I like it, but...why did you make the 1" sched 40 pipe 4 3/4" long? Seems you will have to be really careful with tongue weight when you load the trailer, not that you wouldn't anyway with a car not meant for towing. The 4 3/4" length may promote bending if you happen to hit a bump with a heavy load. Making this length as short as possible would make sense to me. I say drop another 2" not just 3/4". Is their a reason for the added length?

Great hitch though.

Peace
Ian

 

Just a point about being careful if you make another one. When I designed the Twosrus hitch for the Spyder, we found out the hard way that the distance between the two tow hook points was not very constant, nor was the perpendicularity of the threaded nuts.

For those that don't want to do all the work.. twosrus is still selling the basic kit for $150.00 which includes the threaded stainless steel rods and everything except the steel cross bar which is pretty easy to fabricate.

http://www.twosrus.com/catalog/product_inf...products_id=145

 

Is that a Spitfire behind the MGA?

 

borgliel, first, about the schedule 40 pipe: I agree. It would be better if it were shorter. In fact, I an seriously considering shortening it as much as I can. The reason it is so long is simply that, not being an engineer (I'm a fisheries biologist) I wantled to allow enough length to make sure that it would clear all obstructions. I could always cut it shorter, but can't cut it longer. I can see now that I overdid it substantially. But at least it will be fairly easy to shorten -- a pipe cutter works well on the pipe, but then I'll have to shorten the thumbscrews as well. (and I had that possibility in mind when I made it).

I do have a question for you engineering folks: Wouldn't the fact that the mounts in the car were made to tow the whole car's weight suggest that they should be able to handle a substantial tongue load on the trailer? (I doubt that I would ever load it more than 20 - 30 pounds anyway.)

Yes, randychase, I agree here also. Measure it twice and cut it once. Also it takes quite a lot of work (time, that is), so $150 for a mostly pre-fabricated hitch seems like a fair price. When I started this project I had been unable to find a hitch to purchase, so I had to invent something, and it does seem to work very well, and it can be built without a lot of sophisticated tools.

AgSpyder, the Car behind the MGA is a Triumph GT6 with a Buick 215 aluminum V8. It is a project car, and still has a long way to go before it will be usable. I need a transmission for it.

 

Nice, did the GT6 originally have a straight 6 in it? Basically a Spitfire Coupe/Hatchback (from what I remember). The Buick 215 cu in engine is a great engine to work on. It has plenty o'power with the 4 bbl. Don't ever, ever let it overheat though Good luck with your projects!

 

Originally posted by crabby+--><div class='quotetop'>QUOTE (crabby)</div>

...I could always cut it shorter, but can't cut it longer...[/b]

Good choice.

<!--QuoteBegin-crabby
I do have a question for you engineering folks: Wouldn't the fact that the mounts in the car were made to tow the whole car's weight suggest that they should be able to handle a substantial tongue load on the trailer? (I doubt that I would ever load it more than 20 - 30 pounds anyway.)

Tongue load is questionable, since you don't know if the car's structure at the tow points are meant to take shear load when pulled out of a situation by a tow truck. However, if you load your trailer well (tongue weight < 50lbs) it has been argued here at SC that the overall trailer weight could be up to 1000 lbs with a recommended max of around 500 lbs. No one really knows the limits (Stryder back in '03 tested 1000 lbs) since the car is not designed for a trailer and has not been tested to failure. Good luck and be safe.

Peace
Ian

 

Yep, I did the 1000 pound test some years ago.

It was always my opinion, that without access to real data to analyze about the mounts, the only safe assumption one could make is that they are designed for a short term use to pull the weight of the car, and that is presumably with low resistance... ie not pulling the car back up a cliff.

That never included a torsional load or one providing a bending moment. And my gut feel... from what I could see when peeking into the nut area... is that you are still only attached to the sheetmetal and that could be very strong ina direct pull... but not so strong in other loading directions. So I always advised a lower tongue weight under 50 pounds.

 

AgSpyder, Yes it originally had a straight six, but that motor was already gone when I got the car. Thanks for the heads up about overheating, I'll be careful to make sure that the cooling system has plenty of capacity. It should be a fun car, as light as the GT 6 is. Yes it is basically a Spitfire with a hardtop and a Six cylinder motor. It also has a better rear suspension. They got away from the swing axel with the GT6

brogliei and randychase, Thanks for the info. from what you say, I think I should bed safe if all a ever haul is the little 38" x 40" trailer with my race tires and a few tools, and am careful to balance the load so I don't have a tongue load that I can't lift easily. And I will definately shorten the schedule 40 pipe.

thanks for the comments

 

results?

I realize this thread is pretty old but I was hoping you had some results and experiences with the diy hitch. I just bought my first spyder and this is exactly what I was looking for. I have a few questions though.

1. Do you feel that it would be adequate to pull a tent trailer designed to be pulled by a motorcycle?
2. What thread grade did you use for the attachment rods?
3. Is there a reason you chose to use rod instead of off the shelf bolts?
4. Did you ever cut down the schedule 40 and how short were you able to get it?
5. The paint job looks fantastic in the photos. What paint did you use?
6. Were you able to weld any of the schedule 40 to the rear wall of the 2" square tube stock or did you just leave it unwelded at that location?
7. I have a 90 amp 110 volt wire welder. Do you think that would be adequate to attach the 5/8" plate to the underside of the tube stock?

Thanks for any responses/suggestions in advance.

 

Home-made trailer hitch

1. About the size of trailer that it would be safe to pull with this hitch: That is really a question for an engineer, which I'm not. I pull the trailer in the photo, loaded with four racing tires/wheels and the rest of the space filled with an assortment of tools, lunch, drinks, raceing jack, air tank, and such. I've never weighed it though. The trailer is not a lightweight -- its steel, not aluminum. I'd guess that loaded, it weighs between 200 and 500 pounds.

