OK. The way you worded it, I thought other companies did something different. I thought the DDB was supposed to be a direct replacement for all factory Clevite on the TJ. So I assumed they would just press in the same as the Clevite. I think they even have an option for factory TJ control arms. But that was some time ago I heard that and I never looked into it.
Does control arm bushing composition affect ride quality or NVH?
- Thread starter bobthetj03
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OK. The way you worded it, I thought other companies did something different. I thought the DDB was supposed to be a direct replacement for all factory Clevite on the TJ. So I assumed they would just press in the same as the Clevite. I think they even have an option for factory TJ control arms. But that was some time ago I heard that and I never looked into it.
OP
I was trying to it on their website, but are the bushings pressed into their arms, or are they retained by snap rings?
I see they offer a kit for the JK, so?
https://www.synergymfg.com/synergy-jeep-jk-front-uca-axle-side-mount-with-ddbs.html?category_id=4952
I haven't been looking at them that closely to know for sure, but I think they are all pressed in. Rancho has the D2 that looks like the same bushing but I think they use a snap ring with theirs. At least in their own arms. But that might have just been in the JK arm.
Thinking about ways to check NVH. Would it be possible to install an app onto a phone that detects NVH and then just mount that phone to a trackbar and drive around the block? Change out the trackbar and drive it again. No doubt that would be very crude and not as scientifically as accurate as we would all like. But it would give us some real world numbers about just how much NVH a control arm sitting under a Jeep sees. It would give us something to compare some actual numbers. The biggest issue would be how to mount the phone so the mount itself doesn't provide any cushion and so it is consistant across different styles of arms.
Should the sensor device(s) be on the link or on the frame side mount? What about the axle? All three for comparison?
After reading through many many way to many research articles. I have a the answer. No one is going to like.
It all depends on the composition on the urethane used in the control arm bushings.
NVH.
VIBRATION
Just focusing on vibration transmission. Urethane can be better than rubber. It would depend on the hardness and composition of the actual bushing. There is a trade-off when it comes to wear. As I highly doubt most joint manufacturers are going to give you the chemical makeup the answer will never happen.
NOISE
Properly lubed urethane bushings are going to be just as quiet as rubber. Also if you're talking about road noise transferred from the Axel itself. It would fall under the same category as vibration because noise is just another sine wave.
HANDLING
I'm still not convinced that a bushing on a control arm is going to do much for handling either way.
This might be different for high articulation. And heavy off-road use. But then you get your butt Dyno involved. And one personal say this is better one personal say this is better. So God knows what's the right answer.
It all depends on the composition on the urethane used in the control arm bushings.
NVH.
VIBRATION
Just focusing on vibration transmission. Urethane can be better than rubber. It would depend on the hardness and composition of the actual bushing. There is a trade-off when it comes to wear. As I highly doubt most joint manufacturers are going to give you the chemical makeup the answer will never happen.
NOISE
Properly lubed urethane bushings are going to be just as quiet as rubber. Also if you're talking about road noise transferred from the Axel itself. It would fall under the same category as vibration because noise is just another sine wave.
HANDLING
I'm still not convinced that a bushing on a control arm is going to do much for handling either way.
This might be different for high articulation. And heavy off-road use. But then you get your butt Dyno involved. And one personal say this is better one personal say this is better. So God knows what's the right answer.
OP
Called Synergy to ask a couple questions. Didn't get any good answers. First I wanted to know the spring rate of their coil springs so I can plug the formula in to see if they would work for me. Nope, can't tell me the rates. Stupid. 2nd question was whether the DDB's were pressed in or retained via snap rings. They are pressed in, and are NOT the same OD as a Clevite bushing for a TJ. Nor do they make a kit for the front uppers. Matter of fact, he said other than what they had on the website, they weren't really making anything for the TJ, and were focusing on the JK/JL platform. Bummer!
Nor surprising about spring rates. Most mfgs won't disclose that. Especially on a progressive rate spring like Synergy, Nth, Savvy, etc. I'd love to know what the Savvy rates are.
I can understand using a different size bushing in the Synergy control arm. It might have been done for size constraints to give more flex or due to other performance calculations. But it would have been nice if they were the same size as the stock bushings. The most dissappointing thing is that they don't make a bushing for the front uppers. If I am switching my bushings to someone new, I want them all to be the same. I'm really surprised they didn't make something that fits in the location. Does Currie make a JJ for that location or does everyone replace the front uppers with Clevite.
I was just thinking about about just putting something on the link. If the links being compared have matching joints on both ends that would tell us how well that particular joint is dampening NVH. For example if it had JJ on both ends vs one with MetalCloak on both ends. If it has a JJ on one end and Clevite on the other, then its less reliable for a particular joint because NVH could be coming through either end. Although it would still provide some insight.
