Does control arm bushing composition affect ride quality or NVH?
- Thread starter bobthetj03
- Start date
I think you already answered that question when you said a bushing couldn't be used in that location.
Seems like if there's room for JJs in the rear, there should be room in the front. Is the range of motion of that joint such that a JJ isn't required in that location?
Not quite. It seems like Jeep could have put a bushing in the horizontal position. Right now the best I can come up with is that there may be space restrictions resulting from the legacy CJ/YJ dimensions and form factor. The TRE might be the most efficient use of the available space.
Unless the shock mounts are moved, isn't the front is easier to get more travel than the rear? Maybe it is a space restriction in the stock mount similar to the factory's solution to the frame side.
Maybe it wasn't the best solution to the problem. Just the most convenient solution that met the design specs. But that's just speculation.
Anyway, we spent a lot of time discussing the pothole case, which is really Harshness. I think things are a little different when we start thinking about Noise and Vibration. Take that pothole case and scale it down to a tiny bump on a rough road. Then multiply that by 1000 and take those 1000 tiny bumps as input to the suspension every second.
How do the suspension components respond in that case?
A Johnny Joint is a joint the same way a heim joint or rod end is a joint. It is a movable ball inside a race.
The factory rubber bushing is bonded inside an outer shell with an inner bonded bolt sleeve. While MC addressed the rotational limitations by allowing the DF bushing to rotate within its shell, it still requires a return to center and cannot be kept in a permanent state of misalignment. Otherwise, the bond between the rubber bushing and the inner ball will fail.
A tie rod end, heim joint, Johnny Joint does not have any requirement to return to center and can be left in a permanent state of misalignment. This is why it can be used on the factory front frame side track bar mount.
Now I am wondering why there isn't a DF bushing on either end of their rear track bar....
Well said, that was a great explanation. My Johnny Joints live in a perpetual state of misalignment ready to be moved around to their next misaligned position they'll be just as happy in.
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Looks like it. It's a wider vehicle with more room and was a ground up redesign without the legacy restrictions that the TJ had.
https://www.extremeterrain.com/crow...giq-FOPrAPueCkJT9MBoCsMYQAvD_BwE&gclsrc=aw.ds
I would think that any "soft" or isolated connection between the road and the body would soak up noise and vibration.
Years ago, when I set up a 60 gallon air compressor, I needed to set it on thick rubber isolater feet in order to cut down the noise in the shop.
Once again, it makes me wish I knew how heim joints perform in this application.
Concerning noise and vibration, it is amazing how much the motor mounts and trany mount isolate. When I switched my factory trany mount over to UCF's low pro mount, there was a significant increase in noise and vibration from the drive train as a result. Switching back to the factory mount was a measurable difference, in my observations. More dampening material in that case made a difference. Now, if you could make the control arm bushing bigger, with more dampening material, would you feel a difference, ignoring the limiting factor of real estate under there.
The air compressor is a great example. I put the NAS unit in my closet on a silicone hot pad to cut down on the vibrations from the hard drives echoing through the shelving.
I don't know how heim joints respond to this type of vibration, but since they don't have any isolation, I would guess that they transfer more NVH than bushings.
The thing I keep wondering about is whether all the bushings and joints we're talking about are equally "soft." Take these Daystar replacements for Teraflex control arm bushings, for example: https://www.amazon.com/Daystar-Poly...02038BK&tag=wranglerorg-20?tag=wranglerorg-20
They're about half the price of the original Teraflex components. Are they made of the same material? Or something harder, or softer?
Same thing with the Currie JJs. Is the PU in there as good at isolating vibration as the OEM rubber bushings? It could be. But other than butt dyno, how would we know?
When I did the Savvy skid, it took a bit of effort to keep the transfer case away from the tub. I remember the first couple of days before I fully finished the job when I could feel and hear the gears spinning while driving. Savvy used a pair of rubber cleavite bushings in their mount. Now that it is mostly sorted out, the sound and vibrations are very close to stock.
Do we need to know beyond the butt dyno? While I would be curious to know an answer, I already know that there was no change in vibrations or noise between OEM and the JJ that is reaching my feet on the floor. Knowing the nuanced answer wouldn't change anything about my real world experiences with my Jeep.
Fair enough. And if you're happy with the results, that's all that matters. Just trying to stay within the spirit of the OP:
But I think the question about cheap polyurethane bushings is reasonable. Are they any good? Or a waste of money?
fourpointzero
TJ Addict
I appreciate the schooling. I often wondered how much difference, if any, a long arm kit would be vs short arm for daily driving, in terms of ‘softness.’ Surely if the wheel base is stretched, there’s improved stability.
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And that right there is what 98% of us care about really. Would it be neat to see some real data? I suppose, but in the end, the butt dyno reigns supreme!
That is the persistent question. Is there a difference to be made? It seems safe to assume that we know how to make things worse. But can we continue to make things better in a way that is real and perceivable? Or are we already in a state of diminishing returns from the very start?
Yep there's no difference. I replaced a 5.5" RockKrawler short arm suspension with an RE 4.5" long arm into my previous TJ, no noticeable ride difference. Then after that Jeep was stolen I bought my present TJ with a Currie 4" short arm suspension. No difference there either. I can see a stupid high suspension lift with extremely steep short control arm angles riding really stiff but that's it.
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