Does control arm bushing composition affect ride quality or NVH?
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It was a bit of a loaded question, because I have had some of this discussion in other threads. I don't recall if it was MrBlaine or someone else, but the comment was made about surface area. Which makes it really difficult to wrap your head around how much material is really there. But in short, if you consider the JJ is a ball housed inside of the poly, its not just a flat face that is acting against the surface but the rounded surface of one full side of the ball. Of course, the Metalcloak also has a ball encased inside its joint and Synergy has a round shaft that is pushing against the surface. Then there is the issue of how wide the joint is. If you have a wider joint you have more surface area too. It gets really complicated very fast trying to wrap your head around how much surface area each joint has to work with.
Yeah, I see your confusion. I think its just a poorly worded commentary. Think about it like a sealed bearing. The inner sleeve of a bearing rotates freely too. Lets use a bike wheel for an example. The bearings on a bike wheel rotate freely. But once you tighten down the axle between the forks, that inner sleeve no long rotates. However, now the whole tire rotates inside the fork. So now just press the outside of that tire into a GIANT control arm. The control arm will rotate freely around the inner sleeve that is held tight to the mount.
At least thats how I understand it.
EDIT: We will run into issues though if the outer sleeve is the same width as the inner sleeve and both get tightened up against the mounting surface.
Check out this video on the JL Wranglers DDB. At 4:03 he talks about the dual durometer bushing. I think Jeep did a better job with the mounting point so you can see how this will mount solid and allow the outer sleeve to rotate round the inner sleeve. In short the the Synergy video says the inner sleeve rotates, but that is really only in relation to the outer sleeve. If the inner sleeve is in bind the outer sleeve will rotate around the inner sleeve.
That is where I get confused. Looking at both Synergy's and Rancho's joint, the teflon coated sleeve that surrounds the inner metal sleeve that will undoubtedly not rotated once torqued must be the portion that rotates, but looking at it, it looks like that teflon sleeve is the same width as the inner metal sleeve, so it too would be clamped and not be able to rotate as well.
The Duroflex joint does it by the whole bushing rotating within the barrel of the joint end via some synthetic grease applied to the circumference of the bushing.
I understand what you are saying. I really struggled with that same thing for awhile. But I think I know how it works know.
Looking at this image, you can see the entire rotating portion of the bushing in the guys hand. The metal sleeve that doesn't rotate will be pressed inside that teflon layer you see. Like you said, the problem appears to be that the sleeve is narrower than the rotating bushing. I agree that this appears to be a problem.
I think the solution is that once its all torqued down the inner metal sleeve is the only thing that CAN'T rotate so it stays in place while the rest of the bushing will rotate inside of the mounting bracket and basically wear itself into place. Its just poly and will compress right? So it won't put up much of a fight when the control arm starts moving. I don't think its the ideal solution. That inner metal sleeve should be slightly wider than the outer poly sleeve. Maybe the actual TJ bushing is built with a wider metal sleeve.
Looking at this image, you can see the entire rotating portion of the bushing in the guys hand. The metal sleeve that doesn't rotate will be pressed inside that teflon layer you see. Like you said, the problem appears to be that the sleeve is narrower than the rotating bushing. I agree that this appears to be a problem.
I think the solution is that once its all torqued down the inner metal sleeve is the only thing that CAN'T rotate so it stays in place while the rest of the bushing will rotate inside of the mounting bracket and basically wear itself into place. Its just poly and will compress right? So it won't put up much of a fight when the control arm starts moving. I don't think its the ideal solution. That inner metal sleeve should be slightly wider than the outer poly sleeve. Maybe the actual TJ bushing is built with a wider metal sleeve.
Yeah, I see what you're getting at. The ends of the teflon sleeve will "clearance themselves" once enough wear has allowed it to move more freely. Sounds like premature wear to me, but I guess it won't hurt the overall durability of the joint and is the sacrificial lamb of sorts? It's nice that you don't have to lube the joint, but don't you think that over time that teflon inner sleeve will wear to a point that play will become present between the inner sleeve and the teflon sleeve?
Thinking about this, I wonder if they kept the outer poly sleeve wider so it seals up tight against the mounting bracket to help keep water and debris out. But then that seems like a wear item that could defeat the maintenance free idea.
Does anybody know MrBlaine personally? I know he put a set of these on his wifes TJ for testing purposes. Maybe he can shed a little more light on this.
Does anybody know MrBlaine personally? I know he put a set of these on his wifes TJ for testing purposes. Maybe he can shed a little more light on this.
Yep, thats how I saw it. You just said it better.
That is the biggest question. Who knows how long that teflon will wear in this use. Its great for nonstick pans, but don't use a steel spatula. It will scratch it off. Uh Oh. What if we get debris in there. I think that is why the left the poly hanging over the sleeve. Its acting to help keep out the debris. So how long before the Poly clearances itself enough to allow something in there big enough to damage the teflon? How big of a particle and how hard of a particle would it take to damage the teflon?
