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Building a smoothie bumper - how to

83K views 51 replies 27 participants last post by  Ezpilot 
#1 ·
Since 56 smoothies aren't available yet...and may never be, I have resorted to building my own. I'm sure Danchuck will come out with them as soon as I'm finished. ;)

I wanted to show the process I used to build one, and a few tips and tricks since our self-proclaimed resident expert (streaker, or slacker??) smoothie builder wouldn't divulge anything a couple years ago. :rolleyes: :sign0020:

I started by selecting good pieces from the bumpers I had, and separating them from the brackets and from each other by removing the rivets....



Then I removed the chrome and ground the nickel and copper back for welding. It's not easy to remove copper any other way, I have found, and a local plater wouldn't even do it for me. Next, I bolted the pieces to the brackets that I had bolted to the car to check for fit. I found that the bumper was anything but straight at the joint as this picture shows....



So I had to make some cuts in the bumper to get it straight on both sides of the joint. I hammered on it some, then I used a thick straightedge that I clamped to the bumper for tacking the pieces together. I checked for fit again, and you can see it's much straighter....





Once I was happy with the fit, and straightness of the bumper, I welded up the gap on front with a TIG welder and ground the welds some.....



Then I trimmed back the overlapping flange on the back of the bumper...



Then I continued to weld and grind on the front and back of the bumper, and "bodywork" it smooth. This is the result....






I'm leaving the two bolt holes unfilled until last, so I can use the bumper brackets to continue fitting it to the car until I'm happy with it.

Next steps are to modify the brackets on the fender and shorten the diagonal brace to fit the brackets that will be welded to the back of the bumper. The bolt holes will be filled later too.
 
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#2 ·
Very cool!

Your car is gonna look great with that slick bumper on it.
 
#4 ·
Cnut....What a job.....:cool::congrats: How did you remove the chrome?
 
#5 ·
I was trying to remove all of the plating with muriatic acid. It took the chrome off pretty fast, but took a long time to remove the nickel. As you can see, the bumpers are mostly copper now. I wanted to get it to bare steel, but wasn't able to. Seems like a plating shop could reverse the current and de-plate it all, but they told me they would only remove the chrome for some reason.
 
#6 ·
Got a little more done tonight. :) I finished welding the other side, and ground it smooth on both front and back. The bumper is about 1/2" narrower now across the fender bracket bolt holes than it should be, since I straightened the seams out with a straightedge. A little tweaking and it will fit fine. Now I need to get it fit exactly the way I want it, and modify the brackets.

 
#10 ·
Ok, C-nut how much to build me one ? :bowtier:
 
#12 ·
Here's another update. In order to remove the bolt heads from the front of the bumper, you have to build brackets for the bolts to attach to. They used to weld the bolts to the back of the bumper, but it distorted it when you tightened them down. These brackets allow the bolt head to slide in from the bottom, and allows the attachment of the braces to them.

I also got the bumper fitted, and it's back a little from where it was, but only slightly. So I had to shorten the diagonal braces for the added bracket and for the new bumper location. I cut them off with my new bandsaw, fitted them, and tacked them back together.

Next step is to cut and fit the fender extension brackets to make the bumper level and to accommodate the brackets to eliminate the bolt heads.








 
#42 ·
#18 ·
what did you use to make the brackets for the bumper bolts? Do you think this could be done with a mig welder?

Kev
I think a mig would work just fine, but I have found that when you get bubbles in your weld with a MIG, it's hard to get them out. I picked up some silicon bronze TIG rod in case I needed to do any minor filling, but I haven't used it yet. If you get it very clean before you start welding, you should be fine. Get all the chrome and copper off. To fill the bigger holes, I made plugs and welded them in rather than try to fill them all.

I made the bolt brackets using a little trick I came up with. ;)

Since I don't have a milling machine (yet!!) I used what I had. I started with a piece of rectangular tubing and made cuts in it with my 14" abrasive cutoff saw. Then I finished the cuts with a die grinder with a cutting wheel, then cut out the extraneous pieces. When the cutting was done, I split the tubing and ground the brackets to the thickness I wanted (about 7/16"). The pics below show the process I used.
 

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#17 · (Edited)
Here's a little more progress from last night....

I needed to modify the fender extension bracket so I could fit the bolt bracket between it and the bumper, so I had to cut it and move the lower part inboard.

First I decided where to cut it, and took a section about the thickness of the bumper bolt bracket out.



Then I welded it back together, doing some tweaks to make it look almost like stock. This is after bead blasting.



Here's both of the brackets in place. I have the bumper bolt going all the way through the bumper, but I will be filling the bolt hole in the bumper and welding the bracket to the backside just like the bracket for the diagonal brace.



