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Here at Ultramax Racing Chassis, we put a tremendous amount of effort into each and every product we put on the market. However, we realize that it is not enough to give you the highest quality product that we can produce...

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Owners Manual Page 3:

Every driver obviously has different size characteristics: short, tall, big, and small and with every case a different seating position may be needed. With this being the case, it is hard to state a universal truth on how to mount your seat. However, what we will discuss in this section is some things to look for and do on a consistent basis when mounting your seat.

The seat can be mounted on the stand without wheels and tires. In order to do this you need to find a flat board or plate of some sort and place under the center section of the chassis for the bottom of the seat to sit on as is in the picture on the right. The first step in mounting a seat is to place the right side seat strut on the rear cross member and snug it up just enough to hold it in position but not so much that it cannot be moved.

Next, loosen both front seat struts up and push them forward out of the way of the lower portion of the seat for now. Now place the seat on the kart with the bottom of the seat lying on the board we placed under the chassis. Move the rear of the seat around with the right side seat strut getting the spine of the seat to line up with the center of the brake rotor. Line the right side seat strut up with the seat with a slight lean towards the front of the kart of roughly 5°.

Now for the part of the seat mounting that greatly depends on the driver’s height, weight, seat style selection and the type of track. 8 ¾" from the top of the seat to the top of the axle will give you the 14" WKA minimum seat height (shown to the right).

A lot of the newer style seats on the market are built in a way that the 14" minimum cannot be reached due to the severe curvature of the upper rear portion of the seat (consult your nearest dealer or Ultramax Racing Chassis for further information). For these style seats, add 1" to every number that is getting ready to be discussed. The following list is a list of different driver sizes and track conditions that will mandate seat height positioning.



Track Type 6’ and above, 150lbs and above Below 6’, 150lbs and above Below 6’, below 150lbs
Pavement 8 ¾" from axle 8 ¾" from axle 8 ¾" from axle
High speed/ high bite dirt 8 ¾" from axle 8 ¾" from axle 10" from axle
High speed/ medium bite dirt 8 ¾" from axle 10" from axle 11" from axle
Low speed/ medium bite dirt 10" from axle 10" from axle 11" from axle
Low speed/ low bite dirt 11" from axle 11" from axle 12" from axle

As always, this chart is designed to give you an idea of where to mount your seat. There are several variables that can effect where your seat needs to be mounted to transfer weight correctly. However, with the assistance of this chart, you should be able to get your seat height close for every track condition.

Now that you have your seat height set, drill your right side seat strut hole while maintaining proper seat height. Place the bolt through the seat hole, the seat rubber on the bolt and then place the nut finger tight on the bolt for now. Next, put the left side seat strut on the chassis and align it with the left side of the seat and snug it up as you did the right side seat strut. Now make sure the back of the seat is near level from left to right and that you are still maintaining your desired seat height, then drill your left side seat strut hole and place the bolt through the hole, place the seat rubber on and finger tighten the nut.

You can now slide your front seat struts up towards the bottom of the seat and align them with the seat leaving enough clearance to place the rubbers in between the seat and the strut.

Once they are aligned and tightened down, take a marker and mark the two holes to be drilled, take the seat back off and drill the holes. Now you can put the seat back on and place all four bolts through the holes and finger tighten each nut.

Check one last time to make sure you still have your desired seat height, the seat is still level from left to right and that the bottom of the seat does not hang underneath the chassis.

Then tighten the seat bolts and seat struts down. Once your seat is mounted it should look similar to the picture above. Now that we have the seat mounted, we can move to hanging that body.

5 – Hanging the Body
There are three important issues that must be addressed in hanging your body: ground clearance, hanging it squarely to the frame and connecting it freely to your chassis. If you are using the Ultramax Racing Chassis body kit it should be an easy job for you since the bodies come pre-cut for proper clearance and fitted for easy joint connections. There are many different techniques that can be used to hang a body on a chassis. In this section we will discuss what we have found to be the easiest and most consistent way to hang a body.

The first step in hanging a body is to connect the nose to the right side panel squarely to ensure that your body will be square to itself throughout the installation. As shown to the right, you can connect it in three separate places using either pop rivets or small button head bolts.

To do this, first hold the two pieces together and see how the joint will fit. Once this is done, clamp the two pieces together with C-clamp vice grips or something similar and step back and eye it up to make sure that the nose and the side panel are square to one another. Once the two are adjusted to square with one another, go ahead and drill your holes through both the nose and the side panel and bolt or pop rivet them together.


We are now ready to fit this portion of the body onto the kart. To do this, put wheels and tires onto the chassis and place it on the floor where you are going to hang your body. Now, slide the nose/ side panel combination onto the chassis and block it up where it is flush to the bottom of the bumper. You can do this using a level, 1" x 1" box tubing, plywood or something similar to this. Next, place the seam where the side panel and nose are connected together directly over the right front king pin bolt as shown in the picture on the left.

This should ensure the proper wheel clearance for both the front and rear tires. Now, move the body directly left or right on the chassis to get the side panel about even with the right rear rim. Once this is done, step back and make sure the body is square to the chassis. This can be done by sighting down the right side panel and checking its square with the right side tires or by looking at the left side panel joint with the nose making sure it is directly over the left front king pin bolt.



Once your body is square to the chassis and is located from front to rear via the king pin bolts, you can mark your front bumper connections points with a marker and drill each hole, one at a time, placing a bolt and nut finger tight in each one after its drilled. After each bolt has been placed in the nose, tighten them all down. Now that your nose is located, step back and make sure the body is still square on the chassis. If it is still square, relocate the right side nerf bar, if necessary, to fit flush against the right side panel. You are now ready to mark each hole in the right side panel and drill each hole one at a time, placing a bolt and nut on finger tight after each hole is drilled. You can now pull your 1" spacers out from underneath the body and again step back to ensure that the body is square on the chassis and located properly from front to rear. Once this is done, you can tighten each bolt and nut down and move on to mounting the left side panel.

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