Tuesday, February 11, 2014

MattMobile - Rear Bumper and Support Arms

The day started with a quick trip to my favorite metal store, Industrial Metal Supply in Irvine. IMS is a sponsor of the MattMobile project, and I'm absolutely thrilled to have them on board. If you're in need of some metal or expertise, IMS is your place.

I had to pick up some telescoping rectangular tube steel for something that I will discuss in a future blog post, and also grabbed a few supplies while I was there. I got some replacement fiberglass cutoff wheels, some anti-spatter goo for the welding torch, and a piece of aluminum that I'm going to use on my DareDevil billy clubs. But the main purpose of my trip was to pick up some 2"X4" rectangular tube (14 guage) that I am going to use to fabricate a bumper.

As with previous work on the car, I'm sort of following in the footsteps of Tim Neil, who is building the BatBerry up in Canada. He fabricated a bumper using two pieces of 2"x2" stock, welded together. I figured I would skip that step, and just buy some properly sized stock. Also, it's a little thicker than the 2X2 stock I have on hand, so it'll be stronger.

A little gizmo that caught my eye while waiting for IMS to cut my steel to length is this magnet. It has both 90 degree angles and 45 degree angles on it, and the point here is that you use this to set up angles and hold steel in place while you weld it up. Getting 90 degree angles is pretty important to my build, and as you've seen from previous blog posts, I get mixed results.

If you don't have one of these, go get one.

With that said, the chore of the day was to fabricate a bumper and get it installed. MUCH easier said than done. I was experimenting with my new RIGID cutoff wheel saw, and frankly I'm not impressed. What it makes up for in lack of effort needed, it takes back by giving you pretty crappy and unpredictable cuts. The problem is that the blade deflects, leading to cuts that aren't where you want them to be. Still, it does some heavy lifting, which is helpful.

Fabricating the bumper should have been fairly straightforward, but I made a pretty stupid mistake early on and managed to drop an inch off my measurements prior to cutting. Which sucks, because I DID do the "measure twice, cut once" thing. I guess I need to up my game to "measure THRICE, cut once". The new magnet came in really handy for welding together the 45 degree cuts I made on the corners, and aside from being an inch two short, it came out really nicely.

However, I had to cut the thing down the middle and then add in an inch of material. I'm sure this weakened the overall structural integrity of the piece, but oh well. It is what it is.

Here you can see where I'm fitting the bumper into the frame of the caprice. The ends slide into the frame.

Once I corrected the problems of the missing inch, the bumper went into place very easily and nicely. It's also totally level. I was really happy with how it went in.

I was having some troubles with the welding torch, so I googled some troubleshooting stuff and ultimately made some changes to the settings which TOTALLY helped, and I'm now getting even better welds than I was producing before.

Flash forward, I welded in the bumper then welded in top of my welds some strips of steel to add strength. I then cut out a support arm for each side, and welded it from the outer tip of the bumper up onto the frame I've been fabricating inside the shell.

I of course did the same thing on both sides of the car.

Believe it or not, what you see in these last pictures is the culmination of 8 solid hours of work. Fabricating the bumper, installing it, cutting the support arms and attaching them is the sum total of today's efforts. All pretty cool. I noticed while taking pictures that I'm starting to accumulate some rust on my metal. Looks like it is the result of being handled by me. Once I get some more work done, I'll hit them with a wire brush and then give them a coat of primer to prevent further rust.

1 comment:

Anonymous said...

Looking good Matt!

One thing that I would bring up would be starting to think about where you'll be mounting 2 items.

1) Your fuel tank
2) Your air tank for suspension

You'll have to strategically think about where those will go, how big they will be, and how you can get them in and out of the car for repairs without having to tear the car apart once it's finished.

For me, I placed my fuel tank behind the front seats and in front of the rear cross member. However, you need to make sure there is enough clearance between the rear cross member and the arch at the top of the rear hatch opening.

Finding a fuel tank that will fit in this area is tricky. Especially since you will need to have one of your fuel caps sit higher than where the fuel filler neck enters the tank.

I placed my suspension air tank behind the rear axle and made enough room for a little "trunk" between the axle and rear bumper beam.

Hopefully that makes sense. If it doesn't feel free to send me a message on Facebook and I'll give you a call to explain it a bit further :)