Adjustable Strut Rods
Ok, this is the last time I'm going to address Oldmanmopar directly. I know I won't convince him that he's wrong, but hopefully other members here will be able to understand how a poly or Delrin LCA bushing works differently than a rubber bushing. And why that isn't at all a problem (and can in fact be an advantage) as long as you take care of the poly or Delrin bushings according to their material and design.
This will be long, because I'm going to take each and every one of oldmanmopar's assertions and explain why his logic is flawed. I'm not going to call him any names, because I know he calls me names because he can't put together a logical argument.
I've successfully installed and used poly and Delrin bushings for years and tens of thousands of miles. I know they work, and I know that properly installed and maintained they work better than rubber. That's not my opinion, that's a fact, they're on my car right now and I use it everyday. I've never replaced a failed poly bushing- I've never had to because none of mine have ever failed.
So here your claim is that the LCA is not held in place from moving fore/aft on the LCA pin by the strut rod, but is somehow held in place by the rubber in the OE rubber bushing. Rubber isn't structural so that's pretty much impossible, but let's pretend.
The LCA is a rigid bar. The strut rod passes through a sleeve in the LCA and then is tightened on the back side, which pushes the LCA against a shoulder on the strut rod. That connection fixes the fore/aft movement of the LCA to the strut rod. In order for the LCA to move fore and aft at the other end like you're describing one of a few things would have to happen -
1. The LCA would have to move around on the strut rod at the connection- that movement is minimal, the strut rod is a slip fit on the LCA and then is held fixed between the nut on the strut rod and the shoulder on the other side
2. The strut rod would have to flex. That's possible with rubber strut rod bushings- but with an adjustable strut rod, and the pivot at the heim being at an angle to the LCA, there's very little movement there in that direction. Add a very stiff LCA bushing and there's little lateral flex at that end. So the strut rod itself would have to bend
3. The LCA would have to flex on the LCA bushing- again, some movement there is possible with rubber LCA bushings. But with poly, and even more so with Delrin, there's little to no flex there.
So what does that mean? If the LCA can't flex at the strut rod joint, or at the LCA joint, then it can't move backward independent of the strut rod. It's positively located fore/aft by the strut rod.
This is a false example. There's no accounting for the strut rod. The rubber mounted LCA will flex back and forth on the bushing. The poly mounted LCA will not flex on the bushing, but will slide up and down on the pin. That movement is eliminated by the presence of the strut rod, as stated above.
You wouldn't run your rubber LCA bushings without a strut rod would you? Of course not, they'd tear. That's the comparison you're making there, and it's not relevant to the assembled suspension system.
This is actually a perfect example of WHY people use poly and Delrin LCA bushings. Yes, the poly and delrin bushings allow the LCA the hang down. They offer no resistance to the movement of the LCA. The rubber, on the other hand, holds the LCA up because the rubber has to flex for the LCA to move. That resistance keeps the LCA from moving freely- it's basically binding that's built into the factory bushings. The LCA being able to move up and down without resistance provides better feel and suspension response.
I have the tools and tooling to install and remove OE bushings. In fact I've done it several times, just not on my cars. I have a 20 ton press and a tap to fit inside the outer LCA shells. I needed that to install my current set of BAC delrin bushings, because the delrin LCA bushings do not use the old outer shells. You can see my removal of the OEM bushings and installation of the Delrin bushings here. My "new" '74 Duster- or why I need a project like a hole in the head Along with all of my tools to do it. Again, you're making false assumptions here, and obviously aren't familiar with how to install these parts.
Hey look, there's the press I'm using to remove a OEM outer sleeve
Hey look, there's the old outer sleeve that's been pressed out and the tap I used to do it
Hey look, here's me pressing in the new Delrin LCA bushings. Oh, yeah you need a press to install those, they don't just slip in.
Some of this is right, once the bushings are installed in the LCA and the LCA installed on the pin they should be tight.
But they are NOT self locating. If the strut rod isn't the right length, the LCA will not stay tight against the shoulder on the pin. If you use strut rods that are too long, they will push the LCA and bushing backward on the pin like in the picture you posted earlier. That is exactly how you install the bushings the wrong way, it's an improper installation.
This is where you're fundamentally wrong about how the poly and delrin bushings function. With the OEM bushings all of the up/down movement of the LCA is flex in the rubber, nothing spins or slides. When the rubber tears, the LCA can spin, slide, and flex on the pin even more because the rubber is no longer intact.
With a poly or delrin bushing, the LCA bushing is DESIGNED to spin on the LCA pin. But unlike a failed rubber bushing, there's is very little flex in a poly bushing. And almost no flex in a delrin bushing. So there is no flex and slop like there is with a failed rubber bushing. The pin is held tightly in the bushing radially, and the bushing spins on the pin. As it is designed to.
Poly only "turns to powder" if it is not properly lubricated. There's really only two possibilities for your failed bushings. One is that those bushings were just defective. But since you claim that you have had multiple failures of different bushings, that's unlikely.
