poly bushings disintegrating
Thread Starter
Melting Slicks
Joined: Nov 2002
Posts: 2,231
Likes: 7
From: Fort Pierce Florida
poly bushings disintegrating
I have an '82 Vette that I hardly drive anymore. I've probably put 8,000 miles on the car in 10 years I've owned it, and probably less then 100 in the past 3 years. The car spends all of its time in the garage
Well, today I pulled it out and put it up on the rack to get some minor issues I've been neglecting fixed. I was shocked to see that ALL of the poly in the car was rotting away. Not just cracking, but some of it was completely gone! Sway bar cushions, dual mount spring "cushions", spring bolt cushions, etc. The only thing that appeared to be in decent shape was the poly body mounts. I'm not exaggerating when I say that all 4 of my front and rear dual mount spring bolts had at least one cushion that had completely rotted away.
I have a '72 also that I just had to replace all four of my rear dual mount spring mount cushions in for the same reason, but the rest of the poly looks in that car looks OK. That kit has been in there for less then 6 years. I'm just wondering if anyone else has had a similar issue or might know what is causing this.
Well, today I pulled it out and put it up on the rack to get some minor issues I've been neglecting fixed. I was shocked to see that ALL of the poly in the car was rotting away. Not just cracking, but some of it was completely gone! Sway bar cushions, dual mount spring "cushions", spring bolt cushions, etc. The only thing that appeared to be in decent shape was the poly body mounts. I'm not exaggerating when I say that all 4 of my front and rear dual mount spring bolts had at least one cushion that had completely rotted away.
I have a '72 also that I just had to replace all four of my rear dual mount spring mount cushions in for the same reason, but the rest of the poly looks in that car looks OK. That kit has been in there for less then 6 years. I'm just wondering if anyone else has had a similar issue or might know what is causing this.
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
I've had poly bushings in my car for 15 years, and put maybe 20,000 miles on it in that time. They squeak a little, but otherwise they look like the day I put them in. Got them from Vette Brakes.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
My "guess" is that you've been lubricating those poly mounts with something that they don't "like". If so, share that info with the Forum, so that others don't have the same problem. In general, plastics should not have petroleum products put on them...plastic is made out of petroleum substances, and over time they will break down.
But, I wouldn't think a 'good' poly bushing would break down that quickly, even with a 'toxic' substance. Have you contacted the vendor about this problem? They may have info...or even be willing to supply you with 'good' replacements if there was some problem with them.
But, I wouldn't think a 'good' poly bushing would break down that quickly, even with a 'toxic' substance. Have you contacted the vendor about this problem? They may have info...or even be willing to supply you with 'good' replacements if there was some problem with them.
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
I have had poly everything on my car with certain bushings on since 1983 and have not experienced what you are describing:
Front sway bar end link and mounting bushings since 1983 and just this year noticed 1 of the endlink bushings is cracked. Have not replaced it yet.
VBP 360 rear monospring since 1986 and the poly cushings look great today.
Upper and lower front control arm bushings-9 years-look great etc.
The cracked sway bar bushing on the front bar is the first poly bushing that has ever gone bad-29 years.
Something is defective in the bushings you have. I have been using poly bushings since the late 70's/
Hope that helps!
Front sway bar end link and mounting bushings since 1983 and just this year noticed 1 of the endlink bushings is cracked. Have not replaced it yet.
VBP 360 rear monospring since 1986 and the poly cushings look great today.
Upper and lower front control arm bushings-9 years-look great etc.
The cracked sway bar bushing on the front bar is the first poly bushing that has ever gone bad-29 years.
Something is defective in the bushings you have. I have been using poly bushings since the late 70's/
Hope that helps!
Last edited by jb78L-82; Nov 13, 2012 at 07:11 AM.
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
1. Struts rods-Heim joints are the way to go in that location
2. Trailing arms bushings.
Hope that helps!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Other than having a life span of only 20+ years and offering a bit more 'give' in the motion of body/suspension members [exactly what they are supposed to do], what are the downsides to using rubber bushings/cushions like were installed at the factory?
If those are the only 'limitations', that makes a pretty good case for using rubber, rather than going to poly material.....except in the case of someone who might be using his/her C3 for road racing.
If those are the only 'limitations', that makes a pretty good case for using rubber, rather than going to poly material.....except in the case of someone who might be using his/her C3 for road racing.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Melting Slicks
Joined: Nov 2002
Posts: 2,231
Likes: 7
From: Fort Pierce Florida
I don't use anything to lubricate the poly on the car. I'm wondering if it is something in my garage causing the rapid deterioration. I don't store any chemicals other then car care products and they are all on shelves of course. The only other thing I can think of is maybe some of the chemicals from washer or dryer in the air
Just wondering if anyone else has experienced this.
Just wondering if anyone else has experienced this.
Melting Slicks
Joined: Aug 2005
Posts: 2,683
Likes: 34
From: Working on the car NY
Sorry to disagree but after 30 years of using poly bushings on my C3 I have concluded based on my real world experience that poly bushings can be a tremendous addition to the suspension of C3's as long as one can deal with an occasional squeak from them AND in 2 locations I would not recommend them:
1. Struts rods-Heim joints are the way to go in that location
2. Trailing arms bushings.
Hope that helps!
1. Struts rods-Heim joints are the way to go in that location
2. Trailing arms bushings.
Hope that helps!
