thinking about turning/rotating the rear axle to reduce the pinion angle on my 91 tracker with the "blue" 3"+3" lift kit . question is , will tipping the pinion up like that rob oil from the pinion bearing ? and if so how long will the bearing last before i will have to swap it out ? i drive my zuki alot so i have to be carefull of longevity .

Overfill the axle a little bit, if you are concerned about it.

You can overfill a little bit , to much and it will just blow the added oil out the vent.
IMHO a 3" lift shouldn't have you in a bind . your pinion flange should be on the same plain as your transfer case pinion for the u joints to work correctly...Boxcar

thanks guys , it's a split decision , some say do it and others say DONT , guess I'll wait and see how long my universals last and if the work is worth it , is anybody out there running a turned up pinion "daily " ?

Picture your axle ( stock angle) as you apply torque to it . The pinion rotates up towards the floor of your ride. Basically softening the angle under a sudden load (like a whole shot) . Now picture the same driveline with the third member tip ed up . Now under a sudden load your u-joint instantly goes into a bind as the third member rotates past  the sweet spot into the DANGER ZONE.  I see this allot. It's a bad idea and allways has been.....Boxcar...

It shouldn't be a split decision listen to BOXCAR he's right

thanks guys , it's a split decision , some say do it and others say DONT , guess I'll wait and see how long my universals last and if the work is worth it , is anybody out there running a turned up pinion "daily " ?

my pinion is turned up only because I run a CV shaft.

Here is a good pic, for visual reference, from Tom Wood's website on driveline geometery :

gotta admit  , it makes the most sense to leave it alone , and not to play the devil's advocate  , but the rear suspension is three-linked , there shouldn't be much if at all  , pinion twist-up under acceleration , flat spring  , i can see , but with plastic bushings and three-link there shouldn't be much ? I'm going to listen to boxcar , seems to make sense , ! why would running a C.V. shaft make it so you had to tip the pinion up , wouldn't the same "launch" twist effect your set-up

With coil springs and 3 or 4 link systems you do not have spring wrap (they just compress).  Leaf springs especially the weak Samurai ones wrap up in high torque loads (), allowing the differential to twist.  This is more noticeable with larger tires and/or hard launches.  You can run a Drag Link on leaf springs that prevent the spring from twisting during high torque usage.

Brd is correct in some ways. You have to add a drag link on flat springs that are spring over.
 BUT that is assuming that you haven't screwed up the angle first.
 4 and 3 links still have to have a certain amount of axle wrap designed into them for sudden shock load, otherwise you would wipe out the rear bearings on your transfercase or worse.
While these systems limit axle wrap considerably they do not eliminate it.
 That's why cv joints are at the transfercase end of the drive shaft to soften the angle there.
You should allways try to stay at the stock angles as much as possible........Boxcar.....

Picture your axle ( stock angle) as you apply torque to it . The pinion rotates up towards the floor of your ride. Basically softening the angle under a sudden load (like a whole shot) . Now picture the same driveline with the third member tip ed up . Now under a sudden load your u-joint instantly goes into a bind as the third member rotates past  the sweet spot into the DANGER ZONE.  I see this allot. It's a bad idea and allways has been.....Boxcar...

Are you talking front or rear axle, Boxcar? And are you talking going forward or reverse?




I'm pretty certain (the OP situations) that a rear axle under forward acceleration will have a "downward" force on the pinion. This will kind of kill your example....

Also a tracker is a linked suspension and will not be as susceptible to "axle wrap" like its samurai predecessor.  But as far as "correct" pinion angle, well that is an indepth topic. The issue with changing the tracker pinion angle will be more of an issue with a chance of vibrations out of the driveline (due to the fact that the ujoint angles will now be different). If you want to read more I recommend:

http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml


Personally I have rotated the axle on my tracker and I am really pleased with the off road performance, and I think it helped increase my droop. I do not notice any vibration on the road. HOWEVER I drive less then 100miles on the road and no where near interstate speeds.



Ultimately you could do the rotate mod, and test it. If it gets vibration you could move to a custom double cardan type shaft.

<edited- Striked out statement which is wrong. Don't tell my wife I was wrong >

Well I am wrong on the force on the pinion. Boxcar's example is valid. I guess I have been working on my sami front two much lately, and got things twisted......


I had to visually see it, on a leaf setup, to see where I was thinking wrong.....

Axle Wrap rear view

Still your major issue is not going to be related to operating within the ujoints range, because of the link setup....Instead the issue will possible vibration.

Vibration equates to bad alignment . No vibration before rotating the axle , but vibration after equals BAD ANGLE.
 Rotating the housing does nothing good .
All it does is let you run a To short driveline....Boxcar
PS: Nice vidio....And yes you to need a drag link BAD...

thanks for the video heiny , gotta admit , that was the first time for me seeing the pinion angle work in action , would it move as much with the three link in a tracker ? i've got to say , i'm very impressed with the technical help that i'm getting here , great job guys ! with the 3" + 3" calmini lift , is there any chance of the rear drive shaft sliding out ?i've been told a s.y.e. would eliminate almost all chance of it  , but i've had no problems thus far and haven't heard of any problems with this kit doing that'

With only a 3"lift I think your drive line length is probably OK.
 If your worried though it's easily checked.
Jack your rig (from the frame ) until your rears are floating in the air. Then check your slip joints remaining travel .
Making sure to allow for a little axle rap. ...Boxcar...