Author Topic: Building a hitch for my tiny, aluminum car  (Read 20032 times)

Ecky

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Building a hitch for my tiny, aluminum car
« on: November 18, 2014, 02:24:45 PM »
Hey all! This isn't a question thread so much as one to share a project I'm working on.

My wife and I are preparing for our move next year and part of that preparation is downsizing. We're selling random bits we don't need (lamps, excess kitchen stuff, etc.), but even so there's no way we'll be able to fit everything in our 2000 Honda Insight in one trip, or possibly even two. We'll be moving approximately 1400 miles, and renting a U-Haul, even a small one, looks to be more than $700 including gas. Renting a second car (hatchback) one-way is a possibility, but adding a hitch occurred to me as a potentially better option.

After calling around, I got various quotes in the range of $700 to $1100 to install a hitch from a shop, due to the car being a completely aluminum import, so I decided to make it myself. The economics of building a hitch and getting/making a small trailer are vastly superior to any other option, nevermind that the money spent doesn't disappear when we arrive at our destination.

I get 55-80mpg in the city and 65-90mpg highway when the weather is warm, and as long as I'm pulling a trailer that fits in the wake of the car, the negative impact on mileage should be minimal when pulling, and zero when not, keeping the cost of moving down to about $60 plus the trailer.







Last week I found this Reese hitch for sale for ~$18 with free shipping (includes a receiver!), and purchased one. My plan is to bolt it to the aluminum bumper and weld a bar to it to run under the car and mount somewhere a few feet forward to an L bracket, to absorb forces from accelerating/braking and prevent it from torquing off the aluminum beam. I'll also be putting some thin plastic sheeting between the dissimilar metals to prevent galvanic corrosion. Had it been made of steel, I probably would have left the support out altogether and just been careful with what I pulled, causing this to be a roughly $18 job + the cost of some bolts and wires.

First step is to pull the bumper off and take measurements:






The drop from where the hitch bolts on to the top of the receiver is around 10cm, which is very conveniently about where the black plastic starts, so I won't need to cut a square hole in the painted part of the bumper.

Will update as I progress.
« Last Edit: November 19, 2014, 08:27:51 AM by Ecky »

Gone Fishing

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Re: Building a hitch for my tiny, aluminum car
« Reply #1 on: November 18, 2014, 02:48:14 PM »
You might get some naysayers citing liability on this one!  Good for you!  I am currently looking at ways to tow a trailer with my Corolla.  Given the uniqueness of the situation and materials, I would recommend installing safety chain attachments that are not part of the hitch, this will give you a second level of safety if the aluminum attachment point fails in some fashion.  Regular inspections of the attachment points to examine for any cracks, warping, or other signs of stress would also probably be a good idea.

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #2 on: November 18, 2014, 03:26:42 PM »
Good thinking. It would be easy to put some eye bolts through the pan with an L bracket for the chains. The receiver itself shouldn't disattach unless I rip the back of the car off though... which might be a real possibility if I tried to pull a boat or something. ^^

I'll probably rent a small U-Haul trailer for the move (4x8?), and build for everyday use something more like this:




This guy seems to have no problems:
https://www.youtube.com/watch?v=ES6XCCmYuY0

abhe8

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Re: Building a hitch for my tiny, aluminum car
« Reply #3 on: November 18, 2014, 04:01:57 PM »
So how much weight is your car rated to pull? Our more specifically, hire much weight can your brakes safely stop?

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Re: Building a hitch for my tiny, aluminum car
« Reply #4 on: November 18, 2014, 04:32:17 PM »
How do you plan to split the electric for the lights on the trailer?

I think it would work well for the small trailer in the picture. But a larger 4x8 enclosed Uhaul trailer? Those are almost 900 lbs empty. Your car? 1900lbs. All this makes me cringe. I hope you aren't going up and down any hills.... let alone mountains.

You are much more adventurous than me! Best of luck.

« Last Edit: November 18, 2014, 04:39:47 PM by Angie55 »

DarinC

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Re: Building a hitch for my tiny, aluminum car
« Reply #5 on: November 18, 2014, 06:42:16 PM »
I don't think Ecky is going to tow a 4x8 uhaul trailer. A 4x4 or 4x8 trailer from HF should be fine, and only weight ~130-260lbs. Adding a deck and some siding would add maybe 50+lbs, but that still leaves plenty of weight for cargo.

From personal experience, I would be reluctant to haul more than ~1200lbs of people, stuff, and trailer, but below that and the car should be alright cruising at ~50-60mph. Lights are just a matter of splicing into the harness in the back and adding another fuse for that branch.

