pivot bearing / uv joint

[johnl]

just replaced the pivot bearings in the final drive. question is, can i stick it all back together as it came apart or do i have to align the uv joint in any special way?

i'm guessing not but just in case, your input would be appreciated.

ta

[Me-109]

do i have to align the uv joint

Yes, it needs to be properly aligned with the sun and the moon, other Venus will be rising in Uranus - which is bad!

If, on the other hand, you want to consider aligning UJs (universal joints) then you could do a quick search on 'phasing shafts' and find reams on the stuff. Put the two halves back together 90 degrees out, if I remember correctly, such that instead of looking like two back-to-back 'C's in line you have one 'C' and one rotated 90 degrees off. Rubbish description, sorry; go search ....

[r550s]

... a universal joint only transmits constant velocity when the driveshafts are bang straight. If the joint is 'bent' then the middle section of the shaft actually speeds up and slows down during each revolution. This effect becomes greater, the more the shaft is 'bent'. No need to worry though, because the designers cancel this out with the second UJ - 90' out of phase with the first and, importantly, the whole paralever is designed so that the deflection of the first UJ is pretty much the same as the deflection of the second UJ, no matter how much the suspension travels. (unless you go mad altering the length of the paralever arm...) This is the theory though: I'd like to meet the rider who's ever thought "hmm, it feels like the UJs need lining up"...on the other hand, what's this 40mph part throttle/top gear harmonic that came and went during my recent gearobx changes...?

[johnl]

hi thanks for your replies. The phasing can only be altered if you adjust the length of the paralever arm, as i understand.

What i want to know is when replacing the final drive unit having replaced the pivot bearings, is it just a simple matter of inserting the protruding drive shaft from the final drive unit into the receiveing end of the drive shaft located in the swing arm. or, do i have to have the uv joint at any special angle or employ any other matching/mating techniques??? ooh er mrs.

I believe you just slot them back together but wanted to check if there was anything i had missed when reading previous threads.

thanks

john

[Yogi Bear]

When I done my Paralever bearings I just applied some grease to the male and female splines and pushed them together...Job Done.

It's good to get the back end back on with no play.

Cheers

Ali

[Boxadog 2000]

Oh God here we go again

[johnl]

always love the ' oh god here we go again , or rtfm.

we all learnt to wipe our arse oneday

i thought the forum was about openly sharing advice and experience as oppose to randomly pointing someone in the direction of a thread posted way back when.

thanks to those who gave useful feedback.

ta

john

[sandbar]

The phasing can only be altered if you adjust the length of the paralever arm, as i understand.

I don't think that that is right. The length of the paralever arm has nothing to do with the phasing. It just changes the angles of the shafts.

If the shaft universal joints are not 'phased' then there will be added vibration. Sorry guys - the Laws of Physics dictate that.

In addition to the vibrations, there will be a sort of pulsing at the bevel drive and therefore it will increase tyre wear. After time that must also mean some increased wear in the joints and pivots.

Whether or not the vibration is enough to be felt will, I guess, depend on how far out of phase the shaft is.

Here , courtesy of 'Gromit', is a Wikipedia link

http://en.wikipedia.org/wiki/Universal_joint

Also, I do not think that the 90° is right. I think that both ends of the centre shaft need to be parallel. I have tried to find a reference but ran out of time, however I hope that somebody else can either confirm that or prove me wrong!

Back in the old days when nearly all cars had propshafts, they were made such that the two halfs of the shaft would only fit one way. But of course , in those days, vehicles were designed by engineers.

sandbar

[Boxadog 2000]

Sorry Johnl no offense meant.

It's just that the discussion/arguement over phasing will all start up again

[johnl]

cheers boxadog, i just wanted to know if i could stick the final drice shaft in to the drive shaft from the gear box any old how or if they had to be alighned somehow.

i've stuck it in and shall take it for a spin tomorrow.

ta

[sandbar]

i just wanted to know if i could stick the final drice shaft in to the drive shaft from the gear box any old how or if they had to be alighned somehow.

They should be aligned - see above.

Good luck

sandbar

[Boxadog 2000]

When I first did my paralever bearings I did not bother to align the uj's.

2000 miles later I had knackered the final drive.

Trust me you DO need to align the universal joints.

War and peace has been written on this subject and I have been told by many that I am wrong.

Bob

[johnl]

i stuck the uv joint in any old how and took her for a test ride. there was an oscilating vibration around 4000rpm that felt wrong and changing down gear felt very wrong. I carried out further research on ukgser and the pelican and then aligned the uv joints as best i could so that they were 'in phase'. This is not easy. bmw should have marked the uv joints or had a master spline ( i guess this has been discussed before ). I shone a torch up the swing arm and aligned them as best could and went for another test ride. The differance was very noticable. No oscilating vibration around 4000rpm and downchange was as normal. There is still a vibration around 5000-6000 rpm and 120mph so i may still be a spline or two out. I have rebalanced the throttle bodies to see if this cures the 5000rpm vibe but may have to re-realign the splines to get spot on. ( although how your meant to this with any real precision is still a mystery )

without wanting to reignite the phasing argument, my opinion is that they do need to be in correct phase alignment.

if anyone has any tips on the best way to align the shafts it would be appreciated. I may yet go back and do it again.

boxadog you are right. thanks

john

[r550s]

I like the theory about phasing (must add that 90' out of alignment = 180' out of phase). Course, my K100 (non paralever) only had the one UJ - at the front of the shaft - that was a real bugger to get 'in phase'...sorry!

[johnl]

please excuse my art work. The diagram below shows how i believe the uv joints should be aligned.

To achieve this a torch must be shone up the swing arm and a guesstimate made. It is a poor design complicated by there being an odd number of splines, so there really is only one way it can go.

Incidently i spoke to a guy at my local bmw dealers who new nothing about alignment of the uv joints. He said "they never do it, besides it would be impossible as there is no master spline". tell me about it!!!
So if your bmw vibrates like buggery having been to a dealer the uv alignment may be a cause.

anyhoo.......