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double ended double cardan joint - anyone know ?

" GIVEN UP SMART PHONES". That's quite a statement Iwan. Will you always be an addict and have to attend an anonymous group so you don't slip back ?
Lol.... they're a distraction when you need full productivity..... I'm still dreaming of firing up the big colourfull screen with lightening fast text message replies!! :lol::thumbup:

Sorry for the thread jack!!
 
My brother has just restored a Triumph 2.5 pi. All original parts except the suspension bushes which he replaced with hard ones. Now he set off for Europe after a quick test drive but at 65 mph on the first Mway he got such severe vibration he thought he'd better come home. After some research he found the gearbox drive flange was pointing down and the dif drive flange also pointed down. He consulted a drive train specialist to see what could be done. Reply was the factory used extra soft suspension bushes. Apparently all the Triumph 2000's had this problem together with several of their other models. Not sure why they did not get the design right straight away or was it all done like this straight away?
 
My brother has just restored a Triumph 2.5 pi. All original parts except the suspension bushes which he replaced with hard ones. Now he set off for Europe after a quick test drive but at 65 mph on the first Mway he got such severe vibration he thought he'd better come home. After some research he found the gearbox drive flange was pointing down and the dif drive flange also pointed down. He consulted a drive train specialist to see what could be done. Reply was the factory used extra soft suspension bushes. Apparently all the Triumph 2000's had this problem together with several of their other models. Not sure why they did not get the design right straight away or was it all done like this straight away?

I had a Triumph 2000 with Strombergs IIRC (not the pi) but never had that problem. It wasn’t a restoration, so everything was OEM and probably as worn as 150k miles would dictate. I did have UJs fail on me, but I replaced them with Uniparts, the favored supplier of the day back in the 80’s.

I fitted an electric overdrive unit acquired from the local scrappie and it drove like a dream.

It was my introduction to the joys of a straight 6, in preparation for my current ride... :lol:
 
Just pulled the rear housing off the transfer box to replace the seal. I bought in a replacement bearing whilst I was at it because going in there twice would just be daft. Very clearly more play in the old one than the new one which I think has contributed to the seal starting to leak. I guess as these vehicles get older the wear becomes cumulative. A bit here and a bit there all means that when you're rolling you're going to get vibrations and whatnot. I could feel a bit of movement in the prop but the prop clinic have passed that as perfectly acceptable. The play I was feeling then, was probably in the output shaft of the T box. With a new front prop as well, it should positively glide once back on the road.
 
It will be interesting to see what it’s like as the difference should be quite noticeable.
 
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It would be interesting Rich, to see what sort of power losses there are (on a rolling road) as I am sure that all of these vibrations and noises are all sapping energy from the transmission.
 
It would be interesting Rich, to see what sort of power losses there are (on a rolling road) as I am sure that all of these vibrations and noises are all sapping energy from the transmission.
You’ve got a point there. If it’s anywhere near as bad as the sort of ‘windmilling’ you get where a two flute drill bit tries to cut a three sided hole then I can see it being a significant drain on power. I’m sure it’s not that bad but anywhere it’s running out of true, it’s got to have an effect.
 
The outer bearing in the transfer case extension housing is a ball bearing not a taper so there's zero pre load on it. The other end is effectively a first motion shaft and pushes quite deeply into the T box. So it's only job really is to give some rotational support. All the end float is taken up with snap rings. When it's on the bench there's quite a bit of play in it but when it's mounted there isn't any - anymore. It doesn't take a huge load but it does ensure that it spins concentrically. I am pretty sure it was weather vaning around around before.
 
OK so two double cardans is really a bit pointless. The idea of the single - double cardan is that it's self cancelling at one end meaning that the UJ at the other end is free to do what it likes. It essentially turns the prop straight again after its initial angle change. Perhaps on a monster truck where the lift if measured in feet not inches. But on a std spring lift, it's overkill.

Nice though Shayne.
 
Well it's simple if you boil it down. If a drive shaft is perfectly straight from power to drive end then clearly you don't need a joint.

When it comes down and across like it does in real life, you need a joint - well actually you need two joints. One at either end. Well the problem is that UJs only work when they bend a little bit. Bend them a bit more and they're rubbish. That's why a CV joint is called a CV joint. Constant Velocity; they can bend loads with no speed variation. When you bend a UJ they sort of wobble or cycle fast slow fast slow fast slow. You need them in pairs and have to fit them so that they work opposite to each other and go slow, fast, slow, fast, slow. That's what they refer to as phasing. One crappy end cancels out the other crappy end. What a double cardan does is cancel itself all in one unit rather than have one joint at each end. BUT. This only works when the diff end of the shaft goes straight into the diff. As in - it goes in straight. If you get the axle castor right on the 80 then the front prop does go in straight. So castor correction and a double cardan or even a double double cardan aren't necessary.
 
Acceleration and deceleration of the prop shaft every revolution they go through takes a lot of energy. Not too bad when the shaft is in line with its input and output shafts but not good at an angle.

I note some rear wheel drive cars now have fibre prop shafts presumably to save car weight but this must also help to save fuel on the acceleration and deceleration side of things.

I note on the 80 that the front drive flange alters its angle compared with the output flange every time the suspension moves so there must be some leeway in the design. However you are not likely to get a huge difference at high speed as rough ground is taken slowly.

I remember when I was a farm labourer and still wet behind the ears. I was told what to do if you were towing a machine with the PTO engaged and the tow linkage broke pulling the prop shaft in half. The first thing to do, if you were still alive, was to come to a halt in neutral but to increase PTO rpm to ensure the loose prop shaft was spinning straight like a tail, an advantage with a yolk joint over a constant velocity joint which would immediately turn the shaft at right angles. Then you had to jump off the tractor, knock the hand throttle off and run like F towards the front of the tractor. Out of breath you would wait for the inevitable consequence. The revs would die causing the prop to fail more and more at right angles causing terrible vibration. Then the yolk would snap and the prop would fly high in the air or bury itself in the ground. Happy but dangerous days.
 
Without having a camera under there Frank, I wonder how much the prop entry angle changes at the diff due to the fact that the leading arms pivot around roughly the same point at the output flange of the transfer box. The axle doesn't go up and down as we know, it swings in an arc. Perhaps that entry angle doesn't change at all.

Thoughts?
 
I think ideally the flanges should be in planes which are parallel with each other. If not the UJ's will not perfectly cancel each other out. The front axle flange will radius in movement c/w the gearbox flange so the planes will move relative to each other. Obviously movement is slight especially at speed.

Rear wheel drive cars, especially fast ones, have two trailing links on the rear axle to keep the drive flange in the same plane.
 
I like the broken joint warning, I remember my uncle explaining something similar when we used to bale hay using a PTO powered bailing machine.

I think his version was just the “run like feck” bit...

That bailer had a bloody great flywheel, so it would take a bit of stopping. Very dangerous indeed and of course not a guard or restrainer device in sight...:lol:
 
I think there were only 2 criminal offences on farms in late 60's 1. Murder........... 2. Not having a plastic tube on the PTO shaft. Well the plastic covers didn't last long.
 
PTO take off is still very much in use where i'm from , the new stuff is a toy for son's to skive in while the rusty old banger does the work .
 
Managed to actually get a pic loaded up of the 2004 rear hilux DC shaft fitted on my old 81 transfer, after a few failed attempts!
P1010553.JPG


It's a goer, if not a tad bit long.. next to a manual 24v front prop. Definite potential there! :think::thumbup:
 
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