I almost went that route with my Prius b/c the only car specific kit was $50+ more than a generic splicing kit. Fortunately I found out that a relatively inexpensive kit for a Camry could be modified to work by switching the wires. Something similar might work for an Insight if someone could find a kit that has matching connectors.

http://www.evnut.com/prius_trailer_wiring.htm

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #6 on: November 18, 2014, 07:28:11 PM »
Thanks DarinC!

I hadn't checked the weight on the U-Haul trailers, but yes, I don't plan to pull anything remotely near 1000lbs (guaranteed  <300lbs of stuff in the trailer). We have some bulky but light items such as computer printers, a few computer chairs, empty bookcases, boxes of computer components, paintings, blankets, etc. that I'll be taking up I-95 in the summer. I'll be avoiding poor weather until I have a better feel of what it's capable of. My wife and I only weigh about 250lbs together, which helps too.

As I understand, in Europe many small cars like Civics/Fits have tow ratings of around 500kg, but are not tow rated in the U.S., and the Insight probably has more spare braking power than some of the lower trims of Civic/Fit, especially if you take into account what the electric motor and engine braking add (it's a 5MT). It also has ABS and electronic braking distribution.

EDIT: Handling is also very good when not towing. Some people use this car in autocross, and it comes out near the top of its class.

EDIT2: The 5MT trim apparently also has larger disc brakes than the CVT version.
« Last Edit: November 18, 2014, 07:43:05 PM by Ecky »

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #7 on: November 18, 2014, 08:23:16 PM »
Did some poking around, and though I wasn't able to find any ratings on how much the brakes can safely stop, I did find out that a 2011 Civic Si, which has ~200HP and weighs around 2900lbs, has 33.8cm² of area on its front brake pads, while the 5MT variant of the Insight weighs in at 1874lbs and has 36.2cm² of pad area. Area vs area probably isn't a 1:1 comparison as the stock pads for each car may be of different materials, but it's promising.

The rear drums are smaller than the (non-Si) Civic's, at around 2/3 the area, but the car also weighs 2/3 as much.

If the Civic can tow 500kg in Germany, I bet my Insight can tow 300kg.
« Last Edit: November 18, 2014, 08:32:41 PM by Ecky »

Sid Hoffman

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Re: Building a hitch for my tiny, aluminum car
« Reply #8 on: November 19, 2014, 10:32:31 AM »
You want to pull a trailer with a small Honda not intended to be used for towing?  I too like(d) to live dangerously.

So how much weight is your car rated to pull? Our more specifically, hire much weight can your brakes safely stop?

Honda does not rate any of their passenger cars for towing in the US market and never has.  You need to step up to the Odyssey before they offer a tow rating at all.  The CRV, Pilot, and Ridgeline are also tow rated.  The cars never are.  It doesn't mean you can't do it, but it can cause you serious problems if you get in an accident because your insurance carrier has legal recourse to say that you're using the vehicle in a way not approved by the manufacturer, and may attempt to deny your claim.

There was a period in time when I towed a trailer with my Civic.  I think I did this maybe 5 times in total, largely because it scared the heck out of me every time.  The trailer was wider, longer, and weighed something like 1000 pounds loaded, which is a ton of weight compared to my 2350 pound car.  The Insight is similarly lightweight, although with the added danger of having a shorter wheelbase and something like 4 inches narrower rear track than the front track.  The Insight might be one of the worst vehicles to tow with of all time.  I suppose it's possible, especially if the trailer is small and light, but it's still terrible for towing from a design objective standpoint.

Bottom line is that just because you can, doesn't mean you should.  It sounds like the OP wants to tow something pretty small and light, like 400 pounds or so and with small surface area.  That might be fine.  One of the other considerations is that because the Insight is small and has tiny tires and a narrow rear track, it is easy for a cross-wind to wag the tail of the car around.  I know at least one guy who had his Mustang blown off the highway in strong cross-winds while towing a small utility trailer.  While the Mustang weighs more overall, it too is a vehicle without a lot of its weight over the rear wheels.  Still, if a 3200 pounds Mustang with a utility trailer could be blown off the highway in strong crosswinds, I can only imagine how easy it is for a 2000 pound Insight on skinny tires to be blown off the road.

Just something to keep in mind.  I never did wreck my Civic, but it was a scary rig to drive.  That trailer really wanted to wag the rest of the car when you went over expansion gaps on overpasses, for example, and that was with no cross-wind.

enigmaT120

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Re: Building a hitch for my tiny, aluminum car
« Reply #9 on: November 19, 2014, 11:58:10 AM »
Here's the thread from the Insight forum, but I see Ecky already found it:

http://www.insightcentral.net/forums/modifications-technical-issues/56377-trailer-hitch-teardrop-camper.html

I'd like one to tow my little (45 pound) canoe on a light trailer.  The two car solution for drifting rivers is even worse when one of the cars can't carry the canoe.  For nearby destinations though my pickup should work OK. 

