Prop shaft centre bearing.

[GrahamWright]

Originally Posted by Laird Scooby

Crawl under the car with the right size spanner or socket for the bolts that secure the centre bearing to the floorpan. Loosen each by HALF A TURN ONLY.

Take the car for a drive, GENTLY accelerating to the speed where the vibration starts then let the car slow naturally to below this speed and return home. Avoid all harsh acceleration and braking while the bolts have been loosened.

Crawl under again and tighten a SMALL AMOUNT AT A TIME each bolt in turn until they are tight again. Take for another test drive to confirm the vibration has gone.

DO NOT JACK THE CAR to enable you to crawl under to reach the bolts. If necessary use a pair of ramps.

That sounds like mystic magic! I'll certainly give it a whirl.
I have a pit so access is easy. Thanks

[Laird Scooby]

Originally Posted by GrahamWright

That sounds like mystic magic! I'll certainly give it a whirl.
I have a pit so access is easy. Thanks

It's nothing more than the magic of physics - the propshaft is already balanced so will try to regain this balance when rotated if it's slightly out of line. If the bracket is in the wrong place (a fraction of a mm can be a lot!) then allowing the bracket to move slightly when the vibration happens means it will self-align.

[GrahamWright]

I removed the whole shaft to check the spline alignment (it was correct) and when replaced, the vibration was less. Put that down to chance.

However, the bearing adjustment is only fore and aft which cannot adjust the deviation from a straight line (well only minutely).

Despite that, I will do as directed.

I have found this forum very helpful and non critical (unlike some!).

Edit;- just remembered the bearing is not self aligning.

[GrahamWright]

Originally Posted by griston64

Is this any use https://weblisher.textalk.se/gcp/20160129-024/

Page 974 onwards

Looking at that huge list of components makes one realise why vehicles cost what they do!

[GrahamWright]

I have had two attempts to cure the vibration without success. The first was half a turn on the two bearing housing screws, the second a full turn.

Do I keep turning?

There has been a slight improvement but still rumbly. I have checked the shaft to see if any of the balance weights had detached during the man-handling to remove the original bearing and split the spline but nothing is apparent.

[Laird Scooby]

Originally Posted by GrahamWright

I have had two attempts to cure the vibration without success. The first was half a turn on the two bearing housing screws, the second a full turn.

Do I keep turning?

There has been a slight improvement but still rumbly. I have checked the shaft to see if any of the balance weights had detached during the man-handling to remove the original bearing and split the spline but nothing is apparent.

Rumbly? You haven't mentioned rumbly before! No amount of trying to dial out the vibration by slackening the bearing mount bolts and driving it up to the speed where the vibration occurred then back to base to re-tughten the bolts is going to cure a rumbly bearing!

Are you sure you got the diagnosis right in the first place? What's the ride height, measured from the centre of the rear wheel vertically to the wheelarch?

[GrahamWright]

Originally Posted by Laird Scooby

Rumbly? You haven't mentioned rumbly before! No amount of trying to dial out the vibration by slackening the bearing mount bolts and driving it up to the speed where the vibration occurred then back to base to re-tughten the bolts is going to cure a rumbly bearing!

Are you sure you got the diagnosis right in the first place? What's the ride height, measured from the centre of the rear wheel vertically to the wheelarch?

Sorry - misled. VIBRATION NOT RUMBLE!
The bearing housing was disintegrating so diagnosis probably correct!
Up to 40, there is no vibration. Starts at 40 and continues upwards. Same coasting out of gear. The bearing is new and came with the housing. The original bearing was moulded to the housing - the new one is a force fit. Would its longitudinal position affect anything? There is around 15mm to play with.

[GrahamWright]

The ride height varies with the load and is "exercised"! I can measure with no load.

[Laird Scooby]

Originally Posted by GrahamWright

The ride height varies with the load and is "exercised"! I can measure with no load.

Yes please and also test drive without any load too!

[magnus308]

What was the brand of the new bearing carrier that you installed?
Do you have picture of it?

The reason i ask is because its 2 versions of bearing carriers and one of them is too stiff and will create the vibrations you describe.
The more solid version of bearing carrier showed up a few years ago and a lot of people have had problems when they have installed it.
The only way to solve it is to replace it with the old version.

You can see pictures of the 2 different versions on the link below, the top picture is the new version that creates vibrations.

https://www.jagrullar.se/forum/viewt...1612&start=190