Does control arm bushing composition affect ride quality or NVH?

[Chris]

So here's something interesting. @Serbonze had asked me to reach out to @David Kishpaugh today regarding what bushings he uses for the track bars he builds (as well as what he'll be using on my mid-arm install).

This is the conversation between Dave and I:

Me:
Dave, on your mid-arm, do you use Johnny Joints on both sides of the track bar, or just one side? Assuming of course you make your own track bars (not sure if you do or not). Someone on the forum was asking me to ask you.

Dave:
Synergy dual durometer if I make the track bar. I use moog k7252 bushings if I use an aftermarket bar and change them as soon as it comes out of the box.

Me:
Interesting! So no Johnny Joints at all on the track bars, huh?

Dave:
Nope. The synergy has the same amount of misalignment as the jj but isn't squishy

Me:
I didn't think JJs were squishy. I thought they were hard?

Dave:
Harder durometer Polly, but still squishy like metal cloak. Just not as much as the rubber. Rubicon Express flex joints are a plastic type. The synergy are more like a hiem but still have alot of dampening and they self center.

Me:
Why not use them for the control arm Joints then? Is there an advantage to having them for the track bar and not the control arms? Just curious

Dave:
I use them on one end of the bent links to keep them upright and Currie on the other end for extra dampening. The synergy self center and make the bolts hard to get in if the brackets aren't perfectly parallel.​

Still waiting to continue this conversation, but I find it interesting that a well known and reputable builder such as Dave is using this combination of Johnny Joints and Synergy bushings. Actually, I wonder why he isn't just using synergy bushings all around on the control arms instead of just one end of the control arms?

 

[jjvw]

Johnny Joints are squishy!

That statement adds a whole new level of context to this discussion.

 

[Chris]

I didn't think Johnny Joints were squishy at all. I've taken one apart and it seems quite hard... well in comparison to a clevite bushing or something I would think.

 

[jjvw]

I didn't think Johnny Joints were squishy at all. I've taken one apart and it seems quite hard... well in comparison to a clevite bushing or something I would think.

I think this might highlight the difference between what we think is hard versus what a 4500lb vehicle thinks.

 

[bobthetj03]

Head explodes!

 

[Chris]

I think this might highlight the difference between what we think is hard versus what a 4500lb vehicle thinks.

I agree. I suppose when you have all that weight on it, what's hard in my hands is likely squishy under 4500 lbs. of weight.

I find it interesting that Dave does what he does. He's the type of person who has a reason for everything he does in his builds, so clearly he isn't just doing this for no reason.

I'd love to pick his brain more, but he's such a busy guy that I feel bad taking up too much of his time.

 

[bobthetj03]

I agree. I suppose when you have all that weight on it, what's hard in my hands is likely squishy under 4500 lbs. of weight.

I find it interesting that Dave does what he does. He's the type of person who has a reason for everything he does in his builds, so clearly he isn't just doing this for no reason.

I'd love to pick his brain more, but he's such a busy guy that I feel bad taking up too much of his time.

I'm sure you'll be compensating him well once he finishes your Jeep.

 

[JMT]

Dave:
I use them on one end of the bent links to keep them upright and Currie on the other end for extra dampening. The synergy self center and make the bolts hard to get in if the brackets aren't perfectly parallel.

Is Dave implying in this last statement that he would use synergy on both ends of a CA if it wasn't so difficult to get a bolt in the bracket because they self-center?

What would all this imply about the value of a Core 4x4 CA, such as the Tier 2, which has rubber bushing on one end and a JJ on the other?

https://www.xf_vendor_spam_manageme...J-1997-2006-Rear-Lower-Adj-Control-Arm-Set-T2

 

[Chris]

I'm sure you'll be compensating him well once he finishes your Jeep.

Oh yes, perhaps I should write down a list of questions to ask him when I go pick it up and pay him. That way I'm prepared at least... haha.

 

[Chris]

Is Dave implying in this last statement that he would use synergy on both ends of a CA if it wasn't so difficult to get a bolt in the bracket because they self-center?

What would all this imply about the value of a Core 4x4 CA, such as the Tier 2, which has rubber bushing on one end and a JJ on the other?

https://www.xf_vendor_spam_manageme...J-1997-2006-Rear-Lower-Adj-Control-Arm-Set-T2

No idea, but I gather he would be using Synergy in both ends if he could... that's what it sounds like at least.