Maybe I should take a vacation in Tempe, AZ.  Here's what I got on the U-haul hitch site when I type in any first generation Insight:

"If U-Haul doesn't have a hitch for your vehicle, nobody does!

Your vehicle requires a custom-built hitch which we will gladly fabricate for you. If you are able to bring your vehicle to our Tempe, AZ Research & Development facility we'll provide you with a free U-Haul custom trailer hitch, including free installation, and a lifetime unlimited warranty in exchange for the use of your vehicle to fabricate the trailer hitch. We'll need the vehicle for two to three days. If you are interested in this offer please complete the form below and we'll contact you to schedule your appointment. This offer is only valid until one customer per vehicle can fulfill our requirements."
« Last Edit: November 19, 2014, 12:02:47 PM by enigmaT120 »

Sid Hoffman

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Re: Building a hitch for my tiny, aluminum car
« Reply #10 on: November 19, 2014, 08:32:03 PM »
U-haul is not exactly known for doing anything high end.  Chances are any old machine shop that does custom trailer hitches would be able to do just as good a job as U-haul.  You could call around to local off-roading shops; the kind that do fabrication and true custom work, like for sand rails and dune buggies or whatever they are called in your area.  Those are generally the kind of guys that know how to weld up something that would fit right and not tear the frame rails of your car apart.

Forcus

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Re: Building a hitch for my tiny, aluminum car
« Reply #11 on: November 20, 2014, 10:47:56 AM »
(1) Didn't realize an Insight was all aluminum. Cool!
(2) The tow rating / how much should I tow question will never be resolved. Every towing / camping forum I've been on either has a non-stop war or has outright banned conversations. Here are the facts:
- Companies set tow ratings.
- Those tow ratings (except for the new SAE tow ratings, finally being utilized by tpickup truck manufacturers) are set by marketing, engineering, service (warranty), and others. The tow rating will vary based on who wins the fight. Marketing will go for the moon, engineering is generally conservative, and the warranty people don't want to pay for anything ever (so ultra conservative).
- There is sometimes no logic that an end user can apply to ratings.
- Safety is only one component in establishing ratings.
(3) I am a pragmatic guy, so here is my opinion:
- No matter what the rating, the DRIVER is the primary factor on whether you will safely get to your destination.
- Regardless of the rating, if you are not comfortable with how the load handles, it's too heavy.
- Ratings are extremely conservative for late model vehicles, and are not linked to safety but to longevity of components like engines and transmissions.
- Much of my old stuff has comparable tow ratings to new stuff but the new stuff is FAR SUPERIOR in every way (suspension, brakes, power, etc.). My 74 IH 1/2 ton truck has smaller brakes than the '05 Volvo S40 I sold last year. An old IH Loadstar 2 ton truck is embarrassed in every way towing compared to any basic half ton pickup

Not really for the OP but just for anyone reading... my $.02.

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #12 on: December 17, 2014, 07:57:13 PM »
Supplies:

$18 receiver
$20 in stainless bolts / washers / 1x1 steel tube
$8 in paint
$16 in diesel for welder

Aluminum L was scrap, welding rods were leftovers from a job my father had done recently. Plastic sheeting from the bottom of a reusable grocery bag for separating dissimilar metals. Already had anti-seize.















Winner of worst welds in the world goes to me. First time I touched it, I melted a hole in the 1x1, and ended up taking about 3 hours to do all of it, plus grinding off all of the lumps I left. Dialing the amps back a bit (200 -> 40) seemed to help.




Sanded, primed, 3 coats of satin. Had my father lay down the paint. He would've done a better job on the weld too.




Installation:














Tested it by standing on the end of the ball mount and bouncing. Planning on adding some eyes to the bottom of the car for safety chains before I pull a trailer with it.

EDIT: Should add, no part of the hitch is lower than any part of the undercarriage.
« Last Edit: December 17, 2014, 08:00:51 PM by Ecky »

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #13 on: December 17, 2014, 08:04:53 PM »
Did some sketches of a simple trailer based on a $230 Harbor Freight trailer with 12" wheels.







Attaching a 20" (radius) hollow semicircular nose to the trailer and setting it about 6 inches back from the front of the platform would allow for a maximum turning angle of ~80°, a height of 20" at the front and a total volume of approximately 36,700CI / 34,180CI (~21 cubic feet). The car holds 16.3 cubic feet, so I'll have total covered storage of ~37 cubic feet. The tip of the cargo box would be 16" behind the ball. I might decide to extend the trailer and perhaps widen it a little in the front, but I'd like to keep it low so it stays out of the wind.
« Last Edit: December 17, 2014, 08:09:24 PM by Ecky »

AnonymousCoward

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Re: Building a hitch for my tiny, aluminum car
« Reply #14 on: December 17, 2014, 08:50:16 PM »
That project looks like a ton of fun, nice work :)

m8547

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Re: Building a hitch for my tiny, aluminum car
« Reply #15 on: December 17, 2014, 10:40:41 PM »
You want to pull a trailer with a small Honda not intended to be used for towing?  I too like(d) to live dangerously.

