True Johnny Joint vs Generic 'Flex Joint'

[Sundowner]

I found an extensive read from “sundowner” on another forum that might shed some light on the truth of a DDB. The thread refers to the infomercial put out on DDB by synergy. It’s long but a good read if you’re interested!

Speak of the devil and you will summon him.

I've been keeping quiet on this forum until now, but this is as good a time as any to speak up.

There are a couple problems with part of that statement. The DDB was specifically designed to compete with serviceable options by offering a non serviceable one. Yes it presses into end rings like a Clevite bushing but it allows similar misalignment to that of a JJ so why would you compare it to a Clevite?.

I think we're confusing terms, here, so let's speak plainly. The dual-durometer bushing is certainly not competition to any cartridge joint, but it is an alternate option. By my definition and understanding, competing products are nearly-identical in their form and function, but alternate options are fundamentally different in one or more ways, although they may accomplish similar end results. In the case of joints, a non-serviceable press-in bushing is about as different from a rebuildable cartridge joint as sawzalls are to grinders, apples to oranges, or Led Zeppelin to the Rolling Stones. Similar in the big picture, yes, but increasingly different as one's focus narrows and sharpens.

When Synergy first released the DDB it was just replacing the Clevite in their product as they did not have forged ends available to use the DDB in place of a JJ. Most all their current offerings now use a DDB on both ends.

I haven't kept up with what Synergy is doing, but that's irrelevant: Synergy is a business, they're building and marketing both arms and bushings, and they're trying to sell as many as possible...and whether or not they choose to include, exclude, compare, applaud or defame any other product has precisely nothing to do with the definition of terms aforementioned. That said...

You are still operating under the assumption that control arms and joints have much of an effect on ride quality and they really don't. It is a myth perpetuated by folks trying to sell something different as a single point solution and by others who believe that arm angle at reasonable lift height matters and again, it just doesn't.

...this pretty much covers it.

 

[Jerry Bransford]

You are correct. I am still operating under the assumption that control arms (joints and angles) effect ride quality. They really don't huh?

The arm angle thing is hyped by long-arm suspension manufacturers. What they say seems to make sense as the steeper they get, the less they allow the suspension to flex up & down. The fallacy to that is that the arm angles never get steep enough to cause a stiff ride with the suspension heights we install onto our Jeeps. At one time I had a 5.5" Rockkrawler suspension lift with short arms. That was a stupid-tall lift that was taller than was appropriate for my TJ and its tires but it still rode fine. Even its short arm angles at its 5.5" lift height weren't steep enough to cause a bad ride, it actually had a pretty good ride for the short while it was installed into my previous TJ. The whole thing was shitty enough that it didn't last long under my TJ.

 

[Fargo]

The arm angle thing is hyped by long-arm suspension manufacturers. ...

AEV also subscribes to the control arm angle affecting ride qualtiy. That is the reason for their drop brackets. My friend put them on his JK. He said he noticed a difference between even the slightest change of settings within the bracket... From the passenger seat, I could not feel the difference.

 

[mrblaine]

You are correct. I am still operating under the assumption that control arms (joints and angles) effect ride quality. They really don't huh?

I know you'd probably like to hit me on the head with that stick in your (icon) hand, because I keep asking about your experience with the test mule and JJ and DDBs. I just ask for a little more patience. I am listening. Its just that, without driving one, its hard to believe that their really is no difference in ride quality between JJ and DDB (or Clevite). Is everyone that says they feel a difference coming from a biased opinion because they spent the money on something? That is indeed hard to overcome. Or is it a difference of other things such as shocks and tires that absorb the NVH before it ever gets to the arms? I wonder if you would feel the difference between a JJ and DDB in a stock Rubi with those stiff, load range E, MTRs. A poor tire choice for sure. But it would reveal if any NVH is absorbed by an arm.

Thank you Mr Blaine (and Jerry and everyone else) for you continued effort to help me sort this all out.

All I can attribute it to is folks like to justify their choices and get really involved in bias confirmation to justify those decisions.

I tend to want to know how much bullshit is involved in those decisions so I build and test. I can tell you hands down that if I don't tell you what arms are on a rig, you won't be able to tell by driving it.

