Does control arm bushing composition affect ride quality or NVH?

Fargo

TJ Enthusiast
Oct 3, 2018
177
Fargo, ND
After spending hundreds getting rid of my RE super flex control arms and going 100% rubber joints, All rubber joints on my new track bars, rubber in my shocks, my ride is smooth and has less felt vibrations, to me. I am more of a fan of rubber than poly.....
I've never considered before the NVH transferred to the cabin via the shock mounts. I wonder how much difference rubber shock mounts will make. Any NVH transferred from the shock mount would also have to pass through the rubber seals around the piston, so it seems like it would be pretty minimal.

Who's control arms did you go with once you decided so go with rubber mounts? I am still torn between the Clevite, Synergy DDB (which I believe are poly) and good old Johnny Joints. Each joint seems to have its trade offs. I guess the key is to find which trade offs fit your need the best. I wish I had the opportunity to experience them in person. In the flat lands of ND nobody builds up TJs.
 

Blackjack

TJ Enthusiast
Dec 16, 2018
184
Kenai
I've never considered before the NVH transferred to the cabin via the shock mounts. I wonder how much difference rubber shock mounts will make. Any NVH transferred from the shock mount would also have to pass through the rubber seals around the piston, so it seems like it would be pretty minimal.

Who's control arms did you go with once you decided so go with rubber mounts? I am still torn between the Clevite, Synergy DDB (which I believe are poly) and good old Johnny Joints. Each joint seems to have its trade offs. I guess the key is to find which trade offs fit your need the best. I wish I had the opportunity to experience them in person. In the flat lands of ND nobody builds up TJs.
The tradoffs are this:

Clevite gives good control of NVH with mediocre off highway performance at the lowest cost. They are also a pain to replace in the future.

DDB so far in my butt dyno testing gives good NVH control, good off highway performance at a slightly higher cost. They are much easier to service than clevites but you still need a press.

JJs might give up a small amount of NVH control but in reality the average driver is just not going to notice. They give the best off highway performance at the highest cost of the three. While you need a special tool to service you do not need a press so that is worth noting as well.

My Jeep is not a good candidate for the butt dyno but I have noticed no change from going to the DDB over clevite so far. I still have the rear arms to do so that may change or not. My friends JK we put Synergy arms all the way around and you would be hard pressed to tell them over clevites.
 
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bobthetj03

bobthetj03

vibrajeep
Supporting Member
Ride of the Month Winner
Feb 3, 2017
7,655
NorCal
The Duroflex bushings have a durometer similar to a Clevite bushing, don't require any special tools to replace, and don't require any servicing per say. Maybe an occasional cleaning and a fresh coat of synthetic grease to keep them rotating freely in the barrel.
 

Fargo

TJ Enthusiast
Oct 3, 2018
177
Fargo, ND
I have a plan for the 4326-02 I'll find out if viable next week.
Bringing the thread back to life. What was your plan for that JK bushing and why didn't it work out. I got an email back from Synergy today and it sounds like they quite building the TJ bushing due to slow sales. The guy said you could use the JK bushing but you had to drill out the holes on the clevis because the JK uses a bigger bolt. It sounds like a simple enough solution if you want DDB all around.


Chris - any news on your Jeep. Did you ever get to ask Dave some of those questions we had.
 

k-huevo

TJ Enthusiast
Jul 16, 2018
165
Houston
The stock passenger side UCA bracket was somewhat bent, and the sides had collapsed .2 inch inward. When it came time to attempt removing the original bushing, I could see the bracket wasn't suitable for a simple press-in option.

Enlarging the holes in the UCA yoke to 12mm was not a problem. I did it anyway to use the JJs. Synergy also offers a forged replacement yoke with 12mm bolt-holes as an alternative to drilling.

Adjusting pinion angle reached a point where adjustable LCAs were needed for the rear. I installed Synergy arms.
77069
 

astjp2

TJ Enthusiast
Aug 22, 2018
749
Utah and Alaska
The stock passenger side UCA bracket was somewhat bent, and the sides had collapsed .2 inch inward. When it came time to attempt removing the original bushing, I could see the bracket wasn't suitable for a simple press-in option.

Enlarging the holes in the UCA yoke to 12mm was not a problem. I did it anyway to use the JJs. Synergy also offers a forged replacement yoke with 12mm bolt-holes as an alternative to drilling.

Adjusting pinion angle reached a point where adjustable LCAs were needed for the rear. I installed Synergy arms.
View attachment 77069
What is your pinion angle? How much lift are you running? I like the synergy arms.. How much did you have to shorten the lower arms to? Do you have much clearnance between the gas tank and diff cover? Gawd, too many questions after taking an ambien...
 

k-huevo

TJ Enthusiast
Jul 16, 2018
165
Houston
8.6 degrees rear pinon angle
3" lift
rear LCA's were lengthened to 16"

The TJ has a 1" engine lift, stock skid plate with .25" drop, stock single cardan driveshaft, and TC output is at 8.2 degrees. With a slightly longer than stock Moog rear trackbar on an upright relocation bracket, and 1" body lift, there is space for everything to move without conflict. The UCAs reached their limit for rotating the pinon downward on 2" lift springs. A minor belly-up and SYE are in its future.
 