So how much weight is your car rated to pull? Our more specifically, hire much weight can your brakes safely stop?

Honda does not rate any of their passenger cars for towing in the US market and never has.  You need to step up to the Odyssey before they offer a tow rating at all.  The CRV, Pilot, and Ridgeline are also tow rated.  The cars never are.  It doesn't mean you can't do it, but it can cause you serious problems if you get in an accident because your insurance carrier has legal recourse to say that you're using the vehicle in a way not approved by the manufacturer, and may attempt to deny your claim.

My US 2007 Civic was rated to tow 1000 lbs. I never had a chance to try it, but I know I wouldn't want to get close to the limit without brakes on the trailer, especially if there's anything more than just the driver in the car. And the rear suspension is definitely not designed to carry weight (see photo). Sadly it's hard to find small trailers with brakes in the US since people mainly tow with big trucks.

enigmaT120

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Re: Building a hitch for my tiny, aluminum car
« Reply #16 on: December 18, 2014, 11:59:24 AM »
Nice.  Do you think aluminum square tubing would be strong enough?  I don't know how much weight it would save.

Will you be sharing these photos with the Insight forum?


Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #17 on: December 18, 2014, 02:06:33 PM »
To be honest, I bet I could pull a few hundred pounds without the brace at all, but it inspires confidence. I'd hate to slam on my brakes with a load behind me without something to prevent it from torquing the bumper. Things creaked a bit when I bounced on the ball mount without the brace installed, and it doesn't creak now.

The reason I used steel was so I could weld it to the receiver, not really so much that I didn't think aluminum would cut it. The steel tube was only a fraction of the weight of the receiver though. It's ~18 gauge and probably weighs around 2.5lbs.

I have a modification thread over on Ecomodder, and might soon cross-post on InsightCentral as well now that you've mentioned it.

Sid Hoffman

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Re: Building a hitch for my tiny, aluminum car
« Reply #18 on: December 18, 2014, 11:51:21 PM »
My US 2007 Civic was rated to tow 1000 lbs. I never had a chance to try it, but I know I wouldn't want to get close to the limit without brakes on the trailer, especially if there's anything more than just the driver in the car. And the rear suspension is definitely not designed to carry weight (see photo). Sadly it's hard to find small trailers with brakes in the US since people mainly tow with big trucks.

That's a rarity, for sure.  They have traditionally been extremely conservative for the US market and their passenger cars.  I checked though, and sure enough on page 204 of the owners manual it does state it's rated for 1000 pounds.  Nice!

As for the OP's custom hitch on his Insight, I like it.  I might have used slightly larger diameter, thicker steel washers myself, but I suspect it will do the job just fine.  Excellent work!

The only thing I'll say looks off is the trailer's proposed axle placement.  It appears the OP wants to support a great deal of the weight with the hitch itself, rather than supporting the weight on the axle.  You never want to put more than 10% of a trailer's weight on the hitch, you want the axle to be supporting that weight.  Unless that trailer is going to be very rear-heavy when loaded (a bunch of bricks at the back and pillows at the front?) then the axle would need to be placed further forward in order to bear 90% of the weight.
« Last Edit: December 18, 2014, 11:57:41 PM by Sid Hoffman »

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #19 on: December 19, 2014, 06:25:39 AM »
Thanks Sid. I'm hoping to *not* put much weight on the tongue, but that's how the harbor freight trailers are shaped. I'll either need to move the axle forward, or extend the trailer backward.

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #20 on: December 19, 2014, 10:23:51 AM »
Updated trailer designs:










Design two has less volume and less turning radius, but would be easier to construct and will likely have more aero benefit. It also has a wonderful symmetry to it: 6' x 4', 12" in the rear and 18" in the front, 24" from the ball, 30 cubic feet, which effectively triples what I can bring with me. I would likely split the top with hinges on either side, so I can open it and carry large items such as appliances.

ketchup

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Re: Building a hitch for my tiny, aluminum car
« Reply #21 on: December 19, 2014, 11:36:04 AM »
This looks fantastic.  I'm considering getting a first-gen Insight sometime next year, and one of my concerns was the lack of (official) ability to tow a small cargo trailer.  This may have stricken that from the list of complaints.  Other than that, it's an extremely efficient car with a manual transmission, air conditioning (if equipped), unrustable body, and can be found these days for $2500-5000 so I see absolutely no reason not to get one if this can happen.

