Rubber or Poly for a Daily Driven Corner Carving Street Machine?

For a corner carving street machine, should I go poly or rubber for LCA?

  • Rubber

    Votes: 37 43.0%

  • Polyurethane

    Votes: 49 57.0%
  • Total voters
    86
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JoesEdge

JoesEdge

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I'm about to pull the trigger on a front end rebuild kit and I can't decide if I want to go with Rubber or Poly bushings for the Lower Control Arm (LCA).

This is for a '74 Duster and my goal is to build a daily driven street machine that can handle well (hopefully very well).

I'm not planning on entering any AutoX's but some spirited driving up some mountain roads and freeway on ramps would be fun.

Here's my planned list of additional parts:

- Moog Lower Ball Joints, Moog Tie Rod Ends (11/16"), Moog Idler Arm
- PST or Reilly Motorsports Adjustable Strut Rods
- Hellwig Tubular Sway Bar
- Tubular Upper Control Arm (either PST, Reilly Motorsports, or Firm Feel - can't decide)
- PST 1.03" or Firm Feel 1.06" Torsion Bars
- Bilstein shocks all round (maybe up front first, then rears later as budget allows)

I have searched on this subject and there are quite a few old posts regarding this, but I'm still unclear.

Any reasons why I shouldn't go poly?

EDIT: I should mention that if I go poly then I'd definitely get the greasable pivot shafts.

Thanks!
 
I've never heard anything good about poly LCA bushings (mine are rubber). If you don't mind the lack of dampening/vibration resistance you get from rubber, go poly everywhere else. But i don't know **** as my 'driver' is all rubber.. just tossing my uneducated opinion..
 
I went poly on a daily driver, then three years when they were shot, I replaced them with stock rubber and they lasted much longer...

Hard bumps are hard on them, the rubber takes them much easier...
 
I had poly LCA bushings for over 20 years in my 69 383-s with no issues.
 
krazykuda said:
I went poly on a daily driver, then three years when they were shot, I replaced them with stock rubber and they lasted much longer...

Hard bumps are hard on them, the rubber takes them much easier...
Click to expand...

That's the type of info that makes sense to me. Long lasting is a good thing since the streets in L.A. aren't the greatest. That's definitely something I'm taking in consideration.
 
Go with rubber my poly bushings squeak the time have to power warsh all the bushings then spray with white lith to stop the squeak PITA
 
I put poly on my 66 Coronet 500 in 1992. Still there today, car got driven a lot back then. I think the biggest issues for a bodies is the lower poly bushing are incorrect and need to be shaved down. Greaser is your friend with them. They do have their ups and downs.
 
I think you'll be fine with Poly. Unless you're going to go deep into LA where the roads are much worse, it won't be that big of a deal.
 
I haven't had any issues with the poly LCA bushings I've installed. I also installed them with greaseable LCA pins though, because the poly bushings can squeak if they dry out. Not an issue with a greaseable pin though.

Were I going to do another set though I would probably by the Delrin LCA bushings that Peter Bergman sells. More durable than the poly, and even less deflection.
 
wheel/tire combo and t-bars will probably have the most impact over all that you listed vs. stock.


are you doing the work yourself? if yes - poly. because they are cheap and easy to do.

if your paying someone - go for the rubber, pay for the labor 1x and get what most people seem to prefer for a daily driver.

i have run both. no issues with either. its preference.
 
72bluNblu said:
Were I going to do another set though I would probably by the Delrin LCA bushings that Peter Bergman sells. More durable than the poly, and even less deflection.
Click to expand...

That's another option that I haven't really researched much. I'll have to look into that.

340duster340 said:
are you doing the work yourself? if yes - poly. because they are cheap and easy to do.
Click to expand...

Yep, I plan to do the install myself and then take it to a local shop to get it aligned.
 
I run my poly bushings and stabilizer rod grommets pretty hard and have not had a real problem with them at all besides one that occasionally likes to squeak after a rain.
And to me the extra road noise from them is worth the stability.
The more that stuff flexes means more time that the tires are not running parallel with each other. (deflection) as 72bluNblu says.
The other big ones for putting the tires out of sync is vertical movement and the heavier torsion bars cut down on that movement quite a bit and quick stops when you are playing. :D
Yep, stiffer ride but again worth it for what you get out of it, and the poly flexes less in those stops again keeping the tires less deflected under those loads.
 
Do yourself a favor: Check out Energy Suspension's kits,add a "G" onto the part number/s.. The "G" stands for graphite impregnated, squeaks go away,& they seem to last longer than the normal poly bushings.My .02 ..
 
