Prop shaft centre bearing.
 

The bearing feels fine but the housing is shot resulting in vibration at certain speeds.
I have removed the shaft but the splined joint refuses to separate. I assume the grease has turned into glue.
Is there any way other than contriving a splitter at the UJ?

sounds like your vibration issue, or at least some of it, could be with the splined shafts if they are refusing to pull apart.
Have you tried getting some "Plus Gas" or similar using the straw to get it inside the bellows/boot then working it back and forth to free it.

If you can get heat in without melting anything then that normally frees stuck components quite well.

Acetone and ATF mixed (50/50 mix) works very well for freeing rusted/stuck components.

I have the same job to do this weekend if the bearing arrives this week, not looking forward to it, may have to clear my Gran’s garage to get at the pit to make it easier.

I've hacked off the rubber which was completely disintegrated. That was allowing the whole shaft to move up and down significantly. I am now trying to fabricate something that will allow leverage against the bearing housing, which in turn is backed up by vice jaws (a bit nervous in case I crush the spline outer).

The end of the spline is bright and the boot intact so there is a chance the joint is not rusted.

I'm on version 2 of the splitter now!

A bearing puller with long arms will help shift the bearing on the propshaft. Alternatively use some soft jaws to hold the shaft in the vice and a drift on the centre race of the bearing with a lump hammer driving the drift. Go alternate sides to help it come off squarely, it's easier that way.

As already stated WMP (Weapon of Mass Penetration) made from 50/50 acetone and synthetic ATF works well as a penetrating fluid. Shake well before each use and keep sealed to prevent the acetone evaporating.

Once you've fitted the new bearing/bracket assembly, take it for a test drive. If there's any vibration, note the speed and return to base. Crawl under (don't jack the car :nah: ) and slacken the bolts holding the bracket to the floorpan 1/2 a turn.
Go for another short drive, accelerating as smoothly and gently as possible to the speed where the vibration happened. It should disappear, return to base and tighten the bolts a little at a time evenly in turn until they're all tight. Retest, if all good check tighten the bolts and call it good! :thumbs_up:

Well, it took just 5 hours to separate at the spline. I made a clamp that fitted round the male part of the joint (plain not spline) and a series of levers to start it (impossible to describe in words). Once there was a sufficient gap, I could use screws against the clamp.
If anyone is interested (and if it is possible to post photos) I can show the construction.

Now - is this splined joint supposed to free fit? Is it provided to take up dynamic fore and aft movement or is it to take up the static slack between the gearbox and diff?

If the former. I am going to have problems.

Removing the bearing and housing (what's left of it) I hope will be more straight forward.

Thanks for the advice.

The front and back halves of the propshaft are indeed meant to slide freely on the splines but more importantly, only fit one way - there is a keyed slot inside so the spline will only fit in the femal half in the right place.
If you've forced it, you need to separate the front and rear halves again, check for and remove any burrs on the splines and get it back in the right position. A replacement propshaft might be a better idea if you've really chewed it.

As for photos, go to postimages.org and sign up for a free account. Upload your photos there and then when making your post, click on the post where you want to image to be so the cursor is there, goto postimages and click the share button above the image you want to post. A list of links will appear, all with a blue button at the right hand end.
Select the blue button on the end of the "Hotlink for forums" link, click it, it changes to "Copied" then return to your post, right click on the cursor then click paste.

Finally hit "Enter" twice on your keyboard to "set" the image and leave a blank line underneath for ease of reading.

https://i.postimg.cc/cHM4QBCM/IMG_20..._151758036.jpg

Example photo only loosely related to the thread!

I forced the two halves of the prop together first time i put in the m90 into my car, i was tired getting stressed and forced it rather than stop and think.

I was a job to get them apart again, lucky was doing the swap in a large shed, so was able to tie one end to a piller, and the other end to another with some big ratchet straps from the lorry's at work and had to a crank on them pretty hard to get it to separate, good clean out and grease and the slide nicely now.

The propshaft will have been balanced as a whole unit so even if there wasn't a locating groove ideally they will need putting back together in the same place anyway to not affect the balancing. It is good practice to mark the prop halves to ensure you know where they went.