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #22 on: January 22, 2015, 08:17:32 AM »
Picked up a Harbor Freight trailer for ~$200. I've drawn in a rough sketch of what I'd like to do with it:








This image doesn't show the wheel skirts, as they were somewhat obscuring of what I was trying to show:




I'm watching a few listings on eBay for wheel pants for small planes and ultralights:




If I can pick something up for a pittance I'll go for it, but at $100 they'll probably never be worth their cost, even if I drag the trailer all around the country. I have a big stack of corrugated plastic the local politicians were kind enough to provide, but it's difficult to do curves with.

Russ

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Re: Building a hitch for my tiny, aluminum car
« Reply #23 on: January 22, 2015, 08:25:48 AM »
you can always make your own fairings; sculpt with chicken wire or similar and glass over it

Spork

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Re: Building a hitch for my tiny, aluminum car
« Reply #24 on: January 22, 2015, 08:53:50 AM »

Standard disclaimers apply here.  I am not a structural engineer.  Take this with grain-o-salt.

Is that entire hitch attached to the brace with a single bolt?  I'd both be worried that that isn't enough and that the huge lever arm there would turn the whole thing (and eventually loosen the bolt).   I realize you are (probably) not going to be pulling huge weights with this, but ... trailers coming off at speed is a bad thing.  I'm also guessing that your safety chains will attach to the same hitch point?

The one hitch I installed had 8 huge bolts into the frame.  Granted, it was class III hitch, so this may not directly compare.

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #25 on: January 22, 2015, 09:00:06 PM »

Standard disclaimers apply here.  I am not a structural engineer.  Take this with grain-o-salt.

Is that entire hitch attached to the brace with a single bolt?  I'd both be worried that that isn't enough and that the huge lever arm there would turn the whole thing (and eventually loosen the bolt).   I realize you are (probably) not going to be pulling huge weights with this, but ... trailers coming off at speed is a bad thing.  I'm also guessing that your safety chains will attach to the same hitch point?

The one hitch I installed had 8 huge bolts into the frame.  Granted, it was class III hitch, so this may not directly compare.


No, there are 5 bolts in total. The hitch is bolted to the aluminum bumper beam, and I welded an arm to run up further under the car to prevent torquing. I had a friend who weighs ~200lbs bounce on the ball to test, and it didn't so much as creak.


you can always make your own fairings; sculpt with chicken wire or similar and glass over it

I'll see what I can come up with. I've never done any fiberglassing, but certainly one of my friends must have.
« Last Edit: January 22, 2015, 09:03:27 PM by Ecky »

Sid Hoffman

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Re: Building a hitch for my tiny, aluminum car
« Reply #26 on: January 24, 2015, 10:25:27 AM »
Looks good to me!  I wouldn't spend too much effort on the wheel fairings if you can't get them for cheap.  Keep in mind the whole trailer is "drafting" you, so it's not anywhere near the same impact as an object being propelled through still air.  Even at that, look at how many airplanes don't even bother with them, and their wheels are fully exposed to the air and at a much higher speed, too.  I know it makes an impact, but given that your trailer is drafting you anyway, I think you've done the smart thing with the shape of the trailer alone and can probably pretty safely delay doing the wheel fairings until it can be done cheaply.

TheFrugalFox

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Re: Building a hitch for my tiny, aluminum car
« Reply #27 on: January 24, 2015, 01:20:08 PM »
A friend just built a towbar for his old toyota camry. He used 8mm * 40mm flat steel stock bolted with 10mm directly to the chassis.
The forces when slamming on the brakes with 400kg behind would be fairly high I am guessing. I am sure once done you will give it a proper thrashing and make sure all is holding together. But well done, not a job I would tackle.

Posthumane

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Re: Building a hitch for my tiny, aluminum car
« Reply #28 on: January 29, 2015, 04:39:46 PM »
Not a bad looking hitch. A couple of points to ponder though. The end of the torque arm that attaches to the car at the furthest forward point appears to have the bolt going through it without any internal support. If you can, you should consider drilling that hole oversize and welding in an appropriately sized piece of round tube through your rectangular tube for the bolt to go through. This keeps the tube from crushing. As it is right now, with significant load placed on that area the rectangular tube may deform slightly and pull away from the attachment plate, which puts the bolt in partial bending and also puts all of the stress on the upper hole in the tube where it may elongate.

I know the trailer you intend to pull is light so I think generally the design is adequate, though I'm curious what the thickness/cross section of the bumper is, as that may actually be a weak spot. Aluminium will fatigue and crack with cyclical loading over time even if the load is well within the elastic range of the metal. I would tend to design for at least 3G force in each direction, so with a 500 lb trailer assume a 1500 lb cyclical load on the hitch.

