• Want to add an app icon for this forum to your mobile device's home screen? Check out this thread to see how.
  • Have an event you want to share? Check out the new forum event calendar and how-to use it in this thread here.
  • To both new members and existing members, please read this thread about posting your topics in the correct sub-forum. It makes my job (and my life) a lot easier!

Does control arm bushing composition affect ride quality or NVH?

k-huevo

TJ Enthusiast
Jul 16, 2018
200
Houston
The inner sleeve in the DDB isn't bound. I rotates freely and can slip from side to side when unbolted. The bushing also has the same degree of deflection as a standard width JJ. An exception is the narrow JJ, which has 40 degrees of deflection.
 

Fargo

TJ Enthusiast
Oct 3, 2018
264
Fargo, ND
It might be a slight press fit with the DDB's, but the Giiro's are falling out...

Which, as you stated before and I agree, makes the DDB the better bushing. My biggest concern with the DDB would be getting dust on that teflon sleeve and the teflon would then peel off and your maintenece free bushing would be compromised. This would be an even greater concern with the Giro since it fits so loose. But it sounds like it might not be a concern with the DDB if it fits that tight. Thanks for the information.
 

astjp2

TJ Addict
Aug 22, 2018
1,628
Utah and Alaska
I ordered lowers from Synergy and they came in, they are built the same as the Giiro joints except they have a visible steel sleeve between the teflon and the outer rubber (or what ever it is). They both have the plastic outer sleeve and the steel inner sleeve. No real difference that I can tell.
 

Ericshere03

New Member
Apr 8, 2019
8
Feenicks
So! I can offer some input here...

Just installed the lower control arms and with a screwdriver COULD NOT hardly budge the bushing!!! They are stiff, but I’m sure will work loose and NOT did off our mounts. Synergy has a great produce here and like the FIXED lower arm, perfect for my needs. And they look great, nice powder coating.

In terms of the upper fronts, GREAT adjuster style, came with anti sizer applied, the “fork” is a forged piece which is apparently zinc coated AND powder coated. Unfortunately these arms came all tattered up, looks like whoever installed the bushings on these was a real rookie (or otherwise disabled, lol). I have amazon sending another set, with a perfect as the lowers are, I’m think this is a fluke.

NOW! THE PROBLEM! Synergy supposedly discontinued the AXLE side bushing, however they offer a JK bushing that fits but with a larger bolt.

THE PLAN...
I intend on buying the JK axle side bushing, and see if the inner metal sleeve from the upper control arm bushing will fit axle bushing. I suspect they will. I will then buy a set of replacement upper control arm bushings and steal the inner sleeve and put it in the “jk” axle bushing. This should work. IF NOT! Plan “B” would be to buy the JK upper control arm fork and replace it on the TJ control arm. (Drilling a hole would also work, but I don’t want to compromise the zinc/powder coating).

Synergy tech support wasn’t real helpful and made me feel as I was wasting their time! If they only knew how much I spent on my old JK with their stuff, plus what’s goin on my “new” TJ. Whatever...

I will post back with the results. This will accompany my OME HD springs, rancho 5000x shocks and daystar BL and M.O.R.E MML, and ZJ steering.
 

Fargo

TJ Enthusiast
Oct 3, 2018
264
Fargo, ND
Keep us informed. I ordered the Rancho arms with the similar D2 bushings. I really wanted Synergy, but the lower arms were discontinued before I placed my order. I then lost confidence in them when I realized they were no longer supporting the TJ platform. If some big company could purchase the Nth Degree and Synergy product line for the TJ, they would have a nice lineup of top notch products.

My plan for the upper front axle bushing was to get the Synergy JK bushings and just drill out the holes in my control arm to fit the bushing. When I spoke with a Syndergy Tech in the past he said the bushings were the same except the JK used a bigger bolt. I'll be interested to hear what your results are.
 

