LCA Poly Bushing Failure - what to do now?

[66 Sat]

I installed PST greasable poly bushings into my Lower Control Arms about 6 years ago. They say "Proforged" on the shaft.
I noticed last week the passenger side shoulder of the bush was all split, and checking the driver's side from underneath I could see that one was stuffed too.
This morning I pulled the driver's side LCA out and it's a right mess. I kept as many parts on as possible to reduce the time in removing it all but nearly couldn't get the LCA off as it was hitting the header, but I jacked up the engine an inch and it slid right out. Keeping the rotor and strut rod on did increase the weight a fair bit though. The shoulder was all torn up and the bushing itself inside the LCA was twisted and in pieces too. I'm sure I installed them properly at the time, greasing the inside and the outside of the bushing, so not sure what went wrong.
Luckily I have a couple of spare greasable poly bushings as well as a couple of original type rubber bushings and the original shafts, so I've got options.
I admit I'm leaning towards trying the spare poly bushings again as I can install them myself pretty quickly. If I go the other route and use the rubber I need to get the outer sleeve out which is a fairly tough job, get the old inner sleeves off the original shafts and then borrow a press to get it all back together.
Any opinions on which way to go and why the poly bushings failed in the first place?
If I get another 6 years out of the poly then I'm inclined to go that route.

 

[493 Mike]

Go with rubber and it will last the rest of your life and be quieter.
Mike

 

[66 Sat]

Go with rubber and it will last the rest of your life and be quieter.
Mike

I know deep down that is the right thing to do - I think I will go that route, I just wanted to take the easier way out. Thanks for setting me straight.

 

[Mopar Hunter]

PST has a lifetime warranty.

 

[Speedbird]

I hope this is one of those 1 in 10,000 cases.
I've never had any service issue with poly LCA bushing.
I uses them in daily drivers and uncounted miles.
One car for 25 years.
Rubber does fail as well.
Quality on everything isn't was it used to be.
I try and get USA made Moog.
Just as an example.

 

[hunt2elk]

Personally, I don't like poly bushings on these old cars. I have tried them in the past, but went back to rubber. That said, I am kind of surprised of that failure with a Proforged part. I know they are made overseas, but not China. I really like Proforged stuff and think it is good quality, although I have never used any poly stuff from them. Guess I would reach out to PST first, they are pretty good with warranty issues.

 

[HawkRod]

I also like rubber for many of my suspension parts, although I do have Polyurethane in select places. One is for my sway bar since I want it to react right away and not have the rubber deflect too much. The other are the LCAs. I also used PST on my car 9 years ago when I restored it. I have driven it across country, on the Hot Rod Power Tour and of course small trips as well. I have never had an issue with mine.

I was going to suggest that yours might not have been greased, but I see they were. So I am at a loss to suggest something that may have destroyed yours. I'm sure if there was some kind of geometry issue placing stress on your LCA you would see that or feel it with poor handling.

Bottom line is all I can offer is that it seems to me to be a more unusual failure. I'd suggest to replace the polyurethane bushings, being sure to grease them well, and then grease the fitting after they are installed and torqued to spec.

Good Luck!

 

[j-c-c-62]

Any opinions on which way to go and why the poly bushings failed in the first place?

Nobody knows.
I've asked the vendors at PRI and other shows over the decades, and all they give me is that blank twisted head dog look.
You did nothing wrong. I can't attribute the failures to sunlight, high temps, overload, low temps, lack of grease, too much grease, manufacturer, ozone, color, etc, etc other than indeterminant aging.
I have had over decades, many urethane products in sealed boxes on the shelf completely fail as well as installed. My only suspicion might simply be lack of use. Hard to prove or understand how much use might be if needed. I will add one observation, urethane fails like fire ants bite, all at once, somehow.
Delrin is your best replacement, it's a high-performance nylon effectively, and not easily found as a finished product, you need to machine yourself.
I think in light of all of the above, the case can be made urethane might not be an "upgrade " that is really worth it in most cases.

 

[dvw]

I've never had one break apart. I did have some Moog units wear on my old Caravan. The racecar is going on year 12 with them. 1000's of wheel stands. They are still in great shape.
Doug

 

[Bighouse]

Moogs are no longer made in USA.

 

[Demonic]

This might be a silly question but- any chance the LCA nuts were tightened before the height and weight was set? It's the only thing the FSM notes to do when setting up LCA's.

 

[Mopar Hunter]

I wonder if headers had anything to do with them failing.

