First Teardrop build for a lifelong DIY Madman

[MitchReef]

I love your screen name tim. I used to tell people a little skin oil was the perfect lubricant for most rubber O-ring applications. Just a rub to the nose then

[MitchReef]

Thanks for the great response kayakdlk. I am not planning to fiberglass my body. Like I said I wanted to be sure I could go with the AC unit on the roof. It only weighs about 5o pounds but calls for 100 pounds of roof weight capacity. I guess I could go with a support frame for the central roof area between the two 1/4 inch skins. A couple of properly designed kind of inverted U that then goes in the void space. But with the legs extending back at somewhat of a diagonal. And I plan to go with a woody finish.

[noseoil]

Mitch, here's the thread about weight. It should help with planning. viewtopic.php?f=21&t=60392

1/8" ply with 3/4" x 1 1/2" spars will be plenty strong for a roof. Take a look at hollow core doors as an example. You have solid wood for the "hard points" at the edges and cardboard inside. If you use wood for the roof spars & stringers, and 1 1/2" foam insulation for the core, it will be plenty strong enough. You might consider hardwood for the spars which will have fasteners in them supporting the weight of the AC unit, but the rest can be pine, fir or poplar. You could even use 5/8" thick spars if they are clear (no knots) and straight. I'm using 3/4" plywood for the sides, but removing everything except 1 1/2" edges for fastenings at hard points for cabinets, doors, etc. The center will be 3/4" foam, the skins will be 1/8". This is fairly light, strong and durable.

Before you go any further, take a look at a summation of various plywood weights (1/8"=.40#/SF, 1/4"=.70#/SF, 1/2"=1.28#/SF, 3/4"=1.90#/SF) and the actual square footage you will be using. This will give an idea of where you will end up. I would urge you to do a summary first! tim

[MitchReef]

Thanks a million noseoil. I just spent a chunk of the evening calculating the weight of lumber and was a bit surprised with what I found. I'm really glad you brought that to mind.

Now....tell me more about using the foam as a wall layer. Would that pretty well require fiber glass? I was actually looking at using 1/4 for the body panels but if 1/8 is strong enough to hold up I will definitely use it. I was also figuring a fully skeletonized 3/4" framing for the inner wall layer. I was thinking 2 1/2 inches along all outside periphery surfaces and 3 inch webbing bottom to top on front and back of door with the door frame at 3 inches, as well as the door itself, otherwise just a course of three inchers for the barrier wall and main galley items to mount to. The rest of mine is planned for foam panels. Currently I have my lumber estimated at 325 pounds, not including the trimwork, spars or the 3/4" frame. I figure I am okay, and I am at the 1500 towing limit!!! I want to weigh my running gear but the batteries in our damn digital scale are dead.

[noseoil]

I think using 1 1/2" for the web dimensions would be fine on the sides. Why use 3" when 1 1/2" will be strong enough? I will have a total of 2 1/4" for the roof & front edges of the 3/4" plywood sides (1/8" roof & ceiling + 1 1/2" roof framing = 1 3/4", plus 1/2" of margin for a bit more meat = a 2 1/4" wide edge). Everything else will be 1 1/2" for the "hard points" for fastening cabinets, shelves, doors, etc. If you get sheets of 3/4" foam (Home Delay or Low's) you can lay the finished skeleton panel on top of them, then trace the inserts with a magic marker. Cut the foam with a knife & set the panels aside. Once the inside skins are glued to the skeleton, you have a light, strong, insulated panel which will have lights & wiring runs already in place. Make sure you allow for wiring runs & light locations before assembly! It's easier to drill small holes for wires when the panel is just a skeleton. Then pull the wiring, insulate & skin when it is all ready and finished.

I see a lot of 2x4's & 1x4's being used where 1x2's would suffice in builds. Remember the hollow core door! Take a trip to your local Home Delay & pick up a hollow core door with 1/8" plywood skins, not the gray primer coated masonite type, and you'll see what I mean. The skin itself is pretty flimsy, but if it is glued to a frame with titebond glue, it becomes a very rigid, light, strong panel. The masonite doors will feel very heavy compared to the plywood ones. tim

[MitchReef]

I took your advice and did a weight summary and now that I corrected it I got a total lumber weight of 461# I put my bare trailer at under 300 with its 12" wheels and tires. That weight didn't include roof spars or the 3/4" frame and web. I think I will come in under or at least close to 1000# total.

My Elantra said "maximum towing capacity 1500 may require engine or transmission upgrades". Except for maybe an auxiliary transmission or engine oil cooler what else would be done besides good fluid and tire maintenance? I cannot find anything specific about this anywhere.

