I have an 07 Wrangler X. 5 inch Skyjacker, lower adjustable control arms and 35 inch Toyos. I recently put 5.13 gears in it and now I have this oscillating vibration that starts about 45 mph and stop about 65 mph. ( bear in mind my speedometer is off about 10 mph) The vibration is there even coasting in neutral at those speeds. I know the drivelines are spinning a lot faster now.

I had both front and rear cv drivelines balanced. It does not do it if I drop the rear driveline and drive in 4-Hi. If I put it on jack stands and get it up to speed you can still feel it and looking at the rear driveline, looks to be good.

Just frustrated now because I don't want to keep dumping money for no reason. What are the key areas to look for? And can u joints be bad but not visibly? Because they move and act like they are fine but maybe at high RPMs they are not?

 

I'm having the same issues you are, except I just pulled the front shaft and it cured all the vibrations. Gonna get my shaft re-balanced, see if that helps. After that, I dunno, as I'm already running little caster. Hubs would be the best option, but $$$$....

 

Question for the both of you:

Are you running OEM drive shafts?
If they are aftermatket, what are they?

 

Coast shafts for me. Supposedly balanced when made, but we'll see what the driveline shop says this week. Just drove 250 miles across tennessee this morning at varying speeds, and without the front shaft i didnt have a single vibration at any speed. Gonna get the shaft balance, then continue to reduce caster to see how the vibes react.

-Adam

 

Mine are Tom Woods. Mine does it with the front driveline out. ( I already fixed the front driveline issue)

 

Hows your pinion angle in the rear? Mine did it in the rear slightly as well until i angled the pinion upwards so that the pinion and shaft were directly in line. Used my upper adjustable rear arms for this...you running adj arms in the rear as well?

This is essentially whats needed in the front as well, but to achieve that sort of pinion/shaft alignment means horrible caster=VERY flighty steering. The rear doesnt have this steering problem obviously.

-Adam

 

If you have a drive shaft with a double cardan on the t-case end, the other end with the single u-joint needs to have the pinion pretty close to straight in alignment with it.

 

Yes I have my pinion angle 1.5 degrees under to adjust for loading. I also fixed that problem awhile ago. This just started after having my gears installed.

 

Had the same problem and even with o degrees castor I still had vibes so I got another ds and was able to move castor to around 3.5 degrees. Still hav a little give but only around 45 mph.