Adjusting pinion angle question

[Planepal]

I’m changing out the rear drive shaft to a Tom Woods double Cardan and installing new Savvy double adjusting rear upper control arms. I have two questions.
1. Do I need to slightly loosen the rear lower control arm mounting bolts to adjust the pinion angle with the upper arms?
2. My current pinion angle is 6 degrees and drive shaft angle is 14 degrees. I’m guessing I’ll have to adjust the pinion angle up to around 12 to 13 degrees. The oil level on the differential is up to the fill hole now so should I remove the filler plug and let the oil drain out after I finish adjusting the pinion angle?

 

[Tob]

1. If the lowers are still stock, yes.
2. Depends on if you want to make a mess or not.

 

[JMT]

I’m changing out the rear drive shaft to a Tom Woods double Cardan and installing new Savvy double adjusting rear upper control arms. I have two questions.
1. Do I need to slightly loosen the rear lower control arm mounting bolts to adjust the pinion angle with the upper arms?
2. My current pinion angle is 6 degrees and drive shaft angle is 14 degrees. I’m guessing I’ll have to adjust the pinion angle up to around 12 to 13 degrees. The oil level on the differential is up to the fill hole now so should I remove the filler plug and let the oil drain out after I finish adjusting the pinion angle?

1. Yes. Then re-tighten when it is on the ground at right height after your pinion adjustments.
2. No. The pinon angle puts the stock fill hole in an undesirable position (too low), but you still want to get as much gear oil in there as you can. When you do drain and refill you can raise the axle some as well as rotate the tires so some of the oil is being tossed over the ring onto the pinion while you're filling. That can get you a bit more in there. I haven't seen people having problems though. Others drill a fill hole higher to get the required amount after raising the pinion.

 

[Planepal]

1. If the lowers are still stock, yes.
2. Depends on if you want to make a mess or not.

I have adjustable rear lower arms on now but it does make since to loosen the lower arms so the axle can pivot properly. Any idea what the stock pinion angle was? Like I said, the pinion angle is 6 degress now. Not sure if the previous owner raised it after installing the 3 inch lift or not. I was wondering if I should lengthen the lower arms slightly and do most of the adjustment on the uppers.

 

[JMT]

I have adjustable rear lower arms on now but it does make since to loosen the lower arms so the axle can pivot properly. Any idea what the stock pinion angle was? Like I said, the pinion angle is 6 degress now. Not sure if the previous owner raised it after installing the 3 inch lift or not. I was wondering if I should lengthen the lower arms slightly and do most of the adjustment on the uppers.

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View attachment 438922

You should adjust the pinion using both the uppers and lowers.

There’s no reason or need to know the stock pinion or driveshaft angle.

Just set the pinion 1* lower than the driveshaft. E.g. if the driveshaft is 11* the pinion should be 10*.

 

[Planepal]

You should adjust the pinion using both the uppers and lowers.

There’s no reason or need to know the stock pinion or driveshaft angle.

Just set the pinion 1* lower than the driveshaft. E.g. if the driveshaft is 11* the pinion should be 10*.

Will do. Thanks