Have been doing some reading on the tail shaft and issues associated with them as they get older.
As I have mine back in now that I have the decoupler, it's running fine just looking for some thoughts on servicing it. I have no current vibration or play in the shaft at all but I'm also assuming it's all original and never replaced/serviced.
So, on the uni joints, I assume remove carefully, re-grease and re-install will extend their life (better than 27 year old factory grease).
Not sure what to do on the rubber joint and bush though
Any recommendations on this one? I see Phil has mentioned in the past no grease on this one. I am guessing there is no relative movement on this bush, but maybe just a check/clean/light oil is still worthwhile?
One other question, even though I have no play or vibration, there is an occasional metal tinging noise from the shaft itself. The noise is no there when the shaft is removed, and is also not there when in 2WD. In 4WD, if your lugging in low gears off road, so varying loads on the shaft, there is a tinging noise that resonates through the tail shaft. As there is no play in it or the front/rear gear box mounts, no idea where the noise originates?
It's definitely in the in the tail shaft.
If I crawl underneath the bus, grab the tail shaft and rotate it left/right rapidly I can also hear the noise, but no idea where the play is to cause the noise.
The problem with these tail shafts is the ears are too weak. No matter how Careful you are removing the old joint they have a tendency to bend. Best to have a specialist replace uni and balance. The noise is from the slip joint. As Phill suggests it's impossible to stop the noise completely but new bushes and a good dose of high load grease will reduce the noise. Gregor
Thought I’d give the tail shaft (prop shaft) a clean up.
I removed the rubber cushion from the tailshaft to have a look at the shaft/bushes. All looked nice and clean in there, so just gave it a good clean up/paint and re-assemble.
I measured the shaft and bushes:
Shaft OD 24.966
Bush ID 25.020mm
Not sure what standard is, but this is enough to feel some movement in there.
The Uni-joints move nice and freely, and could not detect any movement in them.
Has anyone else measured this up?
My rubber bush has a few small cracks evident, so will have to look at replacing this soon.
There is also an oring to protect the shaft. It is a standard 25x3 Oring. I got a few of these when I replaced mine, so if anyone needs a seal let know.
I think if I get to the point mine needs a rebuild, I think it would be easier to leave the bushed and have the shaft built up and re-ground. I fill the bushes with grease, and the slight tinging in mine has good. Will see if it stays this way for a while.
Also not sure if it helps, but for the uni joints, with the lack of a grease nipple, I have made a small tine up with grease in it. From the uni joint (entire end of the tailshaft) into the tin and heat gently to ~80C. Spin the shaft occasionally so the joint get some movement, then let it cool in the tin. The hope is some of the grease will work it’s way inside the joint.
Richard
I saw this also, the factory looking image is a good resource
I only just replaced mine after having a spare custom made job a few years ago. My old one I had fixed up as one of the unit joints had seized in one direction. Had some Hardy-spicer units fitted with grease nipples and that was OK up to about 70km/hr - then I had to use the de-coupler.
It’s not good the hear the issues most people seem to have with them. I just hope I don’t go through this if/when I need to do mine.
In the mean time, I will continue to keep mine as good as possible!!
Richard
The grease in the shaft has helped a lot with the tinny noise I hear occasionally. Mostly gone now!
I think gear box and diff mounts also add to the vibration issues (assuming the tailshaft is good)
Richard
I went through the nightmare of tail-shaft vibration a couple of years ago, and posted some lengthy dissertations at the time. When it first happened back in about 2012 I replaced the unis with the controversial tractor PTO unis, as OME units were NLA. They worked perfectly. The return of the vibration several years later was my own fault - I forgot to mark the position of the flanges before removing the tailshaft. Dooh! I refitted it 8 times to try all possible bolt locations, then tried the spare tailshaft another eight times. The uni joints had no play, so I studied up on tailshaft alignment - a black art - and made a laser jig to set up perfect geometry between front and rear - still with no joy. Made jigs to check for runout with a dial indicator, and experimented with strobe lights, hose clamps and balance weights. The problem was traced to slop in the sliding yoke bushes. I took it to a good engineer who scratched his head and said that he couldn’t replace the innermost bush without cutting the tailshaft - a job for a specialist, as the shaft would have to be re-aligned and balanced after it was welded back together. No-one in southern NSW had facilities for high-speed balancing. Uwe came to the rescue - he found a specialist who makes new tailshafts with easily available uni’s fitted with grease nipples. I bought two. Immediate cure. Have been running the car daily, plus interstate and off-road holidays with no problems except for an increase in noise, due to the lack of a rubber donut and sliding yoke. The lack of a sliding yoke does not seem to matter as the front diff and rear transaxle are mounted quite rigidly on poly bushes. VW did not fit rubber donuts to the Tristar, so they must have been fitted only to cut down noise transmission. Very happy with the result. By the way, I found out that Hardy Spicer unis are out of production and hard to find - beware of Chinese imports! I think I still have two brand new Hardy-Spicer unis sitting on the shelf if anyone needs them.
Agree Roger the tail shaft balance and alignment is a dark art which very few seem to take on the challenge and I did the same as you and bought a Uwe sourced tail shaft which is brilliant.
That coupled with new well balanced tyres runs beautifully.
Hmm… I may need to get one also if they are still available!!
Not sure why a good engineering shop would not build up the shaft and re-grand given the bushes are impossible to replace.
I must admit I got in the habit of fitting the tail shaft only when needed. Not I have a decoupler, I still remove the tail shaft if I know I am not going off road for some time. I used to note orientation of the of bolts/flanges etc, but have not done this for the last couple of years, and it has not caused any vibrations.
Same when I removed the rear transmission. I only aligned it with a string line and it also did not cause any vibrations.
I just hope with regular greasing, I can make mine last.
If the Tristar did not have the rubber donut, how did it allow for movement between the front diff and the transmission?
Given the design of the rubber donut, I assume it is there to remove shock from drive torque than anything else.
On a separate note, it seems my steering was getting tighter to operate. It was not very noticeable, just just this last week it has been very noticeable, to the extent it was difficult to steer!
Some investigation today tracked it back to the universal joint at the steering rack had one bearing siezing up. I have cleaned it up and got some grease in there for now, but will need to get a new one soon.
It’s amazing how free the steering is now!!
The universal is quite small, so I don’t think there is any way to get a grease nipple in there. The best I could do is lift the seal and spray grease in there.
When I get a new one, I will see if I can pack some grease under the seal for extra protection, but it’s not simple to do once installed.
