Rubber Vs. Poly suspension stuff?

[Brock Samson]

ok guys your help and experience please..
Which make is better and are there any others?..
Just Suspensions or PST?...
  Rubber or Poly bushing material?..

I'm getting different advice from different "experts".. 

I have a warmed up 440,.. and Super Stock springs on the back, I added the hemi T-bars in front and  don't mind a squeak or a stiff ride.
I like stiff. I dont like the jiggilys.. bouncing once is enuff for me.

[8WHEELER]

I run the Polly Graphite bushings on my cars. I was told they can squeak, but mine never has, and my
wife loves them on her 68 RT. She says its drives fantastic, so they can't be as bad as some say squeaking
to much. They have been on her car for 4yrs now no problems. I think they are PST, but they are all the same
pretty much.

Dan

[Chryco Psycho]

I use Energy Poly bushings they fti properly & haven`t squeeked in my customers cars

[4402tuff4u]

I'm not sure if it's standard with all poly suspension kits, but the kit that I bought from Performance Suspensions came with a special lubricant you apply to all the poly fittings. Perhaps this is a solution to all the "squeaking" comments users frequently claim. The instructions state many times to not forget to apply this lubricant to the fittings. Just from feel, the poly sure does seem more durable than the rubber.

[Shakey]

I've heard they usually only squek when it is cold outside.   

[BLAM]

Use Moog high density rubber in your front suspension, period!  Use poly bushings on front sway bars, rear springs, and rear spring shackles.  Use only graphite poly bushings and tap all the poly bushing housings with Zerk grease fittings.  You will save money and be very happy!!!

[Brock Samson]

 FYI: I'm posting this to give an additional opinion and to protect the innocent I'm keeping the author of this PM secret...

Hey Strat, Long time....  I was reading about your rubber or poly Q.

Moog High Density is the only thing to use up front... You don't road rally, you drive.. It will feel great and out last all other rubbers. The poly will beeeeeeeeat you to death. Not to mention your Charger.. It's good for your leaf springs as you want them to track straight with NO DIRECTIONAL GIVE... Polly is ok for sway bars too as the sway bar has a certain amount of give to it..

I sent this to you in an IM as I have been picked apart by people that have NO *&$*! CLUE what they are talking about on this very subject before. I just don't need it right now.. Just keep in mind that POLLY is what MOPAR used in the RALLY cars.. So does everyone else.. Not everyday, GET LAYED CARS...... Hahahaha..... 



Anyway, I hope I helped... Take care XXXXXXX

[4402tuff4u]

Kind of sad that the author of the IM feels that way. If anything, all members here have been pretty open minded and helpful in my opinion. It's all about experiences and opinions each member has had on that particular issue posted. You take it at face value and with the feedback you make your own determination on the matter. I personally have gain so much knowledge from this forum that it has made the restoration of my Charger easier and more enjoyable. In allot of the issues posted, there is sometimes more than one answer to the matter. That's what makes this site so valuable........the different point of views.

[Duey]

Well, secrecy or not, the MOOG HD stuff is what I have...I'll let you know how it works out in a few months when I get back home.

Cheers,
Duey

[Shakey]

Well, secrecy or not, the MOOG HD stuff is what I have...I'll let you know how it works out in a few months when I get back home.

Cheers,
Duey

Call the old lady and ask her to take the car for a spin and give us a report.   

[Duey]

LOL

Actually, all that rubber is siting in the trunk waiting to get installed...that and all the new bits I got have to be installed (Pro-form carb, new ported heads, valave covers, headers, converter, rear-end, etc...) 

Duey

[firefighter3931]

Poly here as well....luv the firmness it produces. It would tend to agree with the "secret poster" that' it's probably not the best choice for a daily driver. I won't ever drive mine as a commuter vehicle so when it goes it i want it to perform like a champ, not a chump. 

These cars were never great handling vehicles to begin with but the poly suspension brings it closer to a modern car. The side affect is a stiffer ride but i can live with that....it is a Charger and nothing beats driving your ride ! 

[Brock Samson]

no way is my car a daily..

[is_it_EVER_done?]

As this boards most ardent Poly hater, I'll offer my opinion. I apologize for the length.

You state that you don't mind squeaks or a stiff ride. If that's what you are after, Poly bushings and a set of KYB shocks will certainly give it to you, however the harshness is caused by a transference of the road bumps/irregularities to the cars body/frame instead of having them absorbed by the suspension as intended. This is a suspension performance decrease, not an improvement.

It is certainly true that road race, autocross, and other race only cars can maximize handling with Poly or solid bushings, but in every case, they are running substantially reduced suspension travel, reduced ride height, very low profile tires, increased spring/torsion bar/sway bar rates, altered suspension geometry/alignment settings, and other modifications so that the suspension is optimized to work in only a small range of motion.

