Topic: pinion rotation angle and drive shaft length questions

[muddpigg]

I have searched and seem to get two responses to pinion rotation angle.  Do I point the pinion at the T-case straight with no angle or drop it 2 degree?  Do I compensate for the CV joint?

Is there a formula for figuring the length of the drive shaft before you rotate the pinion up?

Thanks in advance for responses.

Oh and Thank you to Marlin and crew for their inovations with these trucks.

'86 4rnr

[79coyotefrg]

i would  go with 2 * drop,  this will allow for axle wrap

[Goose]

are we talking about ifs here? or solid axle?
either way, id suggest a 2* drop too,
One: like coyote said, axle wrap,
Two: (if SA) for upflex.

[muddpigg [OP]]

Yes IFS, SAS will be one of my last drive line mods (yeah maybe).  So talking about rear axle.

[Goose]

well then yeah,  for the rear too id aim for something around a 2*
then, if your weighted down a bit for camping or somthing, youll be straight, or during upflex,

oh...yeah and  on the frontend, axle-wrap pulls down...
I was thinkin backwards i guess

[muddpigg [OP]]

So 2* drop.  Thanks.

Is there anyway reliable way to figure drive shaft length, before the install?

[Hammerhead]

I always set mine up at 2° below shaft angle for the rear when using a CV (double cardan) shaft.  It will "climb" the ring gear and end up running at about 0° when on the throttle.

In the front I set up at 2° above shaft angle for the same reason. 

It is best to measure for shafts after the pinion angle is set and rig is sitting on it's wheels again. 

[muddpigg [OP]]

I appreciate the input.

Now how do I measure 2* to get pinion under t-case?

[Goose]

You need one of those degree clocks, and you set it on the axle perch...

[Hammerhead]

I assemble the axle under the rig with the perches not welded and the U-bolts loose enough to rotate the axle.  With the weight of the vehicle on the springs and the driveshaft in place you can use a jack to push the pinion up until the lower U-joint of the driveshaft is perfectly straight.  I then remove the drive shaft and measure the angle of the pinion flange with a magnetic angle finder.  I then bump the flange back down 2° and that is the angle I want to keep.  I tack my spring perches firmly in place and remove the axle for complete welding.

[muddpigg [OP]]

I ordered the perches and speedo extension today.   

Thanks for the direction. 

Is there anything else I should keep in mind?