wildsmith
SILVER Star
I've been busy building a new rear bumper / cross member for my 80 and thought I'd share the build and outcome. This is stage one, stage 2 will be adding a swing out wheel carrier and tow hitch mounting but I need to recharge my brownie points before I disapear into the garage for hours again.
I wanted as much clearance as possible to improve the departure angle but I still wanted it to stick out far enough to protect the tail gate from me reversing into trees.
To get the clearance the old cross member was cut off and a chunk of chassis with it, to within 20mm of the body mount bracket:
I got a length of 120x60x5mm box section, cut a corner out, folded and welded it to get the profile I wanted for clearance. I went for a slightly convex shape rather than a flat face to improve the strength:
I got some 120x80x10mm angle and cut it to form the chassis mounting brackets. I drilled two new holes in the underside of the chassis each side and re-used two holes already there for tow hitch mounting. I then drilled the chassis side to side, 25mm on the inside, 21mm on the outside and welded sleeves with 16mm bores into the holes. In the pictures you can see the captive nut plate, the inserts I welded into the chassis and a bracket. There are 4 M12 and 3 M16 8.8 bolts in each side (!):
I had to cut a small corner out of each rear panel for clearance so that the box section that forms the main part of the new bumper could go all the way out to the side wings to keep it strong:
Now it's starting to come together - I've added a tree tube high up and supported by angled tubes to stick with the high clearance theme but get the tree protection:
Jumping ahead quite a bit, the main box section has been trimmed both in length and profile in the wings and the side tubes have gone on:
Time to paint it and have a #6:
Everything except the very tips of the recovery eyes is inside a line projected from the bottom of the back of the tyre to about 30mm rearwards of the body mounting bracket, about as much clearance as I think you can get without removing or cutting into that mounting.
I wanted as much clearance as possible to improve the departure angle but I still wanted it to stick out far enough to protect the tail gate from me reversing into trees.
To get the clearance the old cross member was cut off and a chunk of chassis with it, to within 20mm of the body mount bracket:
I got a length of 120x60x5mm box section, cut a corner out, folded and welded it to get the profile I wanted for clearance. I went for a slightly convex shape rather than a flat face to improve the strength:
I got some 120x80x10mm angle and cut it to form the chassis mounting brackets. I drilled two new holes in the underside of the chassis each side and re-used two holes already there for tow hitch mounting. I then drilled the chassis side to side, 25mm on the inside, 21mm on the outside and welded sleeves with 16mm bores into the holes. In the pictures you can see the captive nut plate, the inserts I welded into the chassis and a bracket. There are 4 M12 and 3 M16 8.8 bolts in each side (!):
I had to cut a small corner out of each rear panel for clearance so that the box section that forms the main part of the new bumper could go all the way out to the side wings to keep it strong:
Now it's starting to come together - I've added a tree tube high up and supported by angled tubes to stick with the high clearance theme but get the tree protection:
Jumping ahead quite a bit, the main box section has been trimmed both in length and profile in the wings and the side tubes have gone on:
Time to paint it and have a #6:
Everything except the very tips of the recovery eyes is inside a line projected from the bottom of the back of the tyre to about 30mm rearwards of the body mounting bracket, about as much clearance as I think you can get without removing or cutting into that mounting.
Every time I drag something down the side it pulls the light unit out and smashes it up some. Those tubes should hold it just far enough off the things that normally eat the light. Don't know why it's always the (UK) drivers side though! I could have put the tubes up higher but I'm not a great fan of the way that looks. If it still doesn't save the lights then I'll reconfigure the lights 
