Does control arm bushing composition affect ride quality or NVH?

[jjvw]

My understanding of the factory arms and clevite bushings is that they are generally fine within the factory limits of travel, approximately 7.5-8" of shock travel. But once you exceed those amounts of flex and rotation, the lifespan of the bushing is dramatically shortened. This is when a high misalignment control arm end becomes desirable. At the same time one is building to exceed the factory travels, the need to adjust the pinion and axle position becomes increasingly necessary. That would be a reason why adjustable control arms with high misalignment ends tend to go together.

 

[Fargo]

My understanding of the factory arms and clevite bushings is that they are generally fine within the factory limits of travel, approximately 7.5-8" of shock travel. But once you exceed those amounts of flex and rotation, the lifespan of the bushing is dramatically shortened. This is when a high misalignment control arm end becomes desirable. At the same time one is building to exceed the factory travels, the need to adjust the pinion and axle position becomes increasingly necessary. That would be a reason why adjustable control arms with high misalignment ends tend to go together.

And thats exactly why I'm here. Which brings up an interesting question. Do you know if Johnny Joints have more NVH than Clevite or other bushings.

 

[jjvw]

3* doesn't seem like much. You'd think a Clevite bushing would give you more than that.

3* x 2 clevites =6*

Whatever the actual number is, let's assume that is sufficient to accommodate the lateral shift of the track bar. Then we can add in the additional twist of the stamped arm to provide the necessary flex allowed by the factory shocks. Then the rotation of the bonded rubber is enough to let the axle to rise or fall 4" either direction. All of these movements are occurring at once and are accounted for by the clever design of the factory arms. Once we eliminate the ability of the arm to twist, those jobs need to be taken on by the bushings/joints.

 

[bobthetj03]

90% of the time, for most of us, a solid arm with Clevites would probably be fine. They are a pain to change out though, which is why I like the aftermarket options.

 

[jjvw]

90% of the time, for most of us, ....

:shhh: Don't say that too loud!

 

[Rob5589]

Was he referring to the lateral shift from the track bars or the flex/articulation? For some reason I have 3 degrees of misalignment in my head for a single factory clevite bushing.

I don't recall exactly. Basically I asked about the T1 arms and he said they would flex fine. I believe he actually preferred them over the T2 arm which has a JJ/clevite combo.

 

[Fargo]

You guys are to quick. I'll move my addtinal comments down here:

After all of the circumstantial evidence we can gather to lead us to believe there is more NVH or there isn't more NVH. At the end of the day, we are really only left with our best educated guess. I think that is why it gets so frustrating for people.

I would love to see Currie do a test on this. Do you think people would stop buying Currie JJ and switch to Synergy or MetalCloak if the found out JJs have 10% more NVH? What about 20%, 30%? IF we could gather hard and reliable evidence to show real NVH differences. How much difference would it take to pick one bushing over the other on NVH alone. (Including Clevite)

 

[Boinked]

90% of the time, for most of us, a solid arm with Clevites would probably be fine.

You win!!!!

 

[bobthetj03]

There just isn't any hard data out there, so observations is the best we can come up with. I can't imagine why Currie would even want to perform any experiments with NVH. They seem to have no problem selling JJ's, so why stick a wrench in the gears.

 

[bobthetj03]

You win!!!!

Yay! Winning!

 

[Fargo]

3* x 2 clevites =6*

Does it work that way? Can you add up each end. It seams to me that each end needs to move into its own position. Lets take this to the extreme. Put a solid bearing with zero flex into one end of the control arm. Can a bushing on the other end with 30 degrees offset that? I don't think it will. Both ends need to be able to move in releation to where the axle is going. I think that is why its pointless to have a JJ at one end and Clevite on the other. The JJ can't make up for what the Clevite lacks.

 

[jjvw]

And thats exactly why I'm here. Which brings up an interesting question. Do you know if Johnny Joints have more NVH than Clevite or other bushings.

EDIT: After all of the circumstantial evidence we can gather to lead us to believe there is more NVH or there isn't more NVH. At the end of the day, we are really only left with our best educated guess. I think that is why it gets so frustrating for people.

I would love to see Currie do a test on this. Do you think people would stop buying Currie JJ and switch to Synergy or MetalCloak if the found out JJs have 10% more NVH? What about 20%, 30%? IF we could gather hard and reliable evidence to show real NVH differences. How much difference would it take to pick one bushing over the other on NVH alone. (Including Clevite)

In my experience...

