I am just reviving this post following my experience in greasing the U/Js on my 2011 Plus 4, one of the first with the MX5 box.
I decided to have a go at making an access hole, and using the above post, thought that the dimensions might well suffice for a plus 4 too, as I believe it shares the same chassis as the Roadster.There begins my folly!
Using the same datum points as the back edge and top of the cross member in the footwell, I easily cut a 52mm hole at 13mm in front of the datum and 110mm above. It was then evident that the U/J was nowhere to be seen. But by finger poking, it was clear that it was quite a way backwards from the hole.
Searching on TM is not always productive, so I then did a google search for “prop shaft grease nipples”and found a result referring to a posting on TM. This was posted by”Jays” on 11/2/16 ref# 340011. This contained a series of photos from the factory of different prop shafts.
Surprise, surprise…the Roadster is indeed very different to the plus4 and 4/4. Whilst the Roadster has two grease nipples up front (one for the u/j spider and the other at the rear end of the joint for the sliding splines), the 4 and 4/4/only have one nipple for the spider unit and it looks as if the sliding action takes place where the shaft goes in to gearbox itself. Interestingly, there is no mention of this on Gomog either. The general advice there is that all Morgan propshafts have 3 nipples, one at the back and two at the front! So that needs some correction. (Lorne??)
Anyway, back to my car, I now drilled another hole but this time still at 110mm above datum but now 80mm behind the back edge of the cross member.
The UJ was now revealed with the nipple a little bit forward of my hole. That was a good thing as the nipple on the spider was pointing at about 45 degrees towards the rear. This enable me to attach my grease gun, complete with g-coupler, and the other hole was useful to poke a finger in to guide it onto the nipple. The joint was quite dry and took several pumps before a tell tale amount exuded from each bearing, whereupon I ceased.
So job done and I hope this may be of use to other plus 4 owners, to avoid the mistake I initially made. There is always the chance of course, that the spider could have been installed the other way round with the nipple pointing 45degrees forward, in which case the hole could still end up in slightly the wrong place, but its all covered over in the end, so no matter.