I really like the DDB, but it has a lot of unanswered questions. But then again, even if you have to press it out and press in a new one in 50,000 miles is that more or less work than maintaining a JJ. It will all depend on where you drive I suppose.
If I was just a rock crawler I would go with the JJ. But because I think the DDB will offer better ride and NVH charateristics while being maintenance free it has my attention. Most people overlook the maintenance free part because of the unknowns. So that is why it really comes down to NVH I think. And that is why we have threads like this.
Sorry, I shouldn't have joined this thread. This is something I have already spent too much time thinking about and I have no answers. I'm just waiting for MrBlaines final review after his test. I just hope he shares his results.
The TJ style control arms and mounts have been in use since the 1984 XJ. Many of these are still on the road with very very high mileage. Are there reports of the mounts failing from fatigue? I don't know the answer, except that it isn't something that ever comes up as a problem.
This assumes that there is a percievable difference in NVH between bushing X and joint Y. If there was, then why are the track bars offered by the companies who make this claim not treated similarly to their control arms to reduce NVH?
At which point, you are left the choose control arms for other reasons than ride quality.
FWiW, I'm not the only one who has performed little to no maintainance on their JJs.
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I think that is a fair point. I am not aware of this as being a problem. However, Jeep used Clevite for all of those arms. So that only proves that there is no problem with metal fatigue when clevite is used. There is not a similar pool of data to make the same claim regarding JJ or other bushings.
In the case of Synergy they DO use the same bushing in their front trackbars as they use in their arms. For both the TJ and the JK, they setup the front trackbars the same as it was from Jeep, except they switch out the Clevite bushing for the DDB. The JK uses the DDB on both ends. The rear trackbar is more of a mystery as to why they used a heim on one end instead of a DDB on both ends. Is the rear trackbar misaligned or in bind some how on a lifted Jeep? I've never really looked. It seems to me that if you used one of those rear trackbar brackets that are at an angle to get the trakbar out of the way, the bushings would have to be twisted and in tension. It might be that, like MetalCloak, the DDB can not stay in tension without tearing itself apart. Which of course would raise concern about the longevity of the joint in trackbars that are in misalignment, but not the NVH characteristics.
We could ask the same question about Currie? Why doesn't Currie use a JJ on both ends? Its the flip side to the same coin. The answer is, its not the right joint/bushing for the job. Just as having a JJ on the front axle must cause some alignment or flipping issues for a JJ, their must be some alignment issue for Synergy and MetalCloak.
However, let me ask this. If the Currie JJ has as much NVH dampening as Clevite, and the problem with the front axle mount was the trackbar flopping over, then why didn't Currie just make a JJ with restricted movement that doesn't swivel in all directions. Just as MetalCloak made a special joint for the front trackbar, Currie could have made a JJ housing that had controlled movement. All you would need is a big washer of sorts under the snap rings to control the JJ from rolling over. It seems like a simple solution and they could have used their own joint. But I suspect they felt they needed the extra NVH dampening from Clevite at that location.
And that might be what it comes down to. Personal choice. Synergy has nice control arms with a nice pinch sleeve design. Savvy has some nice aluminum arms with JJ. Other companies have other joints and arms as well. The new breed of bushings might have less NVH or it might not be an issue. They might be maintenance free, but how hard is it to grease a joint once a year or so. (How often do they recommend?) So maybe thats why we look at NVH so much. Just trying to find a good reason to choose one over the other.
Reading through this thread (and many others) and processing some of these things in my mind, I highly suspect that the newer bushings do infact have less NVH. But I suspect its more noticeable with some rigs than with others due to other components, including suspension and tire choices. At the same time, I also question if the DDB and Duroflex can sustain prolonged periods of time under bind. Omitting the bushings from the rear track bar where Clevite was always used really makes me question some things.[/QUOTE]
My critique is not about Currie or another company using an appropriate joint or bushing for the desired purpose. It has everything to do with honesty and calling into question the marketing claims and the beliefs that the construction of the control arm bushing or joint has a perceivable affect on NVH. This is why I am making the point to include the track bars as a control arm. If the control arm design matters in this particular regard, then treat the track bars the same. Otherwise, quit the marketing BS and be honest about the inconsistency.
If NVH is not a real world issue, then what remaining criteria are you using to select a joint or bushing on the basis of actual function? Misalignment capabilities? Durability? Ease of maintainance? Do you place value on a bushing (or maybe a joint) that has vestigial characteristics whose purpose was to support a false claim, but cannot be used in a similar application where it's use to support that claim would also apply?
As far as the control arm mount failing from the increased micro-vibrations of aftermarket arms, when does this happen? Yes, the pool is smaller than the remaining OEM configurations. But for as much as people want to complain and find reasons to not like like a particular brand or part, we don't read about this being an issue.