[noseoil]

Mitch, I don't know about your car, but an oil cooler for the transmission would be a must (automatic, not manual, right?). I would look on a forum which is specific to your make & model, then post to other people who already own & use their cars like you are going to use yours for the trailer. They will be able to tell you about specific things and mods which work.

I agree with changing fluids regularly, if not more often than is recommended by the maker. 3K miles for oil changes is the max I would go if towing. Transmission fluid needs to be monitored and maintained. A lot of the newer transmissions are "maintenance free" from the factory, but that's a recipe for disaster on an automatic which is heated up by towing. Summer will find any weak spots when towing in the heat, hills will test the engine & drive-line. Shut off the AC on hills & watch the temperature gauge if there is one. tim

[MitchReef]

I was planning on a transmission cooler already. The transmission is sealed but I have it back flushed more than recommended because I prefer no suspicion of the fluid having a problem. The car is just over 50K and I have brand new fluid now and had it around 25K. I just like to do it that way after having to buy a transmission for a car before. The maintenance is cheap.

I have not yet searched the web boards for Hyundai owners and enthusiasts. I will find out the general opinions on the plan. Might have to wait till the weekend though. I am so behind on my work documentation that I have to give it virtually every minute I am able. I just popped over here to respond to the great comment.

[MitchReef]

Well, some time has passed and the reason I haven't been on here is a total lack of time spent on the tear....makes me kinda sad to think about it, but my job requires a lot out of me. Unfortunately I haven't managed a weekend that wasn't spent finishing the backlog of computer time for work in several weeks. Shame on me, and thanks to a new method of doing what I do should prevent that from being an issue for the most part. The other reason I haven't had any progress was an unexpected need to go buy a new washing machine (when the old one crapped out). Thus, no budget till this week. I will certainly finish the floor completely and also anticipating purchasing the 3/4" plywood, from which I will build the wall inner panel along with a majority of the wall filled with foam board. I also need to use my friend's computer projector and trace my profile onto some heavy paper stock for template start.

Now this is getting exciting. I can't believe I am actually at this point in the project! I may get the wall cores done and then have to wait for more lumber money before I continue, but that's okay too.

Anyway, watch for progress. Pictures will follow major steps....hopefully....

[Sheddie]

Re your transmission cooler. Your car will probably already have one, BUT! they are usually built into one of the engine radiator tanks. The problem there is that you are trying to cool the trans with the same water that is trying to cool the engine, i.e. trans gets hot and helps make the engine hot, and vice versa. You should be able to pick up a remote trans cooler kit at any auto accessary shop, plumb it to the pipes feeding the existing one, and bypass the existing one. For engine cooling, the radiators in most modern cars are only just adequate for the car on its own. Many of them only using single row cores, you may be able to upgrade to a 2 or 3 row, but this would probably not be cheep.
It is also advisable when towing to select the gears manually, rather than just leaving it in drive. The trans is working a lot easier that way.
Another thing to remember for anyone reading this, if the engine does start getting hot (but not from the lack of water) put your heater on hot, turn the fan to high, wind down the windows and suffer the heat. This way you have just added another radiator to help the cooling, and may have just saved an expensive repair bill.

[MitchReef]

Thanks for the input Sheddie. I spoke with my local Hyundai Service Department and they are concerned that a modification to "a sealed transmission" might not be a good thing with the Certified Used Warranty. I am going to write a note to Hyundai America and get a definitive answer, and if it is deemed okay I will just add that reply to my maintenance book and keep it with the car.

It looks like another rainy and dreary weekend so I went and bought a couple of packs of poster board and I will glue them together and work on drawing up and cutting out the master pattern. I will post up the design when I get it cut out and see what the general thoughts are on my idea.

[Sheddie]

Hi Mitch,
Yes, with the warranty it is better to put the question to them. I know what they will say, but the stupid thing is that an external cooler can only be beneficial. As well, they refer to it as a sealed transmission so that you will feel obliged to take it back to the agent for servicing. After all it is the service department that makes most of the income for the dealerships, and they don't want that work going to the independent workshops.
Frank

[MitchReef]

I got a reply from Hyundai's Warranty Department stating that if any non-Hyundai items are put on the car and then that item causes the failure the failure will not be covered. I saved and archived the email to have for all time.

Let the transmission be cooled!

[MitchReef]

I now have no fear about the front top curve. A local builders supply can order a sheet of bendy board for $39. That will be enough for my needs and more!