Trailing arm bushings
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,164
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From: Beringen
Trailing arm bushings
I'm going for final reassembly of my car and going over some of the things i might have done wrong in the past.
One of those is replacing the trailing arm bushing with a poly one. I'm going back to rubber.
Is there any way one can install these without buying the special tool ?
thanks
One of those is replacing the trailing arm bushing with a poly one. I'm going back to rubber.
Is there any way one can install these without buying the special tool ?
thanks
Le Mans Master
Joined: Dec 2007
Posts: 6,422
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From: McHenry Illinois
This is the tool I built, it's built much heavier than needed, but it worked good. After using the tool to squeeze the bushing to the right dimension, I put the small end of the air hammer bit through the hole in the plate, into the sleeve and hit it with a hammer to flare it.
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
This is the tool I built, it's built much heavier than needed, but it worked good. After using the tool to squeeze the bushing to the right dimension, I put the small end of the air hammer bit through the hole in the plate, into the sleeve and hit it with a hammer to flare it.
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
Well, to put a long story short : I was first planning on improving the front end with a better solution. In asking questions and reading up on things i found out that poly is not the best solution for certain applications under which certainly the trailing arm bushing. This bushing due to the motions of the arm, does not merely pivot around the bolt, but also turns on the bolt. A solid suspension typ bushing like poly inhibits this kind of motion.
So either you go to a spherical or a johnny joint for this application. Due to its nature both of these need periodic greasing, which is difficult due the the position of the bushing in the chassis.
Besides going to a totally different setup (6-link) which is expensive, it just made more sense going back to rubber and eliminate the poly interely.
IMO poly has to many drawbacks certainly in this location.
So either you go to a spherical or a johnny joint for this application. Due to its nature both of these need periodic greasing, which is difficult due the the position of the bushing in the chassis.
Besides going to a totally different setup (6-link) which is expensive, it just made more sense going back to rubber and eliminate the poly interely.
IMO poly has to many drawbacks certainly in this location.
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Melting Slicks
Joined: Apr 2005
Posts: 2,777
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Well, to put a long story short : I was first planning on improving the front end with a better solution. In asking questions and reading up on things i found out that poly is not the best solution for certain applications under which certainly the trailing arm bushing. This bushing due to the motions of the arm, does not merely pivot around the bolt, but also turns on the bolt. A solid suspension typ bushing like poly inhibits this kind of motion.
So either you go to a spherical or a johnny joint for this application. Due to its nature both of these need periodic greasing, which is difficult due the the position of the bushing in the chassis.
Besides going to a totally different setup (6-link) which is expensive, it just made more sense going back to rubber and eliminate the poly interely.
IMO poly has to many drawbacks certainly in this location.
So either you go to a spherical or a johnny joint for this application. Due to its nature both of these need periodic greasing, which is difficult due the the position of the bushing in the chassis.
Besides going to a totally different setup (6-link) which is expensive, it just made more sense going back to rubber and eliminate the poly interely.
IMO poly has to many drawbacks certainly in this location.
I asked because I have poly in every place possible (for over 25 years now) - Red ones - except for the trailing arms in the rear. I even have poly trans and motor mounts - I guess Ill leave mine alone!
Last edited by babbah; Mar 7, 2011 at 10:19 AM.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Can you post some pictures of the poly bushings when you remove them? I believed the HYPE in the catalogues and installed poly in the T/A about 10 years ago and have not had any problems but I've since read many post that rubber is better in there.
Thanks.
Thanks.
Thread Starter
Melting Slicks
Joined: Mar 2002
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From: Beringen
The bushing "turn on the bolt"? Explain? The bushing has a steel sleeve in it that the bolt goes through? The A-arms are similar yes? They seem to be fine for three decades? How do you lube a poly fitting after it is installed?
I asked because I have poly in every place possible (for over 25 years now) - Red ones - except for the trailing arms in the rear. I even have poly trans and motor mos.unts - I guess Ill leave mine alone!
I asked because I have poly in every place possible (for over 25 years now) - Red ones - except for the trailing arms in the rear. I even have poly trans and motor mos.unts - I guess Ill leave mine alone!
