Head Scratcher

[Kryptoroxx]

So I was doin some thinking without drinking and looked at all the tire carriers that are for the stock tire sizes. I think our hatch on the 3rd gen could support one but not just mounted just to the sheet metal. So here's my idea for a worjaround .

First I would need heavier duty hinges and struts. The hinge assembly seems simple enough to reproduce for a decent machinist. But the hinges are also where the top mount for the frame would be attached.

For a frame a simple 1.5" tube should support the weight of a tire and rim. The 33" tires and rim on my pickup weigh in at about 80 each so frame plus tire assembly would be 100ish?

With the cargo door closed there should be enough strength in the hinges and the lower support (like how the Gobi ladder attaches) to safely hold a 33" or smaller tire without the huge addition of weight to a custom bumper and also having to swing your tire away to open the rear hatch.

Thoughts? I tried illustrating it in sketchup but that was a fail lol.

[Seanz0rz]

Not worth the effort. The stock hinges couldn't hold a tire. Beefing them up would just find a weak spot somewhere else.

More than anything, its the dynamic weight of the tire. A 100 pound load on the rear door could be 200 or 300 pounds of force, or more while driving. Not to mention the huge moment it exerts on the tail gate when hitting a bump. Center of mass on something like that is 6 inches from the edge of the tire, and 2 feet from each support.

If you ride along the side of me on a bumpy road, you can see my tire move about 1 inch from rest position. That mass really moves!

Overseas, there was an option for passenger side, body mounted swing out, like the one on early 2nd gen 4runners. Aside from the carrier, there are substantial internal quarter panel/ d pillar bracing and tailgate latch system. For aftermarket, the best bet is a rear bumper. If you like the stock look, that can be achieved too. I've always wanted to design a carrier that maintains the stock bumper.

[troyboy162]

anythings possible, but a quick thought on it is that you will have a really hard time finding a strut to hold that hatch up. We can hardle find aftermarket struts to hold up the stock hatch.

I'd love to see it work though! That sure would be a easy way to move the spare out of the rocks

[Kryptoroxx]

Not worth the effort. The stock hinges couldn't hold a tire. Beefing them up would just find a weak spot somewhere else.

More than anything, its the dynamic weight of the tire. A 100 pound load on the rear door could be 200 or 300 pounds of force, or more while driving. Not to mention the huge moment it exerts on the tail gate when hitting a bump. Center of mass on something like that is 6 inches from the edge of the tire, and 2 feet from each support.

If you ride along the side of me on a bumpy road, you can see my tire move about 1 inch from rest position. That mass really moves!

Overseas, there was an option for passenger side, body mounted swing out, like the one on early 2nd gen 4runners. Aside from the carrier, there are substantial internal quarter panel/ d pillar bracing and tailgate latch system. For aftermarket, the best bet is a rear bumper. If you like the stock look, that can be achieved too. I've always wanted to design a carrier that maintains the stock bumper.

I had thought about the dynamic load as well and that's one reason I bounced it off you guys. I had a couple of reasons to think that it might be worth the effort and/or strong enough.

The rear hinge area is going to be a point of reinforcement for several reasons. Maybe not all required to be 200% safe by themselves but spreading the force out is the name of the game with physics.

First that rear door is fairly heavy fully assembled.

Two the top rack strength of my Yakima's is 220lbs per bar (and you could put a fully loaded rocketbox on even the stock bars) plus there has to be some reinforcement for rollover damage.

Three Gobi made a ladder for the rear hatch that is good for 250lbs (while the hatch is closed). I don't think Gobi would sell something that is going to fail.

The big reason I was shying away from the bumper mount is because of the mechanical arm of force dynamically induced with making it an extension of the bumper. There is a lot of reinforcement required to handle the addition of a swinging arm vertically not to mention that there is no additional support used from the rear hatch itself. Everything is supported off the bumper. The force lever is at least 20" where the tire is mounted and that is a huge lever. I don't doubt your tire moves an inch on bumpy roads!

Now I had thought about using the d pillars in addition to the beefed up rear hinges to help support the force on the y axis. The beefed up hinges and placement of the tire would greatly reduce the mechanical arm of force of mass rotating on the x axis.

I hadn't really thought about the latch and that would probably take some thinking to work around. Thanks!

Believe me I know what your concerns are as far as safety and destruction of the rear hatch. I just wanted to make the fact that I had taken those into consideration.

I will give the graphic design another shot to see if I can illustrate what my mind has been thinking. If you still think I'm crazy after that I will probably believe you as I live 90 miles from the Mojave road and I have been here baking in the desert for several years. It had to have burned something up.


anythings possible, but a quick thought on it is that you will have a really hard time finding a strut to hold that hatch up. We can hardle find aftermarket struts to hold up the stock hatch.

I'd love to see it work though! That sure would be a easy way to move the spare out of the rocks

I actually found the place to get struts like that. I hadn't done the exact measurements but an RV store would have heavy struts like that for awnings.