Based on my daily driver of the last 5 years, most of that time with factory arms and now with Johnny Joints, there was no precievable difference in NVH. I've ridden in Jeeps with Duraflex bushings and where I can parse out the differences in the on road ride characteristics and behaviors, there is no difference in between mine and their's that I would attribute to the arms.

I'll hazard a guess that Currie doesn't overly concern itself with NVH. It certainly it's not a significant part of their marketing. Either they don't care about that or they know it is a moot point.

If anything, it would be competition of a given company that would make a mountain out of a mole hill as a way to garner attention for their product. And I will concede that the reported size of this mole hill sounds plausible until you start looking closely.

 

[jjvw]

I don't recall exactly. Basically I asked about the T1 arms and he said they would flex fine. I believe he actually preferred them over the T2 arm which has a JJ/clevite combo.

I do know that he prefers matched pairs, unless there is a good reason not to. Miss-matched control arm ends will force the more compliant end to do the majority of the work. On a TJ with straight arms, there is no functional reason to mix joints and bushings.

 

[Fargo]

I do know that he prefers matched pairs, unless there is a good reason not to. Miss-matched control arm ends will force the more compliant end to do the majority of the work. On a TJ with straight arms, there is no functional reason to mix joints and bushings.

But in the case of the JJ, it can handle the extra work with no problem. It doesn't care if it is in 5 degrees or 15 degrees rotation. So why not save a little money and add in a clevite at one end. Or is the concern that the Clevite will hamper performance.

 

[jjvw]

Does it work that way? Can you add up each end. It seams to me that each end needs to move into its own position. Lets take this to the extreme. Put a solid bearing with zero flex into one end of the control arm. Can a bushing on the other end with 30 degrees offset that? I don't think it will. Both ends need to be able to move in releation to where the axle is going. I think that is why its pointless to have a JJ at one end and Clevite on the other. The JJ can't make up for what the Clevite lacks.

I think you are correct with regard to the lateral shift from the track bar and up/down rotation, but flex/articulation is accumulative.

 

[bobthetj03]

Observation: Duroflex bushing, lower arm, after 32K miles, 90% commute to work, add a few wheeling trips in the mix.

Old bushing,

Side by side comparison of old bushing vs. new bushing,

Barrel of arm with bushing removed,

Old factory arms with 100K + miles,

Does any of this mean anything? Likely not, but I'm a picture whore, so that's my story, and I'm sticking to it.

 

[bobthetj03]

to add,

I ran these up front for 50K+ miles.

when I replaced them with MC arms, my butt dyno felt no difference in dampening or performance. However, when I replaced those factory arms for the Currie arms, I felt a significant increase in road feel in the steering wheel, and not in a bad way. The jeep felt more planted to the road, especially while cornering. I got the same feeling when I switched to MC arms, so if there was any noticeable decrease in NVH, between the Currie arms and the MC arms, I couldn't feel it.

 

[Fargo]

Observation: Duroflex bushing, lower arm, after 32K miles, 90% commute to work, add a few wheeling trips in the mix.

Old bushing,
View attachment 57777

Does any of this mean anything? Likely not, but I'm a picture whore, so that's my story, and I'm sticking to it.

I'll make one observation. It appears to me that the majority of wear on that MC bushing is down the middle of the bushing. I'm guessing thats where they have that metal ball that is incased in the rubber. So that means its surface area for NVH is going to be very similar to the JJ. So now in regards to NVH, its just a matter of material thickness and density. Which still just really leaves us guessing.

EDIT: Is it just me or does anyone else not like that the MC bushing rotates inside the barrel of the arm. I always feel like this is a wear surface and it should be replaceable. Its one of the reasons I am between the DDB or the JJ and not the MC

 

[Rob5589]

Observation: Duroflex bushing, lower arm, after 32K miles, 90% commute to work, add a few wheeling trips in the mix.

Old bushing,
View attachment 57777
Side by side comparison of old bushing vs. new bushing,
View attachment 57778
Barrel of arm with bushing removed,
View attachment 57779
Old factory arms with 100K + miles,
View attachment 57780
View attachment 57781
Does any of this mean anything? Likely not, but I'm a picture whore, so that's my story, and I'm sticking to it.

You should mock up that factory arm and twist it to see how much it actually gives.

 

[Fargo]

to add,

I ran these up front for 50K+ miles.
View attachment 57783
when I replaced them with MC arms, .

Remind me. Why did you switch to MC arms?