Rear Bumper/Spare Tire Mount Thoughts

[Gary Lewis]

I do plan to have a skid plate. I have the factory one off Dad's truck, but if I remember correctly it is a flat plate. Instead, I think I need the skid plate from the Bronco with a 32 gallon tank, which is D8TZ 9A147-A. Then I can shim it off the frame a bit to clear the 38 gallon tank.

Bronco Graveyard has it: https://shop.broncograveyard.com/1978-1979-Ford-Bronco-Skid-Plate-33-Gallon-Only/productinfo/20254/. But I don't know if it will fit a pickup. Does anyone know?

Another option would be to shim the one from Dad's truck.

Thoughts?

I've been slowly re-drawing the bumper and spare tire carrier in 3D. It isn't done but I thought I'd share with you where it is and invite (beg for?) your comments.

Here's an overall view, so let me point out some of the design details as well as things that need to be added or resolved:

• I had planned to design it to carry a 44" tire, even though BB currently runs 31's. But that puts the top of a 31" tire 12" above the top of the tailgate, blocking the vision. So, I might drop the carrier 4", which will mean that a 35" tire will just about be the max.

• The tire carrier is 2 1/2 x 1/4" square tubing. The pivot is a 1 3/4" OD tube that is inserted through the bumper and welded top and bottom. The swivel is a piece of 2" tubing w/a .120 wall, which will give .010" clearance. The square tubing is fish-mouthed to fit the swivel tightly and give as much room for welding as possible. I'll need to put a washer between the swivel and the bumper for wear, and I'll add a grease fitting as well as a retaining bolt and washer at the top.

• The left end of the tire carrier will ride on a little ramp on the bumper, perhaps made of nylon, and be held to the bumper w/a clamp like this one.

• In addition, there will be a tab on the arm close to the left end that will catch the bumper so it can't swing too far and hit the tailgate. Further, I want to put a little catch on the bumper that will pass through a hole in that tab and automatically hold it to the bumper. I cannot find a description or picture of what I have in mind, but there are some on my boat. It's a pin that's split on the end with an unequal length arm pivoted in the split. Normally the long arm is down, and when you swing the tire carrier against the bumper the pin will go through the hole in the tab and then the long end of the arm swings down, capturing the carrier. I know that sounds like a belt and braces approach, but that's me.

  The only issue is how far that pin will stick aft of the bumper and how many times I hit it with my leg.

  So I'm open to other options, like maybe a big wing bolt. Or just a pin with a hairpin to retain it?

• Also, I have to figure out how to prevent the carrier from pivoting all the way around and slamming into the side of the truck. Ideas?

Here are a couple more shots:

[Nothing Special]

I've been slowly re-drawing the bumper and spare tire carrier in 3D. It isn't done but I thought I'd share with you where it is and invite (beg for?) your comments.

Here's an overall view, so let me point out some of the design details as well as things that need to be added or resolved:

• I had planned to design it to carry a 44" tire, even though BB currently runs 31's. But that puts the top of a 31" tire 12" above the top of the tailgate, blocking the vision. So, I might drop the carrier 4", which will mean that a 35" tire will just about be the max.

• The tire carrier is 2 1/2 x 1/4" square tubing. The pivot is a 1 3/4" OD tube that is inserted through the bumper and welded top and bottom. The swivel is a piece of 2" tubing w/a .120 wall, which will give .010" clearance. The square tubing is fish-mouthed to fit the swivel tightly and give as much room for welding as possible. I'll need to put a washer between the swivel and the bumper for wear, and I'll add a grease fitting as well as a retaining bolt and washer at the top.

• The left end of the tire carrier will ride on a little ramp on the bumper, perhaps made of nylon, and be held to the bumper w/a clamp like this one.

• In addition, there will be a tab on the arm close to the left end that will catch the bumper so it can't swing too far and hit the tailgate. Further, I want to put a little catch on the bumper that will pass through a hole in that tab and automatically hold it to the bumper. I cannot find a description or picture of what I have in mind, but there are some on my boat. It's a pin that's split on the end with an unequal length arm pivoted in the split. Normally the long arm is down, and when you swing the tire carrier against the bumper the pin will go through the hole in the tab and then the long end of the arm swings down, capturing the carrier. I know that sounds like a belt and braces approach, but that's me.

  The only issue is how far that pin will stick aft of the bumper and how many times I hit it with my leg.