I wasn't the first to find these struts though. If you go to the Toyota magazine fb page there is a guy that built a roll cage for his pickup and make a vertical rear hatch where the tire is on the hatch. He used 200lbs struts lol. This post is what got me thinking in the first place.

[4x4mike]

There was a guy on Pirate who did something like this. He had a green XJ and I can't seem to find the write up. It seemed like it was a lot and a bumper mount or swing out would be so much better. I did find this picture, it's different but another option.

http://img5.imageshack.us/img5/5357/0222091359medium.jpg

We have Jeep Libertys at work and they have a rear hatch mounted spare. It's a little stock tire and that thing rattles like hell on both of the Jeeps. As it is our hatch doors are very heavy and the struts have a big job as it is. Even the glass weigh effects the way the door closes. Roll your rear window down then open and close the hatch. When I do this the door slams because of the shift in weight. I couldn't imagine having another 100 pounds on there even with a heavier strut.

Jesse, he's on Expo and Pirate, has an All Road he's been playing around with. http://www.pirate4x4.com/forum/expedition-vehicles/1172761-offroad-allroad.html

He built an internal rear bumper to hold and pull his toys. His plan was to incorporate a tire carrier and I liked the idea. The reinforced structure is behind the stock bumper so you retain a lot of the stock look.

http://www.trailslesstraveled.com/media/forums/audi/offroad_allroad_hitch_16.jpg

http://www.trailslesstraveled.com/media/forums/audi/offroad_allroad_tire_carrier_01.jpg

He was doing so much to the all road the thread wondered a bit but it's a good read nonetheless. I've seen guys put the 2nd gen swing outs on Tacomas and they look really nice. I believe the Tacoma is easier to retrofit than a 4Runner because of the bed and accessibility to the inside of the corner for reinforcing.

[paddlenbike]

I wouldn't mind having a factory Hilux Surf rear tire carrier since it doesn't also require a heavy rear bumper, but when I looked into it, the rear hatch is different.

http://i384.photobucket.com/albums/oo281/sovietcraft/9-5.jpg

http://i384.photobucket.com/albums/oo281/sovietcraft/REVISED%20PICTURES/3-10.jpg

More than anything it would allow me to add permanent fuel capacity in the existing spare tire well.

CBI is building a rear bumper and additional fuel cell for the 5th gen.
http://www.cbioffroadfab.com/wp-content/uploads/2013/09/straps1.jpg

The small fuel tank/short range is my only complaint with the 3rd gen.

[Kryptoroxx]

The fuel tank mod is one of the reasons that I want to move the spare. Another is the flat belly idea but that's kind of like a pipe dream

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[Seanz0rz]

The 90 my parents had when I was a kid had the swingout tire. It squeaked like a mofo!

I was thinking about this last night when I couldn't get back to sleep. Somewhere, I have drawings for adding a door bar to my VW as part of a cage idea I had. Idea was that the hinge side would all be beefed up on the jamb and door, with super heavy duty hinges and some sheer pins that engage when the door is closed. The latch side would have a joint in the tube that allowed the door to operate normally, but still engage the door bar. It was too complex to implement on the VW, but something like that might work on the rear hatch.

From what I see, the rear hatch could probably take a stock tire and alloy. 33 and an alloy, maybe. Anything more and I would seriously worry about mid-long term metal fatigue on the hatch and the body.

As for ditching the rear bumper: #1 reason to do so is it is connected to the body. Anything more powerful than Ken took to the rear (lol) last year, and you end up doing significant body damage.

With a lifted 4runner, most things that will rear end you will actually go under, so that crunching of the body is probably not beneficial. Hits to the frame can and will damage the frame and suspension, but for most of us, those are easier fixes than massive body work. Most of the 4runners I come across in junk yards are either rolled or rear ended.

[CJM]

Id say the metal overall would be too weak and probably fatigue over time and eventually crack and fail.

[paddlenbike]

Anything more powerful than Ken took to the rear (lol) last year, and you end up doing significant body damage.



A guy can't even get a break on his own birthday!! lol.

[Seanz0rz]

absolutely not. I wrote it being all serious, then laughed real hard when I reread it.

[Kryptoroxx]

Here is my sad and pathetic attempt at modding someone else's model of a 4runner for my purposes but hopefully it will give a better idea of what I am thinking about. I would never mount something bigger than a 33" on there but I want to design it to carry something heavier than stock. Overbuilding will help with the safety imo. I am also intending to build a rear bumper but not something that sticks out far enough for a spindle.

The graphic is pretty horrible but I had wanted it a little more centered.

[Seanz0rz]

At that rate, go with a hitch mounted swing out. Inexpensive, removable, easy.

[Kryptoroxx]

Eh I have seen those but I need something more permenant as I have a platform bike rack that is hitch mounted as well and the hitch rack scrapes the ground badly enough. I would hate to see what a spare tire holder does.

stamped and snail mailed

[Kryptoroxx]

I will keep working on the design and see if I can create something a little more sturdy.

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