I don't know who to give credit to for this, as I've had it for about six years. Seeing the names of Kevin & Bob, makes me think of the Cape Cod British Car Club archives, but I'm not sure.
And I quote:
TR6 Bumpers and Bumperettes (Update)
The Haynes manual has not been updated for some of the changes in details on the last TR6's. Some folks want to remove the black, rubber bumperettes to obtain the look of the earlier cars. Others need to remove the bumpers for a paint job or rechroming.
The front bumperettes simply unbolt. The front bumper has 4 bolts securing it-- Two on the sides in the wheel wells and two behind the bumperettes -- accessible from the engine compartment. However, to remove the rear bumperettes requires removal of the entire rear bumper to get at the bolts.
Following some good advice of Kevin Thompson and Bob Lang, in preparation for a paint job, I tackled removal of the rear bumper. The bumper has two bolts, one on each fender, accessible from in the wheel well, whether the car has the bumperettes or not. With bumperettes, there are two bolts into the frame that hold the brace to the bumperettes, easily accessible under the car.
Ah! the last two bolts. These bolts secure the bumper to the body in the vicinity of the bumperettes or where they would be if there are no bumperettes. They are virtually inaccessible, cannot be seen, except perhaps with a mirror and judicious placement of light. They are inside a piece of box frame extension, accessible(??) via a slot near the fender. And, oh yes, they are totally accessible to slinging mud, water and gunk from the rear tires. If, like mine, yours have not been removed for 30+ years, be ready for an adventure.
First please note that the nut on the bolt that secures the bumper is 5/8" hex. Mine were badly rusted and a 6pt 14mm or a 12pt 9/16" socket (A socket is your only hope of getting at the nut) is too small. However, on my car a 12pt 5/8" socket seemed to big -- it slipped. I bought a 6pt 15mm deep socket for a 3/8" drive (same as a 6pt 5/8") to be sure to get over the extended bolt and the 3/8" size allowed more room in the slot.
The recommended connection is a short extension into the socket, connecting to a u-joint and a long extension to get the driver outside the fender. My bolts being frozen would not allow this elaborate set up to give me any leverage. I went with a long 3/8" extension on the socket to a 3/8" drive. Even though I could only move about 2 clicks, I could get sufficient leverage to make something happen. What happened on the right side was the bolt snapped. What happened on the left was that the bolt unscrewed from the bumper as the nut was rusted on like a bolt head. (Here I was able to use the long extension when it started to move.) Please note that what is here is a threaded shaft that screws into a plate on the bumper and is held with the nut under the car.
As Kevin and Bob point out you want someone to hold the bumper while you remove these last two bolts. The bumper is heavier than it looks, and if it swings uncontrolled, you may damage your paint or body panels. Also, if the bumper sags as the nut loosens or bolt comes out, the nut angle will change making it more unlikely the socket will hold.
Hey Guest!
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
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smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