However, now that you mention putting a device on all 3 locations that would actually be much better. Because by doing that we could establish a baseline to know if the joint was transmitting more NVH or if the NVH was due to other variables in the road or driver speed etc. If the NVH on the axle and frame devices are similar, then any differences in NVH on the links device must be due to the joints/bushings.
If you had a 4th device, that might be helpful on the other link to run at the same time. That would give you a more direct side by side comparison and would eliminate speed changes from the equation. But the opposite tire would still be hitting different bumps and imperfections. So its not perfect either. But if their is a significant difference in NVH it should show itself.
For what its worth I think it would be best to mount them on the front links. Those are the links taking the most impact because the don't swing away from the bumps like the rear arms do.
For what its worth I think it would be best to mount them on the front links. Those are the links taking the most impact because the don't swing away from the bumps like the rear arms do.
To add to the setup, we would also need to know how much of a change is perceivable by a person in the cab. Preferably in a bind test. An increase or a decrease in NVH from a baseline won't tell us much if that different is not detectable to a human rear. We need meaningful measurements and a meaningful point point of comparison.
One reason the MC shaker table is useless is that we don't know what the graph means.
Is this graph below measuring millimeters/year or miles/second?
One reason the MC shaker table is useless is that we don't know what the graph means.
Is this graph below measuring millimeters/year or miles/second?
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OP
Maybe. Maybe not. What is the question we are trying to answer? Is the question "Do the new bushings transmit less NVH" or is the question "Will less NVH from a new style of bushings be noticable". I think we have 2 different questions. I would like to tackle the first question first. Do the new bushings damp NVH better. Yes or No. If so, then we can ask if you can percieve that difference or not.
Besides, adding a device inside the cab would require you to change out all 8 links and 16 bushings. Just changing one link won't likley make a difference. For know, I just want to know if the bushings themselves transmit different NVH or not. I think the MetalCloak shaker table gives us a good idea of what to expect. But lets run an unbiased test ourselves.
OP
Let's leave these out of the equation so we can focus on whether the control arm bushings are changing anything. Let us assume the control jeep will have factory body mounts in good shape and TB's with a Clevite at one end and a misalignment joint at the other(tie rod, heim, JJ, etc).
We'll need a "before" measurement using factory arms, and a "after" measurement using aftermarket arms/bushings/joints(MC, JJ, DDB, Flex joint, etc). Of course, everything else will need to be the same, tire pressure, load range, jeep path and road conditions, time of day, etc.
Its starting to get complicated now. Which is good to be thourough.
My original thought was if someone 'cough' bob 'cough' had an MC arm and a JJ arm, they could just duct tape (or hose clamp) their phone around the control arm go for a drive and see what the graph said. Switch arms and drive the same route again. Compare the two graphs. What do they show? That would be the simplest and crudest test. It may not show anything. But I think even doing that, we will see the MC arm does infact absorb NVH better. ( Mmm, coolaid)
My original thought was if someone 'cough' bob 'cough' had an MC arm and a JJ arm, they could just duct tape (or hose clamp) their phone around the control arm go for a drive and see what the graph said. Switch arms and drive the same route again. Compare the two graphs. What do they show? That would be the simplest and crudest test. It may not show anything. But I think even doing that, we will see the MC arm does infact absorb NVH better. ( Mmm, coolaid)
OP
Sold my Currie arms, so that's out. Gave my stockers away too, so all I've got is MC Kool Aid brah!
I called Synergy today for some info and I had a fantastic tech guy on the line. He told me everything I needed to know. The springs are rated at 130/155 for the front and 130/195 for the rear. The Jeep will ride in the firm rating.
I also found out that they DO offer a bushing for the front upper control arm on the axle end. It is part #4326-01. They are a direct replacement for the Clevite bushing. This is new within the last year. So maybe the guy you spoke with just didn't know. It is the same as the JK except the JK uses a 12mm bolt and the TJ uses a 10mm. So the same bushing ending in -02 is for the JK.
They do not, however, make a heavy duty replacement bracket if that is what you wanted. But if you really need a heavier bracket I'll bet someone makes one that accepts the factory Clevite and that should work with the Synergy bushing since they press into the factory mounts.
I was also informed that they have updated the braketry for the front axle control arm mounts. So that is stronger now. So it sounds to me like Synergy is still doing work on the TJ line of products. I am happy to hear this. I will almost certainly be going with the Synergy arms when I do my upgrade.
OP
That is good to hear. So, basically the guy I talked to was just a tool, ugh! Are you going to try their springs too? Still don't know what to think of the dual rate springs.