  So I'm open to other options, like maybe a big wing bolt. Or just a pin with a hairpin to retain it?

• Also, I have to figure out how to prevent the carrier from pivoting all the way around and slamming into the side of the truck. Ideas?

Here are a couple more shots:

The factory tire carrier on my early Bronco swings around and hits on the side of the vehicle. It's not that big of a deal because it's the tire that hits. There is a dent in the trim from it swinging in pretty hard once or twice, but with a little care it's not that bad (certainly less damage than I've done rock crawling!).

But originally it didn't swing that far. From thy factory it had an "allsyagotta". As in "alls ya gotta do to keep that from swinging around and hitting the side is put a cable on it." There was a cable hooked to the swinging carrier that would pull tight when it was opened about 100 degrees (I don't recall what the other end was anchored to). It worked OK, but was a little hokey, and didn't seem necessary, so when I took it apart for paint I never bothered to put it back on.

[Gary Lewis]

The factory tire carrier on my early Bronco swings around and hits on the side of the vehicle. It's not that big of a deal because it's the tire that hits. There is a dent in the trim from it swinging in pretty hard once or twice, but with a little care it's not that bad (certainly less damage than I've done rock crawling!).

But originally it didn't swing that far. From thy factory it had an "allsyagotta". As in "alls ya gotta do to keep that from swinging around and hitting the side is put a cable on it." There was a cable hooked to the swinging carrier that would pull tight when it was opened about 100 degrees (I don't recall what the other end was anchored to). It worked OK, but was a little hokey, and didn't seem necessary, so when I took it apart for paint I never bothered to put it back on.

I looks like I can put a tab on the front of the bumper's right end that will catch the arm before it hits the body. Obviously it'll have to be solid, but that would be better than a chain.

I reviewed my plans with my nephew today. He's a mechanical engineer as well as a tremendous mechanic. He liked the plans, although he did seem to think that a ball or roller bearing arrangement for the swing arm would be better than my plans to use the tubing for the bearing. But I think the tubing will be adequate for the limited number of times it'll be used.

Thoughts?

[Nothing Special]

I looks like I can put a tab on the front of the bumper's right end that will catch the arm before it hits the body. Obviously it'll have to be solid, but that would be better than a chain.

I reviewed my plans with my nephew today. He's a mechanical engineer as well as a tremendous mechanic. He liked the plans, although he did seem to think that a ball or roller bearing arrangement for the swing arm would be better than my plans to use the tubing for the bearing. But I think the tubing will be adequate for the limited number of times it'll be used.

Thoughts?

On the stop, keep in mind that anything near the pivot has a big mechanical disadvantage. For instance, if it's 1" from the pivot point and you lean with 10 lbs of force against the other end of the carrier, say 40" from the pivot, you have a 40:1 advantage, and the stop (and pivot) see 400 lbs of force from your little 10 lb lean. Not saying it can't work, just realize that the forces can really skyrocket.

On the bearings, I'd be a little leery of the unfinished ID of steel tubing as a bearing surface. It'll work for the little motion and very low speeds it'll have to deal with, but it'll probably feel rough and it will wear. Rolling-element bearings would be best,but are way overkill (and we all know how much you hate overkill ). I'd maybe try to get a smaller ID tube that I could bore out to get a smoother surface. Or maybe a larger ID that I could press some plastic or sintered bronze bearings into. But again, I do think your idea will work.

[Gary Lewis]

On the stop, keep in mind that anything near the pivot has a big mechanical disadvantage. For instance, if it's 1" from the pivot point and you lean with 10 lbs of force against the other end of the carrier, say 40" from the pivot, you have a 40:1 advantage, and the stop (and pivot) see 400 lbs of force from your little 10 lb lean. Not saying it can't work, just realize that the forces can really skyrocket.

On the bearings, I'd be a little leery of the unfinished ID of steel tubing as a bearing surface. It'll work for the little motion and very low speeds it'll have to deal with, but it'll probably feel rough and it will wear. Rolling-element bearings would be best,but are way overkill (and we all know how much you hate overkill ). I'd maybe try to get a smaller ID tube that I could bore out to get a smoother surface. Or maybe a larger ID that I could press some plastic or sintered bronze bearings into. But again, I do think your idea will work.

I agree with your math on the force on the swing arm. But I don't have a lot of choices - at least few I'm aware of. Here's the one I've got drawn, which is a 1" thick by 1" wide stop with a 45 degree ramp on the front. And, while the ramp won't really be used as the arm should be at the same height as the top of the ramp, it does give more leverage to the weld.

