Archive for June, 2009

15
Jun

Building an MG-TC pedal car: Part 4a

   Posted by: Mark    in Pedal car

Refer to the Introduction for links to all of the posts in this project. This is a continuation of Step 4.

About a week ago I was able to get both the steering and drive systems complete, which had been a hug hurdle for me. After some brainstorming with Dad and some poking around at the Orange Box, I found all I needed.

The plans had called for a galvanized pipe for the steering rod, flattened and bent up at the tie-rod end and fixed with a pipe flange at the other for connection to the steering wheel. I had a version of this completed, but was never satisfied with the roughness of the steering. Not only was it difficult to steer, but it wasn’t particularly reliable. So I ended up using a 3/8″ diameter piece of steel for the steering rod. At the bottom end near the tie rods, I bent it up, ground the sides a bit to make some flat surfaces, and used U-bolts to fasten a 1 1/2″ x 4″ section of flat steel. The tie rods bolt to this flat steel, and there is amazingly little play in the whole thing.

I had ordered tie rods with the ball joints, but the shortest they had were 11″, and I needed something around 8″ long. I used 5/16″x24 threaded rod (or all-thread), which is great because I have enough play to allow adjustment of each wheel separately.

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It’s not the prettiest steering ever created, but it works very well. The steering rod comes through a piece of scrap that I screwed to the front of the body because the original steering column hole was about an inch in diameter to fit the pipe called out in the plans. Once the grill is in place it should look much more clean.

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You can see the flattened sides of the steering rod. The U-bolts I had bought were pretty small, so I had to grind the sides of the rod to get them to fit. There’s no chance they can slip or move — they’re on VERY tightly.

And here’s a poor-quality video of the steering in action. The angle on the tie rods is a lot greater than I would have wanted, but at this point I’m not willing to redo it all. The kids could care less, and I just want to get it painted!

For the drive system, I had two problems: I couldn’t figure a way to affix the single drive wheel to the 3/8″ steel axle rod, and I didn’t know how to attach the drive rods from the pedals to the crank. Although I’m not yet convinced the lifespan of this solution is all that long, I ended up drilling a hole through the drive wheel hub and the axle, and inserted an “R” clip through the holes. My concerns with this are that the hole I drilled is pretty large relative to the small 3/8″ axle, and the hub isn’t really designed to handle the torque that can be applied by an excited child. We’ll see how long it lasts. So far it doesn’t show any wear, so that’s promising.

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Getting a picture of this was harder than I expected, and the sun was fading fast. In the picture above you can see the loop on the “R” clip. I still need to trim the axle, but I’ll probably wait for final, post-paint assembly before I do that. You can also see the colored label on the tire in this picture, which is another thing to fix in final assembly (all the other wheels have the blackwall point out, with the tire graphic hidden; yes, I have issues).

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It’s really tough to make out the “R” clip here, but you can see the top loop of the clip on the right.

For the drive crank, I drilled holes in the drive rods just large enough to be able to slip the axle through them, and threaded them on with a washer and small pipe-band-clamp on each side. The washers and pipe clamps keep the drive rods in the same spot on the crank, and insure that the drive rods don’t slip up the sides of the crank. It’s another case of “not pretty, but quite functional.”

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And here’s another questionable-quality video, this one showing the drive crank and pedals in action. Again, not all that smooth because I was trying to keep the camera steady with one hand. Also, both this video and the above steering video might give the impression that there’s a ton of friction in the two systems. They’re certainly not finely-tuned, but they really are pretty free and smooth.

10
Jun

Building an MG-TC pedal car: Update – videos!

   Posted by: Mark    in Pedal car

Refer to the Introduction for links to all of the posts in this project.

The past two days have been VERY productive days with the pedal car! Not since the body went together have I accomplished this much in such a short amount of time. I finally worked a very usable solution for the steering (at BOTH ends of the steering rod!), and finished that last night. Then today I was able to devote about four hours of uninterrupted time to redoing the drive mechanism, and that’s working better than I could have imagined (thank you, Dad, for your ideas and help, and Tami for letting me do it!). Once the kids drove that around for a little while, I realized I just had to get the fenders mounted. And man, what a difference it’s made having those things on the car!

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I’ll update Part 4 with details and pictures as soon as a I have a chance to get some decent shots of what I’ve done. Until then, perhaps these videos will hold you over! The kids ran it for about three hours today, and the worst I had to do was add a seat support (for those with longer legs) and tighten a few nuts that worked loose.

One of the huge helps in all of this has been the comments and emails I’ve received on some of the other posts in this series. Seeing interest in this project is really pushing me to get it done, so thanks to all of you who have stopped by!