Just had my 5:38's installed. I'm getting a slight vibration above 60 mph, (Yes, they were broke in), I'm currently running 6.2 degrees of caster and a JE Reel OE replacement front DS (re-uses the OE flanges). I removed the front DS and the vibes are gone.

Is the 6.2 degrees too much for the JE Reel DS? Should I adjust my front arms for less caster?

 

with that gear ratio your pinion angle needs to be just right. you may have better luck with a drive shaft that comes with new flanges versus the adapter style yours has.

 

Thanks, I'm considering that. Think I might try to adjust my arms and see if I can find that balance between caster and pinion first.

 

Why does that particular gear ratio sensitive to the pinion angle? Have others had trouble with 5.38s doing this?

 

the high gear ratio will cause the ds to turn at a much higher rpm. which in turn will cause the ds to vibrate much more than a stock 3.73 or 4.11 would if the angle between pinion and ds is not at or near 0 degrees. plus with the adapter flanges there is more unhung weight which will add to the vibration.

 

Yep, you'll want to lower the caster. The joints on the aftermarket shafts like to have less of an angle that the stockers. Mess around and you'll find a balance between vibes and flighty steering that you can handle. (as noted, the adapter plates that you have move the joints further out and increase the angles. New flanges are the better option...)

There are quite a few threads about exploding tcases. A common ingredient in them seems to be lift + larger tires + higher numeric gears + driveshaft angles/vibes + freeway speeds = kaboom... (but it is not the gears specifically that would cause it)

 

Exactly why I removed the shaft after I felt the vibes. Thanks for the input!

 

Interesting. Now I better understand how important adjustable arms are. Thanks!!

 

negative or positive caster? What works on one jeep may not work on another. Due to difference in lift heights, type off drive shaft and gear ratios. The vibration can only be fixed by correcting pinion angle. If your not happy with handling after due to castor then you could cut and rotate c. Or get a after market high pinion axel. 4.5 degrees of castor caused vibes on mine.

 

Several people have used the adapter plate front ds on here have blown, cracked and or f'd the t-case up. I'm one of them. Lose the adapter one and install yokes.