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Does control arm bushing composition affect ride quality or NVH?

bobthetj03

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Ok, here it is. Discuss. Set your butt dynos aside and lets see if we can find some real data and not just observations.
 
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jjvw

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Most of us have some familiarity with the factory rubber bushings. Is that our baseline for comparison?
 

Chris

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Blaine has told me numerous times in the past that a Johnny Joint doesn't affect ride quality whatsoever over any other control arm bushing. While he didn't give me the science behind it, if Blaine is that adamant about it, I'm certain there's truth to what he's saying.

I wish I knew the science though!
 
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bobthetj03

bobthetj03

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That is why I was hoping we could pool up some real data about it. Sure, we can use the factory arms as a base line, but we are still just making an observation. Let's try not to get too involved in misalignment and degrees of articulation the joint can provide, cause all that does is make up for the lack of flex that aftermarket arms have compared to what factory arm provides.
 

jjvw

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Blaine has told me numerous times in the past that a Johnny Joint doesn't affect ride quality whatsoever over any other control arm bushing. While he didn't give me the science behind it, if Blaine is that adamant about it, I'm certain there's truth to what he's saying.

I wish I knew the science though!
I don't recall what he says about rod ends/heim joints, but most of the common control arm joints/bushings have an isolation material as part of their design.

Similar to the differences between spring rates, the assertion is that the differences between joints/bushings are not perceivable. I'll concede just a tiny bit and suggest that the differences are minor to the point of insignificance.

Something else he often brings up is that unless you are only making single changes, how do you know what is contributing to whatever change your are perceiving.
 

Chris

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Something else he often brings up is that unless you are only making single changes, how do you know what is contributing to whatever change your are perceiving.
Very true! If you're installing an entire lift kit and changing a host of things (as well as the suspension geometry) in the process, it would be hard to just point at one thing and blame that for a perceived difference in ride quality.

Perhaps there could be a measured difference in bushing composition, but my guess is it would be negligible at best. I'm no expert on the matter, just thinking out loud.
 

jjvw

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That is why I was hoping we could pool up some real data about it. Sure, we can use the factory arms as a base line, but we are still just making an observation. Let's try not to get too involved in misalignment and degrees of articulation the joint can provide, cause all that does is make up for the lack of flex that aftermarket arms have compared to what factory arm provides.
Factory arms with their rubber bushings have an aspect of isolation that most of us are familiar with. This is often the only point of comparison many will ever experience.
 
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fuse

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Definitely want to see what people have to say about this.

I think consensus among Subaru tuners was that good quality PU bushings did not increase NVH. But some of the cheaper bushings may not have be so good.

If we wanted hard data, we might look at the material properties of various bushings, but I don't know how to get that except in a lab.
 

jjvw

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Here's another very important question. Do the track bars have any more or less contribution to the transmission of NVH as the control arms?
 

jjvw

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Very true! If you're installing an entire lift kit and changing a host of things (as well as the suspension geometry) in the process, it would be hard to just point at one thing and blame that for a perceived difference in ride quality.

...
I do know that small changes in tire pressure have pretty noticable changes in the ride.
 

jjvw

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...

If we wanted hard data, we might look at the material properties of various bushings, but I don't know how to get that except in a lab.

...

Perhaps there could be a measured difference in bushing composition, but my guess is it would be negligible at best. I'm no expert on the matter, just thinking out loud.
There is that shaker table video. Is it an accurate recreation of what a control arm experiences? Do we really understand what the results are telling us?
 

fuse

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I'm just going to toss this in here. It's more reading than I'm up for this late after a couple of beers, but it looks relevant.

http://www.whiteline.com.au/articles/WL_Alloy_link.pdf

"To conclude the alloy [anti-roll bar] link is stiffer than the OEM link at all loads but effectively stiffer at higher loads or roll resistance values ( anti-roll bar sizes). During lower loads the compliance of the polyurethane bushes comes into the picture and reduces this stiffness slightly in order to tackle NVH issues." -- But I gather this depends on engineering the entire system together, including the hardness of the bushings and the elasticity of the anti-roll bar links.
 
