Backdating Bumpers, Hopefully the last thread ever written on the subject Options

[bigkensteele]

When I decided to backdate my bumpers, I wanted to have all of the answers before I started cutting stuff off and drilling holes. Using the fine search function, I was able to find all of those answers, but I had to wade through many, many threads to get them all.

With that in mind, I decided to write one up that will contain every last bit of information needed to do the job. I can’t take credit for much, if any, if any of the information below. I got most all of it from my searches, and I will try to give credit where credit is due. I apologize up front for the crappy phone pictures – while bad, they still tell the story.

While there are a few of us who like the looks of the late bumper (myself included, depending on the color of the car), there is one really good reason to go with early bumpers – weight. I have seen many figures thrown about, so I decided to weigh them both, including all mounting hardware, fog lights, grills, etc. I was quite surprised at just how much heavier the later bumpers are.

Front:
Early – 20 pounds, included pad, dog bones, lights, grills, and hardware
Late – 46 pounds, including the shocks, and hardware (non fog light bumper)

Rear:
Early – 18 pounds, including pad, dog bones and hardware
Late – 50 pounds, including the shocks, and hardware

38 pounds vs. 96 – 58 pounds, or roughly 3% of the entire weight of the car removed from the two places you would most want to lose it!

So, let’s get started.

Tools required:
- safety goggles (ask me how I know how much is sucks to have metal surgically removed from your eye)
-3/8 ratchet, extension and a set of metric sockets
- screwdrivers – both kinds
- pliers
- angle grinder, grinding disk and a metal cutting wheel
- mig welder if you are a hack like me
- left cutting (red) tin snips if you are right handed, right cutting (green) if you are left handed
- center punch
- step drill bit at least 5/8
- drill
- spot weld cutter
- hacksaw
- hammer and dolly

Hardware/misc. required or recommended:
- (8) 8M x 1.25 x50 bolts
- (8) 8M large flat washers
- (8) 8M lock washers
- (8) 8M nuts
- primer, body color paint, sandpaper, tape, paper, etc.
- early bumpers, tops, dog bones, etc.
- beer (optional)

I did the rear first, for no particular reason.

The first order of business is to remove the bumper. This is accomplished by first disengaging the bumper sides from the retaining rails on both sides of the car. Simply pull the bumper sides away, and they will peel right out. Next, unscrew the license plate lights and disconnect the wiring. Finally, remove the two 19mm bolts located in the holes on the underside of the bumper. The bumper should now slide right off, but remember – it weighs 50 pounds, so be prepared.

I removed my valence as well. Not sure if it was necessary, but it needed some dents removed and paint anyway, so what the heck, it was only a few screws.

Next, you will need to crawl under the car with a 17mm socket and remove the 3 bolts holding on each shock and work the shock out. I recommend putting the bolts back in place to keep water out.

Now for the fun part. You will need to remove those retaining rails from each side of the car. They are spot-welded on in 5 or 6 spots. There are a couple of ways to do this. You can use a grinder or cutting disc to grind through the welds, or you can buy yourself a spot weld cutter to drill them out. Or if you are an idiot like me, you can attempt to use a regular drill bit and drill them out, and then weld up the resulting holes. I bought a spot weld cutter before I did the front.

I forgot to take pictures of the rear, but here is one of the front – same procedure for both.


As far as the bodywork required to touch these areas up, I welded up the holes and ground it flat. I then taped off the area, primed it and used a rattle can of a fairly close blue that I found at Lowes. When the bumper is installed, these areas don’t show much, but they still needed to be painted.

[bigkensteele]

Using one of your dog bones (they are the same front and rear), verify that your marks are centered in the holes of the dog bone. If not, adjust the bottom mark accordingly.

The point of no return – drill your holes. I think that the factory holes are about 5/8, but I got by with ½ on the rear. Use a punch to dimple your mark, or drill a pilot hole – either method will keep your larger bit from walking. I used a regular bit on the rear, and it tended to bind up and make for an ugly hole. On the front, I wised up and used a step bit from Harbor Freight. They turned out much nicer.