Rear Bumper/Spare Tire Mount Thoughts

[Gary Lewis]

With the 32" tires on Big Blue there's no way that the spare will fit in the stock place - and especially when I put the Bronco rear tank in. Right now the spare is taking up much of the space in the bed, but when/if I get to go overlanding I'll want it out of there to free up the space for gear.

So I've been thinking about how to make a rear bumper that will carry the spare as well as serve as an air tank for the on-board air compressor. But I was having a bit of trouble envisioning how to support the spare since it needs to pivot out of the way to open the tailgate. However, yesterday we were behind a truck in traffic that had a Wilco Offroad Hitchmate Solo on the back.

As you can see below, that unit, which runs about $800, slips into the receiver and hinges on the right to swing out when the red pin is pulled. I'm thinking of replacing the rear bumper with a piece of square tubing that is closed on the ends to serve as an air tank. And the arm for the spare would fit up against that, which should move it forward a bit.

Thoughts? Suggestions?

[grumpin]

My first thought was something in the receiver so you can take it out when you want. Then you mentioned what you saw.

If that will hinge out of the way that would be great!

I have the rear mounted spare tire carrier on my Bronco. Sometimes it's a pain, but worth it. I would lose a lot of room with it inside.

My wife's Suburbans spare is mounted inside, I assume they all are. Never really notice it till I'm trying to put something big back there.

I like the bumper/air tank idea also. You are a motivated individual!

[Gary Lewis]

My first thought was something in the receiver so you can take it out when you want. Then you mentioned what you saw.

If that will hinge out of the way that would be great!

I have the rear mounted spare tire carrier on my Bronco. Sometimes it's a pain, but worth it. I would lose a lot of room with it inside.

My wife's Suburbans spare is mounted inside, I assume they all are. Never really notice it till I'm trying to put something big back there.

I like the bumper/air tank idea also. You are a motivated individual!

Yes, having the spare in the bed, along with the large tool box, does take up a lot of room. So for real use that has to change.

As for motivated, I'm not sure that's the case. I just have a lot of grandiose ideas.

[85lebaront2]

Yes, having the spare in the bed, along with the large tool box, does take up a lot of room. So for real use that has to change.

As for motivated, I'm not sure that's the case. I just have a lot of grandiose ideas.

Gary, when I had my 1958 F100, I put a front mounted spare tire carrier, but, the 58 had a 6' bed and I never had the bed mount for it. I never had any problems with overheating, but, the radiator on the 58 was bigger than the 80-96/7 trucks have other than the Diesels.

[Gary Lewis]

Gary, when I had my 1958 F100, I put a front mounted spare tire carrier, but, the 58 had a 6' bed and I never had the bed mount for it. I never had any problems with overheating, but, the radiator on the 58 was bigger than the 80-96/7 trucks have other than the Diesels.

I thought about a front-mounted spare, but with the winch it would put the spare too high. And, I don't really want to add that much weight on the front of a truck that is already very nose heavy.

[85lebaront2]

I thought about a front-mounted spare, but with the winch it would put the spare too high. And, I don't really want to add that much weight on the front of a truck that is already very nose heavy.

Other than the unsprung mass of the front axle, Darth is the same nose heavy way, I just have a 168" wheelbase and front coil springs so he rides better.

 

[Gary Lewis]

Other than the unsprung mass of the front axle, Darth is the same nose heavy way, I just have a 168" wheelbase and front coil springs so he rides better.

Well, not quite. Big Blue has the heavy Warn winch bumper, 12,000 lb winch, and auxiliary battery up front. And the bumper and winch are well ahead of the axle so not only add weight to the front, but also leverage some off the rear. So I want my extra weight on the rear.

Speaking of which, I talked to a guy at church that not only has a metal fabrication shop but also has a Jeep he takes off road. He very quickly picked up on what I was talking about, and suggested that we use 6" square tubing with a 1/4" wall, which will allow them to weld on the towing eyes they plasma-cut out of 1" thick steel plate.

So now I need to get busy and design it.

 

[Gary Lewis]

Well, not quite. Big Blue has the heavy Warn winch bumper, 12,000 lb winch, and auxiliary battery up front. And the bumper and winch are well ahead of the axle so not only add weight to the front, but also leverage some off the rear. So I want my extra weight on the rear.

Speaking of which, I talked to a guy at church that not only has a metal fabrication shop but also has a Jeep he takes off road. He very quickly picked up on what I was talking about, and suggested that we use 6" square tubing with a 1/4" wall, which will allow them to weld on the towing eyes they plasma-cut out of 1" thick steel plate.

So now I need to get busy and design it.

First, before designing it, I need measurements and observations. And what better place to capture them than here. But, I welcome your thoughts, comments, and questions.

• Current bumper is 76 1/4" wide, 5 1/2" tall, & 7 1/4" front/rear

• But the bumper is recessed ~2 1/2" into body, as shown below.

• A 6" tube bumper wouldn't recess into the body, but if a 1/4" gap is left between it and the body it would only project 1" further to the rear than current bumper.

• Top of current bumper is only 1" below the bottom lip of the tailgate, and is only 1" below the tailgate when it is open. So anything put on top of the bumper would probably require the bumper itself to be placed lower.

