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Acceptable range from pinion-to-shaft angle

lordoeuf

NAXJA Forum User
Location
Vancouver Island
Quick question. Is there an acceptable range for the difference between the front pinion angle and the drive shaft angle, with 0 degrees being best? How far can you go out of parallel before vibrations typically occur or you substantially reduce the life of your shaft's U-joints, perhaps 10 degrees max? I'm sure some of you guys who setup these rigs frequently have noticed some general trends in this regard. Thanks.
 
Maybe if somebody knows the stock XJ front pinion angle and drive shaft angle for a high pinion and low pinion Dana 30 (XJ 2000,2001) it could provide some insight?
 
Technically a double cardon shaft should have the driveshaft pointed straight at the pinion. I have a 2000 with the LP but I have long arms so my application is not the same as your set-up.
 
I'm new to 4x's, but I've done some research in this area and have some hands-on experience, so I guess I'll chime in. Presumably you are talking about an XJ with a factory double cardan front driveshaft.

First of all, some small amount of angle on the pinion u-joint with a double cardan driveshaft is needed to ensure that the needle bearings in the u-joint get cycled around.

When I did the SYE conversion to my the rear driveline of my XJ, Tom Wood's suggested that with the XJ parked, there should 2-3.5 deg of misalignment on their double cardan rear driveshaft with the pinion pointing down. This allows for some axle wrap. So there is one data point.

I'm contemplating whether to do anything with the front setup because I have 4.5" lift with a LP D30. It currently has 7 degrees of misalignment with the pinion again pointing down. This is clearly more than desired for the pinion u-joint on a double cardan. There is no axle wrap on a non-leaf suspension, and its a radius style long arm setup, so as the front suspension moves through compression travel, the pinion will point further down which will act to make the angle larger, but at the same time the upward motion of the axle will act to reduce the angle. As far a life goes at this angle, this XJ has probably had the lift for at least 10000 miles (was lifted when I bought it), and the front pinion u-joint is fine.
 
The gojeep link mentions, "always run as much caster as you can without vibes" There is also a chart for general guide:

At 5.5" lift, guide stipulates diff angle 4.25 degrees. True caster hi pinion at 4.75 deg. I am at 5.5" lift, but measure diff angle at 3 deg. and caster at 7 deg.

RCP PHx mentioned he is running a D30 LP with long arms. How does long arms affect the ability to run larger angle differences? I also am running long arms. They are from Tomken Machine. I haven't seen many people run these.

I read much of the 4xshaft article as well. It mentions, "The real benefit to a C. V. (double cardan) drive shaft is smoother operation at higher operating angles and longer life." OK, great. However the photo also shows the pinion angle at the same as the driveline angle, so I am confused. For the angles, the resulting conclusion is that it depends on a lot of factors. I read somewhere that doubling the angle could half the life of the u-joints. But as I put only about 3,000 mi (5,000 km) per year on the Jeep (I live in a small town), halving the life doesn't play a large role for me. The article also mentions to fully drop the axle and run the shaft to ensure it doesn't bind.

As for my front drive shaft, it is a Tom Wood A2XB-131-131 with these specs:

TYPE A, DOUBLE CARDAN, CV DRIVE SHAFT
2" TUBE-FULL LENGTH EXTENDED LIFE SPLINE W/ BOOT
1310 SERIES U-JOINT @ TRANSFER CASE
D=1.0625" E=3.2188"
1310 SERIES U-JOINT @ DIFFERENTIAL
D=1.0625" E=3.2188"
FINISHED LENGTH RUNNING POSITION
CENTER OF JOINT TO CENTER OF JOINT= 31 11/16"

Lift at 5.5"; Tomken longarms; Drive shaft angle at 10 degrees; Pinion angle at 3 degrees; Caster at 7 degrees =========> 7 degrees of pinion-to-shaft misalignment, is it OK? No vibes so far, taken it up to 55 mph. Thanks.
 
I installed a HP D30 in my 2000 when I lifted to 3.5". I never checked the pinion angle or the caster, I set the pinion angle for the best comprise between vibes and caster by eyeball, and drove it that way for years. Presently it has 5.5" of lift and the factory original front driveshaft.
 
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