I mixed and matched mine. I run poly for the LCA's,strut rods and sway bar links and rubber for the rest
 
I have poly so far so good but use rubber on the strut rods the poly are to thick and is causing a few issues for me.
 
Poly LCA bushings are not locked in position like Rubber. They can float forward and backwards. Noticed this when driving the 67 in reverse. That said it, probably has 100K on the rebuild. They are noisy. I'll be rebuilding the front end this spring. Moog rubber LCA bushings, Firm Feel upper control arms, Bilsteins all around, 76 cop car front and rear sway bars, Rubber everywhere except the sway bar links. I've also tried the graphite impregnated bushings and they are just a little bit better. On a daily driver Poly bushings are way too annoying for me. I love working on cars, but hate having to work on them.
 
Was informed long ago ( can not remember by who) That rubber works well with original type tires because sidewall was stiffer. On radials, since sidewalls are not as stiff go with poly, tends to even out total cornering " give "
 
66fs said:
Poly LCA bushings are not locked in position like Rubber. They can float forward and backwards. Noticed this when driving the 67 in reverse. That said it, probably has 100K on the rebuild. They are noisy. I'll be rebuilding the front end this spring. Moog rubber LCA bushings, Firm Feel upper control arms, Bilsteins all around, 76 cop car front and rear sway bars, Rubber everywhere except the sway bar links. I've also tried the graphite impregnated bushings and they are just a little bit better. On a daily driver Poly bushings are way too annoying for me. I love working on cars, but hate having to work on them.
Click to expand...

To say that the rubber LCA bushings are "locked in" is a bit of a misnomer. Yes, the bushing shell is pressed in, and yes, the LCA pin is pressed into the insert in the bushing. But the only thing that holds the bushing to the shell, or the insert into the bushing, is the bonding of the rubber. Sure, it's more resistance than the poly LCA bushings, but the rubber can and does separate from both the insert and the shell. That's what happens if you torque the LCA pin nut with the suspension at something other than ride height, and obviously as the rubber wears out.

That said, the LCA pin can slide in and out of the poly bushings. But it's not the job of the LCA bushing to locate the LCA fore/aft. That's the job of the strut rod. If the strut rods are the correct length, the LCA, pin, and bushing don't go anywhere, even with poly LCA bushings. The stock strut rods are a "one size fits most" kind of thing, and what that really means is they don't fit anything all that well, just "good enough" to get the old factory alignment (which isn't what you want anymore!). I have adjustable strut rods on all of my cars, and none of them are the exact same length as the stockers.

I think the adjustable strut rods are the way to go anyway, but if you use poly LCA bushings I think they're more important, especially because the aftermarket strut rod bushings are kind of questionable in their tolerances. Same with the greaseable LCA pins- they aren't mandatory, but they sure do make life easier. The poly LCA bushings aren't the same as the stock bushings, so using them with all of the stock components isn't necessarily the best practice. When you upgrade your cam you have to install new lifters,valve springs, and sometimes that means machining the heads, new pushrods, etc. Same idea, you have to match everything up if you want your new parts to work their best.

For a car that's primary use is on the street the rubber LCA bushings will be fine. The amount of deflection in the original bushings is pretty small. Sure, it's on an important component, and I think the harder LCA bushings are a great thing. But on a street car they aren't necessary, the difference is small. And you can run poly bushings everywhere else without adding any additional new components, the LCA bushings are unique in that respect that you should really upgrade the strut rods and pins too.
 
72bluNblu said:
That said, the LCA pin can slide in and out of the poly bushings. But it's not the job of the LCA bushing to locate the LCA fore/aft. That's the job of the strut rod. If the strut rods are the correct length, the LCA, pin, and bushing don't go anywhere, even with poly LCA bushings. The stock strut rods are a "one size fits most" kind of thing, and what that really means is they don't fit anything all that well, just "good enough" to get the old factory alignment (which isn't what you want anymore!). I have adjustable strut rods on all of my cars, and none of them are the exact same length as the stockers.
Click to expand...

That statement right there explained quite a bit. I did worry about that forward/back movement, but you're right. The strut rod should minimize that.

Hell I worried about the slight chance the torsion bar shot out the back that the LCA would fall off if I had Poly bushings but no, the strut rod should hold it steady. Yeah, I know....I worry too much. LOL

So far the Poll has been pretty interesting. At the time of me writing this, it's almost 50/50.