Not sure on the type of welder you are using, but as you already figured out 200 A for 18 ga is way too high. The locost I'm building is mostly 16 ga 1" tube and I usually run 35-40 amps. With 1/8" sections I bump it up to 45 A or so.

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #29 on: February 08, 2015, 03:14:30 PM »
Thanks for the tips, Posthumane!

Update on my trailer build:

I recently picked up some unwanted corrugated plastic signs, and thought they might make a decent skin, if overlayed like fish scales. If they won't work out I'll get some plastic sheeting, but I'd rather not spend money where I can avoid it. I suppose what will make the decision will be how much water gets in when driving in the rain.




2x2 pressure treated for the frame, some L bracket braces:




After assembling the doors, I decided the hinges I picked wouldn't work, as it would be impractical to load it from the side. I took them back, and ordered a set of lift-off hinges from Amazon. Apparently Home Depot doesn't carry them anymore.




Smooth aero-paneling on the underside:




1/2" PT Plywood floor in-place. I decided a V-nose would be fine as it's not in the airstream, the volume loss was minimal, and the cuts were easier. I had a few half-empty cans of silver and grey spray paint, and decided to combine them in a camo-like pattern.








I have plans to do some fairings over the wheels, but haven't figured out how to approach it yet.

Total cost has been about $230 for the trailer frame, plus registration, and ~$80 for the box on top. I could've gone cheaper but I'm more comfortable with good deck screws, bracing, and PT lumber for something that will be in the weather.
« Last Edit: February 08, 2015, 03:17:59 PM by Ecky »

Posthumane

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Re: Building a hitch for my tiny, aluminum car
« Reply #30 on: February 08, 2015, 09:32:12 PM »
Looks good so far. The coroplast panels are a good choice for bodywork if properly supported. For the wheel fairings, I wouldn't try to replicate a teardrop shape like you see with aircraft wheel fairings. Those are made for open air, whereas your wheels but up against the side of a boxy trailer. If you want to fair them in, I would suggest just a simple smooth slope out from the front of the trailer (covering the top of the wheel) and then back in towards the rear of the trailer. However, I don't think wheel fairings are going to make a noticeable difference on this type of trailer.

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #31 on: February 16, 2015, 12:29:24 PM »
Here's a side profile of the trailer behind the car:




On the highway, I found I was able to maintain ~70mpg at ~60mph with the trailer unloaded and the tire pressure well below what I'll be using once there's some weight in it.

Sid Hoffman

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Re: Building a hitch for my tiny, aluminum car
« Reply #32 on: February 17, 2015, 09:24:37 AM »
On the highway, I found I was able to maintain ~70mpg at ~60mph with the trailer unloaded and the tire pressure well below what I'll be using once there's some weight in it.

That's pretty good.  I doubt weight will make much difference.  At highway speeds, you're competing mainly against aerodynamic drag, not friction from the tires.  For comparison, on the same stretch of road where you got 70mpg at 60mph with the trailer, what is your mpg without the trailer at the same speed, same weather/traffic conditions?

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #33 on: February 17, 2015, 10:22:26 AM »
It's difficult to do an apples-to-apples comparison in Tallahassee because of the hills, but at ~60mph, 75-85mpg is not unreasonable depending on what kind of road it is, and I've had stretches of ~90-110mpg on concrete (not asphalt), which these roads are not. At these MPGs, even small changes such as head/tailwind, road composition, temperature, etc. actually make measurable differences, which is why I'm concerned with wheel skirts. Putting a few hundred pounds in the hatch area has a small but measurable impact on economy, even on the highway.

It's possible my fuel economy may even improve, if this cleans up the airflow behind the car enough through a "boat tail" effect.

I'll need to wait a few weeks to do a true comparison in Jacksonville, where it's flat.
« Last Edit: February 17, 2015, 10:24:48 AM by Ecky »

El Marinero

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Re: Building a hitch for my tiny, aluminum car
« Reply #34 on: February 19, 2015, 11:11:08 AM »
HBut a larger 4x8 enclosed Uhaul trailer? Those are almost 900 lbs empty. Your car? 1900lbs. All this makes me cringe. I hope you aren't going up and down any hills.... let alone mountains.


Many, many years ago, I did a move with '72 Volvo four-banger and a U-Haul trailer.  Those trailers are built like a brick outhouse.  I'd never had overheating issues with that car before, but towing up a grade took the temp gauge to new territory.  It went to eleven.

I'd be concerned about braking, too.  Also, whether all that addition stress on the transmission would do expensive damage.

I've driven a hybrid for ten years now.  The  Insight and the Prius were engineered to do one thing well, which is to get great gas mileage.  I don't think towing enters the picture.

