I'm slowly collecting components for a (complete) suspension upgrade. While I'm thinking about it...rubber or urethane bushings? I've read that urethane last longer, but squeak. It seems to me if one keeps them lubed, urethane should be better. Also, I've read that people particularly don't like urethane in the LCA bushing, why is that? I know firm feel makes LCA pins with grease fittings, but is there another issue with urethane in the LCA?

I'll apologize in advance if this is one of those "hot" topics that create a flurry of debate (but that's healthy, right?).

BG

Yes poly needs lube to stay happy. For lca the greaseable pins are a good idea. On the lca, poly bushings don't positively hold the arm in place. The pin can be moved in and out of the bushing by hand, and the bushing can be moved in the arm by hand as well. Consequently the arm can move fore-aft on the pin while installed on the car. Firmfeel sells a slightly shorter strut rod (their HD strut) to keep the arm in check. You could also use an adjustable strut to accomplish the same thing.

Both of my dusters have the "Ehrenberg" setup where you do poly in everything but the LCA and use MOOG rubber in that particular application, for reasons as Pierre stated, at one time Doc had a little disk that could be placed in the LCA when using urethane to hold the arm and torsion bar in check, but not much forward movement was gained on that project. No squeaks or noise (of course in the Hpak duster you can't hear anything after 2500 rpm anyway...LOL).

-D.Idiot

I look at it as what you are going to do with the car? I am replacing everything with rubber. It's lasted 50 years to this point, it is my Daily Driver and it does not squeak at all.

Well it turns out I will be using Poly Bushings in my Upper Control Arms, and rubber everywhere else.

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1964 Dart GT

Yes, I'm thinking if rubber lasts for decades, why not go with rubber and save the hassle of lube, squeak and LCA issues? My Dart will definitely not see any drastic driving in my hands. It looks like the original LCA bushings are not in terrible shape, but need replacing for sure. If I can get a good 20-30 years out of mine, then rubber is the way to go on the LCA's.

BG

It depends om climate and use.....in more temperate climes poly doesn t necessarily need lube. I never lube poly and have no squeaks......Socal or Florida might be different.

I used poly LCA bushings with washers .....worked fine.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I thought poly provided for better handling via less deflection as well?

Trying to imagine how a disc/washer would work. Do you move the torsion bar forward to butt up against the disc? Wouldn't you need another disc between the rear of the bar and snap ring clip to prevent the bar from backing out? I should have probably thought about this instead of spending money for the HD struts.

Yes, can somebody post pics of how they did their LCA with urethane, what spacers, how placed?

Also, and I realize this is very subjective, but is urethane like way tighter or better than rubber, or just incrementally better? Is it a noticeable difference in suspension feel or just "supposed" to be better?

BG

Unless you find someone that just rebuilt their front end with rubber, then switched just the lca to poly, there's no way to compare directly, even subjectively.

Oh, I was just thinking if anyone had anecdotal evidence of the difference. I hear a lot of discussion about squeaks (or not) and how they are better than rubber, but I've not had anyone give anything further. Are urethane bushings a drastic improvement over rubber or just incremental...if the latter, then why deal with spacers, lube etc.?

I've noticed a significant difference between my duster with all rubber and my demon with all poly (except uca's). Surprisingly the duster's ride is a lot harsher. Besides the bushings the demon has thicker torsion bars, welded plate on the lca, better shocks (bilstien vs kyb gasajust) and the c-body 11/16 tie rods. Oh, firmfeels bearing kit for the idler too.

Firmfeel even has nylon lca bushings.

I didn't expect this big a difference but I still did it. This falls in the "May as well" category since everything is apart.

That's good feedback, thanks so much.

I've read that if you're using urethane in the LCA, you should leave the outer metal case from the rubber bushing in there for the urethane bushing to ride in...I've already taken out the shell; I suppose I could press in rubber ones and press back out to leave a new shell.

Is this true for all urethane or nylon LCA bushings or do some not need the outer shell from the old rubber bushing?

bg

All the ones I've ran across require the old outer shell. That doesn't mean they are all like that though. I recall reading some require the inner shell on the pin if your using the stock pin.

As far as firmfeel's stuff, I can speak to those with certainty. Requires outer shell, no inner shell with their grease-able pins.

Clean up the old gunk real good from the outer shell though. It's a tight fit- the bushing didn't just drop in, had to put a moderate amount of force on it with my palm. Lube liberally, teflon or silicone grease.

What about spacers or different struts? Some earlier posts said you might need some spacers to keep the bushings in place, did you need anything?

bg

No spacers. I used the firmfeel HD strut rods - their heavy duty non adjustable version. They are something like 1/8" shorter. Supposedly they are made shorter to be compatible with the poly strut rod bushings, which are apparently thicker then the stock a body ones. It's my belief the poly strut rod bushings squish anyway thicker or not.