Strut Rod Bushings poly vs rubber

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JGC403

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I'm keep going back and forth with the strut rod bushings and even the adjustable strut rods that have solid bushings like pst adjustable strut rods.
I am happy with the rest of the bushings I have picked out for the front suspension. I'm getting FFI upper control arms with poly bushings, and the lower control arms will be MOOG rubber. I have read a lot of storys about the poly ones falling out of the socket, so I'm just going to stick with the rubber ones on the LCA. I don't think there is that big of a performance advantage with just the LCA bushing either way poly or rubber.
I know I need adjustable strut rods to take out any binding there might be cycling the lower control arm. I was going to go with PST adjustable strut rod but I'm not sold on the solid mount yet. Then I was going to go with FFI adjustable strut rod and use poly bushings, then I had seen some of those bushing fall apart.
A member on here posted a video of his front suspension while driving around. Its a good video for seeing how the suspension moves. You can see the strut rod pivoting around the strut rod bushing as the suspension cycles. The only time that the strut rod actually moves back is under braking. It never moved forward or back under acceleration. So the only time that the settings would change would be under braking and that would probably just change the toe-out a couple of fractions of an inch.


I like how the PST adjustable strut rods are designed the heim joint would take care of pivoting that the rubber bushing would normally do. But I think the solid mount on the PST would beat out where it attaches to the K-member over time. So could we change out the solid mount and use PST poly strut rod bushings there? This would have the advantage being stiffer than rubber and then the rod wouldn't be pivoting on the poly bushing?
 
I have the original style 1 piece rubber bushings on my car and they are just fine. I do not autocross or drive anything more harder than a weekend warrior. The aftermarket MOOG seems fine and even poly, but was wanting the stock look and feel. Cost me more to find the original style cup washers as my car had the MOOG replacements “I put on in the 80’s” that have reversed washers.
 
A few things-

That video shows 6 minutes of easy driving on good roads. While it's somewhat useful to see how the suspension moves about in general, it is not at all indicative of all the loads the suspension can see. It's a basically a cruise around the block, there's no hard cornering, there's no hard braking, there's no big potholes, etc. So, don't base your suspension decisions on that video.

If a poly LCA bushing "falls out" of the socket, it was an installation problem (a really bad one at that). If the LCA slides back and forth on the LCA pin with a poly LCA bushing, it's an installation problem. Period. I've run poly LCA bushings for tens of thousands of miles on multiple cars, if installed properly they work great. I always use them with greaseable LCA pins and adjustable strut rods, and I have never had an issue with them.

You will not "beat out" the K frame where the strut rod attaches by using adjustable strut rods. The whole point of adjustable strut rods is that they DON'T move fore/aft. At all. The heim translates all of that motion, the solid "bushings" just locate the strut rod. The only reason they look like metal "bushings" is because they use the same mount on the K frame. Basically, they're just an adaptor to mount the heim for the adjustable strut rod.

I have the QA1 style adjustable strut rods on my Challenger (actually made by CAP, the design was bought by QA1, that's how old they are). Other than the 1.12" FFI torsion bars, they are the only suspension part that has been on my Challenger the entire 9 years I've had the car and done all ~70k miles I've put on it. Oh, and they're aluminum. Aluminum pillow blocks, aluminum mount for the heim, hollow threaded aluminum strut rod shafts. The only steel is the heims, bolts, and threaded end. I've changed tubular UCA's, I've wiped out a set of heims in the Hotchkis UCA's I swapped over to, I broke a weld on the CAP built tubular LCA's I had on the car, I replaced the shocks, swapped out spindles, even replaced parts of the 11.75" brake set up I installed brand new myself when I got the car due to wear, those strut rods are still perfect.
hal-52312_xl.jpg
 
If a poly LCA bushing "falls out" of the socket, it was an installation problem (a really bad one at that). If the LCA slides back and forth on the LCA pin with a poly LCA bushing, it's an installation problem. Period. I've run poly LCA bushings for tens of thousands of miles on multiple cars, if installed properly they work great. I always use them with greaseable LCA pins and adjustable strut rods, and I have never had an issue with them.

I have seen a couple of threads on here about people complaining about the poly lower control arm bushing and the Lower control arm moving around on the pin. I didn't understand how they could have a problem it shouldn't go anywhere. The lower control arm can't move forward because of the K-member and shouldn't be able to move back because of the torsion bar. I just can't figure out how they were being installed wrong. I'll have to get some poly busing for myself and take a look at them.
I'll give the PST strut rods a shot. I'm trying to make this car handle as good as it can get.
 
I have seen a couple of threads on here about people complaining about the poly lower control arm bushing and the Lower control arm moving around on the pin. I didn't understand how they could have a problem it shouldn't go anywhere. The lower control arm can't move forward because of the K-member and shouldn't be able to move back because of the torsion bar. I just can't figure out how they were being installed wrong. I'll have to get some poly busing for myself and take a look at them.
I'll give the PST strut rods a shot. I'm trying to make this car handle as good as it can get.