The common denominator is that you're the one maintaining them. Which points directly at improper maintenance. Sorry, but as I've said I have had great success using poly bushings for over a decade now, and tens of thousands of miles in multiple applications. If none of your poly bushings last, you're the problem. That's not me making it personal, those are just the facts. Plenty of people use poly bushings with great success. If you've never used one with success, you're clearly doing it wrong.
Every single one of your concerns here is based on your fundamental misunderstanding of how the poly bushing works. They are not the same as the rubber bushings. Totally different material, totally different design, totally different function. You can not make a comparison to a failed rubber bushing, there is no parallel between the two.
I already addressed this. This picture depicts an IMPROPER INSTALLATION.
The bushing is NOT tight against the shoulder of the LCA pin. That means that the strut rod is too long, not installed, or not installed properly. This is the wrong way to install poly bushings, and a perfect example of why adjustable strut rods should be used when they're installed.
Also, I would appreciate if you linked the source thread for this picture. That member needs to correct this, as that's a catastrophic failure waiting to happen.
You are stating something that isn't logical. You can't pry the LCA back out of the K frame if the strut rod is the correct length. What you're describing is not possible if the poly or delrin bushings have been properly installed and the strut rod is the proper length.
In fact, if you CAN do what you described and pry the LCA back on the LCA pin while the suspension is fully assembled it proves you've done the installation incorrectly, and something needs to be adjusted.
PST is a pretty great resource for the members of this site. Not just with parts, but clearly with knowledge of how they're used. I don't agree with 100% of the things I've seen PST post here, and I don't use all of their products either. But clearly they have a pretty good idea of what they're talking about, and compared to most sellers they're very knowledgeable about the parts they offer.
Firm Feel is also a great resource. I'm mentioning them here because of the complete BS that's been posted about their greaseable LCA pins. They make the pins, they do not manufacture poly or Delrin LCA bushings. They make the greaseable pins because they work, and they're a great way to properly maintain the bushings that their customers use. Not so they can sell bushings. Firm Feel has been making parts for handling mopars for DECADES now. Their knowledge and experience is bar none. They were literally one of the first companies to make parts for handling mopars, and their parts are proven in both performance and durability. They were literally the only game in town for a long time, and still compete with the big names like Hotchkis. That's saying something.
Hopefully this explains how these parts work for people so they can make an informed decision. And I'm not saying that rubber LCA bushings don't have their use, they absolutely do. Poly bushings aren't necessary for every build, there's nothing wrong with that. Delrin bushings aren't right for every build either. But if they're properly installed and maintained, they work VERY well, and will outlast and outperform rubber LCA bushings.
Ok, this is the last time I'm going to address Oldmanmopar directly. I know I won't convince him that he's wrong, but hopefully other members here will be able to understand how a poly or Delrin LCA bushing works differently than a rubber bushing. And why that isn't at all a problem (and can in fact be an advantage) as long as you take care of the poly or Delrin bushings according to their material and design.
This will be long, because I'm going to take each and every one of oldmanmopar's assertions and explain why his logic is flawed. I'm not going to call him any names, because I know he calls me names because he can't put together a logical argument.
I've successfully installed and used poly and Delrin bushings for years and tens of thousands of miles. I know they work, and I know that properly installed and maintained they work better than rubber. That's not my opinion, that's a fact, they're on my car right now and I use it everyday. I've never replaced a failed poly bushing- I've never had to because none of mine have ever failed.
So here your claim is that the LCA is not held in place from moving fore/aft on the LCA pin by the strut rod, but is somehow held in place by the rubber in the OE rubber bushing. Rubber isn't structural so that's pretty much impossible, but let's pretend.
The LCA is a rigid bar. The strut rod passes through a sleeve in the LCA and then is tightened on the back side, which pushes the LCA against a shoulder on the strut rod. That connection fixes the fore/aft movement of the LCA to the strut rod. In order for the LCA to move fore and aft at the other end like you're describing one of a few things would have to happen -
1. The LCA would have to move around on the strut rod at the connection- that movement is minimal, the strut rod is a slip fit on the LCA and then is held fixed between the nut on the strut rod and the shoulder on the other side
2. The strut rod would have to flex. That's possible with rubber strut rod bushings- but with an adjustable strut rod, and the pivot at the heim being at an angle to the LCA, there's very little movement there in that direction. Add a very stiff LCA bushing and there's little lateral flex at that end. So the strut rod itself would have to bend
3. The LCA would have to flex on the LCA bushing- again, some movement there is possible with rubber LCA bushings. But with poly, and even more so with Delrin, there's little to no flex there.
So what does that mean? If the LCA can't flex at the strut rod joint, or at the LCA joint, then it can't move backward independent of the strut rod. It's positively located fore/aft by the strut rod.
This is a false example. There's no accounting for the strut rod. The rubber mounted LCA will flex back and forth on the bushing. The poly mounted LCA will not flex on the bushing, but will slide up and down on the pin. That movement is eliminated by the presence of the strut rod, as stated above.
You wouldn't run your rubber LCA bushings without a strut rod would you? Of course not, they'd tear. That's the comparison you're making there, and it's not relevant to the assembled suspension system.
