Hi,

Want to disassemble rear axels for sanding and painting... But wonder how.
Can anyone give me an hint?

do you not have the haynes sierra manual?

nope...

If they are the bolt on type undo the bolts and the shaft will come off.
If they are the pushing ones you will need to seperate the shaft from the hubs first then pull out the shaft fromt the dif, you will need to drain the diff or put a bucket under it to catch the oil.
I would replace the cv boots at the same time.

link for boots
FORD SIERRA COSWORTH STRETCH DRIVESHAFT CV BOOT KIT 96 on eBay (end time 13-Apr-11 09:58:49 BST)

I've taken the axels from diff, no problems there.
What I really want is to tear apart the axel itself for antirust treatment.
There are no bolts or any other kind of locking bolt. They must be on pressure, right?

If they are from a sierra then there will be a cer clip on the end of the shaft pull it apart and the clip will allow you to pull the shaft apart there will be another clip on the back of the cv joint as well this you can leave on as it only stops the boot from slipping down the shaft

Can you post some pictures?
I spent a few hours this afternoon around the driveshafts without getting anywhere...
They're sierra's pushin driveshafts.

If you dismantle a Sierra axle completely you need to reassemble carefully with new crush tubes and set the bearing preload, not a job for the inexperienced.
If it's a beam axle, it's a little more simple but why, just sand it down and paint, they done rust through, ever.
Do yourself a favour buy the relevant Haynes book.

Ok, but what about the rubber boots? They're all ripped apart... I need to put new ones. The only way to do it is to dismantle the driveshaft, right?