Are my driveshaft angles acceptable?

[broken scope]

I have a 06 tj rubicon with a 4 inch rc lift with factory uppers and rc fixed lowers front and back. I checked my pinion and driveshaft angles today. The front was 6* at front pinion. The driveshaft was at10*and has a single cardan at front and double cardan at other end of front driveshaft. The rear driveshaft has 10* at output with 17* on driveshaft and 10* at the pinion. Does the angles look close enough?

 

[Chris]

Pictures would help tremendously. These days I go by more of a visual than I do an actual number.

 

[Jerry Bransford]

Your rear pinion angle should be the same as your cv driveshaft. Period. Nothing else matters.

 

[Chris]

Also, where are you measuring from? I take my measurements as follows:

 

[broken scope]

Your rear pinion angle should be the same as your cv driveshaft. Period. Nothing else matters.

Jerry l forgot to say my rear driveshaft has single cardan son both ends.

 

[Jerry Bransford]

Jerry l forgot to say my rear driveshaft has single cardan son both ends.

Sorry, I misread your initial post. With a 4" suspension lift, there's really no good way to get your standard SWB TJ's rear driveshaft's u-joint angle to an acceptable angle. At least not with a stupid-low tcase drop which is for most people unacceptable.

The commonly accepted rule of thumb is once the suspension lift height reaches 4" with the SWB TJ (non-Unlimited), it's time to install a SYE kit into the tcase and install a CV driveshaft. That's really the only good/acceptable way to run that rear driveshaft. Its angle gets so steep at 4" that its u-joints are operating at angles they were never designed for which is what actually causes the vibrations you feel after installing a tall suspension lift with the OE factory driveshaft.

And you can't just live with the vibrations such a tall lift causes. Eventually they'll cause u-joint, seal, and/or bearing failures. Just consider the installation of a SYE and CV driveshaft to be a part of installing any 4" or taller suspension lift.

This is how your rear driveshaft is supposed to look but it can't due to how tall your suspension lift is. tcase output shaft and pinion shaft are supposed to be parallel to each other. Even if you can get them parallel, which is essentially going to be impossible without adjustable length control arms, the angles the u-joints would be forced to operate at would be excessive and eventually take the driveshaft's u-joints out, if not a seal or bearing somewhere else too.

 

[broken scope]

Sorry, I misread your initial post. With a 4" suspension lift, there's really no good way to get your standard SWB TJ's rear driveshaft's u-joint angle to an acceptable angle. At least not with a stupid-low tcase drop which is for most people unacceptable.

The commonly accepted rule of thumb is once the suspension lift height reaches 4" with the SWB TJ (non-Unlimited), it's time to install a SYE kit into the tcase and install a CV driveshaft. That's really the only good/acceptable way to run that rear driveshaft. Its angle gets so steep at 4" that its u-joints are operating at angles they were never designed for which is what actually causes the vibrations you feel after installing a tall suspension lift with the OE factory driveshaft.

And you can't just live with the vibrations such a tall lift causes. Eventually they'll cause u-joint, seal, and/or bearing failures. Just consider the installation of a SYE and CV driveshaft to be a part of installing any 4" or taller suspension lift.

This is how your rear driveshaft is supposed to look but it can't due to how tall your suspension lift is. tcase output shaft and pinion shaft are supposed to be parallel to each other. Even if you can get them parallel, which is essentially going to be impossible without adjustable length control arms, the angles the u-joints would be forced to operate at would be excessive and eventually take the driveshaft's u-joints out, if not a seal or bearing somewhere else too.

View attachment 70210

The rear driveshaft has a plate bolted on a harmonic balancer at the output,single cardan then a slip yoke then a single cardan at the pinion. I don’t know if it’s stock or not.

 

[Jerry Bransford]

The rear driveshaft has a plate bolted on a harmonic balancer at the output,single cardan then a slip yoke then a single cardan at the pinion. I don’t know if it’s stock or not.

That's a trait of the Rubicon, I zoned out on that since I'm juggling multiple tasks right now. So you won't need a SYE kit, you do need a CV driveshaft plus adjustable length control arms for your rear axle so the pinion angle can be dialed in properly.

This is what your rear axle's pinion angle must look like with a CV driveshaft.

Either of those two flat surfaces circled in yellow provide the best place for measuring your axle's pinion angle from. Rotating the angle finder as shown gives a very precise pinion angle measurement. That flat surface the angle finder is placed against is exactly 90 degrees away from the pinion angle. Rotating the angle finder's 90 degree angled surfaces to use the correct surface causes the angle finder to show the pinion angle directly with no math needed. As it is positioned here.