And here's the final fitment, looking from the top. I snugged up the gap just a tad so it looked cleaner.



So now I have to finish up the bracket for the passenger side, and then finalize the main frame brackets like I want them. Then I need to fill the bolt holes, do some final straightening, weld the brackets on, do any final tweaks, and it will be ready for sanding and chroming.
 
#20 ·
very nice im going to try and do a smoothie on my 57 i cant afford a new one. but can do most of the work myself
 
#22 ·
This evening I got the passenger side fender extension bracket modified and ready to go. And we built a front clip for another '57 C4 frame tonight too!! :happy0030:

Hopefully I can take the bumper off soon and start welding up the rest of the holes in it and then weld the bolt brackets to the backside. :)

I'm anxious to get to work on the rear bumper now. ;)
 
#24 ·
Got a little more done tonight. I removed the bumper and filled the fender extension bolt holes, then reinstalled it with the bolt in the bracket behind the bumper. I used the other brackets to keep things aligned, then I clamped and tacked the bracket to the bumper.

Hole filled with a square plug TIG welded in. I used a plug thicker than the bumper so I could grind it down....



Plug ground inside and outside and clamped in place...







After tacking...



Both sides are done at the fender extension, so next are the bolts for the diagonal braces which I'll do while holding the bumper in place with the other brackets. I'll remove the bumper again, plug the holes, and clamp and weld the brackets in place.

I know I could have done it all at once, but I didn't want to mess up. :rolleyes:
 
#26 ·
Yes it will fit, but it's not a "smoothie". It still has indentations for the bumper guards and the bolt heads all show. Personally I think it might be harder to make a smoothie out of a 1-piece bumper than a 3-piece.

I still don't understand why they didn't tool the smoothies first....seems that's what a lot of people want. :rolleyes:
 
#27 ·
Got back from taking my sweetie to a resort for the Valentine's weekend, so I took some time to work on the bumper again Sunday evening. :happy0030:

Just as I welded up the fender extension bolt holes, I also welded up the diagonal brace holes and "bodyworked" and sanded the areas smooth before welding the bumper bolt bracket on. The bolt areas tend to flatten out a little when welded and some of them are distorted by the bolts themselves, so you need to hammer it back into shape.

Then using the other 4 attach locations (frame brackets and fender extension brackets) to hold the bumper in place, I welded the diagonal brace bolt brackets to the backside of the bumper aligning them to marks I made prior to welding up the holes.



It looks better than this already... :)



With these bolt holes filled on both sides, and the brackets tacked to the backside of the bumper, it's time to finalize the main bumper brackets to the frame. I decided to do them one at a time so the other side would hold the bumper in the correct position.

First step is to weld up the bolt holes in the bumper, and do the final straightening in that area. It's important to have the bumper as straight as possible before welding the bracket on, because it will be difficult to do afterward. I started on the passenger side.....



I used a steel rod to plug the holes, holding it just slightly above the surface, tacking it to the hole, then cutting the remainder of the rod off. Then I used a 4" Makita angle grinder to get close to the bumper surface, then a 7" flexible disc sander, then finally a 3" die grinder with a Scotchbrite pad for the final finishing.

Next step is to weld up the holes in the bumper bracket, reinstall the bumper, and tack the bracket to the backside. Then repeat the process on the driver's side, and the bumper will be ready for final welding and smoothing...then plating. ;)
 
#28 ·
Okay, the front bumper is finished except for the final welding of the brackets, but I thought I'd post some more pics. I'm pretty happy with how it turned out....





Next up is the rear bumper. I've already twisted and pounded on the center section to get it fairly straight to start the fitting and welding.

 
#29 ·
Moving along....

I got the rear bumper guard and license plate light wire holes filled and smoothed, as well as a hole in the center that someone had drilled for some reason. I also did some bending and straightening of some dents and minor damage to the center section, which had a slight twist to it. I installed the brackets and braces for a trial fit...




Before fitting the bumper, I used some straightedges (thick steel bars) and clamps to line up the bumper ends and tack them to the center section, but will leave the final welding until after I do the initial fitting.

To fit the bumper I set the bottom of the bumper level with the bottom of the frame, and adjusted the bumper angle to make it fit correctly to the body and look the way I wanted it to. Next I will modify the bumper brackets to hold the bumper in this position, but I'll move the bumper forward to tighten the gaps to the body somewhat. Once the brackets are modified, I will address the diagonal braces like I did on the front bumper.

 
#30 ·
Looking great Laszlo. Looks like you didn't leave the platers much to do except dip it.
:congrats:
 
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