So, there is not only a rotational movement, but the arm also tries to turn more or less in a clockwise way (when viewed from the rear). Poly doesn't allow for compression, so this makes your suspension in the rear bind when in compression. Rubber is much better since it allows this movement in both directions.
It's difficult to explain (especially since i'm not a native English speaker) but try to visualize what the suspension does when it moves up or down.
Thread Starter
Melting Slicks
Joined: Mar 2002
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From: Beringen
Will do, but remember that my car hasn't had any miles on it since installed.
Race Director
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This is difficult to explain with words, but i you make a drawing of the rear suspension when viewed from the rear, you will notice that the top of the trailing arm will move inward when the suspension is in compression. This is because the halfshaft acts as an upper link, and you have the camber rod below the shaft.
So, there is not only a rotational movement, but the arm also tries to turn more or less in a clockwise way (when viewed from the rear). Poly doesn't allow for compression, so this makes your suspension in the rear bind when in compression. Rubber is much better since it allows this movement in both directions.
It's difficult to explain (especially since i'm not a native English speaker) but try to visualize what the suspension does when it moves up or down.
So, there is not only a rotational movement, but the arm also tries to turn more or less in a clockwise way (when viewed from the rear). Poly doesn't allow for compression, so this makes your suspension in the rear bind when in compression. Rubber is much better since it allows this movement in both directions.
It's difficult to explain (especially since i'm not a native English speaker) but try to visualize what the suspension does when it moves up or down.
Thread Starter
Melting Slicks
Joined: Mar 2002
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From: Beringen
Correct, this is a better explanation i guess
Team Owner
Joined: Jan 2006
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From: Crossville TN
Both of you did quite well at describing the concern for [hard] poly bushings in applications that require flex movement. Some of the bushing applications are merely rotational...and those would be suitable applications for poly...or rubber. For the amount of actual use that most C3's get, rubber is probably a better choice all around. But, that's strictly up to the owner...
Thread Starter
Melting Slicks
Joined: Mar 2002
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From: Beringen
Both of you did quite well at describing the concern for [hard] poly bushings in applications that require flex movement. Some of the bushing applications are merely rotational...and those would be suitable applications for poly...or rubber. For the amount of actual use that most C3's get, rubber is probably a better choice all around. But, that's strictly up to the owner...
There is also another problem with poly's on the control arms, that is seldom mentioned, namely the bolts tend to come loose. This is also due to the fact the bushings rotate in their housings. For an application like that you would need a threaded shaft with a castle nut to secure the nut and not a bolt.
Melting Slicks
Joined: Apr 2005
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There is also another problem with poly's on the control arms, that is seldom mentioned, namely the bolts tend to come loose. This is also due to the fact the bushings rotate in their housings. For an application like that you would need a threaded shaft with a castle nut to secure the nut and not a bolt.
I even have poly dust boots on all my grease-able joints - like tie rods, idler arm etc.....LOL
I don't have them in the torque control arms and my adjustable billet strut rods so I'm good.
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Some day, I may have to replace the bearings again but until then I'll just leave things as they are.
This topic comes up now and then and a friendly discussion is always welcome. Everyone makes a good case for and against but the way I see it "It ain't broke so why fix it".
Regards,
Pete.
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,164
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From: Beringen
Thanks for the reply but pictures of new poly bushings won't show me anything. I understand that the T/A's not only go up & down but there is some arc as they travel. My poly bushings have been in use for many years and there is no problem, the pocket is still solid the T/A's do not seem bent and there are no squeaks.
Some day, I may have to replace the bearings again but until then I'll just leave things as they are.
This topic comes up now and then and a friendly discussion is always welcome. Everyone makes a good case for and against but the way I see it "It ain't broke so why fix it".
Regards,
Pete.
Some day, I may have to replace the bearings again but until then I'll just leave things as they are.
This topic comes up now and then and a friendly discussion is always welcome. Everyone makes a good case for and against but the way I see it "It ain't broke so why fix it".
Regards,
Pete.
I still have the possibility in changing without a lot of work, so that's why.
