I just finished installing OME17 rear leaf springs on my 4rnr, when I took it for a test drive the truck started to shake and vibrate alot (at low spead). I went half a block and came right back. The truck is higher in the back than up front but I think it has to do with the angle of the drive shaft.
How can I fix this? Is it possible to rotate the rear axle up and align it all that way? Here is a picture of the drive shaft not aligned with the differential:
http://community.webshots.com/scrip...hotoID=194899072&security=QACxfS

Thank you for your input,

Can't see your image, but its easy ...ave shims made to correct it, if needed.

This should work...

http://community.webshots.com/photo/194899072/194899072QACxfS

Looks to be tipped up too high, but hard to say only seeing one end. Grab a tape measure and get the flange-flange measurements top and bottom as noted on the page I linked above, and that'll tell you the exact angle you are at now and which way you need to go to get back to stock. Of course, would have been best to measure that stock angle before you installed the new springs.

Don't understand why new springs should affect
that angle, unless shims were installed.
I think the angle between the drive-shaft and
the TC pinion should be the same as the angle
between the DS and the diff pinion.
(ie the diff pinion shaft should be parallel
with the ground). Right Roger ?
Or am I all wet.

Yes, normally springs alone won't affect the pinion angle, at least on a single-cardan driveshaft. However, longer than stock shackles will affect the angle and I recall an earlier post about these springs where there was also mention of new spring shackles. Likely they are longer than stock and you'll typically get a 1 degree change for each extra inch of shackle length.

Roger
I did put back the shims the original setup had. I installed them just like they were, the widest part was placed towards the end of the truck. The shim was under the leaf pack. What if I turn it around, the wide/thickest part of the shim going towards the front of the vehicle. Wouldn't that change the angle upwards?

Thanks ,

You may or may not need any shims. Measure as-is, see how far off you are. Turn shims around, measure, then remove shims and measure. Pick the one that leaves your pinion angle 1-2 degrees below the t-case flange. With a single cardan driveshaft, you usually don't need shims with a simple spring lift. Many spring companies include shims just in case you are installing on a double-cardan (CV) shaft setup, such as on a pickup with a center support bearing/2-piece driveshaft.

I removed the shims and started from scratch. I now have the angles within 1-2 degrees apart and I still have a problem. The shackles are the same size as the original ones, greased the hell out of the drive-shaft and also made sure that the drive-shaft was not loose.



Current measurements without shims:
T-Case : 87 degrees
D. Pinion: 85 degrees
The front end vibrates between 10 and 25 MPH. When traveling at 60 or above and I let off the gas I get a vibe that sounds real loud for a few seconds and goes away. Then when I step on the gas the vibe comes back for just a few seconds again. Both times the noise comes from back of the truck and only happens when I decelerate and accelerate. If I maintain the speed at 55mph or above the ride is smooth without any vibrations.

My rear drive shaft dropped out of the yoke a about an inch farther, would this make a difference?

You can try tipping the pinion up 1 degree more, 2 degree is sort of the lower limit on the static angles. With the slip yoke out 1" farther, it may now be a little looser with less spline engagement, do you feel any play when you grab it and give it a tug? Also, are the u-joints in phase exactly? If they are lined up, one option is to pull the shaft apart and spin one half 180 degrees and put it back together. Sometimes there is a slight variation in the phasing that works better in one orientation than the other. Also, try painting the slip yoke splines with grease (vs. just squirting grease into the zerk - into which you don't want to pump too much). Also, any play at all in the flanges? I often find vibes when backing off the gas are due to something being loose, when you unload the driveshaft, it gets into that loose area and vibrates. Also has the shaft been balanced recently? A small scrape or dent can throw it off and with the added operating angle you picked up with the lift, what may have been indetectable before has now been pushed to the point where you can feel it, BTDT. What is the overall angle on the shaft itself? I found somewhere between 12 and 15 degrees on the shaft is about the limit of smooth operation with u-joints.