My opinion is that Poly is the answer to a question that nobody asked! First of all, Poly does not address any known problem, or fix any perceived shortcomings of the stock Mopar suspension. Instead, it tries to eliminate an essential element of elasticity that is necessitated by the laws of physics.

Rubber bushings are essential, and designed, to provide necessary elasticity in an infinite number of axis's. This is due to the requirements of the suspension to not only move/twist through a large range of motion, but do so while never being in equilibrium with other individual suspension components, as unequal component lengths are necessary to reduce squat under braking and rise under acceleration, provide frame and body protection from shock, provide gradual/exponential loading of the springs/torsion bars/shocks, and always return to their static state in the same gradual time frame. Poly does none of this. – Polly can best be equated to brakes that can only be locked up, or un-applied, with the entire essential "in between" eliminated!

Why does Poly squeak? Because it can't provide torsional flexibility (twist). This caused the manufacturer to impregnate it with Graphite to help reduce the squeak caused by its inability to provide essential torsional flexibility. Since even graphite can't defy physics, they started providing special lube to help it slide (remember, it can't twist). The problem with this is that the lube is not captive, and will eventually migrate out of the load areas, wash out, and allows it attract contaminants from the road (increasing wear). Not only that, but it can't absorb extreme shock, and will shatter under a heavy shock load (big pot hole).

Increasing the torsion and sway bar sizes, and "GOOD" shocks (Edelbrock, Koni, etc.) are the proper way to improve your suspension. Use Moog components with their offset upper control arm bushings (for increased positive caster). This will provide a "real" performance increase that you can feel and count on! Poly is the biggest con ever perpetrated on the auto enthusiast world. Ricer style decals, or an "oil company withheld" 100-MPG carburetor are better upgrades.

P.S. It has been said that the stock Mopar suspension is a poor design. NOTHING could be further from the truth! If you look at the late 60's/very early 70's Mopar NASCAR cars that were running 200 MPH (as fast or faster than todays cars), you will see suspension that is shockingly similar to yours! Besides torsion bars the size of tree trunks, fat shocks, and a few strengthening gussets, the suspension was basically stock. Mopar had the best suspension ever to be offered on a production car, and in all but the most extreme situations, still holds it's own today.

[Mike DC]

Just a couple of thoughts:

--  IMHO, I agree that poly is sometimes used in situations where stiffer rubber would have been better.  The OEMs are paying a lot of attention to the durometer of their various bushings these days.

--  For the rear end of the car, I've heard of people running rubber bushings in the front spring eyes but using poly ones in the rear spring shackles.  So the poly is taking out more slop at the long end of the spring, and the rubber is still doing some cushioning from bumps when the car is rolling forwards.  This is said to be a decent compromise between the two bushing types.

.

[Shakey]

As this boards most ardent Poly hater, I'll offer my opinion. I apologize for the length.

You state that you don't mind squeaks or a stiff ride. If that's what you are after, Poly bushings and a set of KYB shocks will certainly give it to you, however the harshness is caused by a transference of the road bumps/irregularities to the cars body/frame instead of having them absorbed by the suspension as intended. This is a suspension performance decrease, not an improvement.

It is certainly true that road race, autocross, and other race only cars can maximize handling with Poly or solid bushings, but in every case, they are running substantially reduced suspension travel, reduced ride height, very low profile tires, increased spring/torsion bar/sway bar rates, altered suspension geometry/alignment settings, and other modifications so that the suspension is optimized to work in only a small range of motion.

My opinion is that Poly is the answer to a question that nobody asked! First of all, Poly does not address any known problem, or fix any perceived shortcomings of the stock Mopar suspension. Instead, it tries to eliminate an essential element of elasticity that is necessitated by the laws of physics.

Rubber bushings are essential, and designed, to provide necessary elasticity in an infinite number of axis's. This is due to the requirements of the suspension to not only move/twist through a large range of motion, but do so while never being in equilibrium with other individual suspension components, as unequal component lengths are necessary to reduce squat under braking and rise under acceleration, provide frame and body protection from shock, provide gradual/exponential loading of the springs/torsion bars/shocks, and always return to their static state in the same gradual time frame. Poly does none of this. – Polly can best be equated to brakes that can only be locked up, or un-applied, with the entire essential "in between" eliminated!

Why does Poly squeak? Because it can't provide torsional flexibility (twist). This caused the manufacturer to impregnate it with Graphite to help reduce the squeak caused by its inability to provide essential torsional flexibility. Since even graphite can't defy physics, they started providing special lube to help it slide (remember, it can't twist). The problem with this is that the lube is not captive, and will eventually migrate out of the load areas, wash out, and allows it attract contaminants from the road (increasing wear). Not only that, but it can't absorb extreme shock, and will shatter under a heavy shock load (big pot hole).