Same here
Instructor
Joined: Jun 2006
Posts: 104
Likes: 0
From: Missouri City Texas
I had the same issue as SuperJames. The front end control arm busing fell apart. Got them from Corrvette Central. Less then 3 year on the 1978 SA garage queen. I attribute the failure to over tighting, as they kept on coming loose.
This year, I changed all control arm bushings to rubber. They have not come loose or needed any re-tighting.
This year, I changed all control arm bushings to rubber. They have not come loose or needed any re-tighting.
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
Sorry to disagree but after 30 years of using poly bushings on my C3 I have concluded based on my real world experience that poly bushings can be a tremendous addition to the suspension of C3's as long as one can deal with an occasional squeak from them AND in 2 locations I would not recommend them:
1. Struts rods-Heim joints are the way to go in that location
2. Trailing arms bushings.
Hope that helps!
1. Struts rods-Heim joints are the way to go in that location
2. Trailing arms bushings.
Hope that helps!
As for poly's on the front trailing arms : you're probably well aware that poly is a sticky sort of plastic. If you replace the bushing with poly the arm axle has to turn on the bushing. It will smear the poly, which is why it starts to make noise and all sorts of other things. There is more : the axles on which the A-arms turn are not straight. (try rotating one on a lathe and tell me why). Which causes additional force in a point in the poly bushing. This will destroy it in due time.
As for the bushings in the other locations : as soon as there is rotation involved they will cause problems.
Then there are the trailing arms : these do not only rotate on the bolt, but the also twist.
Your choice.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
There are 'good' polymer materials that would have no problem lasting many, many years without problem. But, that would mean the vendors and manufacturers would have to make them out of something better than recycled plastic grocery bags! Since a black plastic trash bag will stay intact for more than 1000 years...buried in a landfill, there's NO reason that a poly bushing in a C3 should fail. Corvette Central just sent you 'dirt-cheap' plastic parts--and smiled all the way to the bank. 
Call them and complain, loudly. Nothing changes until disgruntled customers make themselves heard.
Call them and complain, loudly. Nothing changes until disgruntled customers make themselves heard.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Poly is one of those gray area products, attempting to span the broad gap between stock and full racing kit, and tho it reduces unwanted compliance it does have some drawbacks. That said, my having had poly CA and bar bushings without significant issue for some 30 years, I'd put this down to poor material and/or unfortunate chemical reaction (most likely due to the former).
Regardless, I wouldn't recommend poly in the rear camber struts or TA's, both of which inherently move in 3 dimensions during suspension travel. IMCO one should either stick with rubber in such locations, or if all that serious opt for heim-jointed struts, and sphericals or Johnny Joints for the TA's. For my own purposes I plan on taking care of that last item while my rear suspension is apart for further mods, and I also plan to move away from poly in the front end when all is eventually said and done.
If all of this comes off as if I have a mixed opinion on poly, that would be a resounding "maybe". In any event, those who choose to put it to use should do so with eyes open, and bearing in mind that squeaking poly is always a sign of binding poly. It simply must be lubed periodically, and with the right type of goop, to avoid stiction. My ~$.02
Regardless, I wouldn't recommend poly in the rear camber struts or TA's, both of which inherently move in 3 dimensions during suspension travel. IMCO one should either stick with rubber in such locations, or if all that serious opt for heim-jointed struts, and sphericals or Johnny Joints for the TA's. For my own purposes I plan on taking care of that last item while my rear suspension is apart for further mods, and I also plan to move away from poly in the front end when all is eventually said and done.
If all of this comes off as if I have a mixed opinion on poly, that would be a resounding "maybe". In any event, those who choose to put it to use should do so with eyes open, and bearing in mind that squeaking poly is always a sign of binding poly. It simply must be lubed periodically, and with the right type of goop, to avoid stiction. My ~$.02
Drifting
Joined: Nov 2007
Posts: 1,716
Likes: 281
From: New York
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
I then took another one, with the same result...
If you use poly, it has a little more give than steel, but not much more. That crooked tension originating from the axle has to go somewhere. Guess where ...
Team Owner
Joined: May 2001
Posts: 87,375
Likes: 1,593
From: Western NY
There are numerous other threads about poly's desintegrating. I know of a big one on another forum.
As for poly's on the front trailing arms : you're probably well aware that poly is a sticky sort of plastic. If you replace the bushing with poly the arm axle has to turn on the bushing. It will smear the poly, which is why it starts to make noise and all sorts of other things. There is more : the axles on which the A-arms turn are not straight. (try rotating one on a lathe and tell me why). Which causes additional force in a point in the poly bushing. This will destroy it in due time.
As for the bushings in the other locations : as soon as there is rotation involved they will cause problems.
Your choice.
As for poly's on the front trailing arms : you're probably well aware that poly is a sticky sort of plastic. If you replace the bushing with poly the arm axle has to turn on the bushing. It will smear the poly, which is why it starts to make noise and all sorts of other things. There is more : the axles on which the A-arms turn are not straight. (try rotating one on a lathe and tell me why). Which causes additional force in a point in the poly bushing. This will destroy it in due time.
As for the bushings in the other locations : as soon as there is rotation involved they will cause problems.
Your choice.
What "axles" are you referring to?
And FWIW, I've used poly bushings (exclusively Energy Suspension parts) off and on since the late 70s, and NEVER had one deterioriate.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
It's certainly not for everyone, but my eventual aim is to eliminate compliance from all points which affect dynamic suspension geometry. To that end, tho I was against the idea a few years ago I'm leaning more and more towards converting over to delrin where suitable when I get back to the front. I haven't fully decided yet between sphericals or Johnny Joints for the TA's.