Outer Limits 4x4 Board

Getting closer to finishing the front end, so am starting to get ready making parts for the rear.

Have to replace the redundant old gearbox cross-member


Main problem I've got is this.


As you can see, Centre bearing is useless


Pinion angle is perfect


So....Remembering I plan to drive this @ highway speeds, do I
A: relocate the centre bearing to lessen the total angle and run a double carfin on the rear half shaft? mucking up my pinion angle and creating more work.

B: Use a one piece unit and just have a standard double cardin on the gearbox end.

C: get one of these and use a one piece shaft (remebering my suspension will droop almost foot further than it is now)

i would go 1 peice and double cardin shaft i put a one peice in mine when i did the 60 series diffs(offset rear) and it does highway speeds(and more ) just fine

Lock in B, Eddy!

And check out this link:

http://www.pirate4x4.com/tech/billavist ... ndex2.html

I'm leaning towards B for two reason, the first is obviously cost and the second is that I have to remove/modify the rear tailshaft cross-member anyway

I'd go with B provided that the unsupported length of the tailshaft (centre of front uni or Cardan joint to centre of rear uni) doesn't exceed 1.5m.

The angle across the rear uni should be no less than 0.5 degrees but as close to that as possible. The driveline vibration created by the overall effective angle goes up as the square of the angle in degrees, and a Cardan joint is a CV with an angle of zero within itself so the effective angle will be the rear angle.

The reason for the minimum of 0.5 degrees is that less than that will cause the uni to fail prematurely because the rollers will embed themselves into the trunnion and cups because they're not rolling enough.

If you decide to stay with 2-piece, run a Cardan joint at the transfer, remount the centrebearing square to the tailshaft and set the centrebearing height so that the front shaft and the diff pinion are parallel but still have at least the 0.5 degree operating angle across the unis. The 2 uni joints will cancel each other out in terms of vibration and can be safely up to 6 degrees without a problem. Beyond that it depends on the unis.

Athol wrote:I'd go with B provided that the unsupported length of the tailshaft (centre of front uni or Cardan joint to centre of rear uni) doesn't exceed 1.5m.

The angle across the rear uni should be no less than 0.5 degrees but as close to that as possible. The driveline vibration created by the overall effective angle goes up as the square of the angle in degrees, and a Cardan joint is a CV with an angle of zero within itself so the effective angle will be the rear angle.

The reason for the minimum of 0.5 degrees is that less than that will cause the uni to fail prematurely because the rollers will embed themselves into the trunnion and cups because they're not rolling enough.

If you decide to stay with 2-piece, run a Cardan joint at the transfer, remount the centrebearing square to the tailshaft and set the centrebearing height so that the front shaft and the diff pinion are parallel but still have at least the 0.5 degree operating angle across the unis. The 2 uni joints will cancel each other out in terms of vibration and can be safely up to 6 degrees without a problem. Beyond that it depends on the unis.

As Usual Athol, your advise is greatly appreciated on this forum. thanks again!

From experience, what would worry me about running a DC on that angle, is that even with larger uni joints, the centre bearing doesn't last long.