Ericshere03

New Member
Apr 8, 2019
8
Feenicks
Keep us informed. I ordered the Rancho arms with the similar D2 bushings. I really wanted Synergy, but the lower arms were discontinued before I placed my order. I then lost confidence in them when I realized they were no longer supporting the TJ platform. If some big company could purchase the Nth Degree and Synergy product line for the TJ, they would have a nice lineup of top notch products.

My plan for the upper front axle bushing was to get the Synergy JK bushings and just drill out the holes in my control arm to fit the bushing. When I spoke with a Syndergy Tech in the past he said the bushings were the same except the JK used a bigger bolt. I'll be interested to hear what your results are.
Will do, the phone rep didn’t mention anything about the arms being discontinued, I got them from amazon (SDHQ was the seller, I work down the street actually).

The part number the phone rep told me was incorrect and just took the replacement bushing from the truss 4326-02, the rep told me 4321-01, again, whatever...

But I got bushings in the mail.
 

Ericshere03

New Member
Apr 8, 2019
8
Feenicks
I used the JK bushings, just bore out the holes, go to a junk yard, get a set of 4x4 dodge truck UCA bolts, install them and drive it.
That works too. I have new JK bolts from when I changed all control arm bolts to 9/16 and 1/2 grade 8. I don’t want drill the nice zinc played hardware so I will get Synergy Yokes part# 805305-01 if I go that route.
 

chino1969

TJ Enthusiast
Apr 14, 2019
166
Oxford, PA
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.
That is a very good point. I am an avid hand loader and precision shooter. When working up a new load, changing only one variable lets you know whether the change was good or bad. The same logic applies to this subject if you truly want an accurate comparison. Want to compare rubber bushings vs. poly? Change from one or the other and compare. Changing more than one variable at a time keeps you chasing your tail.
 
  • Like
Reactions: jjvw

astjp2

TJ Addict
Aug 22, 2018
1,628
Utah and Alaska
The one thing that people are not doing is actually putting on any true measurement devices and changing any components to due a real experiment. It is still all supposition until real data is provided.

Case in point: I have an aircraft propeller vibration analyzer that dynamically measures the vibrations of the propeller as the engine is running. I installed a propeller on an airplane, ran the engine, and notice a little vibration (not any more than other airplanes). I installed the analyzer, ran the engine and came up with an reading of very rough. I wound up reinstalling the prop 180 degress from where it initially installed, it cut the vibrations in half. During this whole process, I was not able to actually feel any difference in the seat of my pants. The analyzer did notice the difference and provided a real measurement for me to get the vibrations to "good Levels".
 
  • Like
Reactions: Boinked

Ericshere03

New Member
Apr 8, 2019
8
Feenicks
The one thing that people are not doing is actually putting on any true measurement devices and changing any components to due a real experiment. It is still all supposition until real data is provided.

Case in point: I have an aircraft propeller vibration analyzer that dynamically measures the vibrations of the propeller as the engine is running. I installed a propeller on an airplane, ran the engine, and notice a little vibration (not any more than other airplanes). I installed the analyzer, ran the engine and came up with an reading of very rough. I wound up reinstalling the prop 180 degress from where it initially installed, it cut the vibrations in half. During this whole process, I was not able to actually feel any difference in the seat of my pants. The analyzer did notice the difference and provided a real measurement for me to get the vibrations to "good Levels".
All my Jeep years I have been doing the “wrong” thing with good result. I have run E load tires, poly bushings, OME springs “too” stiff (4”), etc etc. I am on TJ #4 and have The best riding Jeep ever.

Poly Daystar BL
Poly MML
Poly Tranny Mount
Poly syspension bushings (Synergy DDBS, which I know are different than regular Poly bushings)

With my C rated tires, Rancho 5000x and OME HD springs. I’d say YES I can feel a difference but also YES it is actually smoother over rough stuff than stock but a little rougher over smooth stuff ... And I still have all my teeth, mirrors aren’t a blurry mess and washboards are great. I wouldn’t do the Baja 1000 in my Jeep, like some component manufacturers suggest you can do with their stuff, but me and the wife can get out without complaints from her nor I with respect to the suspension.