If NVH is not a real world issue, then what remaining criteria are you using to select a joint or bushing on the basis of actual function? Misalignment capabilities? Durability? Ease of maintainance? Do you place value on a bushing (or maybe a joint) that has vestigial characteristics whose purpose was to support a false claim, but cannot be used in a similar application where it's use to support that claim would also apply?
As far as the control arm mount failing from the increased micro-vibrations of aftermarket arms, when does this happen? Yes, the pool is smaller than the remaining OEM configurations. But for as much as people want to complain and find reasons to not like like a particular brand or part, we don't read about this being an issue.
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I completely agree. I was just trying to point out that one possible reason the Synergy joints may not have been used in the rear track bar may be due to other issues and not the NVH issue. Just like Currie.
Metalcloak on the other hand, I'm not so sure why they didn't use the bushing they use in the arms. Maybe its too soft. Which could also cause shimmy issues in the arms if thats the case. It does call into question all their claims. They like to market their stuff as being all things to everyone. I would prefer if they kept their focus on what they are trying to achieve. Which I believe is flex. If the reason for the Duroflex is to get more flex out of it due to using a narrower housing then just say so. Don't make up a bunch of marketing BS.
Metalcloak has done the same thing in some JK threads comparing their suspension to AEV. Saying they handle just and well and have more flex. But that is simply not true either. The 2 products (AEV vs MC) engineered their suspensions for different purposes, and I think they each achieved their goals. But I don't like how MetalCloak says they achieved their goals and also handle better than AEV. Distributors that sell both products have flat out stated AEV is better on the road. It seems like the same tactic they use with their joints.
I will grant that MetalCloak tried to prove their claims with the shaker table. But I think the test had some real flaws. I'd love to see them or someone else do a different test to show the difference in NVH. I can think of a couple different ways to do this, but I don't have the joints to test or the ability to fabricate the equipment.
Maybe it is best if we differentiate between MetalCloak and dual durometer bushings by other companies. Although they are similar bushings/joints, they seem to be different enough in the way the companies use them and promote them.
That is also a fair question. I had to go back and watch the Synergy video. I found it interesting Synergy never states that they have less NVH than a competitor. They are marketing them as maintenance free, zero binding, provide the flex needed, and are cushioned (you are left to assume for NVH). But they make no claims of less NVH. So they are basically selling them as a maintenance free, zero binding solution to the same problem.
I don't know if it does. But most guys with aftermarket arms do not put 10K on their jeeps every year at interstate speeds. And I know that metal can fatigue from vibrations and continuous movement. So that is why I tend to look at what the OEM uses. As much as like to get offroad. I need to make a lot of the same compromises that the Jeep did during the initial development. So for me I like the idea of a maintenance free bushing that flexes more than Clevite but offers a similar ride. I'm coming at it more from a standpoint of how does it compare to Clevite than to a JJ.
Keep in mind too, the OEM arms have flex designed into them, so a Clevite bushing provided enough support for said design. aftermarket arms don't have that flex, so a bushing/joint needed to be designed to compensate for that loss of flex. The misalignment kool aid that many drink is just a byproduct of the designs they had to come up with to satisfy that flex. I mean come on, 30* of misalignment? Do you really believe that your suspension can use that kind of misalignment? Hell, even a built to the hilt buggy might use 10* - 15* tops! The NVH kool aid is the other tactic they use, so that is the reason I started this thread. There is no hard data that I can tell, so far. It's fun to talk about though, and gets those neurons humming.
I forget if it was this thread or another, but a recent discussion of flex prompted me to figure out how the maximum angle of my rear axle with 12" travel shocks at full flex. I came up with a bit more than 15 degrees. Most, if not all of the common high misalignment joints and bushings greatly exceed this amount with a single joint/bushing. The point here is that if one company is claiming greater flex or suspension travel over another, it certainly is not due to any unusual capabilities of the control arms. So much of what defines the characteristics of our Jeeps comes from the capabilities of the shocks. Following that, it would be valuable to understand how that flex relates to the overall suspension travels.
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I'd like to take a factory arm and see how much actual flex it provides, especially compared to say the Core tier 1 arm with dual clevite bushings. In another thread Blaine said he felt the Core T1 arms with clevites would provide plenty of flex.
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 saw that thread were MrBlaine said the Clevite on both ends was fine. I think he was talking about control arms. But he also mentioned the short life span of that setup. If you are constantly flexing those Clevite bushings they won't last long. That is really the appeal of the DDB to me. Its like Clevite without the drawback of limited flex so it should last longer when used offroad. Johnny Joints are great, but they seem like overkill for something that is 95% highway driven. (Then of course there is the question of NVH for a highway vehicle.)
If I knew that Clevite bushings in a solid arm, set for a 3" lift and appropriate droop, would flex enough and last long enough I would just go that route. And that is the appeal of the DDB.
If I knew that Clevite bushings in a solid arm, set for a 3" lift and appropriate droop, would flex enough and last long enough I would just go that route. And that is the appeal of the DDB.
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