DarinC

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Re: Building a hitch for my tiny, aluminum car
« Reply #35 on: February 19, 2015, 03:45:41 PM »
Towing's fine IME. I've towed 1000+lbs with my Prius. As long as you are sensible, you'll be fine. From the powertrain's POV, 15hp at 55mph with a load and 15hp at 65mph w/o a load are the same.

DarinC

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Re: Building a hitch for my tiny, aluminum car
« Reply #36 on: February 21, 2015, 08:00:12 AM »
I think it's likely that an insurance company might deny a claim in certain circumstances b/c the car isn't rated to tow anything, but I'm not sure he would get nailed in court.

I believe (IANAL) that the reason commercial outfits get nailed is because they have a higher standard of care, custody, and control, and I imagine in the cases you were referring to, had exhibited gross negligence by improperly using their commercial equipment, which has specific instructions for us.

http://en.wikipedia.org/wiki/Gross_negligence

Quote
Gross negligence is a legal concept which means serious carelessness. Negligence is the opposite of diligence, or being careful. The standard of ordinary negligence is what conduct one expects from the proverbial "reasonable person." By analogy, if somebody has been grossly negligent, that means they have fallen so far below the ordinary standard of care that one can expect, to warrant the label of being "gross." Prosser and Keeton describe gross negligence as being "the want of even slight or scant care", and note it as having been described as a lack of care that even a careless person would use. They further note that while some jurisdictions equate gross negligence with recklessness in terms of culpability, most simply differentiate it from simple negligence in terms of degree.[1]

To be honest, as long as the trailer is tested thoroughly on the highway, the testing is documented, and reasonable engineering calculations (relative to other hitches on the market) were documented, that would likely qualify as due diligence above what a reasonable person would do in the same situation. At worse there's a chance it could be considered ordinary negligence, which is what one would expect from a reasonable person.

Anomalous

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Re: Building a hitch for my tiny, aluminum car
« Reply #37 on: February 21, 2015, 10:55:25 AM »
It's good to point out that a homemade trailer may have greater liability than a commercial one if something goes wrong.

However, I think it's absurd to suggest that lawyer should be consulted or that it's reckless to use a homemade trailer on the road. I'm actually upset by the implication that homemade trailers shouldn't be allowed on the road, and only commercially built vehicles are acceptable.

It probably varies by where you live, but a large percentage of non-commercial trailers I see on the road are home made. Lots of them are much more thrown-together than this one. Plenty of things like old pickup truck beds chopped in half with a tongue welded to the front. It's less common for people to build their own hitch for the car, but I do see a few home-made bumpers with integrated receiver (mostly on pickups or jeeps.)

There's also communities just for people building their own trailers. Teardrops and Tiny Travel Trailers (http://www.tnttt.com/) has hundreds of examples of home-made trailers. Many of them use a harbor freight trailer as the base, similar to the OP here. Some of them modify old boat trailers or old RV trailers, some build the frame from scratch.

Of course there are a number of scratch-build complete cars on the road as well. I've looked into this in the past, and to register a scratch-built car there are a number of requirements relating to things like DOT approved lights and rear view mirrors, but there's no requirement for any kind of engineering design. Should the homemade cars be banned from the road also?

If a trailer is built badly, falls apart on the road, and causes an accident, by all means go ahead and sue the owner. But don't use that rare case as an excuse to ban all homemade machines from the road.

DarinC

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Re: Building a hitch for my tiny, aluminum car
« Reply #38 on: February 21, 2015, 01:29:22 PM »
Not sure I agree. Or at least I disagree with your apparent downplaying of normal negligence claims, which is the basis of most successful tort claims.

I'd be chomping at the bit to be counsel for plaintiff or plaintiff's insurance carrier in this instance. And the first thing I would do is cut and paste all of OP's postings above.

Would a reasonable person, with no apparent prior experience in making/manufacturing/modifying/testing hitches and trailers: (1) modify a vehicle that is unrated for towing; (2) modify a trailer with signs and related non-towing accoutrements; and (3) post online about their trial-and-error efforts on a web site focused on saving money and being frugal, vice a serious engineering web site? Heck, even if the facts were the same but this were an engineering web site, I'd still sue.

I'd posit it's a prima facie case of negligence, and perhaps more. And I'd only need negligence to extract a tidy sum to cover my client's damages.

Everybody needs to read the case law on towing accidents with commercial equipment. This scenario kicks it up a notch: towing accidents with DIY equipment (on both ends, no less: vehicle and trailer). Imagine the claims you would bring if your spouse, child or other loved one were killed or injured by OP's get-up.
I don't see it happening in this case. It might be that we come from different backgrounds, but I don't see anything indicating prima facie negligence, at least not w/o a whole lot of precedent. Comparing case law for commercial accidents probably isn't realistic because they have more stringent requirements for care, custody, and control, and also equipment that can do much more damage. I thought the standard for negligence there is lower than it is for private individuals because they should be experts in their trade. I could be wrong about that though.