I’m sure any good instrumentation would take the NVH over the threshold of some design value. And I have the benefit of knowing my Jeep will be long gone before I have to change a bushing or mount. At least I hope.
 

jjvw

0-60 in 18 seconds
Supporting Member
Feb 17, 2018
6,219
Colorado, USA
I still wonder what we hope to find after all of this. The discussions are too similar to the spring rate debates where people are focusing their attention on insignificant details.
 

astjp2

TJ Addict
Aug 22, 2018
1,628
Utah and Alaska
I would put my 2 cents on the spring debate but most will ignore me...but there is a simple formula based on wire size, coil diameter and the number of coils to determine rate. iIt is really accurate. But that one also lacks data, no one has taken the time to actually measure the spring rates, I have the scales that can go to 1500# and I would work someone if they want to build a fixture to measure the rates. I have the steel but I would rather figure out my death wobble problem...Want to come over to utah and give me a hand with that?
 

jjvw

0-60 in 18 seconds
Supporting Member
Feb 17, 2018
6,219
Colorado, USA
I would love to. I do mean that sincerely because I am curious. We can measure and confirm spring rates, but then what? What do we do with that information? Especially when trying to apply that data to adjusting ride quality where the evidence suggests that there are more significant areas to look at other than control arms and springs.
 

Mike_H

Rust Belt Heavyweight
Supporting Member
Feb 28, 2017
4,266
Grand Rapids, MI, United States
There are SO many other factors to consider when you start talking about "ride" in an automobile...I don't think hard, fast data on any one, specific thing will give you any real clue. Each component up to and including your butt has a stiffness and damper in it. Even if we make the incorrect assumption that the stuff that doesn't move (like the frame or the tub) are perfectly stiff and rigid, there are numerous areas that will add compliance along the path to seat of the pants feel. The tires are flexible and contribute to feel. So do the body mounts and the seats. All those items have a stiffness to them, just like a spring.

All of those things combine to create "feel." You can calculate that resolved spring rate (Jeep can, and does). BUT, its not a nice linear equation to say if I increase or decrease this variable the ride will get "better." Better is dependent on who's butt is in the seat. You may also run into areas where resonance happens (all systems can resonate).

So, this, like the spring thread, is all an academic exercise. People might say they fixed this or that...but that doesn't mean that doing the same thing to your jeep will replicate their result. Every jeep is different, and will react differently to any given modification.
 
  • Like
Reactions: jjvw

astjp2

TJ Addict
Aug 22, 2018
1,628
Utah and Alaska
There are SO many other factors to consider when you start talking about "ride" in an automobile...I don't think hard, fast data on any one, specific thing will give you any real clue. Each component up to and including your butt has a stiffness and damper in it. Even if we make the incorrect assumption that the stuff that doesn't move (like the frame or the tub) are perfectly stiff and rigid, there are numerous areas that will add compliance along the path to seat of the pants feel. The tires are flexible and contribute to feel. So do the body mounts and the seats. All those items have a stiffness to them, just like a spring.

All of those things combine to create "feel." You can calculate that resolved spring rate (Jeep can, and does). BUT, its not a nice linear equation to say if I increase or decrease this variable the ride will get "better." Better is dependent on who's butt is in the seat. You may also run into areas where resonance happens (all systems can resonate).

So, this, like the spring thread, is all an academic exercise. People might say they fixed this or that...but that doesn't mean that doing the same thing to your jeep will replicate their result. Every jeep is different, and will react differently to any given modification.
I will still fall back that there is no one supplying data with any scientific measurements. While it is relative, someone likes a 240# spring rate vs someone else likes a 180#, just like someone likes johnny joints vs DDB's, but not one person has actually done any vibration analysis comparing different joints. I looked at buying a transducer, but I don't have access or the money to buy a bunch of arms with different joints and conduct the analysis. I think it is worthy cause, just not one that I can afford.