2 piece driveshaft tech Q's?

[Area54]

Okay, I'm after serious driveshaft tech. No recommendations for a one piece shaft. 2 piece rear driveshaft in an '86 hilux. Now correct me if i'm wrong, but the theory behind the two piece is to act as a 'double cardan', only with the trunions spaced out over the distance to the centre bearing. No manual states the correct phases for the ears of the flanges - as to how they line up or how straight the total assembly is to be. common sense has told me to set up the ears for the front half to act as the double cardan (to create the equal accell and decell speeds in the trunion bearings), got the shafts as inline as possible by lowering the centre bearing a bit, but have yet to parallel the flanges - tcase to diff pinion - with some caster wedges.

Q1: is the centre bearing height critical to vibes, or is it there to help position the output flange for the 'double cardan' effect?

Q2: does the front uni joint require any vibe compensation (accell and decell balancing) or does the centre bearing stabilise the rotating assembly by the flexible nature of it's mounting (isolating rubber bush between bearing and mount)

I will get a custom shaft made (thick wall) for the rear, with a longer spline/overall length to account for the rear diff back mod. This way I will have a reliable heavy duty shaft for trail use, and can still use a cheaper standard length shaft as a spare.

[bubs]

If you do go a one piece - look under the latest hilux dual cabs, 3l diesel i know of for sure - these run a factory 1 piece drive shaft, i am not sure though wether it will fit into the back of a eariler lux

i might be worth a look though if spares is your concern

[bazooked]

the centre bearing height is critical when talking vibes and so is the squareness of the centre bearing to the tailshaft not to the chasis.the shaft has to be balanced as a twin , and wall thickness should be the same on both shafts!

[Area54]

the centre bearing height is critical when talking vibes and so is the squareness of the centre bearing to the tailshaft not to the chasis.the shaft has to be balanced as a twin , and wall thickness should be the same on both shafts!

Now we are getting somewhere. When you say the centre bearing height is critical, do you mean that the bearing should be positioned (in the vertical axis) to create as straight a 'line' as possible between the tranny and the diff pinion. ie if you perform a suspension lift, the rear-rear driveshaft drops, whereas the front-rear shaft remains unchanged, creating more angularity at the uni on the flange adjacent to the centre bearing.

[bazooked]

if u raise the vehicle,the rear shaft will drop and the angle will increase on the centre uni, so you would have to lower the centre bearing. the easy way to do this is if ur custom shop has the driveline angle analyzer program on there pc its a piece of cake they can work out wat angles it should be. if not then you have to do the trial and error method of packing the bearing (with shims) and take it for a drive... till ya get rid of ur vibes or find a happy medium!

[Area54]

it's no problem for me to accurately measure the flange angles. I just need tech to help me understand the accell and decell rates on all the unis (all three) and how to make them all play together nicely.

[ausyota]

I did a 40mm drivetrain lift on my lux so the angles on my two piece are all farked up!
But (touch wood) Im not having much in the way of vibes yet.
Im going to go one piece eventually anyway so Im just hoping it will hold out till then.
So just going from my experience so far the angles dont seem to matter that much...
But only time will tell
Paul.