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Discussion Starter · #1 ·
Since my brake parts are out to be powdercoated, I decided to tackle the Daytona's rear bumper. This was a NY state car, so it was really rusted out. If you want to see how bad, you can look through the build log:


I am intending this to be a project log that others can help add ideas to. Many of us have rotted bumpers and they are no longer available. Just finding information on how they go together is difficult. I scoured the website, but found almost nothing. Even the shop manuals don't show any details. I couldn't even find an assembly diagram until I went to a parts site.

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Just getting the old bumper off was hard. I had to cut a lot of it away. I took a lot of photos, but not as many as I needed to. Word of advice, always take more photos than you think you need.

Here is how the rear of the car looks now.

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After cutting away a lot of the fasteners, I just filled things in. My intent was to put them back the way they were, but I've since changed my mind. My new plan may be better than the original.

These are the parts that I have left.

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It's hard to see, but the bumper is pretty rotted. There's not much thickness to start with, but I was lucky to find one this intact. Newer cars have inner bumpers made of styrofoam, so a pitted, rotted, bumper is no big deal. They are intended to fail, to protect the car itself.

Since the bumper struts are no longer available, I decided to build my own. They sit into the pockets that go into the frame tubes.

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Discussion Starter · #2 ·
This is how the pocket looks deep inside.

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I intend to make this a bolt together project, since a lot of people don't have the ability to weld. Since everything is hidden, I won't be trying to make it pretty, just functional.

Since the original strut brackets were designed to collapse into the frame, I decided to use some 1-1/2" square stock, with 1/2" threaded rod. This will allow me to adjust the bumper spacing, front to back.

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One problem is that the rod has to pass into the hole deep into the cavity. That means drilling it out to 1/2". I don't have a long enough bit, so I was searching for a long bit, on eBay, before realizing that I could use an extension, with a 1/4" shank unibit.

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I opened up the side holes to accept 6mm bolts.

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This is the frame type that the rod will travel into, if the bumper is pushed in.

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This should give you an idea of where this is going.

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Again, if you've got ideas, don't be afraid to add them to this thread. This is intended to help others, not just show my work.
 

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Old School Hot Rodder
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1,516 Posts
I went through a similar situation on my 1986 K-Lebaron convertible front bumper. My front bumper mounts originally had rubber vibration, I assume, where they bolted to the car. The rubber was bad and partially separated from the mounts. I can post the pictures if there is interest in them. The rear bumper was much like yours, actual bumper bar was rusted and had been modified for a trailer hitch. Fortunately in my case, the K bodies are essentially the same in a given run at the back, a 1988 Reliant provided me with a perfect bumper and cover, but had the later single use 2.5 mph mounts (which I still have) my rear mounts were still perfect, so I used them.

One thing, if someone hits that I don't think it will give.
 

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Discussion Starter · #4 ·
I found a pic of the bumper when I removed it, way back in 2013.

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I had made a comment about the lack of info, on the rear bumper, in the shop manuals. This is from any of the manuals from 1985-1992.
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My previous pics were from the driver's side. When I moved to the passenger, I found this little gem residing inside the frame pocket. Fortunately, I was able to pull it out with a slap hammer. It wasn't even locked in place and would probably have pulled out with a coat hanger hook.

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This is all that was left of the brace.

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I had thought about adding a rubber doughnut to the threaded rod, to keep it from rattling around, but found that it wasn't needed. Once the adjuster is locked down, there is enough interference to keep it snug.

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I wasn't going to use any welding, but I decided to weld a nut to the back of the square tubing. You can go without it, but it makes threading the rod much easier.

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Also, the square tubing is only 1-1/4", not 1-1/2".
 

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Discussion Starter · #5 ·
This pic shows how the bumper and upper support go together. The support is what determines the angle of the facia.

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There are two plates that are crucial to adjustments.

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I just cut a piece of rectangular tube in half, drilled two holes, and slotted one. The slotted hole is for the 1/2" threaded rod to move up and down.

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One thing that would have made my life much easier is to remove the center braces. I needed to adjust the outer nut, after everything was completely assembled, and that brace was in the way. It would be very easy to just bolt a flat brace across the open area. I'll do it on the next car.

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This shows the brace and the nut that is hard to get at.

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The bumper skin mounts to the inner metal via screws and rivets. The adjusting plates mount using quick nuts, which allow side to side adjustment.

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The rivets go into the metal upper shelf, which is the key to locking the entire bumper to the rear of the car.

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That support is on the left, in the pic below.

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Old School Hot Rodder
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Looks pretty good, I'm sure it's as least as good as the 2.5 mph ones from the late 80s.
 

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Discussion Starter · #7 ·
The factory has plates on the inside of the car, that have bolts that pass through the rear of the car, and into the "L" shaped plate. Since I had patched over some of the holes, I had to drill them out. I mounted the "L" plate to the vehicle, so that I could locate where the holes should go.

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The inner mounting plates can be made from a piece of 1/8" thick stock, 1" wide. Just place them inside the car and mark them for each hole. I tapped them for M8x1.25 bolts, 40mm long. I first tried 30mm, but they weren't long enough.

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When you put the bumper assembly into place, use a unibit to open up the holes, of you will have alignment issues.

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Make sure that you caulk the area around the bolts, or you will have leaks.

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Once you have the nuts tightened across the entire bumper, you can work on the main adjusting nuts. I used a jack to push everything as far up as possible. I pushed the metal bumper back until it was pushing against the outer skin, then I tightened to outer nuts, onto the threaded rod. That's why removing the supports, in the last post, would have made life easier.

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You will be mounting the wheel well portion using plastic push locks. Once the bumper is in place, they should line right up.

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Here's the finished product. It's strong enough to stand on.

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Old School Hot Rodder
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Very well done, and excellent documentation. I am sure this can be applied to any of the K based Chrysler products.
 

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Discussion Starter · #9 · (Edited)
I came up with a modification that I'm not going to do, but might be beneficial to someone else. This could easily be a spring loaded design, which could prevent damage from minor hits.
 

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Discussion Starter · #10 ·
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The spring would have to be strong, so the it would push outward, against the skin, to hold it in place.
 
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