There are a couple problems that come up. The biggest one is how the poly bushings fit into the outer shells. The tolerances on the outer shells aren’t great, so, if the poly bushings are loose in the shells it can cause issues. But that’s part of a proper installation, the poly bushings should be tight enough in the outer shells that when you install the LCA pin it takes some effort. Not a press fit, but a tight fit.

The other thing is using stock strut rods. The stock strut rods are a “one size fits most” operation. Those big fat rubber strut rod bushings are necessary to make up for the loose factory tolerances. But they let the LCA flex back and forth on the pin. Which kinda works with the factory rubber LCA bushings. But with poly LCA bushings there isn’t much flex at the LCA bushing, so the flex at the strut rod translates to the LCA sliding back and forth a bit on the LCA pin. And if the strut rod isn’t quite the right length it adds to that problem.

Which is why I use adjustable strut rods and greasable LCA pins. The strut rod can be adjusted to suck the LCA right up against the bushing on the pin, and it won’t move much because there’s no slop in the strut rod. And the greasable pins fit the poly bushings better, and allow you to keep them greased so you don’t get the “poly squeak”.

You can use adjustable strut rods just fine with rubber LCA bushings, but I wouldn’t use stock strut rods with poly LCA bushings. And I don’t think poly LCA bushings are a good idea, because if the strut rods aren’t exactly the right length they’ll cause issues because there’s no give to make up for the tolerances.
 
The factory bars can be made adjustable. Step 1: Cut in half. Step 2: Thread ends. Step 3: Add threaded sleeve and jam nuts.
 
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The factory bars can be made adjustable. Step 1: Cut in half. Step 2: Thread ends. Step 3: Add threaded sleeve and jam nuts.

Sure. If they’re straight, if the threaded ends on the strut rods are still good, if you have the right die to thread them (assuming they’re the right diameter), if you shorten them the right amount and don’t have to cut and thread them more than once. And then you’ve still got bushings.

No thanks.
 
I agree about the easy driving and the great road condition. It's actually kinda funny. BUT, it's still a very good video. Take a look at how the strut rod actually bends where it goes into the K frame. You can see the strut rod flex and the nut on the other side remains still. On greater dips, you can see the nut move, but for the most part it does not and this means the strut rod actually flexes. That's something I never knew went on. It's a wonder more strut rods don't break.
 
I think you're seeing more then there is in the clip, or your monitor is exaterating the curved wide view of the action cam this video was shot with.
Where are you seeing any bending in the strutrod?

The only thing (where I can see some) actually bending are the lips of the K-member where the swaybar is mounted to.
The swaybar bushing itself has some play as well which can be seen by the up&down movements of the bar at times.

The intention of the clip was to simply see if there were some funny/worrying things happening while driving around the block and encounter some speedbumps at some considerable speed. I didn't intent for the strutrod end-nut to be in view, but I'm glad it was.

If the strut was actually bending/flexing as much as you think, it would probably have failed some 6 years already because of metal fatigue when I started using the car as a daily driver.
 
Pretty easy to see, all you have to do is watch.
 
I don't think the strut rod is actually bending in the video, I think the movement is so slight and the pivot being all the way by the nut on the K-member its hard to see the nut moving.
The extra slop in the sway bar bushing is more noticeable while its moving and you can see a little flex on the bracket for the sway bar mount.
 
I have poly bushings on my lca's . The pin is loose on the driver side and tight on the pass side. At the time I put them in I had stock "73" struts. I just changed to QA1 adjustable struts. When the drivers side bushing is snugged up it doesn't move, it stays in place. I can't see how it could come out. Is this something to worry about
 
I am putting in the PST strut rods. Qkcuda installed his and says they were a great upgrade. Andrew.
I installed RMS adjustable strut rods in the cuda a few years ago. They are almost identical to the PST ones Andrew just bought. The aluminum biscuits basically sandwich the hole in the K frame so it becomes a solid unit with nothing to wear. The heim joint takes all the movement. These were probably the best single change to free up the front suspension. I will be installing complete set of PST polygraphite bushings this winter, which I hope will help further.
 
If you decide to use any kind of Heim joint, be sure to lubricate it often. They do not have the ability to retain grease like a ball joint or tie rod with the grease boots.
 
I have poly bushings on my lca's . The pin is loose on the driver side and tight on the pass side. At the time I put them in I had stock "73" struts. I just changed to QA1 adjustable struts. When the drivers side bushing is snugged up it doesn't move, it stays in place. I can't see how it could come out. Is this something to worry about

the strut rod holds it in place for the for and aft movements...
 
If you decide to use any kind of Heim joint, be sure to lubricate it often. They do not have the ability to retain grease like a ball joint or tie rod with the grease boots.

You can buy boots that cover the heim joints, like these

Seals it RERS36PK

If you run them without boots (as I did on my Challenger for close to 70k miles) you need to use a dry lubricant, like a graphite spray or similar. Grease, oils, etc will just catch dirt, might as well use valve lapping compound. Gotta run boots with a wet lubricant.
 
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