61 photos


-= (updated 10/06/05) =-

There are pictures, just scroll down below the text.

This is a work in progress...

10/6/05 - it's been a while since an update... I lost track of miles at this point, no problems to date, it will be a year old in January. One other observation that is obvious to most now is that the bolts used on the differential to hold the front mounting bracket are off set from center. When I made my hitch the bracket was made first with the receiving point centered. This explains why the spherical ball end (proper name?) on the front end of my hitch was welded on off center. The off set from center is about 5/8 of an inch. This calculation was based on data from one person's (Coop) measurement. If I did it over I would not weld the mount point on the front bracket until the rest of the hitch was complete to allow proper alignment.

5/27/05 - over 1,200 miles and no issues. People are amazed when it comes off in less than 30 seconds without jacking up the car.

5/4/05 - picture of second piece of angle iron added, see note below from 4/4/05, see very last picture of this gallery.

4/8/05 - If you are interested in making a hitch, be sure to see the pictures (full size by clicking thumbnail) within this gallery that have yellow annotations, they provide dimentions and other notes. I mention this below, be sure to cover up any surface (like the chrome exhaust tips) that can be damaged by weld splatter when welding parts while attached to the car. A friend made one and repeated the same mistake I had done and got weld splatter on the chrome exhaust tips. Now we both have some rust forming where the splatter is located.

4/4/05 - Total milage is about 700 and this setup is working very well. Others envy how fast the hitch comes off and goes on, while they unscrew multiple bolts... I found that the center cross member of the trailer was leaving significant groves in the tires, so I have added another piece of angle iron across the center of the tailer for the tires to rest on (no picture yet). This works well and the tie down strap can be left taught between events without concern.

2/12/05 - Another 160 or so miles have been covered, making a total of about 300 miles on the hitch and no sign of problems. I have hit some big holes/bumps that have made the whole trailer bounce intensely. The hitch comes off so easily with or with out the car raised. It's certainly easier to get the front pin in with the car raised. It should see about another 500 miles in March while traveling to events in Tucson, Sierra Vista and Phoenix.

1/14/05 - I added some annotations to some of the pictures that provide some material and size information.

Feel free to link to this page or any of the pictures in the gallery if you want to. I am providing this for informational purposes only (in case you want to build one) and have no intention of building these to sell. Use as your own risk.

EXPERIENCES and LESSONS LEARNED
It worked, got to the first event (1/9/05) and back! It was at the Sierra Vista (AZ) Municipal Airport (awesome large concrete pad) and is about 130 miles round trip, mostly highway (75 MPH speed limit), from my home in Tucson. I did get up to 85 at one point to pass, but generally I cruised at 75 with no issues.

I will continue to add here...

Tongue Weight - with all that was loaded (list later) the tongue weight was about 35 pounds.

Tire Pressure - the max rated tire pressure is 60 lbs and the max load is 1075 lbs, what should the tire pressure be for a load of about 300 lbs? I drove the trailer to the DMV for inspection and registration with no load and no box, nothing on it with 20 lbs pressure in the tires to avoid a bouncy trailer. It worked, the trailer towed nicely and did not bounce around when going over bumps at various speeds. I used 30 lbs with the trailer fully loaded and it road nicely as well. My rationale was that 300 lbs is about 25% of the load capacity, so with 40 more pounds of pressure before max pressure I added 10 more lbs or 25% of the difference between 60 and 20 lbs pressure.

Rattles - this is a detachable trailer hitch with three pins connecting it to the car. Would you expect it to rattle and make noise when going over bumps? Well it does, nothing terrible, but definitely something to get used to. I think you would hear some kind of noise any way, not sure how much the the detach points add to this. The front pin is 0.5 inches and the hole in the mount point is 0.5 inches and the hole in the spherical ball end of the hitch is 0.5 inches. The mount point hole was enlarged just a bit to allow the pin to move through it. It's still a tight fit going through both the mount point and the spherical ball end, so the front mounting point has no play in it, nice and tight. The two rear mounts use 7/16 inch pins that go through slightly larger than 7/16 inch holes in the mount point. There is some play in the vertical direction, no play fore/aft because the front mount point is a tight fit. This play allows the hitch to move when going over bumps and cause a rattle like sound when going over some bumps. If I remade the rear attachments with smaller holes then this problem may be solved.

If you do any welding while pieces are attached to the car make sure things are covered up. I got some splatter on the chrome exuast tips that won't come off. I may buy replacements some day.

TRAILER
This is a small (4x3.3 foot) Harbor Freight utility trailer with 12 inch wheels (#90153) that is used for transporting tools and a second set of wheels with race tires to/from autocross events. A piece of angle iron was added across the back (picture added) to allow the tires to be supported and tied down using a nylon strap. A tool box (found one at Sears for $75) was added to the front to carry a jack and other items. The bolts at the front corners of the trailer frame were removed and the corner welded. The bolt heads were in the way of the box sitting down flat on the frame. Two supports for the box were welded in using angle iron to help provide some more support for the box bottom. Quarter inch bolts were used to hold the box to the trailer frame (see pictures). Zinc paint was sprayed on all exposed metal surfaces for the added pieces and where the paint was burnt off from welding. The trailer is now complete except for red paint if a color match can be found. The trailer was loaded and went for a test drive today (everything work as expected). It will now be towed to the event 1/9 in Sierra Vista.

HITCH
The trailer hitch is home made and detaches using three pins. This design is based on the detachable Hammerly hitch that is no longer sold/made. The remaining weight on the car for the attatchment points is about 5-7 pounds estimated (will measure some day). The hitch and pins weigh about 20-30 pounds estimated (will measure some day). It can be installed and removed without raising the car if you are willing to lay on your back and reach under. Still need to paint the hitch, did not get to it before autocross event (January 9th).

WIRING
Just bought the harnesses for the car (basic to attach to trailer connector and converter from separate brake/blinkers on car to combined on trailer), installed before autocross (January 9th). Don't have picture of this installation, forgot to take them during the procedure. The harness was attache to the driver side tail light wiring harness by cutting the wires and soldering in the trailer harness. I chose to leave the harness in the trunk when not in use and just run it out when needed and close the trunk lid on the wires. I covered the harness with a shamy to protect the paint on the bumper (see picture). The ground wire on the trailer appeared to have the potential to break off from flexing so a strain relief was added using a tie wrap (see picture)
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