 

[Speedbird]

Last USA Moog I got were from Ehrenberg via ebay.
NOS? IDK.
But hard parts I like to buy local over the counter to see them in hand.
Order at auto store.
Unfortunately that my not be an option for the OP.

 

[Bighouse]

I have a set of Moog lower bushing sitting on my chargers fender right now. They say made in India. I’m contemplating what to do.

 

[AR67GTX]

There’s the same issue with polly bushings in certain locations on the 66 Corvette I own. Certain suspension bushings are subjected to more than simple shaft rotation like an a-arm bushing. Some like the LCA shaft on Mopars and the trailing arm mount on a C2 Vette are subjected to twisting and lateral motion and poly bushings just do not deal well with that. If you got 6 years out of them in your LCA I would say that’s pretty good. Quality rubber is the best bet for any bushing in a mount that does more than simply rotate.

 

[69_Coronet]

This might be a silly question but- any chance the LCA nuts were tightened before the height and weight was set? It's the only thing the FSM notes to do when setting up LCA's.

This shouldn't be necessary with poly bushings as they are a sliding joint, whereas the rubber bushings are bonded to the inner and outer sleeves and set to their relaxed position when the car sits at its normal ride height, so suspension movement causes the rubber to stretch when the car sits lower or higher than normal (going over bumps, cornering, both, etc). It's still probably a good idea to follow the FSM recommendations, it can't hurt and you get in the habit of doing it the way that will work with both kinds of bushings. Cheers!

 

[66 Sat]

Thanks for all the replies and experiences.
I'm really at a loss as to what happened - I put the whole front end together myself and am usually very meticulous. I'm also very busy so sometimes am very meticulous on everything apart from the one thing I forget and it causes a major boo-boo. Did I somehow forget to grease the outer part of the bushing? Maybe. I'm trying to recall if the original bushings were so tight that I got them pressed in by a local shop. If so that may explain it. That they weren't able to rotate in the LCA socket and I thought that would be ok as the inners were greased and the shaft could rotate? Then I've neglected to re-grease the inners often enough (I've probably done it twice in 6 years...), and they've bound up on the shaft and twisted the whole bushing in the socket, tearing them apart? Maybe the extra heat from the headers dried up the grease? Who knows, just spitballing here.
Until they failed I had ZERO issues with them, in terms of noise, movement, handling, everything was great.

I'm on a very tight schedule with work, family etc so being able to re-assemble myself quickly is a big plus. I might give the poly another chance, and just re-grease them every 3 months (meticulously haha).

 

[Demonic]

This shouldn't be necessary with poly bushings as they are a sliding joint

I have no experience with Poly myself. Are they designed that way? Seems obvious that if the bore isn't smooth then that would be the cause of the OP's part failure. That alone would make me want to use standard rubber. Upgrades are great, but sometimes if you deviate from design, you're asking for trouble.

 

[Speedbird]

Don't beat your self up.
When I was working with a disable wife getting in a rush and effing up was standard practice.
I'm retired and if I rush still make mistakes.
I just spent 1000 dollars on a leather recliner that I didn't really need because of a mistake.
I can use it, sure.
But....long story.

Anyway, FWIW I have never greased the poly bushing except on initial install.
You have the aftermarket grease type shaft?
I have always used factory parts. (Junk yards were gold mines years ago. Not so much now.)
Therefore, I don't think lack of grease should really be a problem.
Years ago I parted out a low milage 74 Valiant and the K member hole for the shaft had sort of a common "wallered" out issue.
I scrapped it and used it for a work stand base.
Now, I would have welded it up and saved it.
Will rubber really hold up better?
All the weight is basically on the shaft busing.
That's asking a lot.

Over the years people have also debated if the poly will let the shaft work it's way out.
In other words, does a pressed rubber bushing not help retain the LCA?
I say it doesn't make any difference.
Because the tire action is normally pushing the shaft fwd acting as a lever to push the shaft back in place.
Sorry, I think I just opened a can of worms.
Um...... what the best motor oil?

 

[69_Coronet]

I have no experience with Poly myself. Are they designed that way? Seems obvious that if the bore isn't smooth then that would be the cause of the OP's part failure. That alone would make me want to use standard rubber. Upgrades are great, but sometimes if you deviate from design, you're asking for trouble.

Yes, polyurethane bushings are built the same as any conventional bushing like brass and such. The shaft rotates inside the bushing, making it a sliding joint, which requires lubrication, you can get lower control arm shafts with a grease fitting if you don't already have them. One other thing to remember is that poly is not compatible with hydrocarbon grease, you should use silicone grease instead. Energy suspension makes a grease specifically for this application, and it is very sticky. Cheers!