Adjusting front axle pinion angle

bobthetj03

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I have a quick question about adjusting my pinion angle on the front axle. Where do I want to put my angle finder on the drive line? I'm assuming you would put it on the H yoke of the double cardan joint like you would if you were doing a SYE/DCDS for the rear? Also, can I put my angle finder on the front flats of the pumpkin where you would put a case spreader and then just subtract from 90* to get the pinion angle of the axle?
 
Also, can I put my angle finder on the front flats of the pumpkin

This is where I put my angle finder every single time.

Though I've never had to adjust the front, and to my understanding, you shouldn't really need to adjust the front, even with 4" of lift.

Maybe I'm wrong, but I thought that's how I understood it.
 
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The two round circular flats on either side of the differential cover are perpendicular to the pinion angle. You can rotate most angle finders 90 degrees until the angle it indicates is the pinion angle.

The front pinion angle should be the same as the driveshaft angle. As Chris said it rarely needs adjustment.
 
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Your caster is more important than your pinion angle on the front axle.
Absolutely backwards, the pinion angle always (!) takes precedence over the caster angle.

The way to dial it in is to dial in as much caster angle as you can get without the pinion angle getting excessive which causes vibrations. Once you get vibrations from the pinion angle getting excessive, you have to roll back the caster angle until the vibes go away.

The deal with caster angle is that there's no 'precise' caster angle that is needed... you just need 'enough' caster angle to give you good steering return-to-center and stable highway steering. 5 to 5.5 degrees or higher is normally enough, with larger tires not needing as much caster angle for good return-to-center as smaller tires do.
 
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Which is why I asked the question. After my re-gear, my drive shafts are spinning X amount faster than before, so I'm getting a vibe above 60 mph. Pull the front drive shaft and the vibe goes away. I've been thru 2 new Adams drive shafts with no change, so I think I need to get my pinion angle closer.
 
Which is why I asked the question. After my re-gear, my drive shafts are spinning X amount faster than before, so I'm getting a vibe above 60 mph. Pull the front drive shaft and the vibe goes away. I've been thru 2 new Adams drive shafts with no change, so I think I need to get my pinion angle closer.
I hope the pinion angle is the problem and your vibration problem can be fixed by adjusting it JB. Fingers crossed....
 
Which is why I asked the question. After my re-gear, my drive shafts are spinning X amount faster than before, so I'm getting a vibe above 60 mph. Pull the front drive shaft and the vibe goes away. I've been thru 2 new Adams drive shafts with no change, so I think I need to get my pinion angle closer.
The front and rear drive shafts are opposite in forgiveness when it comes to angle. The rear will almost always have an issue if it is adjusted slightly higher. It is very forgiving if it is too low though.

The front is the opposite. Get it slightly low, probably going to let you know about it. Lose some caster and get it too high, it pretty much doesn't care.
 
My front is low by 3.2*. Not sure how much higher I can go before my caster turns to shit. I'm hoping to cure the rear with a SYE/DCDS. I've adjusted the rear pinion so that the TC yoke is exactly parallel with the rear pinion yoke. Didn't help any though. Still get that rhythmic voom....voom....voom vibe at about 50 mph. Secondary vibe kicks in above 60 mph.
 
Worry less about the caster angle and more about the pinion angle. Read Blaine's post immediately above again. The front pinion angle absolutely cannot be too low as it appears yours is.
 
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The front and rear drive shafts are opposite in forgiveness when it comes to angle. The rear will almost always have an issue if it is adjusted slightly higher. It is very forgiving if it is too low though.

The front is the opposite. Get it slightly low, probably going to let you know about it. Lose some caster and get it too high, it pretty much doesn't care.

Took some measurements this morning with my digital angle finder. My front pinion is 5.7* above 0*. My front drive shaft tube is 4.2* above 0*. My H yoke is 2.3* above 0*.

If I'm reading this correctly, my pinion is high, correct?
Which measurement am I trying to get close to, the tube or the H yoke?
 
You don't care what the pinion angle is above 0, you only care about its angular relationship to the driveshaft.

For the front driveshaft, which is a CV driveshaft, the pinion angle needs to be essentially that of the driveshaft. The front pinion can point slightly above the angle of the driveshaft but it can never in any case point below the angle of the driveshaft.

Forget that the last illustration shows the rear driveshaft, its angular relationships are correct for your front driveshaft.

PinionAngleMeasuring1.jpg

PinionAngleMeasuring2.jpg

cv_angle.gif
 
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Double checked my digital angle finder with my needle angle finder. Looks like they read about the same. Obviously my angles are different since I'm dealing with the front drive line.
 
It appears the front pinion angle is slightly higher than the front driveshaft angle which is fine.

Note for those with rear axle issues, it is just the opposite for the rear... the rear pinion angle can be slightly lower than the driveshaft angle but the rear pinion angle can never be any higher than the rear driveshaft angle.
 
It appears the front pinion angle is slightly higher than the front driveshaft angle which is fine.

Note for those with rear axle issues, it is just the opposite for the rear... the rear pinion angle can be slightly lower than the driveshaft angle but the rear pinion angle can never be any higher than the rear driveshaft angle.

That is what I gathered too. Thanks guys for your help here. I think I'll leave the front alone then and focus my efforts on the rear.
 
Did you ever get this sorted out? I am dealing with the same issue right now.

No, I have not. I'm saving my caps right now for the SYE/DCDS. Once I get this done I'll post my results as to whether it fixed my vibe or not. Gonna be a couple months away.