The other side of that is if you have a crap riding rig, do you really think you can fix that with ANY control arm and joint?

 

[mrblaine]

AEV also subscribes to the control arm angle affecting ride qualtiy. That is the reason for their drop brackets. My friend put them on his JK. He said he noticed a difference between even the slightest change of settings within the bracket... From the passenger seat, I could not feel the difference.

We tend to spend a lot less money from the passenger seat. The less money we spend, the more objective we tend to be.

 

[Jerry Bransford]

AEV also subscribes to the control arm angle affecting ride qualtiy. That is the reason for their drop brackets. My friend put them on his JK. He said he noticed a difference between even the slightest change of settings within the bracket... From the passenger seat, I could not feel the difference.

Companies have meetings where they discuss what they can make that people will buy so they can make $$$ and stay in business. If a good enough story can be created on why people need something they'll buy it... regardless if the story is complete BS or not. And then they'll tell others how well it worked for them because they want to believe they made a good decision.

Traveling medicine salesmen used to make a lot of $$$ selling complete BS aka snake oil. Lots of people claimed it cured what ailed them when all that helped was the placebo effect.

 

[S.McArthur]

Companies have meetings where they discuss what they can make that people will buy so they can make $$$ and stay in business. If a good enough story can be created on why people need something they'll buy it... regardless if the story is complete BS or not. And then they'll tell others how well it worked for them because they want to believe they made a good decision.

Traveling medicine salesmen used to make a lot of $$$ selling complete BS aka snake oil. Lots of people claimed it cured what ailed them when all that helped was the placebo effect.

View attachment 77356

Want to buy some essential oils? I know a dealer or 48 of them that can regurgitate BS "science" they heard from a friend who heard from a neighbors cat.
Today's snake oils

On a serious note, I don't trust my RC joints, they are next in line for replacement. They look beefy, but I don't trust them.

 

[Sundowner]

A word of advice to those that haven't done so, yet: read the following question VERY carefully.

...if you have a crap riding rig, do you really think you can fix that with ANY control arm and joint?

Now, having done that, spend a long, long, long time thinking about the answer. Get all of what you think you know out of your head. Forget what advertisements have told you. Don't listen to your buddy, or your mechanic, or the Internet, or a forum, or anyone. Get under your rig, LOOK, and THINK. You may just surprise yourself, with all the things you can figure out...and even if you can't figure anything out, you'll be one of the rare people that have done the foundation work to start asking the right questions.

 

[Blackjack]

You are correct. I am still operating under the assumption that control arms (joints and angles) effect ride quality. They really don't huh?

I know you'd probably like to hit me on the head with that stick in your (icon) hand, because I keep asking about your experience with the test mule and JJ and DDBs. I just ask for a little more patience. I am listening. Its just that, without driving one, its hard to believe that their really is no difference in ride quality between JJ and DDB (or Clevite). Is everyone that says they feel a difference coming from a biased opinion because they spent the money on something? That is indeed hard to overcome. Or is it a difference of other things such as shocks and tires that absorb the NVH before it ever gets to the arms? I wonder if you would feel the difference between a JJ and DDB in a stock Rubi with those stiff, load range E, MTRs. A poor tire choice for sure. But it would reveal if any NVH is absorbed by an arm.

Thank you Mr Blaine (and Jerry and everyone else) for you continued effort to help me sort this all out.

NVH and ride quality are two very different things that happen to cross paths.

NVH is just that Noise, Vibration and harshness. Noise like squeaks (the infamous steering shaft grommet), whistling, popping and the like. Vibrations like a buzz in your steering wheel or under your seat. Harshness is where NVH crosses paths with ride quality. When you hit a bump and it feels like someone took a hammer to the underside of your rig or a jarring sensation that could be harshness. So then the question becomes why did that occur? When it comes to your control arms the only real culprit would be if you preloaded a clevite or standard poly bushing by tightening the fasteners when you were not sitting at ride height. And that lends itself more to popping noises then any kind of harshness.

