Not happy with PST poly graphite lower control arm bushings

[R/T Boy 67]

In order for the LCA to move back,it would have to take the torsion bar with it. Probably not going to happen, with a fully loaded bar.

 

[1 Wild R/T]

In order for the LCA to move back,it would have to take the torsion bar with it. Probably not going to happen, with a fully loaded bar.

And yet it does... At different times I saw the inboard end of the LCA's move as much as 3/4".... No it can't go anywhere, no the outboard end doesn't move nearly as much as the inboard end but it does move.... I've never seen any movement with OE bushings unless the bushings are toast...

But wait, I must not know what I'm doing... PST rep says so....

 

[kiwigtx]

A lot of Prothane products I've used in the past squeaked like an old spring bed in a cat house.

Curious minds ask how you know this?

 

[Mike67]

Curious minds ask how you know this?

So I heard...them on my 70 GS....

 

[Kern Dog]

In order for the LCA to move back,it would have to take the torsion bar with it. Probably not going to happen, with a fully loaded bar.

Not necessarily. The torsion bar will keep the locating pin in place but the hex on the control arm is open and will allow the LCA to slide rearward.
I vote that the rubber does keep the control arm in place.

 

[1 Wild R/T]

Not necessarily. The torsion bar will keep the locating pin in place but the hex on the control arm is open and will allow the LCA to slide rearward.
I vote that the rubber does keep the control arm in place.

The torsion bar socket is captured by the control arm... But it still moves... The hex of the torsion bar is greased at both ends & while it would seem that it would lock in the socket that doesn't hold true in the real world...

 

[R/T Boy 67]

All the ones I have seen are blind on the hex end, and the T bar bottoms out on the shoulder.Well maybe not blind, but there is a shoulder in there.

 

[1 Wild R/T]

All the ones I have seen are blind on the hex end, and the T bar bottoms out on the shoulder.Well maybe not blind, but there is a shoulder in there.

But the distance between the rear crossmember retainer clip & the bottom of the socket in the LCA is greater that the length of the torsion bar....

 

[R/T Boy 67]

I agree. I tap them forward against the LCA shoulder, and tension them in that position. I have not seen any that have moved back, even the poly bushing ones, but as you have seen, it happens.

 

[StrokerSpanky]

Wow, nice introductory post.

Any chance of some background to how they were installed before racing off and blaming the product? They were installed with my press in my shop with new shells and new shafts. And I don't drive it like the Duke Boys. The first time I slammed on the brakes when a Honda minivan pulled out in front of me the control arm slid back on the polygraphite bushing. And I also have new PST adjustable lower strut rods with the hiem ball fittings which I DO like. Here's your pic.

Pictures will speak 1,000 words.

 

[68 HEMI GTS]

I put a pair of these in my barracuda during a complete front end rebuild. Everything new. I noticed rather quickly the lower control arm did slide back a bit. I ended up pulling it back down and putting rubber LCA bushings back in (as they do contribute to holding the fore and aft movement of the pivot point). The graphite’s need some more engineering, I wouldn’t use another set after my experience.

After reading through these posts it appears several people have all had similiar experiences. Starts to tell a story. Even the vendor stated this keeps coming up. As a vendor that should put up a red flag that the product needs a revamp.

 

[hunt2elk]

View attachment 1141532

Yikes, I wouldn't be happy either. Can't say that I've ever seen that happen before. Used poly in one car years ago and didn't like them. I only run rubber now.

 

[StrokerSpanky]

When you have a moment please private message me all of your information and I'll look into your issue. As for the lower control arm bushings if you're using the poly graphite style you would need to reuse your inner and outer shells. In Chrysler's design the lower control arm bushing is not designed to hold the lower control arm in place. The original rubber style bushings are vulcanized to the inner and outer shell and that in itself is not designed to bear the weight and hold the control arm in place from moving forward and aft. What essentially holds the control arm in place is the strut rod and strut rod bushing. If you have premature failure of the strut rod bushings this can lead to issues with the lower control arm bushings that you have described. Please feel free to contact me and we will work with you.

We are here to help but you need to reach out to us with your issues either direct through our website or by PM

Thanks
James From
PST

I have the PST adjustable lower strut rods with the hiem ball. I had them adjusted properly. Nice to get just a little more +caster with my radial tires. Bushings were installed properly with new shells and new shafts on my press, not with a hammer. Just so you know I'm not some shade tree mechanic I have an automotive engineering degree from OSU and worked for GM for 17 years and have almost all of my ASE certifications. Like that means anything. Those tests were easy. I went on to get my Airframe and Powerplant rating and work engines and flight controls on Boeing 737s and do a lot of work on Cessna's on the side including engine overhauls. The strut rod out at the ball joint end of the control arm can't do much to keep the lower control arm bushing from sliding back in a hard braking situation. That's when mine failed.

 

[StrokerSpanky]

I have came up with an engineering fix for this problem AND it will make removing the outer bushing she'll in the future much easier. No more welding a washer to the forward lip of the shell so it can be pressed out. If you would like I could draw it up and send it to you. With the limited number of these old molars on the road it may not be worth the design changes even though they are limited changes.