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Fargo

TJ Enthusiast
Oct 3, 2018
177
Fargo, ND
The stock passenger side UCA bracket was somewhat bent, and the sides had collapsed .2 inch inward. When it came time to attempt removing the original bushing, I could see the bracket wasn't suitable for a simple press-in option.

Enlarging the holes in the UCA yoke to 12mm was not a problem. I did it anyway to use the JJs. Synergy also offers a forged replacement yoke with 12mm bolt-holes as an alternative to drilling.

Adjusting pinion angle reached a point where adjustable LCAs were needed for the rear. I installed Synergy arms.
View attachment 77069
Thanks for the info. Did the bracket bend when using the stock arms and bushings? Sounds like the Currie upgrade might be good insurance.

I'll have to look into that Synergy bracket too. I have concerns that it might not be the right length since it was designed for a JK. I do like how the Currie gets welded to the bracket and not the axle.
 

astjp2

TJ Enthusiast
Aug 22, 2018
749
Utah and Alaska
Ok, here is some scientific research on vehicle NHV...for those who want to read it. I am now looking for a vibration analyzer that can be mounted on the suspension...which would eliminate the butt feeling. Tim
 

Attachments

Fargo

TJ Enthusiast
Oct 3, 2018
177
Fargo, ND
I am now looking for a vibration analyzer that can be mounted on the suspension...which would eliminate the butt feeling. Tim
Could you find a secure way to mount a (old) smart phone to an arm and just run an app like this:

Mounting could be as simple as a couple of hose clamps tighted around the phone. Not perfect, but if the differences are large they would show up. Then just drive around the block a couple times and take the average. Provided you can find an app that stores enough info.
 

Fargo

TJ Enthusiast
Oct 3, 2018
177
Fargo, ND
If you have two sensors, another option would be to run 2 different arms at the same time. Then mount one sensor in the middle of each arm. Obviously pot holes hit by only one wheel would be different, but general road aggregate would be more or less similar and would give an idea about control arm isolation.
 

astjp2

TJ Enthusiast
Aug 22, 2018
749
Utah and Alaska
I was thinking that the axle side would be my baseline and the frame side would be the amount reduced, if the bushings isolate the vehicle from the road nhv... you could test tires, control arm bushings, the road itself, mount it the same way for shocks to see its isolation...this is just a mental exercise for me. If I could come up with something like a wilcoxin 991v sensor that I could bolt to each end, attach wires to and then monitor on an tablet, it would be real neat to do comparisions of different products. Tim
 

fuse

TJ Enthusiast
Jun 5, 2018
264
San Diego, CA
Could you find a secure way to mount a (old) smart phone to an arm and just run an app like this:
Mounting could be as simple as a couple of hose clamps tighted around the phone. Not perfect, but if the differences are large they would show up. Then just drive around the block a couple times and take the average. Provided you can find an app that stores enough info.
Collecting accelerometer data in Android almost trivial -- I could write that code. Analyzing it is not as simple as just averaging the raw data. At a minimum, you need a spectral analysis, and you may need a filter to remove some noise levels. You may also need to do some normalization to compensate for gross changes in orientation and velocity.

So you could get the raw data from an old phone. But do you have an environment for a controlled experiment with different control arms? And would you know how to process the data?

These aren't rhetorical questions. I know enough to know the problem isn't simple, but not enough to solve it. Maybe someone else here does.
 

astjp2

TJ Enthusiast
Aug 22, 2018
749
Utah and Alaska
I was thinking of something more basic, a comparative of 2 different sensors, so if the axle side has an IPS of 4.9@ 1100 hz, and the frame side is 3.6, then there is a reduction with such and such bushing...

If you want to compare tires, use the axle side, calculate the RPM at a given speed, and measure the lug spacing, that will give you the frequency, analyzer will give you the IPS, anything under .9 is not really felt by a person, 1-1.5 is minor feeling...there is a chart that I use for dynamic balancing airplane propellers, I would have to find it. You would mount the sensors vertical to calculate the load transfered from the axle to the body for one data set, another would be parallel to the arm...
 

astjp2

TJ Enthusiast
Aug 22, 2018
749
Utah and Alaska
Collecting accelerometer data in Android almost trivial -- I could write that code. Analyzing it is not as simple as just averaging the raw data. At a minimum, you need a spectral analysis, and you may need a filter to remove some noise levels. You may also need to do some normalization to compensate for gross changes in orientation and velocity.

So you could get the raw data from an old phone. But do you have an environment for a controlled experiment with different control arms? And would you know how to process the data?

These aren't rhetorical questions. I know enough to know the problem isn't simple, but not enough to solve it. Maybe someone else here does.
You know this might be as simple as sitting on your phone, that would be a true "by the seat of your pants" evaluation.
 

Fargo

TJ Enthusiast
Oct 3, 2018
177
Fargo, ND
You know this might be as simple as sitting on your phone, that would be a true "by the seat of your pants" evaluation.
I wonder if that would work. Wouldn't your body be acting as a shock absorber though?
You might be able to just set it on the dash or something. That would tell you if the road NVH is more than the drivetrain NVH as you drive. Part of what makes this difficult is that much of what we feel comes directly through the steering wheel. But now you got me curious. I might try to find a good app and just try that in different vehicles. If there is no difference between my Pathfinder and my Jeep I'll know the test is faulty, because I can certainly feel a differnance driving them.
 
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