LCA Bushings and Other Bushings
I don't know why I bother, but what the heck.
Yes, you can improperly install poly bushings. The "slap them in and slap the pins in" mentality is exactly why people have problems with them. Because the original style of poly bushings reuse the factory bushing shell, the fit between the bushing and the shell has to be checked and it has to be right. It should be a tight slip fit, like autoxcuda shows in his post. The same is true if you re-use the factory pin and inner shell, it has to fit properly. The factory shells are not all the same dimensions, when I installed my Delrin LCA bushings I measured 4 different sets of factory pins with their inner shells still in place and got 4 different numbers. All were close, but they were more than enough to alter the slip fit on the bushing. If the poly bushing is loose in the outer shell, or the pin is loose in the bushing, you have to correct that fit. If you don't, they will fail- and that's improper installation.
The strut rod maintains the track of the LCA. If you use the factory strut rods and bushings, the large rubber bushings will allow the LCA to move around. They do that with the OE LCA bushings too, btw, it's just flex instead of slip. The torsion bar may ultimately stop the LCA from falling off, but it would allow it to move entirely too far to maintain an alignment.
I don't need to "try this for myself", I do it everyday. As I have explained a hundred times, I daily drive my cars with these bushings that you couldn't make one pass down the track with. I run 275mm wide FRONT tires on them. That also means I have almost no extra clearance to the fenders. If my tires moved back and forth a 1/2" every time I stepped on the brakes, I would have destroyed my tires AND my fenders on two different cars. Nevermind that a 1/2" movement at the lower ball joint would result in a MASSIVE change in the caster angle, making the car straight up scary on the street. Properly installed poly bushings, with proper length strut rods, do not allow the kind of movement you describe. If they did, I couldn't drive my car everyday. It would not hold an alignment, and it does just fine.
I don't know why your car did what it did, or why your customer's Challenger did. But I can assure you that properly installed poly bushings, used with the proper length strut rods, don't do that.
Gun drilling a small hole for grease does almost nothing to weaken the pin. With the proper materials, the grease hole is not a structural issue. I've used Firm Feel's greaseable LCA pins for tens of thousands of miles on both my Challenger and my Duster, both with 275mm front tires and 1.12" torsion bars. Those pivot pins failing is the least of my concerns.
I'm glad you're making your own LCA pins now, because the 3rd party ones you recommended I buy for your Delrin LCA bushings didn't fit properly at all, they rattled around in the bushing. The Firm Feel pins fit perfectly, even if I don't ever need to re-grease the Delrin.
The easiest way to remove the inner shells is with a large tap...
And I do not like that extra poly material pushed out around the pin. The whole point of the poly is that it should rotate smoothly on the pivot pin. I very much doubt those will do that.
Exactly. The bushings and pins should be a tight slip fit. Another street and road course driven car that hasn't had any issues with poly LCA bushings. It's almost like the LCA sliding off the back of the pivot pins with poly bushings is total hogwash.
I don't know why I bother, but what the heck.
Yes, you can improperly install poly bushings. The "slap them in and slap the pins in" mentality is exactly why people have problems with them. Because the original style of poly bushings reuse the factory bushing shell, the fit between the bushing and the shell has to be checked and it has to be right. It should be a tight slip fit, like autoxcuda shows in his post. The same is true if you re-use the factory pin and inner shell, it has to fit properly. The factory shells are not all the same dimensions, when I installed my Delrin LCA bushings I measured 4 different sets of factory pins with their inner shells still in place and got 4 different numbers. All were close, but they were more than enough to alter the slip fit on the bushing. If the poly bushing is loose in the outer shell, or the pin is loose in the bushing, you have to correct that fit. If you don't, they will fail- and that's improper installation.
The strut rod maintains the track of the LCA. If you use the factory strut rods and bushings, the large rubber bushings will allow the LCA to move around. They do that with the OE LCA bushings too, btw, it's just flex instead of slip. The torsion bar may ultimately stop the LCA from falling off, but it would allow it to move entirely too far to maintain an alignment.
I don't need to "try this for myself", I do it everyday. As I have explained a hundred times, I daily drive my cars with these bushings that you couldn't make one pass down the track with. I run 275mm wide FRONT tires on them. That also means I have almost no extra clearance to the fenders. If my tires moved back and forth a 1/2" every time I stepped on the brakes, I would have destroyed my tires AND my fenders on two different cars. Nevermind that a 1/2" movement at the lower ball joint would result in a MASSIVE change in the caster angle, making the car straight up scary on the street. Properly installed poly bushings, with proper length strut rods, do not allow the kind of movement you describe. If they did, I couldn't drive my car everyday. It would not hold an alignment, and it does just fine.
I don't know why your car did what it did, or why your customer's Challenger did. But I can assure you that properly installed poly bushings, used with the proper length strut rods, don't do that.
Gun drilling a small hole for grease does almost nothing to weaken the pin. With the proper materials, the grease hole is not a structural issue. I've used Firm Feel's greaseable LCA pins for tens of thousands of miles on both my Challenger and my Duster, both with 275mm front tires and 1.12" torsion bars. Those pivot pins failing is the least of my concerns.
I'm glad you're making your own LCA pins now, because the 3rd party ones you recommended I buy for your Delrin LCA bushings didn't fit properly at all, they rattled around in the bushing. The Firm Feel pins fit perfectly, even if I don't ever need to re-grease the Delrin.
The easiest way to remove the inner shells is with a large tap...
And I do not like that extra poly material pushed out around the pin. The whole point of the poly is that it should rotate smoothly on the pivot pin. I very much doubt those will do that.
Exactly. The bushings and pins should be a tight slip fit. Another street and road course driven car that hasn't had any issues with poly LCA bushings. It's almost like the LCA sliding off the back of the pivot pins with poly bushings is total hogwash.
