Vibration after Regear

Question: just had 4:56 gears installed on my jeep with new carrier for d30. 2014 jku non rubicon auto, 3.5" rubicon express lift, 35" tires. Followed break in protocol. Starting to drive faster, then there was a major vibration when getting towards 50mph. Replaced front driveshaft with CV shaft. Now I have vibration around 65 and gets pretty steady at 72. Don't think is normal for a regear. My Mustangs never did this. I can't even get north of that speed. Thoughts, suggestions?

I would take it back to shop that installed the gears. You could pull the front driveshaft and drive it to rule out that as a cause for vibrations but if a shop installed the gears, I'd let them do the work. Hope it's an easy fix for you.

Sounds like you might have too much positive caster set. Your front drive shaft will be spinning a lot faster than before and that increase in caster will cause a vibration especially if the shaft is a bit out of balance. That being said, I would remove your front shaft to verify that it is what is causing your vibration before doing anything.

With no ds, it spun fine. Replaced stock with a CV ds and now the vibration starts at higher speed. You speaking of the same caster as in getting an alignment or with new control arms?

Deez2014JK said:

With no ds, it spun fine. Replaced stock with a CV ds and now the vibration starts at higher speed. You speaking of the same caster as in getting an alignment or with new control arms?

Click to expand...

New adjustable front lower control arms will help you to set caster. Depending on how much lift you really have, you may find it helpful to have lower arms to just set the position of your axle and then use adjustable upper arms to set your caster. If you're still getting vibrations after setting your positive caster to about +4° which is essentially stock, you may have a shaft that is out of balance.

until you get it fixed, you can drive without the front DS

check your current caster so you know what it currently is, if it's within specs, you may just need the DS balanced.

As mentioned, with 3.5" of lift you should have at least lower adjustable control arms, both lower and upper would be better but lower will allow you to set your caster.

this will help, begins on post#4

http://wayalife.com/showthread.php?3861-Basic-Do-it-Yourself-Jeep-JK-Wrangler-Front-End-Alignment

So have you removed the front shaft and driven it to see if it is purely the shaft that is the issue? It seems like around 50% of people who install double cardan front shafts have vibe issues with them, myself included. I bought a pair of the big name brand nice shafts and the front vibrated straight out of the box. I removed it and took it to a driveshaft shop who said the balance was decent but they got it as perfect as possible. It definitely helped but I was never able to remove the vibrations completely. I have adjustable control arms and I tried to set the pinion angle straight on with the shaft and then adjusted several degrees on each side of that to try and diagnose / cure the vibrations. I probably adjusted the arms a dozen times and although I found a "sweet spot" I was never able to remove all of the vibrations. I wound up selling those to a guy who had zero issues with them but he wasn't running 5.13 gears either. As has been said if you have a high numeric ratio that shaft is really movin at 55mph and up.

I wound up getting the replacement teraflex high angle rzeppa joints for $150 each and put them on my stock shafts and it has been great ever since. I think some people assume that 1310 joints are stronger than the stock rzeppa joints and not only are they not, they are far less forgiving, and tend to be maintenance whores.