Which one ??

[69hurstolds]

I went with poly mounts for my car. A car even with poly mounts will still ride smoother than a car with bad rubber mounts. Also rubber mounts contain a molded in sheetmetal reinforcing insert. These inserts rust out inside the bushing leaving it hollow, and you can't tell until you remove the bushing. Worse yet, when the insets rust out, they often rust out the mount hole in the frame too.

However, for suspenison bushings I suggest OEM rubber bushings as poly bushings have binding issues. Especially in 4 link rear suspension setups like in our cars. 4 links require deflection to operate bind free.

I disagree. If you go poly, you can't go half way and get my respect. Go whole hog or go back in the house. Pick one and stick with it. Why does everyone think they deserve the best of both worlds?

J/K.

I don't care. Each has their benefits and drawbacks. You put stock rubbers back in and it'll be 20 years or so before you have to worry about them again. So if you don't have the car anymore by then, who cares. If it's a forever car and you don't care about stock, do it. Rubber bits on the suspension are way easier to replace than the risk of body mount bolts not coming out if you want them to.

My own plan comes with graphite and never-seize action on the body mount bolts. Just in case.

 

[pontiacgp]

The 4 link rear suspension uses the arms to twist to prevent binding, especially the upper arms. The rubber bushings have more give than the poly bushings but the rubber would not compress enough to prevent binding.

 

[Clone TIE Pilot]

The 4 link rear suspension uses the arms to twist to prevent binding, especially the upper arms. The rubber bushings have more give than the poly bushings but the rubber would not compress enough to prevent binding.

Rubber bushings in the rear suepension arms act like crude heim joints, alowing for mutiple axis of rotation. Poly bushings act like metal bushings, only allowing a single axis of rotation. Put poly bushings in a suspension designed for mutiple axis is going to give rise to binding issues, even if the arms flex.

The rear 4 link in G bodies have non symmetrical axis between each joint, so converting them to single axis joints will cause issues since their geometry are not in the correct alignment for that. Poly isn't bad for every suspension design, but it is for 4 links which are badly outdated. The closet thing to a real fix short of a complete redesign is to install a Watts setup in the rear with an axle mount rear sway bar. Basically it is highly difficult to improve one aspect of 4 links without making the other aspects worse. G body suspensions are far from being precision mechanisms.

As for body mounts, there are no binding issues as they are compression bushings rather than being rotation bushings, so no binding to worry about in this application.

 

[pontiacgp]

Rubber bushings in the rear suepension arms act like crude heim joints, alowing for mutiple axis of rotation. Poly bushings act like metal bushings, only allowing a single axis of rotation. Put poly bushings in a suspension designed for mutiple axis is going to give rise to binding issues, even if the arms flex.

we did testing on upper control arms to see if we could improve the rear end on a circle track G body since we had to use stock control arms. We boxed the lowers with no problem but the upper boxed were another story. We used the rubber bushings to see what the results were.....here is the elongated hole created because the rubber bushing could not pick up the deflection. We ended up with poly bushings and open uppers and never had an issue with an elongated hole.

 

[69hurstolds]

Nobody should have an elongated hole...

 

[fleming442]

Nobody should have an elongated hole...

Yet, the condition runs rampant......

 

[superbon54]

Rubber bushings in the rear suepension arms act like crude heim joints, alowing for mutiple axis of rotation. Poly bushings act like metal bushings, only allowing a single axis of rotation. Put poly bushings in a suspension designed for mutiple axis is going to give rise to binding issues, even if the arms flex.

The rear 4 link in G bodies have non symmetrical axis between each joint, so converting them to single axis joints will cause issues since their geometry are not in the correct alignment for that. Poly isn't bad for every suspension design, but it is for 4 links which are badly outdated. The closet thing to a real fix short of a complete redesign is to install a Watts setup in the rear with an axle mount rear sway bar. Basically it is highly difficult to improve one aspect of 4 links without making the other aspects worse. G body suspensions are far from being precision mechanisms.

As for body mounts, there are no binding issues as they are compression bushings rather than being rotation bushings, so no binding to worry about in this application.

Did somebody say watts link? This setup will either handle like it’s on rails or be a massive expensive disappointment. I’ll let you guys know in about 6 months.

 

[1983calais]

The rear 4 link in G bodies have non symmetrical axis between each joint, so converting them to single axis joints will cause issues since their geometry are not in the correct alignment for that. Poly isn't bad for every suspension design, but it is for 4 links which are badly outdated. The closet thing to a real fix short of a complete redesign is to install a Watts setup in the rear with an axle mount rear sway bar. Basically it is highly difficult to improve one aspect of 4 links without making the other aspects worse. G body suspensions are far from being precision mechanisms.

So if I’m reading and understanding correctly, the poly bushings bind and the rear 4 link doesn’t do or react how it supposed to. Would spherical bushings in the top axle points and the axle to frame mount sway bar be the solution? I have poly bushings at all points with tubular arms, top and bottom, in the rear of my car and sometimes it does some crazy stuff. Like the rear of the car just pulls the car to one side or the other and freaks you out.

 

[fleming442]

Poly bushings are good everywhere EXCEPT the rear, upper control arms, frame side. Solid upper bars work best in a solid, spherical mount.

 

[jiho]

I've seen some bits of this argument before, between the same two members.

Only here we're confusing some issues. The problem with binding on the rear upper control arms is caused by a stiff sway bar that attaches to the lower control arms, not by your choice of bushings.

The comparison of rubber to polyurethane is an urban legend. Take a polyurethane mount or bushing in your hand. You can squeeze it with your bare hand.