Outer Limits 4x4 Board

I am sick of getting conflicting stories about tail shaft (universal joint) alignment!!!!

I have a GQ shorty and am spring lifting about 4". All i wanna know is how the tail shaft needs to be put back to standard??

Is the priority, getting the two uni joint angles the same????? 1) out of the back of the transfer 2) going into the diff.

I will sort out myself HOW to go about getting it aligned right cos everyone seems to do it differently.... Drop gearbox/ lengthen lower trailing arms/ shorten top arms..

Does the diff housing need to be parallel to the ground? Or is the angles of the unis the over riding concern. (As they can not transfer constant velocity) Is this why the angles need to be equal? HELP???

Steve

I am pretty sure,

Get your diff pinion to point to the transfer case, depending on your angle out of the transfer case you may need to drop the transfer case or put in a double cardin joint, some like these some don't.

Try nissan tech, those boys will have to tricks

Check this out. Read carefully twice if you have to. Explains every thing spot on.

www.4x4wire.com/toyota/tech/driveline/

When i did my lift I had problems with the whole driveline osilating back and forth while under float (no exceleration)
This was hapening because of the front drive shaft angle. The dif pinion was pointing straight at the transfer case.
So the uni at the dif end was operating straight, no angle and the one at the transfer case a fair bit of angle.
Therefore the uni at the transfer case end was trying to speed up and slow down, through each revolution and the one at the dif pinion was trying to spin at a constant velocity.
This is where you have the problem. It is not the servere angle but the differing, or mismatched angles.

I fixed this by puting a double cardon joint at the tx end.

A double cardon joint is not used because of great angle. (they infact they are limited to smaller angle) They just correct rotaional velocities.

Suming up. Generally, well on cruiser's any way you need to eaither rotate diff so that the angle at the dif end and above is the same as the angle at the transfer case end below.
or put double cardon at tx end and get the diff pinion to point straight at the tx case.

Hope this makes sense.
Read article.
Steve

Just noticed your an engineer.
I found a sight which explains the whole angle, and uni joint slowing and speeding up thing with a whole list of equations.
If your interested I could probably find it again and post.

Back to question.
options
1 Keep angles the same
2 one angle 0 degrees and the other with double cardon.
3 both ends at any angle and d/c's at both ends.

Thanks very much that helps reinforce what i had suspected. One last issue though. Which option would therefore be the best for promoting Universal life..

I don't know for sure, but.

I believe that you are better off without the d/c and have equal angles at either end.
reason.
The d/c dose not work as well at the sharp angle. and will wear quickly.
They are expensive to replace.
also i have been told, and also tend to believe that the extra weight of the d/c at the transfer case output will lead to quicker wear on the transfer box.

Running two uni's at the correct angle should work.They will probably wear quicker than normal, but they are cheap and easy to replace. You can easily carry spares. A d/c is to expensive to carry a spare.
If it fails in the middle of knowhere your screwed.

This is just my theory though and not the way I went beacuase I could not be bothered trying to align the angles.
Steve

mate..get ur pinnion angle to match ur transfer output. single uni joints need to be like this to over come the accleration/decelration issues. u only aim ur pinnion at the transfer when u use a double carden joint, which i wouldnt reccomend because they are weaker than the standard shaft.

use longer lower arms to tilt ur pinnion down after ur lift. if vibes are still felt u can use raised engine mounts to tilt back of transfer down to closer match pinnion angle. u can use crossmember spacers here to do the same thing.

people used to put big spacers in the crossmembers to fix vibes but all that did was drop the tranfer angle to match the now aimed higher pinnion. this placed massive loads on engine mounts and made underchassis clearence bad.

ive got 5 inches of lift in my mav shorty done with longer arms and about 6mm of crossmember spacers. no dramas. have done about 25,000k's driving in mixed conditions with no dramas.

the only other concern is that of increased wear of the slip shaft spline..makes that awful gringing noise when floating or feathering the throttle at speed...not much can be done about this except keep shaft well greased with a high quality high temp grease very regularly. i hope this makes sense...

and oh...call cheezy

yeah. try stay away from d/c if you can help it.

I have a bad knocking sound coming from under my car which i think is the d/c. And its only done 5000k's
Steve

Thanks very much lads u guys have helped heaps!! I will now draw up my suspension geometry on Auto CAD and figure out my arm length adjustment to get the angles equal. If anyone else wants me to do this for em just let me know. I draw on AutoCAD all day at work and i have it at home too.. Thanks again.. Steve