Rubber vs polyurethane bushings

Kiwi TJ

Kiwi TJ

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Ok I'm in the process of thinking about an up and coming Autumn/Winter project and thought about upgrading my control arm bushings, sway bar bushings, track bar etc (you guys know the drill.)
Question is...Should I stay with rubber or go Polyurethane?...(I'm thinking is a preference thing)
 
Kiwi TJ said:
Ok I'm in the process of thinking about an up and coming Autumn/Winter project and thought about upgrading my control arm bushings, sway bar bushings, track bar etc (you guys know the drill.)
Question is...Should I stay with rubber or go Polyurethane?...(I'm thinking is a preference thing)
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Well if you drive over a half dollar piece do you want to feel it. Really there are pros and cons to both but the rubber is what it came with and it's still a good choice. The poly bushings do not dampen any vibrations and tend to be squeaky.
 
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In past "non-TJ" vehicles I've owned, I've used poly bushings. At first I was impressed with how much they tighten things up. After a while, however, I became weary of the harshness they gave to the ride. The smallest of road imperfections became more noticeable, and the ride quality suffered in that regard. I'd use poly in my sway bars again, but that's about it. Just a "for what it's worth"...
 
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Mmmmmm just as I thought, on previous cars I've gone with rubber, but saw the Poly one's advertised and thought, I wonder.:thinking:..
Plus the fact that I can get the poly ones in Blue as well got my attention lol...I thought if they work as well as rubber and increase curb appeal then I'd go for it...but think I'll stick with rubber.
 
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Squatch said:
They have a fascinating rear suspension set-up, don't they? Dang well better know what you're doing if you're going to restore one! One of my favorite body designs...
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I think the show Overhaulin did one of those with some subtle modifications.
ab03a0407d8a800253f9ea4ca6d4b660.jpg
 
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Squatch said:
Subtle, huh? LOL Not sure about that trunk area. Looks like the start of a skateboard park! Or a great place for a waterfall... ;)
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Cough cough its called a water feature its very fens shui haha..if I remember is was to make it look a bit GT40. The owner was a happy chappie come the end though.
 
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04/01/18

If I can jump in on the thread and ask for a little help I would appreciate it.

I'm conducting research also on the topic of bushings. Rubber, Clevite and Poly. So, I'm tossing out Poly now, thanks.

This is for my sons 2003 TJ. We don't have vibrations, but we do have some serious rear end sway going on. We bought the TJ in October 2017, its 15 years old and needs to be gone through.

1. Does anyone know of a complete REAR Clevite bushing kit? I have seen some individual Clevite parts but not an entire kit.
2. Is there a OEM or better rubber bushing kit that is superior to the other manufacturers?

I only want to replace the rear bushings once and not regret my decision on choosing the wrong manufacturer, product, rubber or poly.

Thanks in advance,
Puffer
 
Fresh oe bushings will be fine, it's not something that generally gets upgraded on a jeep without going to a flex joint.

—
There must have been a time
when we could have said no.
 
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Wondering.....🤔why is it every magazine and TV show rave about the poly bushings like Christ himself shat them out, yet everyone here damns them for harshness?
Wondering...🤔why is it every time metal mounts (Currie, etc) are claimed to NOT effect ride quality🤯? If the poly are bad because they are too hard and transmit vibration and impacts to the driver why don't the Johnny Joints🤨?
Seriously. I don't see how that works.
 
There are a few things being conflated in these comparisons. For starters a polyurethane split bushing is very different than a Johnny Joint. They are designed differently and will behave differently.
 
Goatman said:
Wondering.....🤔why is it every magazine and TV show rave about the poly bushings like Christ himself shat them out, yet everyone here damns them for harshness?
Wondering...🤔why is it every time metal mounts (Currie, etc) are claimed to NOT effect ride quality🤯? If the poly are bad because they are too hard and transmit vibration and impacts to the driver why don't the Johnny Joints🤨?
Seriously. I don't see how that works.
Click to expand...
Maybe because Jonny joints aren’t metal on metal....
 
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This is a serious question. I'm not being a smart (or dumb) ass. Obviously poly is more compliant than a Johnny joint. Yet here it is claimed that using poly bushings in your control arms will give a harsh ride. Yet the Johnny joints will not effect ride quality over a rubber bushing.
And when I put that bolt through a Johnny joint it is metal on metal where a poly joint has a thick cushion of urethane to absorb shock and vibration.
I'm not saying anyone is wrong, just wondering why this is. If you use a Johnny joint on both ends of your control arms it pretty much IS metal on metal. Or are you saying that thin layer between the ball and housing allows more absorption of shock than a thick layer of poly, or even rubber, for that matter? Seriously would like to understand this better.🤯
 
The Johnny Joint steel ball is surrounded by a poly shell. I think the key to understanding the differences between these joints and bushings is understanding how they are assembled.

First, I'll say that I haven't ridden in a vehicle with split bushings in it's suspension in a long time and I wasn't thinking about these things at that age.

On a normal drive down the street, I suspect that a fresh set of poly split bushings will be about as smooth as anything else. But the components of a split bushing are loosely fitted and as they wear the connection gets sloppy and unwanted movement quickly starts to occur.

The rubber bushings we tend to say are so good are bonded to the inner sleeve and outer shell. That bonded unit is pressed into it's larger component. And that component is to be bolted in with a correctly torqued bolt. The connection is tight the movement is controlled. There is no slop until one of those connections or bonds fails

A Johnny Joint is assembled by pressing (preloading) the poly shell tightly around the ball. The compressed shell and ball unit is also tightly compacted within the outer housing. The connection is tight and will remain tight as the poly shell and steel ball wear into each other. Obviously lubrication will greatly slow down this wear. And this preloaded connection also helps seal the joint from contaminants.

Like the bonded rubber bushing, the preloaded Johnny Joint packed into it's housing is a tight snug connection that remains tight and snug for a very long time as it wears. Add to that the JJ's greater ability to move within it's sealed poly shell without deforming it like a split bushing or even a bonded rubber bushing and the result is a tight isolated joint with a high range of motion and a long lifespan.

The tightness and the control of the movements of the various connections within the bushing or joint are the key to understanding why one type might be preferable over another.
 
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Per jjvw above, there are plenty of reasons a JJ is superior to a poly split bushing but I'm not sure harshness is one of them....and I think the harshness thing with poly can get overplayed. I put poly bushings throughout the suspension on a Datsun 280z that I dailied for 4 years and had zero regrets and didn't find it significantly harsh.

I'm much more concerned with its resistance to misalignment and the extra stress that puts on control arm brackets, which is why I wouldn't hesitate to use them again on a road car but would never put them on a Jeep.
 
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