Vanagon – rear bumper build

I figured I need to post what I have done so that I have more reason to finish the job. I want to make new bumper, front and rear. Not because the stock bumpers are damaged or rusty, but because I want bumpers that are a bit stronger and will be able accept a spare tire carrier on the rear and better aux. light mounts up front. And just because I want to make some bumpers.

It’s a project that never seems to get really going nut here is the progress to date.

Last year I fooled around with making a mock up rear bumper out of door skin and hot glue. I came up with a shape that to be honest was the best I could given the brief of it being simple, slim (not bulky like some aftermarket bumpers – yes, I’m looking at you Go-Westy) and easy to make. The door skin and hot glue construction makes it easy to add or remove material and have a relatively solid model to play with. I have a hard time visualizing an object from drawings so I tend to make a mock up (or remake the real object).

I started with a slim bumper design, very simple with a flat top surface (to make standing on bumper easier), a gentle curve on the rear vertical face that closely mimics the stock bumper, and a curved lower edge rather than straight lines to where the bumper caps would be. I took the first design over to let Simon have a look. His tastes lean a bit more towards a heavier bumper so I stuck on more door skin and made it so.

BTW, in the mock up pics the bumper is shifted to the left due to interference between the stock bumper mounts and some wooden braces in the mockup.

I don’t like this at all.

IMG_1974

I removed some wood, looks better. Probably would please Simon.

IMG_1976

But I like ’em slimmer still. Ended up back to the original shape.

IMG_1978

Right then, I’ve settled on the rough shape now what material will the real bumper be made from? Silly question, aluminum naturally. I’m using some off-cuts of 1/4″ aluminum plate (6061). I think that thickness will be plenty strong, especially when it is bent and welded up into the final “C” channel of the design.

I should mention that I took dimensions from the mock up and “projected” the 3 faces onto the top of the workbench. I used a bit of wood to fair the curves and picked up the shapes for the 3 main parts (top, bottom, rear face)h onto some polyethylene sheet. I could then tape the pattern onto the aluminum stock and use a prick punch to mark the shape on the aluminum. But I’m getting ahead of myself, I have to weld some of the aluminum together before cutting out the shapes.

My lumpy and large TIG weld. In my defence, I hadn’t touched the welder for a couple of months so what little skill I did have seemed to have slipped away.

IMG_2482

IMG_2483

IMG_2484

I’ve cut out the 3 main parts, rather roughly I’m afraid, and if I have time today I’ll try bending and tacking them up. I’ll need to make some internal braces just to make the weld up easier. I’ll TIG weld the tacks, then I think I’ll use the MIG welder for the final weld up. It would be sort of silly for me to TIG the long welds.

  1. #1 by famillysyncro on August 1, 2013 - 3:10 pm

    It is going to look sweet…..

    • #2 by albell on August 1, 2013 - 6:38 pm

      I hope so, especially when I grind my welds smooth 🙂

      ab

  2. #3 by Tim Risk on August 2, 2013 - 6:34 am

    I built an experimental house that had large framing members made of 1/4 inch aluminum welded into “box” shapes weld seams at the outside corners. We finished these welds by running a standard carbide router bit with a guide bearing around the edges. Much cleaner than grinding

    • #4 by albell on August 2, 2013 - 7:20 am

      Tim,

      you’re spot on. We use a standard woodworking router to radius some parts at work (router table, pilot bit). One gotcha with the bumper is that the top and bottom plates are not at right angles to the face plate. I haven’t held the router up to the bumper yet to see how it will work, might, might not.

      cheers

      ab

  3. #5 by Pz on August 2, 2013 - 6:18 pm

    Looking good Alistair.
    Your welding skills and finesse are looking good.

    Choice of Al alloy is the same Volvo utilized when producing their extruded
    5 mph bumpers for the 240 Series Cars.. The thickness was variable but, averaged
    around 1/8″ to nearly 5/16″, depending where, in the extrusion…
    They were stiff as a 14 year old’s johnson.

    May recall, I used a pair of 240 Volvo bumpers, modified to fit onto my Westy.
    Grinding and sanding the joints and cuts were the most time consuming part of the project.
    I finished with a wet sanded (120 grit carbide) finish.. Easily cleaned up when necessary with
    more wet sanding. I would prefer to have them anodized but… that means Vancouver shipping!

    For weight saving… I still stand on; your lab rats otta mould up some carbon fibre ones
    made on the oem glass fibre ones… Add some kevlar and you could hang a spare tire
    or whatever off that bumper!

    Pz

    • #6 by albell on August 2, 2013 - 7:19 pm

      Phil,

      I recall your Volvo bumpers, they looks good on the van.

      As to carbon fibre, well, you priced resin and carbon fibre cloth recently?

      🙂

      And it would probably need to be vacuum bagged….so need to make a mold….

      cheers

      ab

      • #7 by Pz on August 2, 2013 - 9:33 pm

        Carbon and Kevlar cloth…. cost’s like gold!
        Darn Wars and Police Protection of late.
        Epoxy resin… same old same old… Good Stuff!
        The mould….shoot… use an old fibreglass bumper as a mould?

        Ps I paddle a kevlar canoe so realize the cost associated with
        the fabric.:-)

      • #8 by albell on August 2, 2013 - 9:46 pm

        Ok Phil, I’ll bite after you go first 🙂

        How about a carbon fibre pop top ?

        🙂

        cheers

        ab

  4. #9 by Francis X. Watts on August 21, 2013 - 8:01 am

    Looking goood!!!

    Yes, a carbon fiber Pop top would be a cool idea. I have been thinking about that too.

    Chees!
    Francis

    • #10 by albell on August 21, 2013 - 8:09 am

      Thanks Francis,

      Project has been on hold while I do actual work. But I have started on the trailer hitch – steel tubing etc – that will go behind the aluminum and mount to frame just like the factory set up.

      A carbon fiber pop top is interesting, but I would lean towards a double walled lay-up with a foam core. For insulation and stiffness. Carbon fibre might not be needed, some other fabric perhaps – kevlar? or that that polyolefin (I think) stuff.

      cheers

      alistair

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