2" receiver for SOF Bumper

[sleeoffroad]

how thick is the metal the SOR bumper is made of?

3/16" grade 80 steel. It is not just the tickness, but the type of steel that matters. Grade 80 has a much higher yield strength than regular grade plate steel. So you get a much stronger product for the same thickness. Most bumper are made from around a grade 30. Grade 80 has about 2.5 times the strength of Grade 30.

So when comparing apples to apples, one has to make sure one is not an orange.

 

[Doc]

So when comparing apples to apples, one has to make sure one is not an orange.

That's perhaps one of the most quotable lines I've heard in a long time.

 

[Josh83]

So here's an interesting question. Could this be installed without the slee bumper? I ask because I already built my own bumper, but it would be nice to have a hitch back there. Are they for sale seperately? If so, how much? Would the stock crossmember "theoretically" support the stresses of towing, say, 3500 pounds with no other steel plate in front of it?

 

[cruiserdan]

You could make your own like I did. I would not fit one to a "stock" vehicle that has only the OEM rear crossmember in place. I don't think thats heavy enough.

 

[sleeoffroad]

It could be fitted, but as CDan said you will not have a very strong system. The holes that mount to the framesides might be slightly off since the receeiver will sit further forward (with reference to the truck) since the bumper material thickness is not there.

 

[Beowulf]

"Buy my 84 4Runner"

Linkie no workie.

-B-

 

[Uncle Ben]

"Buy my 84 4Runner"

Linkie no workie.

-B-

If you look at the properties of the link it has a double "html" in front of the link. I think Christo has it listed on his site too under "vehicle for sale."

 

[waldrtw]

Price??

 

[Rich]

Chritso, has an engineering stress analysis been performed for your design? What is the tow rating?

 

[cruiserdan]

My bet is that there is no rating either expressed or implied.

In my case I have towed my 19 foot Chaparral I/O with a gross weight of about 3,700 lbs flawlessly.

I DO NOT claim that my design is rated for towing. MY reciever on MY vehicle is used at MY OWN RISK, PERIOD.


That being said....if one examines the OEM platform hitch and it's mounting points and then overlays this particular design, it appears that one is at least as well supported as the OEM design.

Tow at your own risk........................

D-

 

[Romer]

Sometimes having Christo so close by isn't a good thing for my wallet! I don't even have anything I want to tow and I want one!

 

[Rich]

Christo, Is this receiver intended for towing? How much trailer wieght?

 

[BOZ]

reciever issues

I too am interested in the bumper. I have a draw tight hitch and still need to tow every now and again.

Does the Slee bumper drop to the same level as the stock? if so the hitch should work. If not I would have to use the built in version of the slee.

Ok there should be some engineers in the crowd. The book says the fj80 is rated to pull a max of 5,000 pounds. It should not be that hard to get this rated.

What do you think.

Boz

 

[sleeoffroad]

The receiver is not rated for towing. To be honest, I am not sure what is involved with getting it rated. I have tried to determine what is involved, but I have a sneaky feeling it is more related to how much insurance we need to carry than the actual product design. I have looked to see if there are design specs for hitches, but have not found any. All in all, it might be beyond the scope of a small company to even get a rating on a tow hitch. So for now, not rated for towing.

Other comments. The Slee bumper can be used with a rated oem or aftermarket receiver that bolts to the stock locations. Just requires longer hardware.

 

[Rich]

I expect that the hitch manufacturer is responsible for determining and specifying the weight rating for the hitch. No doubt an engineering firm could be contracted to provide this service.

http://www.sae.org/servlets/productDetail?PROD_TYP=STD&PROD_CD=J684_200507 is perhaps a good place to start with respect to standards for automotive hitches and couplings.

 

[Rich]

I would propose an alternative design approach. The design would be in principle equivalent to the existing stock Toyota Land Cruiser hitch with two changes: 1) the square receiver tube would be longer and be butt welded to the cross tube, (in contrast to the factory design where the receiver tube is welded underneath to the bottom of the cross tube), and 2) instead of the hitch being dropped down below the frame rails it would be installed up in between the frame rails.

With this approach the bumper itself is not required to provide any support, and is not a factor in determining hitch strength. All you would need to do to the bumper and the rear cross member is cut the hole for the receiver tube.

I believe it would be rather simple to modify an existing factory hitch to accomplish this and that you would be able to use the existing captured nuts in the frame to mount the hitch. I think all you would have to do is cut off the existing receiver tube, and weld on a longer one with appropriate gussets, cut the clearance holes in the bumper, and bolt it up to the frame with the cross tube up in between the frame rails. You might also need to remove the sheet metal gusset that is forward of the factory rear crossmember. In the end you would have a hitch that is pretty much identical in design and materials to standard frame mounted hitches, and you avoid the complication of needing to determine the stress on and the strength of the bumper and the rear frame cross member.

One can easily visualize this approach by taking a stock Land Cruiser hitch and holding it up to the frame rails upside down. It is very simple in concept.

 

[Rich]

...The Slee bumper can be used with a rated oem or aftermarket receiver that bolts to the stock locations. Just requires longer hardware.

I have done this from time to time when I have needed to tow. In addition to six longer bolts, one needs two .5 inch spacers between the hitch and frame at the two forward mounting points.

 

[sleeoffroad]

I am pretty sure with enough money and time one can produce a tow rated receiver for the bumper. However if people are concerned about towing heavy weights, we recommend the Kaymar bumper. It is rated (although I am not sure if that is Australian or US) and we are not trying to redesign the wheel. We wanted to offer a 2" recevier option for people that tow trailers off-road, install bike carriers etc etc. It is pretty much up to the customer to decide how they will use it.

I can see what you mean with the receiver you postulate, however there are some issues with it. One, Cost, it will be a lot more expensive to make that one. Two, even if we did figure it out, then we still have to get it rated. Three, possible market. Most people that buy our bumper are into heavy rock crawling/off-roading. Trucks with 6" lifts etc, does not make good tow vehicles. So the market is very small, if we had to recoup the cost of doing all the registration etc etc, then we are going to have a really expensive hitch. Which comes back to the first point, there are rated hitches and bumpers our there, so if the rating is that important to the customer, then they should stick to the Kaymar or factory receiver.

I will look into those documents and see if I become any the wiser. I am not trying to skirt the issue, just trying to explain why producing a rated receiver is not really high on the priority right now.

 

[PHAEDRUS]

Rich,
I theorized and even started cutting up a frame mounted receiver off a 91 4 runner, My thought was to invert the stock mounting brackets so they tucked up inside the frame rails, then taking the lower box tube set up and cutting a section out of the middle of the cross bar and grafting and gusseting into place. This concept would not work with the spare tire in its current location. I ended up building a bumper with a receiver tube integrated to it. and used Christo's spindle to mount the spare on a swing arm.
Dave

 

[Rich]

Dave, yep, no way to do what I postulate and keep a spare tire under the truck.