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2005 rubi strange vibration after lift

1K views 7 replies 8 participants last post by  Fuji_san 
#1 ·
I just recently bought my wife a 2005 rubicon and just put a 3.5 rubicon express lift in it with 285s on stock moab wheels . Lift went in good no issues there no rubbing or dumpster but we have a weird gyrating vibration just off idle up to 5 miles an hour and it comes and goes from there just not as bad . I have a transfer case drop i haven't yet installed but my feeling is my rear driveline angle is my issue . Will dropping the t case be enough or do i need to do more?
 
#4 ·
You need adjustable control arms and a CV driveshaft and a proper adjustment of the driveshaft axle input to point at the T case output.
 
#5 ·
i have the same problem i have a 4 inch lift and i took the drop trans, when i raised the body and motor up i raise the trans back up too and i only get the vibes when in 4wd and thats it no other vibe i think it is the drive angle . do i need the adjustable control arms to fix this issue and/or do i need to do something else too ? i did not have the vibes before that . and only in 4wd never any other time . thanks for the help . useful info on this post
 
#6 · (Edited)
Odds are that the vibrations are simply caused by an excessive angle at the rear driveshaft u-joints now that you have the new RE lift in.

RE's lifts are often up to an inch taller than their advertised height so odds are very good your 3.5" RE lift is more like 4-4.5" tall in reality which would definitely cause driveshaft vibrations.

I'm confident dropping the transfer case will help but I'm no so confident it will completely eliminate the vibrations with that tall of a lift. Adding a set of 1" taller motor mounts to the transfer case drop may be enough but that size suspension lift warrants installing a CV (constant velocity aka double-cardin) driveshaft. The CV driveshaft will eliminate the vibrations completely which is the correct/best way of doing that job... and a much better way than installing a tcase drop and taller motor mounts.

Go to http://4xshaft.com/ then click on Tech Info, then click on Geometry 101 to understand what has happened from installing the suspension lift.

But basically speaking, your rear driveshaft's two u-joints are now working into an excessively higher angle than they were designed to. The u-joints are now vibrating which is what you're feeling. The cure for that is to reduce the excessive angles which is best done by installing a CV driveshaft (which has 3 u-joints vs. 2 u-joints on your OE driveshaft) and raising the rear axle's pinion angle to work properly with the CV driveshaft That will also require adjustable length upper rear control arms to set the rear axle's pinion angle to work into the different design aftermarket CV angle as is shown on the Geometry 101 page at Tom Wood's webpage.
 
#7 ·
^^^x2, while your 1" mml no doubt helped, it is very likely not enough to compensate for your lift size. Since you apparently have a rubicon, you wouldn't need the sye, but just adjustable rear upper control arms and a double cardan drive shaft.

...or try lowering you t-case skid a little.
 
#8 ·
X3 on Jerry and Waterdog:
Putting in a nice double carden drive shaft (from say Tom Woods) would do the trick. The double joint connects to the transfer case side slip yoke shaft and takes up all the angle. Therefore, all you need to do is set the rear driveline pinion angle
 
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