This is actually a perfect example of WHY people use poly and Delrin LCA bushings. Yes, the poly and delrin bushings allow the LCA the hang down. They offer no resistance to the movement of the LCA. The rubber, on the other hand, holds the LCA up because the rubber has to flex for the LCA to move. That resistance keeps the LCA from moving freely- it's basically binding that's built into the factory bushings. The LCA being able to move up and down without resistance provides better feel and suspension response.
I have the tools and tooling to install and remove OE bushings. In fact I've done it several times, just not on my cars. I have a 20 ton press and a tap to fit inside the outer LCA shells. I needed that to install my current set of BAC delrin bushings, because the delrin LCA bushings do not use the old outer shells. You can see my removal of the OEM bushings and installation of the Delrin bushings here. My "new" '74 Duster- or why I need a project like a hole in the head Along with all of my tools to do it. Again, you're making false assumptions here, and obviously aren't familiar with how to install these parts.
Hey look, there's the press I'm using to remove a OEM outer sleeve
Hey look, there's the old outer sleeve that's been pressed out and the tap I used to do it
Hey look, here's me pressing in the new Delrin LCA bushings. Oh, yeah you need a press to install those, they don't just slip in.
Some of this is right, once the bushings are installed in the LCA and the LCA installed on the pin they should be tight.
But they are NOT self locating. If the strut rod isn't the right length, the LCA will not stay tight against the shoulder on the pin. If you use strut rods that are too long, they will push the LCA and bushing backward on the pin like in the picture you posted earlier. That is exactly how you install the bushings the wrong way, it's an improper installation.
This is where you're fundamentally wrong about how the poly and delrin bushings function. With the OEM bushings all of the up/down movement of the LCA is flex in the rubber, nothing spins or slides. When the rubber tears, the LCA can spin, slide, and flex on the pin even more because the rubber is no longer intact.
With a poly or delrin bushing, the LCA bushing is DESIGNED to spin on the LCA pin. But unlike a failed rubber bushing, there's is very little flex in a poly bushing. And almost no flex in a delrin bushing. So there is no flex and slop like there is with a failed rubber bushing. The pin is held tightly in the bushing radially, and the bushing spins on the pin. As it is designed to.
Poly only "turns to powder" if it is not properly lubricated. There's really only two possibilities for your failed bushings. One is that those bushings were just defective. But since you claim that you have had multiple failures of different bushings, that's unlikely.
The common denominator is that you're the one maintaining them. Which points directly at improper maintenance. Sorry, but as I've said I have had great success using poly bushings for over a decade now, and tens of thousands of miles in multiple applications. If none of your poly bushings last, you're the problem. That's not me making it personal, those are just the facts. Plenty of people use poly bushings with great success. If you've never used one with success, you're clearly doing it wrong.
Every single one of your concerns here is based on your fundamental misunderstanding of how the poly bushing works. They are not the same as the rubber bushings. Totally different material, totally different design, totally different function. You can not make a comparison to a failed rubber bushing, there is no parallel between the two.
I already addressed this. This picture depicts an IMPROPER INSTALLATION.
The bushing is NOT tight against the shoulder of the LCA pin. That means that the strut rod is too long, not installed, or not installed properly. This is the wrong way to install poly bushings, and a perfect example of why adjustable strut rods should be used when they're installed.
Also, I would appreciate if you linked the source thread for this picture. That member needs to correct this, as that's a catastrophic failure waiting to happen.
You are stating something that isn't logical. You can't pry the LCA back out of the K frame if the strut rod is the correct length. What you're describing is not possible if the poly or delrin bushings have been properly installed and the strut rod is the proper length.
In fact, if you CAN do what you described and pry the LCA back on the LCA pin while the suspension is fully assembled it proves you've done the installation incorrectly, and something needs to be adjusted.
PST is a pretty great resource for the members of this site. Not just with parts, but clearly with knowledge of how they're used. I don't agree with 100% of the things I've seen PST post here, and I don't use all of their products either. But clearly they have a pretty good idea of what they're talking about, and compared to most sellers they're very knowledgeable about the parts they offer.
Firm Feel is also a great resource. I'm mentioning them here because of the complete BS that's been posted about their greaseable LCA pins. They make the pins, they do not manufacture poly or Delrin LCA bushings. They make the greaseable pins because they work, and they're a great way to properly maintain the bushings that their customers use. Not so they can sell bushings. Firm Feel has been making parts for handling mopars for DECADES now. Their knowledge and experience is bar none. They were literally one of the first companies to make parts for handling mopars, and their parts are proven in both performance and durability. They were literally the only game in town for a long time, and still compete with the big names like Hotchkis. That's saying something.
Hopefully this explains how these parts work for people so they can make an informed decision. And I'm not saying that rubber LCA bushings don't have their use, they absolutely do. Poly bushings aren't necessary for every build, there's nothing wrong with that. Delrin bushings aren't right for every build either. But if they're properly installed and maintained, they work VERY well, and will outlast and outperform rubber LCA bushings.