The inside edge of the stop is 1" from the center of the pivot, and the outside is 2". So the force will average a bit less than you calculated, but will be spread over a larger area.

As for the pivot, Ben said his company has several and he'll see what he thinks is best. But I've looked at trailer spindles and there's one which uses 1" bearings and is good for 1250 lbs. The large end of the spindle is 1 1/4" and it is, obviously, steel so can be welded. However, all the hubs I've seen are cast, so welding to them is questionable. So Ben will see if he can find one that is steel and not cast. I could turn it down in the lathe to get a reasonable diameter.

Anyway, please keep those cards and letters coming in!

[Gary Lewis]

I agree with your math on the force on the swing arm. But I don't have a lot of choices - at least few I'm aware of. Here's the one I've got drawn, which is a 1" thick by 1" wide stop with a 45 degree ramp on the front. And, while the ramp won't really be used as the arm should be at the same height as the top of the ramp, it does give more leverage to the weld.

The inside edge of the stop is 1" from the center of the pivot, and the outside is 2". So the force will average a bit less than you calculated, but will be spread over a larger area.

As for the pivot, Ben said his company has several and he'll see what he thinks is best. But I've looked at trailer spindles and there's one which uses 1" bearings and is good for 1250 lbs. The large end of the spindle is 1 1/4" and it is, obviously, steel so can be welded. However, all the hubs I've seen are cast, so welding to them is questionable. So Ben will see if he can find one that is steel and not cast. I could turn it down in the lathe to get a reasonable diameter.

Anyway, please keep those cards and letters coming in!

I fear y'all have tired of this subject. But I haven't, and have done some more work on it.

But first, I've created a page for this project on the website: About Me-Contact Me/Projects/Rear Bumper and Spare Tire. And, I created a "project" called Rear Bumper And Spare Tire Carrier in the Project section here in the forum.

My reason for creating the two is to test how well they work. The one on the website gets the pictures automagically updated as I work on the project and "print" new pics. And, the viewer can zoom in and pan around on them, which you can't do in the pics in the Project section of the forum. So, please tell me your thoughts as I can't keep two different places up to snuff. (I like the webpage best, so....)

Now, for the updates and questions:

- I've added a license tag holder and a 3rd brake/license tag light/backup light in the middle of the spare tire. But I'm not happy with the lights I've found as most are too tall - it shouldn't be more than about 3". So, if you have some to suggest....

- I've added a filler panel to the top front of the bumper to keep the yuk from being kicked up and getting onto the bumper

- I made the swing arm go all the way across and the angled spare tire support arms go basically to the ends of the arm. There are two reasons for that. First, by making it a full triangle the thing can't sag. Second, it makes each arm almost 38" long and I think I can get a hi-lift jack mounted on the arm.

Thoughts? Please? I'm hoping to have this made for my Christmas present, and need to get it right.

 

[Dyn Blin]

I fear y'all have tired of this subject. But I haven't, and have done some more work on it.

But first, I've created a page for this project on the website: About Me-Contact Me/Projects/Rear Bumper and Spare Tire. And, I created a "project" called Rear Bumper And Spare Tire Carrier in the Project section here in the forum.

My reason for creating the two is to test how well they work. The one on the website gets the pictures automagically updated as I work on the project and "print" new pics. And, the viewer can zoom in and pan around on them, which you can't do in the pics in the Project section of the forum. So, please tell me your thoughts as I can't keep two different places up to snuff. (I like the webpage best, so....)

Now, for the updates and questions:

- I've added a license tag holder and a 3rd brake/license tag light/backup light in the middle of the spare tire. But I'm not happy with the lights I've found as most are too tall - it shouldn't be more than about 3". So, if you have some to suggest....

- I've added a filler panel to the top front of the bumper to keep the yuk from being kicked up and getting onto the bumper

- I made the swing arm go all the way across and the angled spare tire support arms go basically to the ends of the arm. There are two reasons for that. First, by making it a full triangle the thing can't sag. Second, it makes each arm almost 38" long and I think I can get a hi-lift jack mounted on the arm.

Thoughts? Please? I'm hoping to have this made for my Christmas present, and need to get it right.

I don't have much to contribute, but I'm looking forward to watching it progress.

 

[Gary Lewis]

I don't have much to contribute, but I'm looking forward to watching it progress.

