Sprint Car Chassis Assembly
It’s the offseason where a lot of the work happens in our great sport. After a long and grueling racing season concludes, it might be best to pick up a new chassis from your chassis builder. In this article, we will cover some important points to make sure the assembly of your new chassis goes smoothly so that you can make it back out to the track for the first race of the year!
First things first, your chassis will most likely come as bare Chromoly, unless your chassis builder has the option of powder coating the new chassis for you. That will be something that you will need to line up on your own. Powder coating is by far the best method for protecting your chassis, as it can withstand the flex that the chassis will incur through a standard night of racing. It will also withstand rocks, dirt, and other debris that may come into contact with your chassis, keeping your car looking good on the track! A lot of people will decide on a color to powder coat their chassis. However, if you like the bare metal look, you can also have it clear coated as well. Whatever look you are going for, you will need to make sure that you have that protective cover, whether it is a color or a clear, to keep the chassis from rusting.
Once the chassis has come back from powder coating, there will probably be a few steps that need to be taken to make your car ready for the assembly process, especially if you have some select chassis options. Here is an overview of what I like to do to prepare a new chassis for assembly.
When you take your car to powder, a lot of times, the shop doing the powder coating does not complete all prep steps before applying the powder coat. Not that they do it wrong, a lot of them just are not racers themselves and do not know a lot of the places on the car that can’t have powder get in them, so they do not plug the holes up. The first thing that I do is I will take a Dremel with a very fine sandpaper head, and go through all the nerf bar spuds, as this is one of the most common places that collect excess powder in the coating process. I will often open them up larger than they originally were anyway because if a crash occurs, it always seems hard to get the nerf bars off the car. Our EMI chassis come with larger nerf bar spuds, so the grinding is minimal on them.
The next part of the car that I will grind some powder out of is the torsion tubes. Here, you need to be very careful not to remove original material from the tube, only removing the excess powder in the hole from the coating process. The reason for that is you will still need the torsion bar bushing to fit snugly in the chassis. If you remove too much material from the torsion tubes, the bushing will fit in the tube loose and essentially will not be effective. Be careful when working with this area.
Next, I will work with the steering gear clamp. Powder builds up in this area as well and will make the clamp hold incredibly tight on the steering gear. In some cases, I have seen it where the clamp will not even go on the steering gear from so much build-up. Additionally, if you are running a dead tube or a full steering gear, you will need to also do this to the ring on the right side of the car as well so that the steering gear will slide nicely into that ring.
The last of the important pieces is the through holes for the radius rods, shocks, etc., especially if your chassis has threaded bosses or welded on nuts for some of these systems. The actual boss for the bolt should be okay, so the bolt should slide right through, but if not, you can sand that out. Where a lot of problems arise is powder being in the threads. You will want to take a tap or thread chaser and chase the powder out of the threads before installing a bolt in them.
Lastly, you can install your torsion bar bushings and ream them. For this, you will need to know what tubing your torsion racks are made of. The racks of sprint cars are either made with .095 wall tubing or .120 wall tubing. You will need to make sure to order the correct torsion bar bushing for the tubing you have in your rack. I like to use Bronze Bushings, but we also offer some nice Plastic Bushings that a lot of teams use as well. You will simply need to pound the bushings into your chassis. They will fit snug, so there is no gluing them in or anything like that. Once you have pounded the bushings in the car, you will need to ream them out using a Torsion Bar Reamer.
Once you have completed all of these steps, your chassis is pretty well ready for assembly. Keep in mind that you may come across some areas that have built up powder that you can’t get a bolt through, such as a wing tab or a wing spud. You can simply drill those holes out to size if you ever run across something like that, and you should be good to go!
Like any other time, if you have any questions about anything, feel free to give us a call at 800-979-0122 anytime Monday through Friday, between 8 am and 5 pm CST to speak with our Sprint Car Technical Specialists or our EMi representatives. We would be more than happy to help you!