In this specific case, looking at the exterior of the trailer, I would think that if zip-tying corrugated pieces of plastic was negligent, then pretty much every individual who stapled/tied those signs to telephone poles and so on next to roadways would also be considered to be negligent. I haven't heard of an individual being held liable for improperly affixing a small (~1'x1') plastic sign that blew into the roadway and resulted in a driver getting in an accident. Small road debris is a common part of driving that people have to deal with on a daily basis a should not cause any accidents.

I think the same applies to the construction of the hitch. Most cars only use 4 bolts to attach a hitch to a unibody frame, so even if a hitch is fabricated by an individual, the fact that is uses more bolts (6) along with angle iron for reinforcement doesn't seem negligent to me. The same applies to the weld. Just because the OP commented that it looked bad doesn't mean it's structurally deficient. Provided he used properly working equipment and had good penetration, I don't see anything implying that's negligent.

I don't disagree that even normal negligence claims shouldn't be downplayed, but I don't see anything here that would be considered negligence. Having said that, my wife has access to lexisnexis, so if you have anything specific in mind it would be interesting to compare it to this situation for everyone's benefit.

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #39 on: March 04, 2015, 07:40:31 AM »
So far, I have about 800 miles on the trailer, mostly highway. I tested it up to 85mph and found I needed to reinforce the coroplast panels in the nose (they slid down about a quarter of an inch from bowing in the wind), but otherwise had no issues. I haven't tried pulling with more than ~200lbs in it yet, but it handles surprisingly well, loaded or unloaded. I haven't yet felt any fishtailing or pulling on the back of the car when passed by larger vehicles.


68mpg @ 60mph over 65 miles on level terrain:



At higher speeds there's definitely an aero penalty over driving without a trailer. At 75mph, for instance, my gas mileage is down to ~50-55, from around 65 without the trailer.

As for power, I can feel it with ~200lbs loaded (probably ~350 total?), but the loss in acceleration is near-negligible, and I have no worries about merging.
« Last Edit: March 05, 2015, 05:24:31 AM by Ecky »

Ecky

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Re: Building a hitch for my tiny, aluminum car
« Reply #40 on: May 18, 2015, 01:11:05 PM »
In the days leading up to our move, I worked on the aerodynamics a little more:








On May 1st, my wife and I packed our 50lbs Border Collie, 15lb Sheltie, and everything we owned into the car and trailer. We pulled out the carpet and secret compartment box, and stuffed the spare tire area and other unused space around the wheel wells completely full, with items like blenders, books, and clothing to fill in the gaps. The cargo area was packed to the roof, aside from  approximately 2' x 3' for our Border Collie, and the Sheltie sat in my wife's lap. During some parts of the trip the Border Collie insisted on sitting there too. She had items around her feet, and we packed full the spaces beneath and behind our seats. We packed the trailer full too, with not enough space left to fit a book. I left my tools in an easy-to-access spot in the hatch, in case we had any major disasters.

I can only guess what the total weight was, but I would be surprised if the trailer had a pound less than half a ton, and there was at least 500lbs of stuff in the car too. With my wife and I, and a full tank of gas, our gross weight was probably in excess of 3500lbs.




Our route:




A 5MT Insight has around 110ft-lbs combined torque, but is geared like a V8. Even under full assist, the car accelerated at a snail's pace. Braking distance was still reasonable though, and at no point did I experience any instability. I loaded the trailer so that the tongue weight was only around 50lbs, and handling was excellent, even in wet conditions and with significant sidewinds.

We stopped the first night to camp at the edge of Great Smokey Mountains National Park, because who wants to pay for a motel room?




Getting up to the top of Clingman's Dome required 2nd gear WoT almost the entire way. I kept an eye on coolant temperature, but it never exceeded 197F. The brakes held up great during the rapid 4000ft+ descent, and despite some serious potholes which scared the living hell out of me, the 2x2 and corrugated plastic trailer survived without any damage.

Even cruising at ~65mph when the speed limit allowed it, and frequently in 3rd gear at WoT to get up one mountain or another (I-81), I still averaged around 57mpg for the full trip pulling double the car's normal weight. By avoiding 95, we were able to drive a bit slower to conserve fuel, and avoid tolls entirely. Our total gas cost was under $70.

I consider the trailer experiment a success, but would consider upgrading the brakes if I frequently pulled close to a ton of cargo.

~

Now that I'm in Vermont, gas mileage has skyrocketed. 35-50mph rural roads with gentle hills are nearly ideal for hypermiling, and this first tank is looking to be around 80mpg despite cool weather. I've been close to setting my 220% EPA trip record.




« Last Edit: May 19, 2015, 09:04:48 AM by Ecky »