• There is 4 1/2" of space from either edge of the tailgate's opening to the outside end of the current bumper. So, the pivot for the spare tire holder could be put there and clear the tailgate.

• But, there is 3" between the bottom of the current bumper and the top of the receiver hitch, so the bumper could be lowered or it could be taller. But, I might want to take the hitch off for offroading to get more clearance, so don't go too low.

• Could put a 2 1/2" angle on the front of the bumper between the body to fill in like the current bumper does, although I'm not sure why other than to reduce gaps. And, if that's desired I could put similar angle on the end of the tube to close that off like the current bumper does.

• Don't forget the license tag. It is currently recessed into the bumper, but could be on the very back of it. And, it needs to have lighting.

[Gary Lewis]

First, before designing it, I need measurements and observations. And what better place to capture them than here. But, I welcome your thoughts, comments, and questions.

• Current bumper is 76 1/4" wide, 5 1/2" tall, & 7 1/4" front/rear

• But the bumper is recessed ~2 1/2" into body, as shown below.

• A 6" tube bumper wouldn't recess into the body, but if a 1/4" gap is left between it and the body it would only project 1" further to the rear than current bumper.

• Top of current bumper is only 1" below the bottom lip of the tailgate, and is only 1" below the tailgate when it is open. So anything put on top of the bumper would probably require the bumper itself to be placed lower.

• There is 4 1/2" of space from either edge of the tailgate's opening to the outside end of the current bumper. So, the pivot for the spare tire holder could be put there and clear the tailgate.

• But, there is 3" between the bottom of the current bumper and the top of the receiver hitch, so the bumper could be lowered or it could be taller. But, I might want to take the hitch off for offroading to get more clearance, so don't go too low.

• Could put a 2 1/2" angle on the front of the bumper between the body to fill in like the current bumper does, although I'm not sure why other than to reduce gaps. And, if that's desired I could put similar angle on the end of the tube to close that off like the current bumper does.

• Don't forget the license tag. It is currently recessed into the bumper, but could be on the very back of it. And, it needs to have lighting.

A bit more info. A 76" long piece of 6" square tubing with a 1/4" wall will weigh 125 lbs. So, by the time the spare carrier is added this will be a significant piece.

And a square tube of that size will create a 10 gallon tank, which is said to be a good size for a system with a York/Techumseh engine-driven compressor. But I need to remember to put a drain in it.

[Steve83]

...a rear bumper that will...serve as an air tank...

I've never liked that idea; and even less since watching an air tank explode a few feet from me. Even on my SWB Bronco, I was able to find plenty of room inside the frame to put a useful-sized air tank (actually 2).

https://supermotors.net/getfile/951538/thumbnail/16oba.jpg

...square tubing that is closed on the ends to serve as an air tank.

Sharp corners (like square tubing) are natural weak-spots for pressure vessels. I'd avoid that.

And the arm for the spare would fit up against that...

Do you mean the swing arm would be the rear-most object on the truck at bumper height when no trailer is connected? I'd be really nervous about backing into something or getting rear-ended, and damaging that arm.

I thought about a front-mounted spare, but...I don't really want to add that much weight on the front of a truck that is already very nose heavy.

...the heavy Warn winch bumper, 12,000 lb winch...

My front bumper & winch are heavier than those, and I'm not damaging my front wheel bearings yet, with several dozen thousand miles hauling it around on a 1/2-ton suspension. This was the previous bumper:

https://supermotors.net/getfile/524743/thumbnail/weightbwinch.jpg

The current one is slightly heavier, though I'm not sure how much:

https://supermotors.net/getfile/997240/thumbnail/9321tethes.jpg

Your 3/4-ton should have substantially more front-axle reserve capacity. What does it say on the VC label?

https://supermotors.net/getfile/72354/thumbnail/doorsticker.jpg

..auxiliary battery up front.

I put that in the middle of the chassis under the floor, so it actually helps the CG, and distributes the weight to both axles.

...tubing with a 1/4" wall, which will allow them to weld on the towing eyes they plasma-cut out of 1" thick steel plate.

The frame is less than 1/8" thick - it has never made sense to me to add anything more than double the frame's thickness to the frame. It's just overkill, and unnecessary weight; usually an attempt to make up for a poor design. My front shackles are on 1/8"-wall square tube inserts, and they've taken the full 12Klbs from the winch.

So anything put on top of the bumper would probably require the bumper itself to be placed lower.

...

So, the pivot for the spare tire holder could be put there and clear the tailgate.

If the pivot is outside the t/g swept volume, then the arm can ride inside that volume when the t/g is up.

...the receiver hitch...

My truck's receiver was originally a few inches below the bumper, but when I designed mine, I integrated them. Look at this & the NEXT several:

https://supermotors.net/getfile/292107/thumbnail/rear-seethru-s.jpg

The design includes integral pivots for future mods like a swingaway, but I haven't built those yet. The factory swingaway has survived my "exuberant" off-roading style.

...I'm not sure why other than to reduce gaps.

To prevent the tires from slinging dirt (or dirty rainwater) up on top of the bumper, or against the front lip of the t/g.

...similar angle on the end of the tube to close that off like the current bumper does.

Think about how that will snag things that the bumper rubs against; on-road, or off-.

...could be on the very back of it. And, it needs to have lighting.

Consider a t/g-mounted license plate, like early Broncos.