front pinion angle problem with lift (1 Viewer)

[goranvolvo]

a cant find answer to my Q
so i have 4" lift , in front i have caster correction plates and i'm getting driveshaft vibration when i measure angle on pinion flange and transfer case flange there is 7 degree difference
where is the problem ?

 

[White Stripe]

If your tcase flange measures 90 degrees, your pinion flange needs to measure 90 degrees. More than 2 degrees difference can cause vibration typically.

 

[baldilocks]

Post a pic of you pinion with driveline installed. You probably need a DC front driveline.

 

[Nay]

when i measure angle on pinion flange and transfer case flange there is 7 degree difference
where is the problem ?

Ummm...that is the problem.

Caster plates rotate the pinion down and your driveshaft u-joints are running at different angles.

A u-joint running at an angle rotates in an elliptical path - unless each is at near the same angle (equal or opposite) it will vibrate.

That’s why with AWD you don’t correct caster, you correct pinion angle.

 

[-Spike-]

The stock driveshaft geometry in front is weird by design, and gets weirder when you lift it. What you are seeing is typical. A combination of caster correction and possibly re-phasing the driveshaft or replacing it with a dc shaft might be helpful.

 

[Nay]

There is no amount of phasing that is going to fix a 7* misalignment of u-joint angles.

The beauty of the 80 is that the broken back configuration of the front driveshaft means you have to rotate the pinion down for a DC driveshaft instead of the typical need to rotate up, and pinion down = increased caster.

So long as the caster plates were correct for a 4” lift and DC conversion, meaning near 0* axle end u-joint angle, then swap the driveshaft and all is well again.

 

[-Spike-]

There is no amount of phasing that is going to fix a 7* misalignment of u-joint angles.

The beauty of the 80 is that the broken back configuration of the front driveshaft means you have to rotate the pinion down for a DC driveshaft instead of the typical need to rotate up, and pinion down = increased caster.

So long as the caster plates were correct for a 4” lift and DC conversion, meaning near 0* axle end u-joint angle, then swap the driveshaft and all is well again.

I get that the math doesn't work, but there are lots of folks running 4-6" of lift with caster correction and a stock shaft with no vibrations. Results don't lie. Not everyone needs a DC shaft.

 

[goranvolvo]

There is no amount of phasing that is going to fix a 7* misalignment of u-joint angles.

The beauty of the 80 is that the broken back configuration of the front driveshaft means you have to rotate the pinion down for a DC driveshaft instead of the typical need to rotate up, and pinion down = increased caster.

So long as the caster plates were correct for a 4” lift and DC conversion, meaning near 0* axle end u-joint angle, then swap the driveshaft and all is well again.

When you say 0° you thinking on Caster angle I wonder if I can use offset bushings in combination with Caster plates or do a radius arm drop

 

[Nay]

I get that the math doesn't work, but there are lots of folks running 4-6" of lift with caster correction and a stock shaft with no vibrations. Results don't lie. Not everyone needs a DC shaft.

I’d believe it when I heard it, although solutions looking for problems is not my thing. Some people are a lot more sensitive to this stuff than others.

The key is that the stock front isn’t weird, it is just properly angle aligned with both t-case and pinion pointing up at the same angle - “broken back”.

You could turn your rear driveshaft into a broken back - the pinion would pointed be way up, but angles are angles and the operating angles of the joints would be a lot less.

You could also point the front way down and have high equal but but opposite angles and a ton of caster. U-joint life would suffer, but it could be done.

The point of the DC shaft is simple: on a 4” lift you can have proper caster and a proper pinion angle because the conversion requires increasing caster and that’s because of the atypical broken back config. There’s zero reason to suffer beating one’s head against a brick wall that doesn’t exist.

 

[Nay]

When you say 0° you thinking on Caster angle I wonder if I can use offset bushings in combination with Caster plates or do a radius arm drop

You’ll need to study u-joint angle alignment - there is tons of info online. The 0* is not caster. On a double cardan driveshaft, the double cardan end has two u-joints that cancel each other out, therefore the axle end had to run at 0* angle or it will vibrate because it doesn’t have a u-joint on the other end to cancel out its elliptical path of rotation.

Zero degrees means the pinion angle is directly in-line with the driveshaft - they have the same angle and therefore the u-joint has no operating angle, rotates in a circle, and does not vibrate.

Your caster plates should have achieved this alignment as that is what they are designed to do.

But you have to stop thinking about caster. Caster is an effect - it follows pinion angle. The alignment is proper u-joint angles, which you do not have. The DC shaft will correct this *if* your caster plates have correctly rotated your pinion for your specific lift.

If you start messing around with caster more, then your pinion angles will follow and proper alignment will be pure luck.

 

[landtank]

Try this

DC-Shaft pinion check

 

[baldilocks]

This isn’t rocket science, maybe bananas at most.

 

[dugsgms]

Keep in mind that vibration-wise the difference in angles of the flanges relative to each other isn't nearly as important as the angles of each relative to the driveshaft.

 

[-Spike-]

I’d believe it when I heard it, although solutions looking for problems is not my thing. Some people are a lot more sensitive to this stuff than others.

I believe Tools is one of the many around here. Running for 15+ years that way. I can't speak from experience as I installed a full Slee kit before driving mine, and then replaced the DC a couple of times, the latest iteration is a Tundra re-tubed.

The key is that the stock front isn’t weird

I guess I shouldn't have said 'weird', perhaps 'unusual' would be a better adjective.

You could turn your rear driveshaft into a broken back - the pinion would pointed be way up, but angles are angles and the operating angles of the joints would be a lot less.

Yeah, I did that. And love it. Angles are less, shaft is up out of the rocks, and the pinion bearings haven't burned up yet. I do have an extra oil slinger in it to hopefully prevent that.