Planning my rear bumper

[yosh18981898]

Well, I made the front bumper and now I'm hooked!

Here's a pic of what I want to do with the rear:

It may be a little out of scale but you get the idea.

It will be 1/4" x 8" steel on the back, 1/4" x 6" on top, 1/4" x 3" on the bottom. 3/8" on the ends where the tube gets welded on. The mounts will be 3/4" x 4" and go through the bumper and have the D-rings mounted on them. The mounts and hitch tube will be angle braced on all sides. The "tubes" will be 1.5 Galvanized pipe (which carries the same ASTM spec as HREW of the same size) It will bent at the ends. I plan on keeping the plastic rear fenders and putting some kind of bracing behind them that can take a good hit.

Well, what do you guys think?

 

[appx91]

Looks good! But I would go ahead and chop the plastic off in the back and wrap around the bumper.

 

[Bronco638]

Looks good. Any chance you'll want to make two (w/o the wrap-around)? I have an idea for a rear tire carrier that you incorporate into your design. Let me know - Dave.

 

[DrtTrac]

http://www.zjstech.net/~meetphotos/AZ04/

Here's what I did with mine...

 

[yosh18981898]

OK, here's an updated pic. This one is to exact scale and has the tire carrier on it:

Tell me what you think

 

[XplorerKid]

what about the stress of the area i encased in red box, when the carrier is swung open?

and that bumper is gunna be one haevy ****

and how bout something a little bigger than 3/4" for the tire carrier? seems like it might not be strong enough, not sure, never really messed with designign something besides my old front bumper, but 3/4"s sure seems small for a tire, how big of a tire you gunna run? Even plan on going bigger? Say 33", 35"? Might as well make it strogn enough for that now so you dont have to redo it in the future

 

[yosh18981898]

Thats the latch side. The hinge is on the right side. The latch side doesn't support any weight. I estimate the weight of the bumper (without tire carrier) to be 90 pounds. Do you know what the stock bumper wheighs? I'd guess at least 70 pounds....

 

[yosh18981898]

I figure if I build it in the "truss" design, the 3/4" will be just as strong as 1"x3" square tubing with the same wall as the pipe (0.14")

Remember that the 3/4" is inside diameter, the OD is about 1-1/8"

I guess I could make it out of 1" pipe...

 

[XplorerKid]

Thats the latch side. The hinge is on the right side. The latch side doesn't support any weight. I estimate the weight of the bumper (without tire carrier) to be 90 pounds. Do you know what the stock bumper wheighs? I'd guess at least 70 pounds....

Ok sorry from your drawing that looked to be the hinge point..... i guess there wont be much stress there.... what kinda hinge you gunna run? Something liek this?

 

[yosh18981898]

yep

The hinge pin itself will be 3/4" round hardened steel rod. I found some nice 3/4" ball bearings that fit super tight inside a piece of 1-1/4" pipe. I'm gonna brace the pin on top like your picture shows. Do you think that will work good?

 

[Robb]

The problem with that design, and all horizontal latch tire carriers with a single bearing mount position, is the simple amount of weight placed on the bearings. What kind of bearing setup are you planning on running at the hinge? Most run a type of trailer wheel bearing kit. IMO, and from what I have personally witnessed, the play inherent in these bearings is enough to drop the latch side of the swing-arm up to 1-2" depending on tire weight (and of course is no good for the bearings). An alternative to the horizontal swing-arm setup that I have seen, and been most interested in, is a fold down type of tire mount.

 

[yosh18981898]

Hold on, I'll draw my design up real quick...

 

[Robb]

Oh, and another obsevation before I hit the sack. Centering the tire mount blocks your view out the rear glass. If you designed it so that the tire mount was placed off to the side (off to the right for your example), would allow for a more open view out your back window.

 

[yosh18981898]

OK, heres what I was gonna do for the hinge...

 

[yosh18981898]

I've got a tire carrier on my stock bumper right now. The hinge is just a 1" bolt inside two pieces of 1" pipe, one of which is welded into the bumper. That one only flexes about 1" at the latch end, and most of flex is in the bumper.

 

[Dannyboy]

like Robb said, put the tire off to the side. I chose the drivers side. I can look out the window and see more out of that side mirror, when backing out of a parking space or wheeling it's nice to be able to see that back passenger side without the tire.

 

[jimbo74]

also if yuo plan on wheeling i would ditch the dual exhuast, especially exiting that low...i have used my stock bumper as a skidplate befroe dropping off of ledges, and that was in sand... jsut imagine what a rock would do to the exhuast

 

[yosh18981898]

The exhaust is just there for looks on the drawing. I'll probably have it come out through the bumper, or if I do put it underneath, make the last sections of pipe easily removable so I can just take the exposed part off before I wheel it.

 

[yosh18981898]

I was thinking about moving the tire to one side and I decided against it for these reasons:

1) I don't want to put it on the passenger side because I look through the glass in that area more than I do through the center (like every time I move from the left lane to the right) and I can see a lot more out of the driver side mirror than the passenger side mirror.

2) I don't want to put it on the driver's side because that's not going to help the 3/4" of driver's side sag that I already have.

3) My current tire carrier (I'll get pics this weekend) has the tire mounted in the center and I don't mind it at all (although it is only a 235/75R15)

 

[yosh18981898]

I was thinking of ways to make this thing lighter and heres what I came up with:

I could make the top and bottom 1/8" thick and leave the face at 1/4" and put a bunch of angle braces in the inside corner (where bottom meets face and top meets face). I could also make the end caps 1/4" instead of 3/8". Instead of 3/4"x4" for the bumper/shackel mounts, I could use 3/4"x3". I think this would still be plenty strong for the hitch. This would cut the weight to about 68 pounds.

Does this sound like a good idea?