While trying to work on some front end issues I decided to crawl under the car to look at the rubber driveshaft coupler.

cracks in the rubber driveshaft coupling

Years ago I have replaced these rubber couplings on old BMW cars (2002 and 1600) before but not on the XJ40.
In looking at the driveshaft and the exhaust covering it up, I am guessing I might have to remove part of the exhaust so I can lower the center support bearing so I can change this coupling.
I searched here for "driveshaft coupling" or "driveshaft coupler" and did not see any posts with any specifics about what had to be done to change this.
Any and all information would be most helpful.

 

That thing is called a Jurid coupler. They are available but not cheap. Try searching Jurid , I think you'll get better results. I have not changed one myself though. Keep us posted.

 

Jerry:
The Jurid coupler is available for $45 plus shipping from rockauto.com
--
Steve

 

Though I can't point to an online procedure for the replacement, I can say that when I recently changed mine, I removed the exhaust first. Unbolted at the front and cut the pipes in front of the rear subframe. Made working on the prop shaft a relatively straight forward process. Hoisted the exhaust back in place with a transmission jack, bolted the front and welded the rear section. Crude but effective.

 

These are alternately called a flex disc, flexible coupling, flex joint, elastic or elastomeric coupling, Jurid (after the German manufacturer), Boschi Joint (after Antonio Boschi, the inventor), giubo (a contraction of giunti Boschi, or Boschi Joint in Italian, often misspelled guibo). During the XJ40 era, much of the Jaguar service documentation used the term Jurid.

I haven't typically had to mess with the exhaust to replace the Jurid. You probably will need to disconnect the center bearing bracket so the bearing can move forward to allow the extension on the end of the driveshaft flange to be pulled out of the Jurid. Before you remove the center bearing bracket screws, scribe around their heads and mark the location of the inner bar so you can get it all back in the same position on reassembly. The slight sideward orientation of the center bearing is important to reduce driveshaft/propshaft vibration.

If the new disc you receive has the bolt holes arranged in three reinforced pairs, you want to be sure to install it so that the driveshaft's direction of rotation causes the bolts connected to the driveshaft to apply force to the bolts connected to the differential by way of the reinforced areas. You don't want driveshaft bolts in the reinforced areas pushing against un-reinforced sections of the disc. I'll try to think of a better way to describe this.

I did not have good luck with a flex disc from ÜRO Parts that vibrated badly in all six positions (I tried them all). Switching to an OEM disc by GKN solved the problem.

Cheers,

Don