Harmonic vibrations in Jeeps: A new theory (please read!)

freedom_in_4low said:

well that would have saved me about $250 on a new front driveshaft when mine ended up too long . How much runout did you measure?

Click to expand...

Enough to say "good thing i purchased this two yokes, few month ago, during my typical late night drunk Jeep shopping spree"

I have no tools to do such measurements.
What i did was lift front tires off the ground, disconnect rear DS, put it in 6th and let spin at idle speed. Then i put my hand on DS to get the feel for how even it spins.
After that, i used slow motion option of phone camera to capture DS spin at axle yoke, middle of DS and TC yoke. TC end had the most wobble

This is some really good info lads.

I re-geared my '97 2.5L/AX-5 with 2" lift on 33" tires from the stock 4.10 ratio to a Yukon 4.88 ratio. The work was done at a shop. After the re-gear i developed a noticeable harmonic sound that is most apparent at roughly 36mph (58km/h) at 1800rpm in 4th gear. Like most harmonics they have a certain frequency that seems louder than others, and the above mentioned speed causes it. At higher speeds the pitch of the harmonic sound increases and becomes less noticeable but the road/wind noise also increases so it's a bit hard to tell.

Anyway, just adding my two cents with regards to mystery harmonics and how they affect each jeep differently.

So I’ve been dealing with harmonic vibrations concerning my front drive shaft for about a year now. I’ve rebuilt the transfer case, new seals and bearings in both pinions and on carriers, adjusted my control arms more times than I would have cared to, added and removed weight from the jeep, swapped all u joints everywhere. Was never really able to get it to an acceptable level for my standards. So last week on a whim I said fuck it and just ordered the balancemasters driveshaft balancing ring. Whats another $120 at this point right? It showed up a few days ago and I finally got around to installing it last night. I didn’t have high expectations at all, but I was wrong. On my 35 mile commute into work just now I was pleasantly surprised at just how much more smooth the ride was. Almost eerie feeling to not have my feet shaking the whole time. While it did not 100% solve the problem it is definitely a major improvement. Vibes used to set in around 50-55 mph, now that speed is smooth as glass. They did set in again around 72ish mph but nothing like they were before. I live in socal and drive a 25 yr old jeep so 72 is a rare speed for me anyways. I’ve been following this thread for a few years now and just tell my experience on something that seems to have worked well for me…. So far.

Anyhow. If your vibes aren’t too extreme I think they are worth a shot to try. Price isn’t too bad in the long run and has made a pretty significant improvement for me as of right now. Part link for reference.

https://balancemasters.company.site...ust-measure-every-section-of-shaft-p438095967