Vibration after rear prop UJ change...

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Hard-Drive

Hard-Drive

Active Member
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359
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Rugby
Booger. Swapped the UJs in my rear prop and I now have a vibration around 45mph. In fairness it's only around that speed...slower or faster is OK. It was only after the event I've realised that you are possibly supposed to mark the positions of the prop on the flanges.

However most googling seems to suggest that vibration tends to happen when the splines have been split, and I did not do this, I only took the yokes off, however again I did not mark anything so I guess they could be 180 degrees out on the ends.

Is there an easy way to fix this? By my reckoning I have so many permutations of having screwed this up it could be an impossible task to work it out.

Any thoughts anyone (apart from what a muppet...)
 
Hard-Drive said:
Booger. Swapped the UJs in my rear prop and I now have a vibration around 45mph. In fairness it's only around that speed...slower or faster is OK. It was only after the event I've realised that you are possibly supposed to mark the positions of the prop on the flanges.

However most googling seems to suggest that vibration tends to happen when the splines have been split, and I did not do this, I only took the yokes off, however again I did not mark anything so I guess they could be 180 degrees out on the ends.

Is there an easy way to fix this? By my reckoning I have so many permutations of having screwed this up it could be an impossible task to work it out.

Any thoughts anyone (apart from what a muppet...)
Click to expand...
on the rear prop both yokes should be in the same plain
 
Thanks for the reply James. They are in the same plane...I did not pull the two halves of the prop apart. My understanding though is that where the rear UJ mates to the rear diff flange, in theory it could be 0/90/180/270 degrees and only one of those is correct...
 
Due to bolt spacing it can only 0 or 180 degrees and would make no difference either way.
After new uj's fitted could they be moved by hand?
Have you checked for up/down/side to side movement in the diff output flange?
 
Hard-Drive said:
Thanks for the reply James. They are in the same plane...I did not pull the two halves of the prop apart. My understanding though is that where the rear UJ mates to the rear diff flange, in theory it could be 0/90/180/270 degrees and only one of those is correct...
Click to expand...
oh that doesnt matter at all ,prop yokes been inline does
 
Sounds sill but are all the fixing bolts the same length? are both prop flanges located correctly in the tfer/diff flanges?
I know you didnt split the prop but are the yokes inline with each other?
 
Yokes are inline, bolts are all correct, flanges seated OK. Tony e, if 180 out will make a difference, am I best to start at the diff end?
 
Wont make any difference at all unless you have some sort of damage to the flanges, ive changed quite a few u/js and centre bearings and the only rule was line up the yokes job done, some people marked the splines on the slider but if you line the yokes up again theres no need.
I assume the circlips are all seated okay in their grooves and were a nice tight fit or did they just fall in?
What make was the u/j?
 
If:-

Hard-Drive said:
Yokes are inline, bolts are all correct, flanges seated OK.
Click to expand...

then I'd be looking at :-

lynall said:
I assume the circlips are all seated okay in their grooves and were a nice tight fit or did they just fall in?
What make was the u/j?
Click to expand...

New joints should be pretty tight.... ('cept the BP ones :rolleyes::D)

And I'd be giving the new joints a damn good greasing too - as in make em have it
 
OK, I'm going to double check the circlips. I think they are all seated, however I did "tweak" the fit to ensure that the UJs were still loose-ish...if they are supposed to be tight I wonder if I need to just apply a bit more welly...
 
Hard-Drive said:
OK, I'm going to double check the circlips. I think they are all seated, however I did "tweak" the fit to ensure that the UJs were still loose-ish...if they are supposed to be tight I wonder if I need to just apply a bit more welly...
Click to expand...

Joints should be free but there should be no sideways movement at all in the yolks to the spicers.
 
Right then, took the prop off and checked the circlips, everything is in place (although one was questionable before), although the diff end one really did seem a bit tight in one direction, and after a 5 or so mile test drive had got a bit warm, even though it was well greased. Vibration is still there, but perhaps not quite as bad, and still only around 45mph.

I'm assuming that if I'd messed up the install and knocked one of the needles into the bottom of the cup, there's no way I would have got the cups in all the way and the circlips in...or could I?

The UJs I am using are part number PUJ2018, which I believe is an equivalent to HS166, the 82mm UJ. Annoyingly, the ones I was sent by a specialist mail order are 75s and clearly would not fit. The 82s came from my local motor factor. Are these correct?

However according to a Haynes manual, the new UJ has got to be installed with the grease nipple in a specific position...is this right or is this Haynes "first disconnect the battery" irrelevant stuff?

However, the plot now thickens as I have noticed that the front prop is also in phase. If this is wrong...not guilty...I have never split either prop on the splines. Do I need to make this out of phase? Google throws up conflicting answers...and seems to point to the fact that the vibration would be catastrophic. Bear in mind that with a disco t/box I'll happily cruise at 70, I've never noticed my teeth about to come out...

Help...confused!!!
 
I always used to fit the u/js then set about the yokes with a copper hammer so they were nice and slack not quite floppy but easy to move and all cups would take grease.
All my discos and defenders and series have all had the props in phase, but i have seen ones with them out of phase but that could either be from new or someones had them apart for some reason?
Yes if you have dropped a roller you cannot get it together without cracking the cup.
The nipple position is not mission critical but its is best to have it towards the prop ends so when prop rotated its easier to get the grease gun on.

I service quite a few trucks a week and all the props are in phase (I know because i check one end then do the other and would see straight away if it was out of line) obviously they arent 4 wheel drive but Im not sure if that would make any difference.

Im sure Ive read about some front props being out of phase for vibration issues, but as yours wasnt vibrating before I reckon we can ignore that.
 
Forgot to say if you google prop phasing you will see some charts that shows the prop speed oscilates and does not rotate at a constant rpm, constant rpm in and constant out but prop tube itself is all over the place.
Its a bit of a science and can remember arguing with a supplier about prop 3rd angles which you are meant to avoid at all costs for max prop and u/j life, they wouldnt do the work so someone else got it and the compressors ran for years with no issues, Im sure in the end years later even this supplier went to cv joints which do actually rotate at a constant rpm.
 
Just a thought but when I did the rear prop shaft on my 110 some years back, I inadvertently slackened off the nyloc nut holding the rear drive flange into the diff, this introduced a bit of play until it eventually vibrated itself loose. Just thought it might be worth a check.
 
tottot said:
Just a thought but could your prop have lost it's balance weight?
Click to expand...
Ah! ..... which reminds me.... SWMBO's front prop had lost its balance weight.... vibrating at about 60 ish... so I measured the "shadow" in the paint, allowed a bit extra for the curve of the tube, cut the new weight out of the same thickness steel as the rear weights... and then welded it on - it even worked too !! :cool::)
 
Cheers guys. The motor factor UJs are different makes, which in theory should not matter but I don't like the way the t/box end seems fine but the diff end really is tight and getting warm after a few miles. I did carefully clean the prop and yoke, and clean out the circlip grooves, so I do wonder if the tight one is perhaps out of manufacturing tolerance or something? The mail order supplier are sending me the correct 82/27 Hardy Spicer UJs to replace the 75s sent in error so I am just going to swap them both over and try again. If that does not cure it I'll rotate the diff end 180 degrees.

The balance weights are still in place so I don't think it's that, and as lynall says for now I will leave the front prop as is as I have not touched that.

Stay tuned...
 
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