How to unbend aluminum bumper

[BigR]

Hi All,

Looking for bumper options for my 544 Volvo "lead sled". The original ones are old, dented, and too big, especially with the overiders. So far I have tried on Morris Minor front and rear and old (non BMW) Mini bumpers, that were donated to me. They weren't right.

Here is the look I'm going for, see pics. Not my Volvo. The blurb on the car pictured said that the bumpers were VW items that he straightened and adjusted for fit. You can see how much of a curve they have from the pic of the Bug. I can get the VW billet aluminum bumpers from a number of places for about a hundred apiece.

The Briz ribbed aluminum ones look good to me but of course they would be expensive. Also I need to know how the bumper looks on the car, and make adjustments as needed.

Here's my question: How do I take the center arc out of the billet aluminum VW bumpers? The Bug front and rear is curved, while the Volvo has more of a flat face and tail. There must be a way using weight, a floor jack, winch, etc. to take part of the curve out. I'm counting on them to be sort of flimsy anyway. Probably would get bent easily in a parking lot encounter.

Naturally using heat is out of the question, can't control it that well, and aluminum melts instead of glows when it gets too hot.

Looking for a rat rod low buck fix, not interested in the "Take it to so and so's shop, they are experts" answers. This is MY build. Easy to throw money at a problem, not my style. I wanna do it in my garage; the fun is in figgerin' out and fixin' the problem. This is a cut and try operation. I have lots of patience. If I mess it up, then I've learned something.


John in Prescott.

 

[kenny c]

Haven't worked with them but you could try putting them in a press and working them a little at a time. If you don't need the ribs a set of 40 ford bumpers may do. They are steel and you could paint them any color you like.

 

[Sam_Fear]

"take it to a shop." BAH! You won't hear that around here to often.

Rolling it might work? But I'd be afraid it would mar the surface. Maybe a wooden jig to press it into shape? Most anything else seems like it would run the risk of bending in one spot.

 

[Dr Crankenstein]

Just a semi-educated thought or three...

It depends a lot on what the bumper is actually made of. ("Billet" doesn't tell you the alloy or grade of the material.)

At $100 each, I suspect they're rolled from a relatively light, soft alloy extrusion. (If that's the case, you can probably bend it over your knee.)

"Harder" alloys require heavier equipment to form. (You're not likely to bend a heavy 6061 or 6063 piece at home without cracking it.)

Anyhow, I wouldn't be afraid to mess with the $100 bumpers. I'll bet they'll bend easy as a coat hanger...


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[anvil]

The way to tell if the temperature is right for forging aluminum. A pice of hard wood slips. Yes it melts before color.

 

[BigR]

Well, if I was still in Kalifornia I could probably find a "Cal Look" VW Bug with these bumpers on it. That way one could find out how easy it would be to bend the extruded metal. This would require, of course, someone to distract the owner while the experiment was taking place. I doubt they are made of some strong alloy.

John in Prescott

 

[Bamamav]

If you have access to a press, it would be pretty easy to block and press a little at a time until you get what you want. I had an aluminum door off my headache rack get bent, I used the dolly on my loaded semi trailer to press it back into shape. A lot of crank twisting, but it got the job done. In a pinch, you could do it with a hydraulic jack and something heavy to press against.

 

[BigR]

Here is how I took the excess curve out of the trunk lid on the Volvo. I cut some wood blocks to support the ends of the lid, following the contours of the edges. Then I used a big padded wood block as a press. The weight of the car provided the force. Don't know why can't use the same general idea for the bumpers. They would be much easier to bend.

John in Prescott

 

[Tripper]

Here is how I took the excess curve out of the trunk lid on the Volvo. I cut some wood blocks to support the ends of the lid, following the contours of the edges. Then I used a big padded wood block as a press. The weight of the car provided the force. Don't know why can't use the same general idea for the bumpers. They would be much easier to bend.

Sometimes the simplest way is the best! [cl[cl[cl

BoB

 

[Dr Crankenstein]

Here is how I took the excess curve out of the trunk lid on the Volvo. I cut some wood blocks to support the ends of the lid, following the contours of the edges. Then I used a big padded wood block as a press. The weight of the car provided the force. Don't know why can't use the same general idea for the bumpers. They would be much easier to bend.

