Jerry Feather

Jerry Feather

here are a couple of pictures of my prototype in quarter inch plywood of the first main member of my Trailer hitch.

76FJ55

Definatelt a different approach than the other designs. I'm inuntrugued to see how this profresses into a completed hitch assembly.

hwyengr

I'm looking to tow at the factory rating, 3520 lbs.

Jerry Feather

Jeremy, at some point I'm going to need to know just how high above the ground you will need the center of the hitch ball to be.

Jerry Feather

I think that it is turning out that my Hitch Design is simply going to amount to a very hefty stiffening of the rear of the 928 frame with a hitch receiver welded to it. The only thing that I think will be changed with the car is the moving of the rear bumper aft about a quarter inch. There should be enough stiffness built into my Hitch crossways to shift just about all of the push-me/pull-you forces to the bumper mounting points and the end of the frame rails, and what might be left of the torsional forces will be shifted thru the top of the center of the rear cross member into the total structure of the car forward of that, such as the baggage floor and everything in it up to and even including the cross member just forward of the battery box.

I have abandoned the idea of incorporating the 2 inch hitch receiver in favor of the 1 1/4 inch one. My reason is that on simply looking at some of my own 2 inch hitch tongues they simply look too hefty for the 928. I also went to look for a hitch tongue in 1 1/4 inch and could find only one in three stores look at. Then I also noticed that many of the 2 inch ones looked at were rated for about 35000 pounds of pull weight. The 1 1/4 inch one that I bought is rated at 3500 pull weight and I think that should be just about maximum for the 928 in any case. I think that putting a 2 inch receiver on my hitch will simply send the wrong message about what ought to be pulled with it. This is in spite of the advantage of putting things like a bicycle rack or luggage rack of some sort on the back of the 928 in the 2 inch hitch receiver.

Petza914

1 1/4" should be fine and will look nicer. There are adapters available to go from 1 1/4" to 2" which will then open up the range of all the 2" accessories. The only very limiting solution would be one like the European setup with just a ball mount as that only allows towing and not transporting other accessories.

Shawn Stanford

I found a hitch thread a couple years ago and in that thread the designer used a section of box beam inserted into the bumper to help spread the load. The hitch receiver was bolted all the way through the box beam. If I ever get around to doing it, that's what I'll do.

76FJ55

For those that only want to tow a minimal load, this design is probably visble, but in my opinion far from ideal. One of the major limitations of this design is that you are towing through the rear bumper shocks, which are not designed or intended for this type of load.

Jerry Feather

Jeremy, please explain in detail what it is that you hope to tow with your 928.

hwyengr

I'm towing a single axle 15' teardrop camper that weighs 1990 lbs dry and has a maximum axle load of 3100 lbs. Its trailer has a 2" ball receiver with a level height of 21" from the ground to the top of the receiver. Due to the 928s limitation of 150 lbs of tongue weight, it has to be pulled level as any tilt downward increases the tongue weight.


Here it is with our regular tow vehicle.



I've been thinking about this, and so greatly appreciate the offer, but am willing to throw open the availability for the prototype to anyone else who's interested. I'm an engineer by trade and get obsessed with factory correctness, so no matter how strong and able the kit is, it's just going to burn at my mind that it's repurposing mounts and pieces that weren't "designed" for the load. OCD is a pain in the a$$.

hwyengr

The 4Runner is the only car in the house with an automatic transmission. I take several guys trips out west with my buddies for baseball games throughout the year and can't take her car if she's not going, or else there's nothing left for her to drive. My other car is tow rated in its home country at 3200 lbs, but for some reason the US import version says "This vehicle was not designed for towing" in the owners manual, which puts me in hot water for insurance purposes if I ever got into an accident. The 928 HAS a factory tow rating. I've got a Euro 2.73 final drive, which makes it even more capable of fulfilling the duties that it was designed to do.

And I HATE the mentality that only pickups can tow. That's just marketing bull. I don't have any problems following the Euro towing specs, guidelines, and limitations. 10% tongue weight recommendations are just so people can drive 70mph when towing. I love being on the 2-lane roads bumbling by at 55.

Jerry Feather

"Factory correctness" isn't always what it is cracked up to be. As an engineer, why don't you come up with a Hitch Design that meets your needs and simply have someone build it for you. On the other hand, why don't you simply keep hauling that tear-drop trailer with the usual vehicle shown. Or better yet, why don't you trade in your trailer for a more streamlined and somewhat lower-riding kind of trailer that better suits the pull behind the 928?

Jerry Feather

Jeremy, I can make a gooseneck tongue for a ball at 21 inches above the ground, but there is something about that that is just WRONG for the 928.

Jerry Feather

Jeremy, can you please post a picture of the coupling of your trailer to the back of the SUV it is attached to