Centre Bearing Bracket Query & Tailshaft Ends Query

[Sojourner353]

Hi all,

Can anyone tell me which way the Centre Bearing Bracket goes on the VR?

I was under my car today while it was on a hoist at Midas as I have been experiencing bad vibration and thought I may have had a bad Cat, they called me under to have a look and they said my Tailshaft was changing direction at the Centre Bearing, I notice the bracket that holds the Bearing to the car can offset the Bearing if put on wrong as the holes that hold the Bearing to the Bracket are off centre, there is a arrow on the underside of the bracket and at the moment that arrow is pointing to the back of the car, I feel it is in the wrong way as the Tailshaft is not sitting in the middle of the well with the bracket like this.

So if anyone knows if this sounds wrong could you please help?

Also if anyone knows the position of the X's on each end of the shaft where the uni's this would also be a big help are they meant to match at both ends (mirror image of each other)? The reason I ask this also is because mine don’t match and if they are meant to I suspect the CV Joint has not been put together correct when I had the Centre Bearing fixed.

Thanks again for all the help,

Regards,

Kevin

 

[Boonz]

hey... the tailshaft shuld always go on the same way it came off because the cv's wear in a certain way and if changed then you get that shuddering feeling

 

[hako]

Grerorys says to clearly mark all components to ensure they go back the same way. It also says "If the propellor shaft is separated, it is important to mark the relationship of the front and rear shafts to ensure correct universal joint phasing on assembly". The book says nothing of "X's" so maybe they were put there by a previous mechanic. Common practice is to centre punch one or more marks on each component before disassembly.

 

[Sojourner353]

Hi, I am aware of that, and that is why I am asking, I have a funny feeling the mechanic that done the Centre Bearing hasn’t put the CV Joint back together properly (right way), he recently told me I needed a new engine because I had a bad rattle in it (sounded like marbles rattling inside the engine) then told me $3000 reco fitted funny thing was the noise went away when he took the Drive Belt off and when I said where’s the noise he said I still needed a new engine, I ended up finding the Harmonic Balancer was stuffed and once replaced the noise was gone, can you see why I am concerned with his repair?

 

[Sojourner353]

Hi hako,

The Gregorys Manual is very vague in relation to the Tailshaft, the X's I am talking about are where the uni's sit in each end (sorry mechanic term used there) its not punch marks, imagine the tailshaft is sitting on a bench and one end is Verticle, on mine the other end is out its not a mirror image of the other end, hence why I think my CV has been put together wrong.

 

[hako]

I think I know what you mean - like at one end of the shaft the uni 'cross' is not the mirror image of the other end. The only thing I can suggest is that you talk to the people at Midas and ask when are they having another VR on the hoist - they are pretty common so I'd figure for sure that tomorrow morning they will have at least one on the hoist. Then eyeball just where the centre bearing sits and turn the prop shaft etc to try and ascertain whether your is the same. Take your digital camera and get some shots just to make sure. I've never touched my VS driveshaft but have had problems with a Jag XJ6 that I owned which had a 2 piece prop shaft identical to the Commodore except that the centre bearing was a ball bearing with uni's either side....the centreing of this bearing was very critical. Another way to get a look is to ask someone who you know who has a VR - just jack it up safely and put a mirror underneath or crawl under if you have stands for safety. Gregories mentions "phasing" which is unclear but seems to mean something about the angles which the unis pass thru when the shaft is rotating. ( the shaft rotational speed actually varies 4 times for every turn as the crosses in the uni changes angle - that is why constant velocity joints are called 'constant velocity' and are preferred when large directional changes are required like in front wheel drive) Your assumption re the CV joint may well be correct. Good Luck.

 

[Cheap6]

The uni. crosses aren't designed to line up in a Commodore. There should be about 15-20 degree difference when looked at along the direction of the shaft. Arrow to back of car is correct.

 

[Sojourner353]

Umm no the arrow is meant to point forward on my car, solid rear end it points back and 5 point rear end it points forward, I changed mine to point forward now 70% of the vibration has gone, also just replaced the rear mount under the gearbox and that has improved it even more, very happy now, thank for the help.

 

[jaylee]

Tailshaft query

Hi
I just took my car down to the mechanic and he told me when he looked under it that the tailshaft was sitting on an angle! Is this how it should sit or should it be completly straight.

The centre bearing in mine was shot so I went out and got another and put it in the same way it came out, but it still sits on an angle. PLEASE HELP!!
Thanks

 

[hako]

If the car is on stands and the solid rear in hanging down, the rear half will be at an angle. Sitting on it's wheels it's more or less in a straight line. Dunno about IRS but I'd imagine should be in a straight line whatever.