Swing aways

[ZUKEYPR]

Hey all you big brained engineers, help me out here. I'm thinking about revamping my rear bumper a bit and i like this concept, but i got a few questions.

Q: I would think that if you have two points of pivot (the end link on the door and on the carrier) that wehn you open it eventually the two will collide or you can do it, but the length of the link and location of the pivot point on the door would be crucial?

Q: Based on the design of this bumper, with all that high speed trig, calc, and geo, would the door hold up to this kind of stress, especially if it were also to have a high lift mount and CO2 bottle mount.

PS: just pretend you don't see the bad hinge design. I know better to not use it and go with a double shear.

 

[Caleb]

I'm not an engineer by any stretch of the imagination

however, I know people try to get them off the door cause the hinges on the doors tend to not like an oversized tire hanging off them. That puts some of the stress back on the door. I agree with you have two pivot points you will get binding at some point, where is determinded by the design. I don't like that design because then if you open your carrier you also HAVE to open the door.

 

[ZUKEYPR]

Actually I believe the door is sharing the load, and not much of it at that. However my suspicion though is that there would be a force (don't know how much) working front to back as you drive on the door and I'm not sure what that would do to the locking mechanism. I actually like the idea of the door opening when you swing out the carrier. This is really easy to build, I'm just concerned wih the loads and potential binding/contact.

 

[Bart]

Again, from a non engineer, I don't see the problem with that design. If the bar between the tire carrier and the door is long enough it could swing open far enough before a bind occurred, as long as they swing on the same plain. Also, the load that design would put on the back door doesn't seem to be as much as what the door was originally designed to do, and that is carry a stock sized tire and wheel.

 

[78mitsu]

depending on how rigid that pivot point is I don't think the door is taking that much weight, and if the D. side locks and becomes paritally bearing, I think it would be negligable, use a quick disconnect pin on the door side of the tire carrier then you could open it seperatly.

 

[lenny]

Looks VERY simliar to how the D-90 tire carrier is setup from the factory. I would assume that you would be ok running a 35-36" tire on that style carrier

 

[Herzog]

As long as the basic hinging carrier section is built to hold the weight of the tire, the door connecting rod primarily serves as an aid to prevent excess vibration in the carrier and not to hold more weight.

I think it's a great idea.

 

[Brad]

Excellent design, I foresee no faults with it except I would build a cantilever latch on the bumper as well, requiring the lever to be pull AND the door be opened to swing out. I've seen 35s mounted on the stock Wrangler tire mount and the door seems to hold up to that weight just fine. It definitely looks like little, if any, weight will bear on the door with the design and the door linkage will go a long ways in stabilizing the tire carrier.

 

[I Lean]

Almost a good idea, but I'm not sure the door will really be taking any significant load at all. Since the piece attaching it to the door is basically a link with bushings at both ends, it can only really stabilize the carrier from motion side to side, which most likely isn't the problem he's trying to avoid by attaching it to the door in the first place.

The support that probably needs to be added is in the front to back direction, and that's gonna be a lot tougher to accomplish unless the carrier's hinge is exactly in line with the door's hinges, which isn't going to be very likely.

 

[Herzog]

Almost a good idea, but I'm not sure the door will really be taking any significant load at all. Since the piece attaching it to the door is basically a link with bushings at both ends, it can only really stabilize the carrier from motion side to side, which most likely isn't the problem he's trying to avoid by attaching it to the door in the first place.

The support that probably needs to be added is in the front to back direction, and that's gonna be a lot tougher to accomplish unless the carrier's hinge is exactly in line with the door's hinges, which isn't going to be very likely.

I'd dare say that the pivot arm will work... as long as the carrier is secured on both sides (latch on one, hinge on the other). The pivot arm wont allow much front to back movement because of the difference in geometry between the other attacment points... if there is absolutely no allowance for side to side movement, it will bind and not allow front to back movement.

 

[SundancKid]

I can say anything more then what has already been said except...gusset the tire mount. The one in the pics needs a gusset.

 

[cruiseroutfit]

Looks like a neat deal to me...

That is basically a 4-bar mechanical linkage, and yes given some situations it will obviouysly bind, but designed right and it might bind exactly where you want it to (thus preventing it from swinging all the way back into the body, etc.).

If you REALLY wanted to know when/where it will bind, I have a mechatronics software called FourBar that evaluates just that... linkages, lengths, binds, anglular velocity, etc. I think it is shareware so if your interested I could find the link.

As far as the loading it sees... entirely up to the design, bushings/harward used, etc. I fully agree with Brad than additional mehcanism should be added at the DS of the bumper for clamping shut, though that makes an almost annoying redundant system with the current door.