Real world Acco fuel economy

So I had it arse about, thanks for the correction.

Oilman,

I think you mean 90degrees out. 180 degrees would put them in phase.

Some shafts are built int he factory intentionally out of phase.

Land-Rover Discoveries had their front shaft out of phase to smooth out the motion. It doesn't make sense to me but that's what Mr Land-Rover did.

I pulled a Nissan pulsar steering column apart when building the MightyBoy and it was out of phase and it was so built you couldn't put it in phase as the factory had a filled spline so the shaft would only go together one way.

Jim, you don't have a centre diff in that, so you would need one front and one rear to spin to lose traction.
Phasing of front not related to phasing of rear drive shafts. I must admit I didn't think the wheelbase would be long enough to have multi section driveshafts.
The ASW has a jack shaft between the gearbox and transfer, only about a foot long. My front drive shaft is longer than the rear.
Hope I've understood everything correctly here.
Another cause of driveline vibes (the ASW has this) is worn yokes allowing the universals to float a bit off-centre. I had to clock mine and lock everything up on-centre. BIG difference.

Jarrod.

So if I’ve understood this, the shafts can be 180 out but not 90 degrees relative head to head .... and maybe someone has pulled the shaft apart and when the two ends back together even one spline out will cause binding against itself .....what I’ve described is two different things that ultimately mean the same outcome of the end to end are not exactly aligned head to head , it only has to be one spline out and it causes misalignment.... and I understand the 90 and 180 degrees as well , I’ll check for those too I’ll rip off a coupla snaps and post em , thanks to jarrod Paul , zuffen and the oily one ,Jim .ps I’ve a feeling somehow it won’t be over but who knows they put a man on the moon .............. or did they?

Of course if the shaft has been phased 180degrees out due to assembling that way it could be out of balance.

Whilst it would be unlikely as the yoke etc is short and should be fairly well balanced it could still be a problem.

Yeah well I didn’t find any thing in the shafts, as it turns out all three shafts have slip yokes , I’ve taken a couple of pictures and I’ll put them up in case someone can see something I didn’t, oh I mentioned it in an earlier post about the little pretend hand brake is covered in oil on the inside mainly ....so when I can get under and give it a good shake and see why it’s leaking

Everyone is talking about possible problems but there is no confirmation happening.

You are dealing with some sort of transmission, axle, bearing, tyre vibration.

Just my two bobs worth. Assuming the wheels have been balanced on a machine. You should be trying to eliminate possibilities to home in on the problem.

Go for a drive and put the clutch in going down a hill at reasonable speed.
No change - it is not in the engine/clutch area.

Do the same and put the gearbox in neutral.
No change - it is probably not in the gearbox

Do the same and put the transfer case in neutral
No change - it is probably not the jack shaft

Go for a drive with the front drive shaft removed.
No change - it is probably not the front shaft or universals.

Go for a drive with the rear drive shaft removed.
No change - it is probably not the rear shaft or universals.

You are now looking at diffs, wheel bearings, bent axle shafts, swivel bearings. Loose or worn pinion bearings are also a good suspect.

Just my thoughts.

Lang

I’m leaning the same way , I know what a three vibration is and feels like, this is a different feeling, I can’t explain the words to describe it, tyres can thump and down to a shimmy , this starts fine and Within 5ks an hour you need to back off because fear of something coming through at you, when I drove it home it was fine and about 10 kms from home the truck started to slow down fast and I let it slow some but I dared not stop as no where to go so I slow down and with in 500-750 metres away it went as if nothing had happened.... now this was November last year and I only got it registered last month, I done the 60km trip at 75-80-85 depending on the vibration, I’m thinking about the bearing in the handbrake Housing in the transfer case simply because of all the fresh oil the brake shoes are soaking up , I’ll drop the oil at some point on the weekend and go from there, I did mention this when I got it home and we threw around some ideas , whether anyone remembers it was last year, heck I can’t remember if I had breakfast this morning so I don’t expect anyone else to.!

I don't think your rear output bearing on the transfer case is guilty just because of oil leaks. Probably just the seal gone. But it could be a stuffed rear output bearing so loose it has worn the seal as well. You can eliminate by going through the above check list. You can fix the leak in 20 minutes with a speedy sleeve and new seal.

I can't help but think you have a tyre/wheel balance problem. Mechanical problems tend to be fixed ie come in at the same place under the same circumstances. On the other hand tyres react to a bump or a shimmy from bad balance, loose bearings/steering rods even crook alignment and everything will be trotting along nicely and suddenly turn to s...t. Driveline problems are much more predictable.

Lang

I would start with the simplest fix, tyre balance all round. then fix the oil leak and while in there check for movement.

It will be like eating an elephant, one bite at a time.