I can't speak to the Core control arms. All rubber bushings aren't created equal I suspect. Apparently Dave really likes the Synergy ones due to the fact that they offer just as much mis-alignment as the JJs. I'm not sure if the Core ones are the same... who knows?

And here I thought Synergy only made crap quality stuff (well, their ball joints are at least).

 

[jjvw]

Is Dave using the stock frame side mount on his front track bars?

 

[bobthetj03]

Is Dave implying in this last statement that he would use synergy on both ends of a CA if it wasn't so difficult to get a bolt in the bracket because they self-center?

What would all this imply about the value of a Core 4x4 CA, such as the Tier 2, which has rubber bushing on one end and a JJ on the other?

https://www.xf_vendor_spam_manageme...J-1997-2006-Rear-Lower-Adj-Control-Arm-Set-T2

More importantly, At what point would the CA brackets NOT be parallel?

 

[Chris]

Is Dave using the stock frame side mount on his front track bars?

Good question, I'm not sure. On the rear I saw photos and he was using an aftermarket mount. I can't speak to the front though... yet.

 

[jjvw]

One reason he is using the synergy bushing on the control arm is that the arm is bent (if I'm reading correctly). The bushing will hold the arm in the proper orientation.

 

[bobthetj03]

Is he using the Synergy joints for the frame side of the front TB?

 

[jjvw]

Good question, I'm not sure. On the rear I saw photos and he was using an aftermarket mount. I can't speak to the front though... yet.

If he's using a bushing on the front factory frame side, then he must be taking into consideration the bushing's position at normal ride height. If he is switching to a double shear, it wouldn't matter as much.

 

[Fargo]

Whoa, my brain just melted. That can't be right can it? Just so I am clear on who Dave is, that is MudB8 on jeepforum right? I have a lot of respect for that dude.

I have never before heard anyone say that a JJ was squishy. I've read many of these threads and that has never been said by anyone that I can remember. Its possible I guess. If its a thin enough bushing it could be squishy and still give better control than stock. But I'm surprised the JJ doesn't wear out faster if it is that soft. I guess a little grease goes a long ways.

If this is accurate information, it totally changes the dynamics of how I need to view JJ vs Synergy. I've been planning on going with Synergy arms in my re-build, but now this really confuses me all over again.

Please invite Dave to participate in the thread or write down some of his thoughts on this subject for you to post. I would like to hear more of his insight on this.

 

[jjvw]

Dave is Mudb8.

 

[Chris]

If he's using a bushing on the front factory frame side, then he must be taking into consideration the bushing's position at normal ride height. If he is switching to a double shear, it wouldn't matter as much.

I thought about that as well. When he responds to me later this evening after work (which I'm sure he will) I'll ask him if he's using the stock frame mount in the front, or a doubles shear.

Whoa, my brain just melted. That can't be right can it? Just so I am clear on who Dave is, that is MudB8 on jeepforum right? I have a lot of respect for that dude.

I have never before heard anyone say that a JJ was squishy. I've read many of these threads and that has never been said by anyone that I can remember. Its possible I guess. If its a thin enough bushing it could be squishy and still give better control than stock. But I'm surprised the JJ doesn't wear out faster if it is that soft. I guess a little grease goes a long ways.

If this is accurate information, it totally changes the dynamics of how I need to view JJ vs Synergy. I've been planning on going with Synergy arms in my re-build, but now this really confuses me all over again.

Please invite Dave to participate in the thread or write down some of his thoughts on this subject for you to post. I would like to hear more of his insight on this.

Yes, Dave is MUDB8. He works at Jeep West up here in Oregon. He's currently building me his custom mid-arm that he runs on many of his TJs / LJs. I was going to go with the Savvy mid-arm, but Dave steered me towards his for a variety of reasons. Mostly though, I just went with his mid-arm because I have a ton of respect for him, and he knows his shit inside and out when it comes to Jeeps.

Don't worry... I'm just as confused as you are now.

 

[Fargo]

Don't worry... I'm just as confused as you are now.

I'm not so sure you are. At this point, I don't even know what questions to ask.

It would be greatly appreciated if you could ask him some of the questions that have just been brought up here. Maybe you can make list of questions right here in this thread and the rest of us can help you add to them. Maybe together we can assemble a list of 'intelligent' questions for him.