 

[broken scope]

That's a trait of the Rubicon, I zoned out on that since I'm juggling multiple tasks right now. So you won't need a SYE kit, you do need a CV driveshaft plus adjustable length control arms for your rear axle so the pinion angle can be dialed in properly.

This is what your rear axle's pinion angle must look like with a CV driveshaft.

View attachment 70224

Either of those two flat surfaces circled in yellow provide the best place for measuring your axle's pinion angle from. Rotating the angle finder as shown gives a very precise pinion angle measurement. That flat surface the angle finder is placed against is exactly 90 degrees away from the pinion angle. Rotating the angle finder's 90 degree angled surfaces to use the correct surface causes the angle finder to show the pinion angle directly with no math needed. As it is positioned here.

View attachment 70225View attachment 70226

That's a trait of the Rubicon, I zoned out on that since I'm juggling multiple tasks right now. So you won't need a SYE kit, you do need a CV driveshaft plus adjustable length control arms for your rear axle so the pinion angle can be dialed in properly.

This is what your rear axle's pinion angle must look like with a CV driveshaft.

View attachment 70224

Either of those two flat surfaces circled in yellow provide the best place for measuring your axle's pinion angle from. Rotating the angle finder as shown gives a very precise pinion angle measurement. That flat surface the angle finder is placed against is exactly 90 degrees away from the pinion angle. Rotating the angle finder's 90 degree angled surfaces to use the correct surface causes the angle finder to show the pinion angle directly with no math needed. As it is positioned here.

View attachment 70225View attachment 70226

That’s where l measured it from. Looks like l need a cv and adjustable ca. Thanks

 

[Blackjack]

For the front you need to be more concerned with caster angle over driveshaft angle. Get it where it needs to be for good road manners. The driveshaft will live with whatever it is at.

 

[k-huevo]

...The rear driveshaft has 10* at output with 17* on driveshaft and 10* at the pinion. Does the angles look close enough?

On paper yes. Subtract 10 from 17 leaves an operating angle for the u joint at 7 degrees. The u joint operating angles on each end of the driveshaft are equal; that's a good thing. Spicer recommendations can be seen in the chart below. The greater the u joint operating angle, the quicker a u joint will exceed its service life, even without perceivable vibrations.

 

[broken scope]

Thanks for all the help. Im actually considering going to 21/2 in ome springs with rancho 5000x shocks. I dont ever go off road anyhow.

 

[wyorob]

That's a trait of the Rubicon, I zoned out on that since I'm juggling multiple tasks right now. So you won't need a SYE kit, you do need a CV driveshaft plus adjustable length control arms for your rear axle so the pinion angle can be dialed in properly.

Pardon me for butting in, but I'm Jeepnew and I that sounds like my setup too. Am I picturing it correctly or does this still require a SYE? I attached a picture for reference. Looks like harmonic balancer on the output, slip, then u joints on each end between. Trying to figure out what exactly I need to do to get this thing dialed in

 

[fixmysix]

Pardon me for butting in, but I'm Jeepnew and I that sounds like my setup too. Am I picturing it correctly or does this still require a SYE? I attached a picture for reference. Looks like harmonic balancer on the output, slip, then u joints on each end between. Trying to figure out what exactly I need to do to get this thing dialed in

View attachment 139145

You need a SYE. The long shaft coming out of your t case is the yoke. That rubber boots indicates that it slides in and out and is there to keep dirt out of the seal. The other way to tell is to look at the driveshaft. See how it is completely solid with no way to change length? That indicates a slip yoke also.

 

[wyorob]

You need a SYE. The long shaft coming out of your t case is the yoke. That rubber boots indicates that it slides in and out and is there to keep dirt out of the seal. The other way to tell is to look at the driveshaft. See how it is completely solid with no way to change length? That indicates a slip yoke also.

Well, shucks. Saw the harmonic balancer and got optimistic about saving a few bucks for a minute

Thanks!

 

[someguysjeep]

Pardon me for butting in, but I'm Jeepnew and I that sounds like my setup too. Am I picturing it correctly or does this still require a SYE? I attached a picture for reference. Looks like harmonic balancer on the output, slip, then u joints on each end between. Trying to figure out what exactly I need to do to get this thing dialed in

View attachment 139145

you have a 1" skid plate drop to allow the drive line to sit at a steep angle into a pinion angle that is not set similarly.
get an angle finder like above and see what they are both at, maybe you can get what you need from just a pair of adjustable control arms