Here are some chassis considerations when building your Fray and or racing car. As you know Aurora mass produced the parts for the T-Jet, therefore, there were varying degrees with respect to quality. After all, these were made as toys. I don't think Aurora ever thought the T-Jet would evolve to it's current level of performance. That said, here are some guide lines when choosing a chassis and top plate.
Not all parts were made equal. First, most number 4 open rivet chassis had alignment issues with respect to the axles. This was a defect in the mold used to make the chassis. These chassis should not be considered for racing. You can use them for your "Shelf Queens" and displays.
Second, with respect to top plates, look for the top plates with the squared off idler post as compared to the plates with the rounded idler post. The top plates with the squared off idler post reduces the movement of the idler gear and helps with the gear alignment on the top plate.
In the picture below the gear plate on the left has the rounded post and the gear plate on the right has the squared post.
Here is another picture showing the difference in the posts. The plate on the top of the picture has the rounded post and the bottom plate has the squared post.
Here is a list of chassis that have been found to be better than others as a general rule, with respect to alignment and flatness. Hopefully this will give you something to start with, however you still need to check for alignment and flatness using a tech block.
- Chassis Numbers are 7, 9, and 10
- Chassis Letters include A, D, G, and H
Now for the the top plates with the the squared off posts
- Top plate numbers include 7, 8, 9, and 10
- Top plate letters include A, B, G, and H
Remember this is just the start. Now you will start checking for the best possible fit with respect to flatness and hole alignment. By using 0.063 drill blanks and a flat tech block. The more you do this the better you will become at matching the chassis with the top plate.
The first thing I check is the flatness of the chassis. To have a solid car it must have 4 wheels that touch the track at the same time. To check the chassis I will use a tech block and drill blanks. I am looking to see that the drill blanks are all touching the tech block when I rest the chassis on the tech block.
Below is an example of a chassis that is not flat. Notice the space between the drill blank and the tech block in the front right.
Once I have found a flat chassis I will look for the flattest top gear plate and hopefully the gear plate will match fairly close to the chassis. First to find a flat gear plate... I will again use my tech block... the bottom this time. I check basically three things, that it is flat, and there is no "cupping" of the plate in either the width or length. The idler gear post should have a square top as opposed to rounded off if possible.
After I check the chassis and the gear plate the next thing that I will do is to try to match the gear plate with the chassis. I know some try to match numbers, however, after 50 years that pretty tough so I try to match the holes between the gear plate and the chassis. Again I use my tech block, drill blanks and calipers. I attach the gear plate to the chassis and then run the drill blanks in the holes and measure the distance between the drill blanks on either end. Hopefully the measurement will be the same or very close.
When I am satisfied that I have a flat matched chassis and gear plate I will start looking at the chassis closer for mold burrs particularly the axle holes, armature shaft holes, and cluster shaft holes.
Hopefully this will help get you started in building a fast great handling T-Jet.
Hopefully this will help get you started in building a fast great handling T-Jet.