up from the friction of the bushing spinning on the pivot or in the shell. That’s why they squeak and deteriorate if not lubricated. Nothing spins in the OE rubber bushings, which is why those don’t need to be lubricated. So if your poly bushing starts squeaking, it means it needs more lubricant.
Which is why the people that complain about their poly bushings squeaking are also the same people that complain about them failing. All it means is they don’t know how to properly maintain a poly bushing. If someone told you a certain brand of oil turns to sludge after 20k miles you’d blame them for not changing their oil, not the oil for turning to sludge right? Same deal with poly bushings. They aren’t rubber, they don’t get maintained the same way.
