Harmonic vibrations in Jeeps: A new theory (please read!)
- Thread starter psrivats
- Start date
For the same reason that most folks don't get out of control vibes at lower speeds.
He is trying to make the point that with a steeper trackbar angle, the lateral shift is higher as the suspension cycles.
For pinion angle reasons sure. But not because the suspension compressing makes the track bar move the axle over and create vibration from lateral angles not being exact.
Shhhh. I know.
I answered your question. Do you have a different question?
Make the angry face all you like but do you actually know that the offset angle isn't adding to the vibes when the suspension squats?
Minor but when you deal with them enough, you learn a few things. One is the pinion is forgiving when low and not forgiving when high. So, it is very easy to set them a tiny bit low to compensate for the small rise in angle under the minor squatting that happens when wind load increases.
The vibes do not change at the same rate the suspension moves and are instead a cyclical harmonic that travels fore and aft through the rig whenever the resonant frequency is reached. If pinion angle were responsible fully, that frequency would change when the suspension moves and it doesn't.
You have to turn the driveshaft faster to go faster. The driveshaft turns faster when you regear lower.
I never had a hub kit. Removing the front driveshaft made the vibration reduce but it was still present, just less annoying.
Adjusting pinion angles very carefully, drive shaft balancing (on the vehicle) and changing front driver inner axle shaft helped reduce vibrations down where I can drive the jeep at 55-60. Previously vibes would start at 40. Beyond this, pinion angle adjustments did not help much, front or rear. I have spent money trying to swap transfer cases and transmissions individually one at a time for testing purposes and both did change the "feel" of vibration (ie the tone of the droning sound inside changed a bit), but did not change anything reg vibration onset speed or the intensity.
The biggest differences in terms of feel came from (a) going to a heavier tcase skid (b) sound dampening the tub.
As of today, I still have vibrations at 65 .. they are intolerable at 70mph.
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I know, but removing the front driveshaft is similar, which is what I was trying to ask.
They are not exactly the same as to what happens in the front axle. But in terms of load on the tcase, perhaps you can consider them to be similar.
Not likely in my opinion (and both Dave's/6states opinion too). Which is why I haven't had the immediate urge to buy the kit or new wheels.
I am curious to see what happens to the vibrations with the new suspension. Might be foolish of me to be spending the money on the suspension. I felt I have exhausted all other options at this point of time. Even re-regeared the rear (Dave set it up) and no change.
And in my case, I pull the rear ds and she's smooth as glass in 4hi. Do they make a hub kit for the rear? Lol!
Interesting. Well, it's too bad you can't put a hub kit on for cheaper, just to see. They may be right, but naturally I'm still curious.
Perhaps a bit extreme, but has anyone removed BOTH driveshafts and had someone flat tow them at highway speeds?
There's thinking outside the box! I could flat tow behind my RV. It's in neutral, and while the drive shafts are still hooked up and spinning It possibly could rule out the t-case, transmission, and engine as a culprit.
In a more extreme case of tracking down vibes, you could pull the inner shafts and drive with the driveshaft connected if you suspect an issue that hubs may solve.