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Chris

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There is that shaker table video. Is it an accurate recreation of what a control arm experiences? Do we really understand what the results are telling us?
Are you talking about the shaker table video demonstrating the Duroflex bushing? I wouldn't get Blaine started on that one... I wish I remember the conversation, but he really, really has a problem with that video and how misleading it is. I'm not 100% sure why it's misleading, but he sure seemed to have a strong opinion about it.
 

jjvw

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I'm just going to toss this in here. It's more reading than I'm up for this late after a couple of beers, but it looks relevant.

http://www.whiteline.com.au/articles/WL_Alloy_link.pdf

"To conclude the alloy [anti-roll bar] link is stiffer than the OEM link at all loads but effectively stiffer at higher loads or roll resistance values ( anti-roll bar sizes). During lower loads the compliance of the polyurethane bushes comes into the picture and reduces this stiffness slightly in order to tackle NVH issues." -- But I gather this depends on engineering the entire system together, including the hardness of the bushings and the elasticity of the anti-roll bar links.
Something to add that might be relevant, but will probably only create confusion...

A while back I discovered that my rear shock bushings and rear sway bar bushings were very worn and loose. Over a short period of time I replaced all 10 of those sloppy bushings. As each group of loose, clanging connections was tightened up, the NVH decreased significantly and the ride improved dramatically. How does this relate to the shaker table?


Unrelated, but related... The JKS Flex Connect is a replacement sway bar link with a tunable spring. This will turn a sway bar into a dual rate sway bar with a softer initial travel. This sounds similar to what the article is describing.
 
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Jerry Bransford

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Are you talking about the shaker table video demonstrating the Duroflex bushing? I wouldn't get Blaine started on that one... I wish I remember the conversation, but he really, really has a problem with that video and how misleading it is. I'm not 100% sure why it's misleading, but he sure seemed to have a strong opinion about it.
I can assure everybody here that when Blaine has an exceptionally strong opinion on something like he does this subject in particular, he didn't just pull it out of his ass.

I'll just add that my TJ's Currie Johnny Joints have hard polyurethane races and it has a great ride.
 
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fuse

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Something to add that might be relevant, but will probably only create confusion...

A while back I discovered that my rear shock bushings and rear sway bar bushings were very worn and loose. Over a short period of time I replaced all 10 of those sloppy bushings. As each group of loose, clanging connections was tightened up, the NVH decreased significantly and the ride improved dramatically. How does this relate to the shaker table?
I don't know anything about the shaker table, but as long as we're talking butt dyno, most of what I've done to my Jeep since I bought it was replacing old, cracked rubber with new OEM rubber. NVH decreases each time, and the ride improves each time.

No surprise there though.

Control arm bushings are next, so I'm watching this thread.
 
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jjvw

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Are you talking about the shaker table video demonstrating the Duroflex bushing? I wouldn't get Blaine started on that one... I wish I remember the conversation, but he really, really has a problem with that video and how misleading it is. I'm not 100% sure why it's misleading, but he sure seemed to have a strong opinion about it.
If the bolts are tight, does the control arm get hammered like that in the real world? Why couldn't they, or why didn't they attach a factory control arm? How would they do that in any reasonable manner and still get the hammering action?

What about a track bar?

Isn't it convenient that their bushing falls perfectly within the ideal Phase 1. What is Phase 2-3 and what does that feel like? I don't know either. Look at the graph again and notice how wide Phase 1 is compared to the subsequent Phases.
 
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fourpointzero

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I cant see a type of rubber bushing making a major difference in “feel” of ride or quality of ride. Maybe metal on metal, somewhat? But when it comes to a differently engineered rubber joint, it’s probably not humanly detectable. Let me clarify, I have no data to back up my statement. But it is a Jeep. You have to expect jolt and bounce in their general ride quality. Especially w the short arms.


Sent from my iPhone using Tapatalk
 
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