Do you like the pics on the webpage or in the Projects section? I could, as I think about it, keep the pics on the webpage updated and have a discussion on the Projects section. The pics on the webpage let you zoom in, scroll around, etc.

Boy, it sure would be nice for y'all to be able to pan and tilt. Meaning for me to have a full 3D model and you be able to view it from any angle. I wonder how that could be done?

[Gary Lewis]

Do you like the pics on the webpage or in the Projects section? I could, as I think about it, keep the pics on the webpage updated and have a discussion on the Projects section. The pics on the webpage let you zoom in, scroll around, etc.

Boy, it sure would be nice for y'all to be able to pan and tilt. Meaning for me to have a full 3D model and you be able to view it from any angle. I wonder how that could be done?

Well, there have been some significant changes on the bumper design, as explained on the Projects page. But, here's the Reader's Digest version:

• Hinge: I found what I think is the right arrangement as it it very solid, with tapered-roller bearings, very strong spindle, seals, etc. And, it just tucks in below the active tail light - look at the pic.

• Swing Arm: I've been a bit concerned about the mass of the spare tire causing the swing arm to flex and something hitting the tailgate. But the taller hub on the hinge allowed me to upgrade the swing arm from 2 1/2 x 2 1/2 to 3 1/2 high and 2 1/2 wide, and that will significantly increase the torsional rigidity of the wing arm.

• Lower Support: I had planned to use a piece of angle welded to the bumper and the bottom of the tow eyes, and then bolted to the bottom of the frame, thereby significantly increasing the vertical strength of the connection to the frame. However, it now appears that the frame heights are different to some extent between the F150's, 250's, etc - and that means I can't use that method and have a universal-fit bumper. So I'm still searching for how to use the bottom flange of the frame, and would appreciate your ideas.

• Bumper: I've shortened the bumper's height from 6" to 5". The main reason is that the hinge really fits properly in 5" bumper. But, there are ways to make a 6" bumper work, so let me know what you think on this - and on all of theses things.

• Light: I need a light in the center of the spare tire to light the tag, but wouldn't it be cool to have one that is also a brake light as well as a backup light? Tell me what you think of this one from Rigid And, please suggest others. An option would be to put LED's in the bumper as backup lights, but that's added expense that wouldn't be needed if the one light did everything,

Input, please!

[Gary Lewis]

Well, there have been some significant changes on the bumper design, as explained on the Projects page. But, here's the Reader's Digest version:

• Hinge: I found what I think is the right arrangement as it it very solid, with tapered-roller bearings, very strong spindle, seals, etc. And, it just tucks in below the active tail light - look at the pic.

• Swing Arm: I've been a bit concerned about the mass of the spare tire causing the swing arm to flex and something hitting the tailgate. But the taller hub on the hinge allowed me to upgrade the swing arm from 2 1/2 x 2 1/2 to 3 1/2 high and 2 1/2 wide, and that will significantly increase the torsional rigidity of the wing arm.

• Lower Support: I had planned to use a piece of angle welded to the bumper and the bottom of the tow eyes, and then bolted to the bottom of the frame, thereby significantly increasing the vertical strength of the connection to the frame. However, it now appears that the frame heights are different to some extent between the F150's, 250's, etc - and that means I can't use that method and have a universal-fit bumper. So I'm still searching for how to use the bottom flange of the frame, and would appreciate your ideas.

• Bumper: I've shortened the bumper's height from 6" to 5". The main reason is that the hinge really fits properly in 5" bumper. But, there are ways to make a 6" bumper work, so let me know what you think on this - and on all of theses things.

• Light: I need a light in the center of the spare tire to light the tag, but wouldn't it be cool to have one that is also a brake light as well as a backup light? Tell me what you think of this one from Rigid And, please suggest others. An option would be to put LED's in the bumper as backup lights, but that's added expense that wouldn't be needed if the one light did everything,

Input, please!

Turns out I can type, albeit slowly. But I can TurboCAD almost as well as w/o burned fingers. And today I got the trail jack drawn up and properly placed. Turns out that there is just enough room between the tire and the tailgate.

And, with some testing I got it where it doesn't obscure the tail light and doesn't hit it when the swing arm is fully open. But that wasn't the case initially.

It fits pretty well just ahead of the spare. And, by removing the top end of the jack it doesn't stick up in the air - although I don't have a pic to prove that.

Anyway, check it out in Projects, or even better on the webpage.