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View Full Version : FJ40 Bumper Build - Phase 1


RicardoJM
04-10-2008, 08:18 PM
Inspired by the Technical Links information on Rzeppa’s web site and needing a bumper on the FJ40 I decided to build one. I want the bumper to have D-rings (for a tow bar), a winch plate (for an 8274) and nice tapered ends (to look cool) and I’d like to be able to say “yup I built it”. The whole project will be done in phases and could take me a long time, but with Phase 1 complete it seems appropriate to post up some details. The first phase was done with a grinder, sander and drill for power tools - pretty common to even the most simple home shop. Subsequent phases will need a welder.

The most challenging part of this first phase is the amount of grinding that is needed. If you decide to take this on, keep in mind there will be a bunch of time spent grinding. Get some good ear plugs.

The starting point for the bumper is a 5’ length of 5” c-channel. Atlas is just a couple of blocks from the office so I went over and checked the scraps pile. The longest piece of 5” c-channel was 2’, so I had them cut it off a fresh stick. The c-channel was $37 including tax.

The starting point for the frame on the FJ40 was not as straight forward. At some point in the past the stock gussets and brackets for the bumper were removed and steel plates were welded to the frame. Here you can see the plate on the passenger side.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/02passengerplate.JPG

I sourced some bumper gussets and brackets from Craigslist. I could have drilled the holes and mounted them right up to the steel plates, and in retrospect this would have been a much easier way to go. I convinced myself that the steel plates needed to be removed so the brackets would be in their “stock” position, as insurance incase the project became too big and I decided to buy a pre-made bumper. With the brackets in their stock position I would know the brackets would be in the right place. Here is a test fit of the gussets and brackets after grinding off the steel plates.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/05testfitoffactorybrackets.JPG

Prior to taking that test fit picture, I had to get those plates off so I took out the grinding wheel and got to it.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/03grindingoldplates.JPG

Grinding these steel plates off took the better part of a Saturday. On one side I was able to carefully cut out the center portion of the plate and grind down the edges. On the other side the plate had been welded on the edges and the backside, so I had to carefully grind off most of the plate. The end result on driver’s side looked like this.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/11driversholes.JPG

The sparks for the grinding wheel really did a number on my knee pad.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/06grindersparkstearupkneepads.JPG

With the plates all off, it was clear they had been put there to cover rust. With the rust exposed, I hit the frame up with a wire brush and coated the area with Permatex Rust Treatment. This makes a nice hard surface. You can see the treatment as it was curing here.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/13rusttreated.JPG

Next step was to grind away the ridge in the inner corners of the c-channel so that the brackets can be slid all the way in. The boys and I shared the grinding duty each evening for a bit and after a week we had cleared enough metal for the brackets. With patience and hard work, the brackets slide in quite nicely.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/08Allfitsinnow.JPG

Drilling the holes was the next step. We used the approach of starting with a small bit and increasing the hole diameter with larger bits until the desired size is reached. Of course this was after trying the 5/8” bit and convincing ourselves it was not the right approach. You can see here where the holes were started

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/12holesgohere.JPG

With holes all in place, we cleaned the bumper up hit it with primer and sprayed it with some Rustoeleum grey paint. I like the color better than black and as it is my bumper that is the color I used. Here is TheBoomBoom is sanding the iron.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/15preppingforprimer.JPG

Grade 8 mounting nuts, bolts and washers were sourced at the hardware store. I went with 5/8 bolts and they fit the holes very well. I’m pretty sure the original bolts were metric, but my hardware store did not have them thick enough in the grade 8 equivalent. With a bumper, knowing the mounting hardware is strong is critical. With 22 holes needing hardware, the nuts, bolts and washers about doubled the materials cost.

All mounted up, it looks pretty good.

http://www.risingsun4x4club.org/uploads/ricardojm/bumper/Finishedandmounted.jpg

subzali
04-11-2008, 08:02 AM
Nice work Ricardo! Way to stick through the grinding to bring it down to a clean frame! I know it's not fun but after a couple years you won't remember it and I think you'll be happier knowing your frame isn't b*&^*(dized...

FWIW when I bought my bumper it came with Grade 5 mounting hardware. I asked around, and the response I got was that Grade 8, when it does fail, is more catastrophic because it's more brittle; there's very little release of energy before failure. With Grade 5 there are indications of failure (deformation) before that actually occurs, which also releases some of that stored energy so bad things are less likely to happen...either way though I think with 22 5/8" bolts you'd be doing something really wrong to break anything...

Rzeppa
04-11-2008, 09:34 AM
Very nice write up and photos Ricardo! I saw the finished product at the WBPP and it looks fabulous! If and when you're ready for stage II (tapered and/or capped ends) I'll be happy to let you use my MIG.

Rezarf
04-11-2008, 10:40 AM
Keep it up Richardo, nothing like doing it yourself!

Drew