John in Prescott

Sounds like a plan. [cl

I used the dolly on my loaded semi trailer to press it back into shape.

Pomona CA 1998: We badly boogered the body latch (among other things) on our funnycar. We used the same method to straighten it out!

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[BigR]

Here's a quote from the description blurb from one of the suppliers of the VW bumpers. I assume they are all made in the same Chinese "factory", whoever sells them. Even reads like Chinglish!

Billet Aluminum Front Bumper, Beetle, is the beautiful Billet Aluminum 3-RIb Bumper Blade. They are not designed for protection, but FOR LOOKS!

That implies they are not too strong, just what I need!

I doubt that they are "billet." More probably extruded.

I'm assuming these are pretty flimsy, worth a try you think?

BTW, I wrote to Briz about ribbed bumpers for the Volvo. They said to make a template on butcher paper and send it to them. I can imagine they wouldn't be cheap!

John in Prescott

 

[dutch]

I bet you can shape them any way you like if you stick them between a couple pieces 2x4

 

[05snopro440]

Could you make a wooden buck a little flatter than you're looking for, and carefully and slowly form the bumper to fit the buck? Accounting for a little bit of ductility in the steel, it should get you right about where you need to be.

 

[dutch]

I`d draw a crayon line on a flat floor and start bending. Using the floor gives you a good view on the curve you`re making.

Make sure the 2 posts you use to bend are 100% parallel or you will end up with a weird shape. for bending this soft alu I would use wood or nylon posts to bend over.
Use a marker to mark the center and mark the center of the shape drawn on the floor. Keep them lined up. Just work methodical one side from the center outward then the other side. Place 2 marks on both ends of where it needs to stretch or curve. I`ve shaped dozens and dozens of bars that way. Check what you did and Just take your time. [P

 

[BigR]

That's a good idea. One could just project a line down from the body to the floor using an "L" square. That would establish the curve. If one used butcher paper then would be able to transfer this line to a piece of thick wood to be used as a three dimensional pattern. Would have "male" and "Female" pieces and trap the bumper between them to see where the pressure needed to be applied. I agree it should be symmetrical.

Maybe we are just overthinking this whole thing. Time to start banging on metal.

I did check out a Bug today in a parking lot. The rear bumper seemed to have more of a curve than the front. Think I'll order two fronts.

John in Prescott Arizona

 

[Dr Crankenstein]

Maybe we are just overthinking this whole thing.

Probably.

I'd expect the chinesium to be a soft alloy and easily "reformed" by whatever method you choose. I would proceed with confidence and caution. Aluminum "work hardens" quick, so you want to creep up on the desired profile...

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[BigR]

Another excuse to go to HF. appropriate to use a Chinese tool on Chinese parts.

Suspect I will find lots of use for this thing once I get it home. Looks like it will take a while to assemble. I like to put stuff together.

John in Prescott, AZ

 

[dutch]

so... you (tack) weld a couple 1", 6" long round bar or tubes to your bench , set them square and start bending by hand....
really ,that press wont be any help as the post are right where you want the bumper to rest.

 

[Bamamav]

so... you (tack) weld a couple 1", 6" long round bar or tubes to your bench , set them square and start bending by hand....
really ,that press wont be any help as the post are right where you want the bumper to rest.

He'll probably need to make a jig that straddles the main beams, then bend between the points on it. Something like an H, with the top uprights being farther apart and shorter. Then you could press it flatter is short presses, kinda like reversing the eye on a leaf spring but not going a complete reverse, stopping when it gets as flat as he needs.

 

[BigR]

Keep those ideas coming, all input is welcome. Unfortunately, I don't have any welding equipment, yet. While I was still in Kalifornia I had my brother do all my welding. He's still there.

Might just obtain some aluminum stock and experiment. Unfortunately, the local scrap yard went out of business. Looks like another sacrafice to the gods of development. Probably will be an apartment complex someday.

John in Prescott, AZ