Ride quality is the ability of the suspension to absorb road imperfections without adversely upsetting the passenger compartment. Several thing contribute to that. Springs that give you the ride height you desire without being too soft allowing the suspension to bottom out easily or too stiff and riding like a truck. Shocks valving is probably the number one thing as too many shock companies seem to always valve shocks like we are jumping our stuff all the time. As Blaine has put it you should not be able to tell what side of a coin is up when you drive over it. Control arm angle could be a factor in ride quality but on a TJ but only with lift heights well above four inches.

So you have to ask yourself this. How could a JJ, DDB or clevite prevent the coil spring from compressing or drooping? A clevite can but only at the most upper most ends of the suspensions travel. Since they really cannot, then the logical conclusion is that they do not contribute directly to ride quality. Now NVH is different but even a JJ has enough "bushing" material in its construction that NVH is not really going to be an issue. Besides if you are running any kind of aggressive tire you really do not care about NVH anyway.

 

[Fargo]

NVH and ride quality are two very different things that happen to cross paths.

NVH is just that Noise, Vibration and harshness. Noise like squeaks (the infamous steering shaft grommet), whistling, popping and the like. Vibrations like a buzz in your steering wheel or under your seat. Harshness is where NVH crosses paths with ride quality. When you hit a bump and it feels like someone took a hammer to the underside of your rig or a jarring sensation that could be harshness. So then the question becomes why did that occur? When it comes to your control arms the only real culprit would be if you preloaded a clevite or standard poly bushing by tightening the fasteners when you were not sitting at ride height. And that lends itself more to popping noises then any kind of harshness.

Ride quality is the ability of the suspension to absorb road imperfections without adversely upsetting the passenger compartment. Several thing contribute to that. Springs that give you the ride height you desire without being too soft allowing the suspension to bottom out easily or too stiff and riding like a truck. Shocks valving is probably the number one thing as too many shock companies seem to always valve shocks like we are jumping our stuff all the time. As Blaine has put it you should not be able to tell what side of a coin is up when you drive over it. Control arm angle could be a factor in ride quality but on a TJ but only with lift heights well above four inches.

So you have to ask yourself this. How could a JJ, DDB or clevite prevent the coil spring from compressing or drooping? A clevite can but only at the most upper most ends of the suspensions travel. Since they really cannot, then the logical conclusion is that they do not contribute directly to ride quality. Now NVH is different but even a JJ has enough "bushing" material in its construction that NVH is not really going to be an issue. Besides if you are running any kind of aggressive tire you really do not care about NVH anyway.

Blackjack- that's a nicely laid out description of the difference between ride quality and NVH. I agree that ride quality is much more affected by springs and shocks. Since both a DDB and JJ move freely around the control arm bolt axis, there would be no difference in ride quality there. So then it comes down to NVH.

Bushings like DDB and MC Duroflex will have more material than a JJ to absorb NVH, but the question is how much is needed. If your running big balloon tires on a little 15" rim then your needs will be different than the guy running a small stock tire on a 16" rim. Your choice of MT vs AT and your tollerance for NVH will also play a role. I think all of these things work together. Its not a single point solution. You can't ignore arms and say its all tire any more than you can ignore tires and say its all arms. Its a system.

Nice write up though, I like how you laid it all out. It gives a great starting point to read from and thing through what a persons needs are.

 

[mrblaine]

Blackjack- that's a nicely laid out description of the difference between ride quality and NVH. I agree that ride quality is much more affected by springs and shocks. Since both a DDB and JJ move freely around the control arm bolt axis, there would be no difference in ride quality there. So then it comes down to NVH.

Bushings like DDB and MC Duroflex will have more material than a JJ to absorb NVH, but the question is how much is needed. If your running big balloon tires on a little 15" rim then your needs will be different than the guy running a small stock tire on a 16" rim. Your choice of MT vs AT and your tollerance for NVH will also play a role. I think all of these things work together. Its not a single point solution. You can't ignore arms and say its all tire any more than you can ignore tires and say its all arms. Its a system.

Nice write up though, I like how you laid it all out. It gives a great starting point to read from and thing through what a persons needs are.