Increasing the torsion and sway bar sizes, and "GOOD" shocks (Edelbrock, Koni, etc.) are the proper way to improve your suspension. Use Moog components with their offset upper control arm bushings (for increased positive caster). This will provide a "real" performance increase that you can feel and count on! Poly is the biggest con ever perpetrated on the auto enthusiast world. Ricer style decals, or an "oil company withheld" 100-MPG carburetor are better upgrades.

P.S. It has been said that the stock Mopar suspension is a poor design. NOTHING could be further from the truth! If you look at the late 60's/very early 70's Mopar NASCAR cars that were running 200 MPH (as fast or faster than todays cars), you will see suspension that is shockingly similar to yours! Besides torsion bars the size of tree trunks, fat shocks, and a few strengthening gussets, the suspension was basically stock. Mopar had the best suspension ever to be offered on a production car, and in all but the most extreme situations, still holds it's own today.

You have answered all of the questions I have ever thought of and some I hadn't thought of and some that I probably couldn't even put into words.

Thanks & well done.   

[is_it_EVER_done?]

Just a couple of thoughts:

--  IMHO, I agree that Poly is sometimes used in situations where stiffer rubber would have been better.  The OEMs are paying a lot of attention to the durometer of their various bushings these days.

--  For the rear end of the car, I've heard of people running rubber bushings in the front spring eyes but using Poly ones in the rear spring shackles.  So the Poly is taking out more slop at the long end of the spring, and the rubber is still doing some cushioning from bumps when the car is rolling forwards.  This is said to be a decent compromise between the two bushing types.

Though this may sound like a reversal of what I previously stated, it really isn't. Believe it or not, I edited out over half of what I said before, in order to not go into two pages.

--------------------------------------

I totally agree with you that specific and adjusted durometer values of rubber is the absolute ideal, but since that will never exist, the possible use of Poly components, in addition to rubber for a performance increase can be achieved. I don't just hate Poly because it exists, I HAVE used it (and removed it) a couple of times! However, I have found that Poly strut rod bushings (on the front of the rods only) provide an improvement that can be felt (due, I believe, to better controll of caster fluctuations, and caster increases due to the rubber rear bushings being forced to compress). I also agree that Poly rear spring bushings can help make the suspension "work" better by reducing sideways flex, but will also require periodical disassembly for lubrication. I have also had decent results experimenting with Poly bushings for the link rods of sway bars (not the horizontal "K frame" mounting bushings), and have found that adjustable shocks can be set one or two clicks lower if Poly is used in the mount bushings.

My statements were more of a general nature, and for the "average enthusiast", All rubber is not only better, but will eliminate a performance decrease from an "across the board" replacement of rubber with Poly. It all depends on your intended use. A strip only car Will be best with all rubber, smaller torsion bars, loose shocks, and no sway bars, whereas an autocrosser "MAY" be better with the absolute reverse of that.

The best compromise is all rubber (good Moog stuff). Certain Polly components can offer an improvement, but ALL Polly WILL be a reduction in handling and performance, (not to mention a dramatic decrease in longevity).

Well thought out experementation is always recommended (at least by me), but if I was going to put my family into an old car, I wouldn't use any Poly.

[Brock Samson]

I've gone with the Moog HD Offset stuff as I.I.E.D? recommended,    The steering box needed to be tighened up too,.. should have it on the road today for a test    !

THANKS!  I LEARNED A BUNCH! 

[71charger_fan]

Opinions are like... well, you know the rest.

I put in poly almost ten years ago. I like the feel of the car, the ride of the car, and have no issues with squeaks. I like the fact that the poly is impervious, at least relative to rubber, to ozone breakdown. For my car, I'd never consider putting rubber bushings in again. I just wish I wasn't too lazy to pull the leaf springs and change those too. Although, for the record, I did upgrade the shocks and install heavier torsion bars when I had the suspension apart.

[is_it_EVER_done?]

Opinions are like... well, you know the rest.

I put in poly almost ten years ago. I like the feel of the car, the ride of the car, and have no issues with squeaks. I like the fact that the poly is impervious, at least relative to rubber, to ozone breakdown. For my car, I'd never consider putting rubber bushings in again. I just wish I wasn't too lazy to pull the leaf springs and change those too. Although, for the record, I did upgrade the shocks and install heavier torsion bars when I had the suspension apart.

It's OK, you can say it (this isn't moparts), nor does it offend me in any way. However, my "opinion" is that I don't like poly. My explanation of why rubber is used and not other material, and what each material can, and cannot do is fact.

