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Jun 19, 2003
Nowhere Nebraska
My driveline has a vibration, enough so that if I rest my hand on the shifter going down the road it goes numb. It's high frequency. There's also a cyclical growl coming from the rearend at hiway speeds but it don't seem to match the shifter as far I as I can tell. I took the driveshaft off and the u-joints are nice and tight and other than the smallest amount of radial play, the slip yoke is tight. U-joints are in time. So, do I need to pull the third member and have it rebuilt? or is everything I just described considered "normal" for a fj-40?
I would check your pinion angle first. If you have a lift or ext. shackles, you should install caster shims to tip your pinion back down.
Just did that a couple days ago, 4 deg. didn't do anything for the rearend, but wow, what a difference it made with steering on the highway! Oh, just incase I screwed up, on the rear the shims should be thick part forward to actually tip your pinion up...correct?
I forgot to add... Drain the oil in the rear end and look for chunks. I had to replace the 3rd member in my rig due to metal in my oil.
No, IIRC the fat part should be back so that it tips the pinion down. You want the pinion and the transfer case output to be parallel.
I had a growl from my rear end. It turned out that the bearing retainers had spun. I ended up getting a replacement 3rd member.
If the pinion is supposed to be level with the t-case, then I'm way off...don't make much sense, at least in my little brain. I really wonder if there's something way out of quilter in my third member.
The pinion should only be pointed at the rear of the T-case when using a double-cardan CV shaft. Which I assume you are not.
As fjcruiser said, with normal d-shafts the pinion should be parallel with the rear output of the t-case. It has to do with funky driveline shiz. This could very well be your problem.
Bailey is right. Get the pinion angle right before messing with third member. It only takes a few degrees to make it vibrate. Correcting the pinion angle is a lot cheaper than dealing with your third member.
Depending on your lift springs/shackle combo, 4 degrees may be too much. Be sure to visually check it all out as well.
I needed 2.5 degree in the front only with skyjacker springs and stock length shackles.
I haven't figured out exactly how much lift I do have, the springs are after market and the shackles are 5 1/4" between bolt centers. I do know that even before I tipped the pinion up with the shims that it was already tipped up quite a bit.
Flipped the shims and it got rid of the vib. in the shifter, but the growl is still there. I'll just live with it for the time being until I can get the third member rebuilt. Oh, checked the plug and found no metal chips in the gear lube.
If I've got a 4" Skyjacker lift with stock length shackles, do I need to shim and how much? Front & rear?
2.5 in the front.
I don't have any in the rear, I may put a 1.5 or 2 on the rear when I get a chance, to see if it helps, I don't get any vibration until I exceed 67 mph.
Don't forget to get new spring pins, and space the head up with some pipe so that it still protrudes into the spring plate on the axle.

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