Vibration after rear prop UJ change...

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Rotating the prop 180 degrees will make no difference, and neither would rotating it any number of degrees at one end or both. The only important thing is that the two ends are 'in phase' - when the centrelines of the two joined shafts are parallel to each other. I know nothing of Discos and RRs, and only a little about Series, but 90/110's rear diff input shaft is horizontal at rest on a car with standard suspension, so should have an in phase propshaft to the equally horizontal transfer box shaft. The front axle has the diff pointing uphill (partly due to the propshaft being short) and so the front propshaft should not be 'in phase'. I didn't know that when I had my first encounter with a front propshaft, and having separated it and then finding no alignment marks had to get under other LRs to compare and adjust it. It might have been helpful if I'd written down the number of teeth or degrees - but I didn't. You might need to do the same, but it's not hard - one tooth on the spline is very obvious at the ends.
 
According to my copy of Brooklands, pp153, "(The front propeller shaft is intentionally assembled with the universal joints not in line with easch other."
Remember that if you are gooing to pull it apart, scribe a line so that you can always put it back 'as was'.
 
Cheers guys. I'm just going to leave the front as is for now as I've not touched it and I don't want to introduce any more variables. However as an aside, as my 110 is pre-Defender, and has larger 82mm yokes, is it possible the front should be in phase anyway?

Anyway, as I said I'm going to leave as is for now, and swap both rear UJs and see where that gets me...
 
My 93 front prop is in phase and that was the new one to replace the old shagged one which was also in phase, the new one was GKN I think.
Of course unless you have had the car from new you have no way of knowing whats gone on before.

A very old mech gave me some advice years when I was the boy ago and it was, if you didnt have the problem BEFORE you touched it its something you have done even if its unrelated and the number of times that old bugger (Ronnie) has been right is unreal!
 
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...




Going back to the beginning, why did you change the rear prop UJs, are you sure the front prop UJs are OK.
 
No, you don't need to mark the prop's relationship with the diff or tbox. Makes no difference.

Make sure the drive flange and handbrake drum aren't loose - I've had that one. Did you check for play in the sliding splines? Then it's on to the front prop, and I think you need to know whether or not it should be out of phase. I think it should, and it will make a difference.
 
Rear UJ at the diff end was not great...I've seen worse but there was movement felt there just by grabbing the propshaft yoke and giving it a wiggle. Driving wise TBH it was more noise than vibration, however post surgery its vibration at a specific speed. So going back to basics, I'm not even going to look at splines, front prop phasing, or anything else for now. The t/box end was OK, although I replaced it anyway, and I'm happy with the feel of that UJ. The other end is very stiff and gets warm...not good. My feeling is that the rear prop, with one UJ quite tight, and the other one normal, is vibrating...it's this difference in tightness that is the problem. I shall have a crack with fitting a matched pair of Hardy Spicer UJs tonight and report back...
 
Right, finally sorted. Thanks to all who have helped me here.

I'm going to put it down to those mismatched UJ's. I need to have a really proper look at the UJs I've just removed in the morning (had enough for tonight) however there's something funny going on. Although they are both 27/82mm, one of them had eaten the rubber seals in about 5 miles of driving (the one that was "normal" rather than tight strangely)...that can't be right. So I have fitted the Hardy Spicer ones and it runs like a dream. Zero vibration all the way up past 80mph.

So, I think the key lessons are for an early 110 with the 82mm UJs...

-The correct part number is RTC3346G (same as Series vehicles and pre '86 RRC)...don't be tempted to use anything else even if it measures up OK on a micrometer. --Front prop shaft should also be in phase.

Thank feck for that...I've changed UJs on my old Disco and SIII plenty times and I could not figure out why I could not get it right this time!
 
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