Going the Poly route I was thinking of going with this kit since it includes everything I need to rebuild the LCA's: PST Performance Mopar Lower Control Arm Deluxe Rebuild Kit

That includes these: PST Greasable Control Arm Pivot Shafts

I wonder if they are Proforged parts because they look exactly like these Summit parts: Proforged Control Arm Shaft Kits 120-10003

I definitely plan to get the Adjustable Strut Rods since I'm already tearing the front end apart anyway. I was looking at either PST Adjustable Strut Rods or RMS Adjustable Strut Rod. It probably doesn't matter which I get because I was told that the PST branded parts are actually RMS parts.
 
72bluNblu said:
To say that the rubber LCA bushings are "locked in" is a bit of a misnomer. Yes, the bushing shell is pressed in, and yes, the LCA pin is pressed into the insert in the bushing. But the only thing that holds the bushing to the shell, or the insert into the bushing, is the bonding of the rubber. Sure, it's more resistance than the poly LCA bushings, but the rubber can and does separate from both the insert and the shell. That's what happens if you torque the LCA pin nut with the suspension at something other than ride height, and obviously as the rubber wears out.

That said, the LCA pin can slide in and out of the poly bushings. But it's not the job of the LCA bushing to locate the LCA fore/aft. That's the job of the strut rod. If the strut rods are the correct length, the LCA, pin, and bushing don't go anywhere, even with poly LCA bushings. The stock strut rods are a "one size fits most" kind of thing, and what that really means is they don't fit anything all that well, just "good enough" to get the old factory alignment (which isn't what you want anymore!). I have adjustable strut rods on all of my cars, and none of them are the exact same length as the stockers.

I think the adjustable strut rods are the way to go anyway, but if you use poly LCA bushings I think they're more important, especially because the aftermarket strut rod bushings are kind of questionable in their tolerances. Same with the greaseable LCA pins- they aren't mandatory, but they sure do make life easier. The poly LCA bushings aren't the same as the stock bushings, so using them with all of the stock components isn't necessarily the best practice. When you upgrade your cam you have to install new lifters,valve springs, and sometimes that means machining the heads, new pushrods, etc. Same idea, you have to match everything up if you want your new parts to work their best.

For a car that's primary use is on the street the rubber LCA bushings will be fine. The amount of deflection in the original bushings is pretty small. Sure, it's on an important component, and I think the harder LCA bushings are a great thing. But on a street car they aren't necessary, the difference is small. And you can run poly bushings everywhere else without adding any additional new components, the LCA bushings are unique in that respect that you should really upgrade the strut rods and pins too.
Click to expand...

It is a bit disconcerting to see fore aft movement when you are going backwards, especially when the tires slightly rub on the fender. I've been running graphite poly bushings for decades on more than one "A" body for hundreds of thousands of street miles. The strut rods keep the LCA pretty close, but that is too much of a moment arm for me. And, so no one worries, there is no problem going forward since all the forces hold the LCA in the correct position. The bonding of the rubber is not insignificant, as you probably know from removing them. I do agree with your arguments if you are going to use poly LCA bushings.
 
66fs said:
It is a bit disconcerting to see fore aft movement when you are going backwards, especially when the tires slightly rub on the fender. I've been running graphite poly bushings for decades on more than one "A" body for hundreds of thousands of street miles. The strut rods keep the LCA pretty close, but that is too much of a moment arm for me. And, so no one worries, there is no problem going forward since all the forces hold the LCA in the correct position. The bonding of the rubber is not insignificant, as you probably know from removing them. I do agree with your arguments if you are going to use poly LCA bushings.
Click to expand...

I don't disagree about it being concerning to see the LCA moving around that much. But if the strut rods are the right length the LCA won't move forward or back regardless of the bushing. Unless your car has perfect tolerances, the only way to have strut rods the right length is to have adjustable strut rods. Even if your factory strut rods are the right length, the strut rod bushings will allow some movement.

I have 275/35/18's on the front of my Duster, and 275/40/17's on the front of my Challenger. Both required some trimming and readjusting of the fenders to clear those tires. If the strut rods allowed the LCA's to move in any direction at all I would have issues with the tires rubbing on the fenders or the frame because I have almost zero "extra" clearance.

As for the rubber bonding, it isn't insignificant when new. When worn, I have had LCA's fall right off the pins with the strut rods and torsion bars removed, leaving the pin bolted to the K frame by itself.
 
I've been reading up on this topic also... I think I'm going to stick with good ole Moog rubber components for now on this rebuild.
 
Forget both an use my delrin lca bushing. Quiet and stiffer than poly and does NOT use the outer shell. Corner carving and rubber dont go together, sorry.
 
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