How to build a Drag Rail

Before we begin.....

This chassis design is effecient and works well with S-16 motors, stock or pumped up. I am not sure what it will do with bigger motors since I have not tried anything bigger that a S-16. I did not design this chassis and I DO NOT know who did. But what I have done is taken various designs and mixed them to come up with what I am about to present you with here. While racing last year I have notice most of these drag rail were similar but not all the same. This design I am showing you has been tested and runns extremely stable and fast. Please do not copy this info to anywhere else. This page took time and effort to make. So please if you must just link to this entire page.

Ryan

Parts list...

This is a list and general costs of what you will need to buy. You may buy other stuff etc. but this is hwat I use.

-Monogram Drag rail model $7 Your raceway should be able to get these cheap because they know your building a drag car out of it. And if they dont I guess they dont want your business!

- Model glue

- REH Inline motor braket $2.50-$3

- Slick 7 Guide stiffner $2

-1/16" Piano wire 3' piece $0.75

-1/16" Brass TUBE $0.50

-RPM soft fronts with holes $1

-Pro Track 'Cudda's S-16's use the 1.01 Tall X .200" Wide. Bigger motors try the .435" wide. $5-$10 depending on if you go cheap.

- 1 Fast Ones or equivlent motor screw $0.30

- 1 Set oilitles $2

- 1 axle $2

- 1 Guide flag assembly. For this rail DONT use a cut down! $1.50

- 1 set braids $0.50

- figure 2' motor wire, will have leftovers $2

- 2 body pins $0.06

Tools you will need...

- Dremel tool with cut off wheel

- Soldering Iron, flux and solder

- Normal building tools

- drill and drill bits or use the dremel tool and drill bits

The Jig!

Ahh my Top Secret drag car building jig! Get a piece of 2X6 lumber a good 18" long. Plane it flat on a planner and run it down a table saw 1/2" deep or so. Now for the jig part of it. Take a square and a magic marker and make a line 90 degrees to the slot about 2" back from the edge. From that line mark another 11 11/16" from it. Bingo, your jig is completed!

The chassis

Now that I am high ontop my soap box here it comes. I will try to explain everything as clearly as possible. You will need some building expeirence to build this.

1) First thing to do is to make the REH inline braket square. These are not always square when you get them. Make sure your oilites and axle go into it and work as smooth as possible.

2) Cut two pieces of piano wire 11 3/4" long. Make a slight ben in each one 2 7/8" from an end. Make the bend about 3-4 Degrees, you dont need much.

3) You will need to use a small round file or the cutoff disk to grind a little off the bottom side of the REH motor mount to allow the piano wire to sit good. Now solder the part closest to the bend to the REH motor mount so each piece angles in. Solder the pieces square to the REH motor mount. Keeping everything square as possible is the key to making a good chassis.

4) Now install your oilites as you would normally. I like the Slick 7 ones. They will last a lifetime and are smooooooth!

5) Insert your axle into the chassis. Line the center holes of the motor mount up with the slot. Line the axle up with the line on the jig. Now the goal here is to get the Slick 7 Guide stiffener soldered in 11 11/16" from the rear axle. Give or take a little wont hurt! You will need to tweek the piano wire so its even. Where the piano wire hits the stiffner on mine are about 1/4" wide. Try to keep it the same so the chassis will fit inside the drag body without touching it! Now place the slick 7 Guide stiffner on TOP of the piano wire. Line the center of the hole up with the other line on the jig. Tack solder it on in the back. Make sure everything is nice and square to the slot. Also make sure the rear axle is square to the line. Flip the chassis over and solder the stiffner in good. Take the dremel tool and cut off wheel and cut off any piano wire that interfears with the guide flag. Then grind the edges of the stiffner down so its the same width as the radius.

6) Make two z bends out of piano wire. Bende them 90 and 90 with no more than 3/16" inbetwwen them.

7) Solder each one to a rail so the open end is back. Make it so the center is 8 5/8" from the guide flag center. Solder them so when you put the 1/16" brass through it there is about .030-.060 clearance. If you leave to much clearance the boady may drag on the track which will slow you down! You may need to adjust this when completed!

8) Cut a piece of the 1/16" brass tube about 1 1/4" long. Solder it somewhat centered 5/16" back from the center of the guide flag. Bend them up slightly and intall your fronts with two pins. You will need to probably cut the pins down to fit.

9) Install your guide flag. You wont need any spacers. Make sure there is a hole drilled in the top of it. You will be needing to run the motor screw into it to thread it.

10) Get out the rail body. Set it on your chassis. Get your fronts to line up good in the slots on the body. Make sure the chassis fits into the body nicely in that location. You want to keep the chassis from rubbing on the body as it will kill the FLEX effect. At this point drill a hole through the nose of the body to line up with the hole ontop of the guide flag. Run the screw through the hole into the guide flag. This is the front body mount.

11) Drill a 1/16" through hole on each side of the body so when you insert a piece of the 1/16" Tube it will hit the top of the Z bends. Keep it back a little from the upright piece of the Z bend. You want this area to float. Next insert the brass piece and bend it so it dont fall out. Or you can use some screws so it looks nice.

At this point the chassis is finished. You can see that the chassis is flimsy. It is ment to flex. This flex really helps it take off good. The way I look at it the body IS the chassis. If need be adjust the Z bends so the body dont drag or have to much flex. You may or may not need to add lead. I like to have a little up front. Please click on the thumbnails below for full size pics. The first pics shows dimesions and a pic of a chassis. The second pic is a completed chassis on my Jig.

Final Assembly

Well heres what I did to my first one. I used the front wings from the model. I glued them on good and used some bondo and smoother them out nice. I also used the rear tire deflectors. I did cut them down in size, to about half of what they were. Used the dremel tool and 1/2" roll sander to smooth out the radius. When you glue these on use a piece of plastic to back it up on the inside of the body. Its not a good design. I also used the windshield. I dont use the rear wing because its serves no use and makes it hard to get in and out of my box. I used the RPM tires because they are cheap and lightweight. I like the Pro Track cuddas. If you run a S-16's and cudda's you probably wont need glue!

Overall....

These are cool chassis that are fairly cheap to build. The cars run quick and consistent. Mine has a stock sealed S-16 with foil tape. It runs within .002 consitentsy. If I remeber right, on the 1/8 Mile it was hitting 38 mph at .47X. Dont remember for sure though. If you have good reaction time this chassis design just might be what you are looking for. This is by far the coolest chassis I have seen or built.

More Pics to come,

Eventually!

Send me your pics, thoughts and ideas.

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