I just want to point out that you installed heavier torsion bars, and upgraded shocks, yet you attribute your increased enjoyment of the feel of your car to the installation of poly. It is my belief that had you used rubber (moog) instead, particularly if you had used their offset upper bushings for increased positive caster, you would like the "feel" as much or more with the upgrades you did, but with no A-B tests to go by, you state that you would "never consider putting rubber bushings in again". Thats fine, but it really doesn't address the "which is better" discussion.

As for 10 years of no squeak use from your poly install, I assume that this has to be with very low use (milage), as it's hard to get 10 years of use out of ball joints, or U joints (each of which have captive lubrication), if the car is driven on a regular basis . Again I must point out that poly HAS to slide, wherein rubber twists. The sliding creates wear points as the lubrications diminished, instead of rubbers ability to dissapate motion through heat due to it's ability to twist. Personally, I have never been able to get a fraction of that time/wear out of a "non lubrication captive" moving item. It would be like never lubing your disk brake calipers. They may still work, but nowhere near optimum or even within design parameters. -- For the record, I do put much more than 10,000 miles each per year on my cars, so certain thing show up that may never be a factor for others.

In regards to Ozone breakdown of rubber vs poly, I'll take you word for it as it is nothing I have ever even thought about nor tested. That part aside, I would still recommend rubber for the best performance, even if it does brake down through Ozone sooner than poly, as poly will wear out, or shatter long before it ever becomes an issue. This is not an opinion, but a guarantee.

[Brock Samson]

 O.K.
  Well, It seems now after driving,..  the rear seems abit too stiff for my liking, it hooks up fine from a dead stop because i guess thats what S.S. Springs do,.. but I feel like if i put one of those little chiwaawaa dogs in the back window,.. the ones with the bouncing heads?.. It'd would beat it's self to death!.. Prolly 'cause now the front has some compliance and the rear doesn't.. Funny cause i was used to the SS Springs with my previous front bushings' PST poly stuff. Now the front also seems to tramline a bit too,.. which is to say it's riding invisible irregularities in the road (at Speed) and hitting imperfections (pot holes etc.) make it kinda hop sideways.. (perhaps the rear is getting off traction and comming down abit off to the side?) the  steering box seems to need a tick more tighening too...  But hammer down it still chirps the tires at approx. 55 MPH, Now That part I like!  It worries me though, because I'm afraid the combo of factors might snap the car sideways.. 
  As Re: the Carb. Holly 770 Street Avenger on a Weiland Stealth, the plugs were white so I added fuel.. (more tweaking to come)..

  Has anyone got any thoughts?.. I've never had (so) many folks to bounce this stuff off of before,  cause I haven't messed with (Tuned) the car other then oil changes since '99..

[firefighter3931]

Hey Strat, what kind of bushings are you running in the rear spring eyes/shackles. What you're describing sounds typical for a loose front end/tight rear end chassis combination. SS springs ride hard and even harsher with a looser front end....at least that's been my experience. If you're running poly bushings out back....possibly a change to rubber would soften it up a bit. Or you might need to back to an XHD 440/hemi spring.

Ron

[Brock Samson]

  yeah the rears are poly,..    way too stiff with the Moog front end rubber,.. so my thought is while the front is now forgiving the rear is now harsh in comparo. which accounts for the rear "stepping out". Squirrly and unsafe... 


I'd really appreciate hearing about your experiance with Dual Purpose cars guys, street and strip with and without the S.S. Springs... 

I only expected to do a front end alignment, then the steeing gear was sloppy as i was able to turn the front tires about two inches side to side without the steering wheel budging while up on the rack...

... and now a switch to front end rubber makes the rear ride like an unladen flatbed... 

As i wasn't unhappy with the freeway ride before, so maybe?.. I should switch back to the poly in front?.. as the rear don't need referbishment...

 

[BLAM]

Personally I believe the rear end bounce has less to do with the poly bushings and more to do with the new S.S springs!  I would never run S.S. springs in anything but a pure race car period!

If you do put new poly up front I think you will find both ends of the car ride like an unloaded flatbed truck!!

I think you have the perfect set up accept for the S.S. springs.  The springs should be the be HD ones.

[Brock Samson]

 When i (Finally) got the BB drivetrain in the car with the S.S. springs, the massive torque avail at low Revs.  (2,300) simply spun the back tires for the first two or three seconds under any kind of accleration short of lightly feathering the go pedal..

So,..  I went to more agressive tires front and back, uprading the rears to the widest and tallest (28 inchers) to give more gear ...in anycase, the taller, wider tires and the new tighter quicker 727 tranny with a shift kit did wonders for increasing traction, so I was not unhappy with the S.S. Springs... Till now,.. So i guess my question is...
   What differences might i expect with the H.D. springs and rubber bushings in the rear?..
Sure it's gonna be softer, but will the rears still hook up from a dead stop?. & will i have a return of the dreaded bobble?... 

update:
It's raining here and  predicted to rain for the next two weeks!