2. For threading the rods, I just went to a local machine shop and told them that I was going to use the rods to pull a small trailer, gave them the eye-bolt that came with the spyder to use as a model/template, and left the rest up to them. I asked them to make it extra long, and then I cut it down to size as I progressed with the project.

3. The only reason I chose to use a threaded rod instead of off-the-shelf bolts is because I couldn't find any bolts with both the right diameter and right thread pitch. Toyota did not use a standard size for this, and I searched everywhere I could think of but never found any bolts in the size that I needed. Other Spyder folks had told me that I wouldn't find any such bolts, but of course, I had to look for myself. They were right.

4. I did shorten the schedule 40 pipe. I cut it down to 5-1/8 inches. That makes it extend 3-1/4 inches from the square tubing. I couldn't go any shorter without risking the hooks on the safety chains scratching the bumper. If I were starting over, I might install the U-bolts horizontally, instead of vertically. That would allow you to shorten the pipe a little more.

5. For paint, I just used a spray can of Rustoleum. first a coat of metal primer, then two coats of gloss. If you start with a smooth, clean surface it will produce a servicable finish. It won't be as tough as a proper automotive paint, but then it is not exposed to the weather as much -- less than 20 days per year in my case. I've been using the hitch for a year-and-a-half now, and it still looks good.

6. I did weld a little of the schedule 40 pipe to the rear of the square tubing, about 1/2 inch of bead where I could reach through the open end of the square tubing.

7. I used a Miller model 135 MIG 115 volt (wire) welder. I made three passes in some places, cleaning up the surface between passes. I would guess that your welder would be adaquet. Your skill in using it would be the critical factor. If you are able to run a consistent bead with good fusion/penetration, I'd guess that you'd be OK. If you're in doubt about that, you should consider having a professional or a very skilled friend do the welding.

Since I originally posted this topic, I've used the hitch for a full season and-a-half of racing. That amounts to sixteen trips of 100 miles or more each and the hitch has worked very well, and the trailer pulls nicely behind the Spyder.

Hope this is helpful. I'd be interested if you (or anyone else) builds a hitch like this, and how it has worked for you.

 

Thanks very much Crabby. You don't know how helpful you've been. I will be purchasing the material to duplicate your hitch tomorrow afternoon.

 

Glad I could be of help. Good luck with your project!

 

I plan on replicating your hitch sometime in the next week. I will let you know how it turns out. One question though, is 1 7/8" the most common ball size for small trailors?

 

When I get some spare time, I'm going to be running a GB on the basic hitch package (everything but the cross bar) to clear out my inventory. If you want to save yourself some time and effort, give us a call and I'll set you up with the hard parts for a good price.

717-638-1108

 

Originally posted by David Hawkins
When I get some spare time, I'm going to be running a GB on the basic hitch package (everything but the cross bar) to clear out my inventory. If you want to save yourself some time and effort, give us a call and I'll set you up with the hard parts for a good price.

717-638-1108

When are you going to start that David? I'll be in.

 

I don't know for sure...I've been swamped the last two weeks. If you're in a hurry, call us. If you can wait, expect to see a GB within the next week or two.

I've got about 12 hitch kits left - when they're gone, I'm out of the hitch business.

 

I am not in a hurry but I will definitely buy a kit from the group buy whenever you are ready to go.

 

I'll buy a kit also. Let me know when your ready.

 

digging ancient thread from the grave, I'm interested in buying a towing kit like this. Anyone know where anyone may be still selling them? I would build it myself, but I don't have welding experience or easy access to the components.

 

The sketch and photos from 2005 are fantastic. Print them out and present to your local (or not local) machine shop for a bid. I'm about to do the same thing. Add thread spec M22x2.0 to the sketch.

 

It's an old thread, but still a good idea. This would be my variation of it: use most of it, but instead of a hitch, build a small basket out of expanded metal, just big enough to hold a couple of suitcases and when you travel you can put all of it in the motel.

 

Great idea! I had been wondering about this for the spyder after seeing a similar one on a mx5 with tyre trailer.

 

Good job

Crabby, you have no problem at all with the hitch, for what you will be pulling. The week link will be the trailer tongue. If you worried about it set a jack under the hitch and I bet you can lift the back of the spyder with it. what you have fabricated up is a pulling eye, and it is designed to pull the weight of the car with just one eye. you have two. You made a nice looking hitch. HTH JD :biggthumpup:

 

Sorry to bump an old thread, but it became very useful for me. I had a twos r us trailer hitch years ago, but when I quit autocrossing i sold it off. big mistake, seems everyone that got their hands on them refuse to let them go. Anyway, I got back into auto-x. With the help of a friend, and the scrap pile at his work, we have begun constructing another. We are currently waiting on the factory tow hooks to modify. Then we will cut everything to fit. Almost there.

 

... begun constructing another. We are currently waiting on the factory tow hooks to modify. Then we will cut everything to fit...

Be sure to design some "float" into one of the pin attachments. The spacing between hitch pins varies a little from car to car. You probably don't want to end up with a trailer hitch that will only fit one spyder.

 

Good stuff! The gentleman I bought my spyder from said he had made a hitch for the car and when I purchased it from him he offered to sell it for a few hundred dollars but I knew it could be built for much much less

Best part is the car is, already wired for a trailer so that saves me from bothering with that

 

Finished. Put the "rod extensions" on the lathe a bit so there was a bit of play. This should compensate for the nut differences on other cars. I am happy with how it came out.

Couldn't have gotten it much closer