How do you know that other joints have more material to absorb NVH than a JJ?
And again, ride quality is not affected nor is it discernible to any difference by any commonly available spring we can put under a TJ.

I've mentioned this before, it bears repeating. I did a ton of testing shocks, arms, joints, and other things on the test mule. The single thing that made the absolutely most improvement was tires. With no other change, I swapped on a set of JK street tires. Night and day difference in all aspects of comfort and NVH transmission into the vehicle.

 

[Fargo]

How do you know that other joints have more material to absorb NVH than a JJ?

That is a very fair question. It appears much thinner at the thinnest part of the race. But because it is spherical, its really hard to tell the direction of force. I was contemplating this once before, but I had forgotten about my own ponderings. So thank you for this reminder. Maybe you can help me out here.

Since the JJ is a sphere inside of the race, is it possible that the force is distributed in more than one direction? Does the spherical nature of the ball cause it to put force on the side of the race as well. Thus requireing the stronger, heat treated, retaining rings you mentioned earlier?

 

[Mike_H]

You are correct. I am still operating under the assumption that control arms (joints and angles) effect ride quality. They really don't huh?

I know you'd probably like to hit me on the head with that stick in your (icon) hand, because I keep asking about your experience with the test mule and JJ and DDBs. I just ask for a little more patience. I am listening. Its just that, without driving one, its hard to believe that their really is no difference in ride quality between JJ and DDB (or Clevite). Is everyone that says they feel a difference coming from a biased opinion because they spent the money on something? That is indeed hard to overcome. Or is it a difference of other things such as shocks and tires that absorb the NVH before it ever gets to the arms? I wonder if you would feel the difference between a JJ and DDB in a stock Rubi with those stiff, load range E, MTRs. A poor tire choice for sure. But it would reveal if any NVH is absorbed by an arm.

Thank you Mr Blaine (and Jerry and everyone else) for you continued effort to help me sort this all out.

One thing to note about ride quality and joint replacement that I've been thinking about. You get a lot of responses on the internet from guys that:
A) have spend generally a lot of money on their new arms, so there is a bias to their opinion
B) Are replacing old, worn out components so ANYTHING will be better and provide an upgrade.

Very rarely will you see a guy compare Brand New components with brand new aftermarket components. That would be the only way to really tell what's what. Brand new Factory components (nearly impossible at this point) compared to Brand New After market components of all the different types you want to try.

 

[mrblaine]

That is a very fair question. It appears much thinner at the thinnest part of the race. But because it is spherical, its really hard to tell the direction of force. I was contemplating this once before, but I had forgotten about my own ponderings. So thank you for this reminder. Maybe you can help me out here.

Since the JJ is a sphere inside of the race, is it possible that the force is distributed in more than one direction? Does the spherical nature of the ball cause it to put force on the side of the race as well. Thus requireing the stronger, heat treated, retaining rings you mentioned earlier?

Of course it constrained in more than one direction. If it wasn't, it would just slop around inside the race. The compression on the races compresses them around the ball. It is a ball so its force is on all the sides that a ball gets. In the older days before the advent of the body grease fittings (which I don't like for this reason) folks used a single JJ at the end of a wishbone link with a horizontal bolts to control lateral movement of an axle. What happens in that scenario is as the ball receives the side load, it expands the race further against the inside wall of the joint barrel and that increases resistance to prevent lateral dislocation. In effect, the load on the retaining washers was very small.

 

[mrblaine]

Very rarely will you see a guy compare Brand New components with brand new aftermarket components. That would be the only way to really tell what's what. Brand new Factory components (nearly impossible at this point) compared to Brand New After market components of all the different types you want to try.

Not that impossible. I bought a new set of OEM as a factory baseline on the test mule. I spent as much on them as I would some aftermarket stuff.

 

[Mike_H]

Not that impossible. I bought a new set of OEM as a factory baseline on the test mule. I spent as much on them as I would some aftermarket stuff.

Nice. I assumed that OEM wouldn't be readily available anymore. Seems like there was a member struggling to get a full set about 6 months ago, but I may be mis-remembering. Anyway, good to know they are still available, though expensive!