I've just replaced my two tubby mounts so I thought I would add this.
The car is 40K+ so I decided to replace them now before they inevitably go. Nearside was O.K. but the offside had in fact gone but I wasn't aware of it. Must be cos I drive like a big girl's blouse.
Nearside removal and replacement was straightforward except that all bolts were absolutely solid and took a lot of shifting. Offside was the same, in fact the bolt nearest the back bulkhead refused to shift and rounded off, I hammered a marginally smaller a 1/2" socket on instead pf the 13 mm and it rounded again so I was temporarily stumped.
Here we come to the reason for this post, it may have been mentioned here but I haven't seen it. Many more experienced people here will be aware but this is for the benefit of those who are not.
There are two types of socket, There’s the conventional type you buy in Haulfrauds etc which have the serrated inner. The serrations fit and grip on the corner of the bolt/nut and are OK for most applications however if you get a really stubborn one, the socket will simply round off the corners and you will not be able to remove the bolt/nut.
There is however a second type of socket called a Hex socket which most professionals use. Instead of the serrated inner face, the socket has flat hexagonal faces (the higher quality ones in fact have a slightly concave towards the bolt face shape) that match the face of the nut or bolt head thus it works on a different gripping principle to an ordinary socket. Instead of gripping on the bolt/nut corner, it grips on the flats (nut/bolt face). So if you 'round' a nut/bolt using an ordinary socket, all is not lost because you can have a second go if you have a hex faced socket set (that you haven't used in the first place
). Unfortunately I don't have a hex set; the only hex socket I have is the one I use for the wheel bolts. It's intended for an impact driver (they are invariably hex sockets) which I bought because it has a plastic sleeve that protects the alloys.
So I went to see my friendly mechanic 'cos I know he has a hex set. The bolt in question that wouldn't move is the only one of the three that can in fact be accessed from above and outside the engine compartment by fitting a slim 3/8 drive extension bar between the engine and the bodywork with an articulated connector on the socket.
With the hex socket on the bolt it took an 18" breaker bar to get the bolt to shift, in fact it went with such a crack I thought the bolt had snapped. Turns out the bolt was rusted alon the whole thread length. A hex socket, it will not round the bolt head; the bolt shank will snap before the socket will let go. If you have space with a bolt/nut that's really tight you can always apply heat with a blowtorch to shift it, but that's not really an option in confined spaces or on a plastic car.
You can also get hex ring spanners as well.
Took me a totally uneccesary 6 hours 
2 of which were spent trying to get the damn arch liner off - had to take a dremel to the screws as they were shagged. That also included lunch and a trip to Halfords in the middle 
? it's a little more awkward 
