Take a Seat

by Jimmy Rivers in Maintenance & Repair
Originally published in Chase'n Race'n Illustrated Volume 6 Issue 8

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In last month’s installment of the “Grassroots Tech Barn,” we discussed the initial assembly of your new chassis. From an out of the box state, we assembled our chassis and short of a few minor details, we were track ready. This month we want to dig a bit deeper into a very critical part of kart assembly; seat mounting. An improperly mounted seat can seriously affect the performance of your chassis. We will discuss the placement of the seat as well as the mounting procedure.

To get started, place your chassis onto a large table, or place a couple 1x6 boards under your frame if working on your kart stand. This means that the top of the boards and the bottom of the frame are at the same point. Using this as a base not only helps hold the seat in position, but it allows us to set the seat as low in the frame as we can without going lower than the frame and risk dragging the track.

Lay out both seat struts as well as the mounting hardware. Attach the seat struts to the rear crossbar and tighten just enough that they become self supporting. We want them tight enough to hold their position, but loose enough we can locate them properly. Loosen the front seat slides and retighten in the same fashion.

Place the seat into the chassis. I prefer to keep the center of the seat aligned with the steering post and position the rear of the seat to the driver’s left just a couple of inches. This has the seat in approximately a one o’clock position as viewed from the rear of the kart. If I plan to use a high amount of left side weight, I will adjust the entire seat to the left as needed, but I do not like to have the rear of the seat excessively to the left. The weight effect is greater moving the front of the seat as opposed to the back.

Determine the height you want at the back of the seat. Most of today’s chassis like the weight, and conversely the seat as low as possible. This means the center of the seat should be between 8 1/2” and 10” above the rear axle. Any lower will put you below the mandated minimum of 14” as raced. Junior drivers, depending upon their height usually fall into the same range.

Move the rear struts to locate and hold the seat in position as described above keeping the seat as far forward as possible. Check the alignment between the seat struts and the seat slides to the seat at the point of contact. If you have misalignment, you can easily bend and/or twist the metal tabs with an adjustable wrench. Replace the seat into the correct position.

Use a silver sharpie to mark the seat for drilling. Often, because of the cramped area, it is difficult to mark the front holes with the marker. To make this easier, spray paint the tip of a q-tip and mark the seat with the wet tip. A light spray is sufficient, too much paint will make a run. Pre-drill the holes with a small bit, approximately 1/8” to 3/16”. A small bit is much less likely to walk away from the mark, and will keep the hole location more accurate. Finish drill the seat with a 11/32” bit, this gives a little clearance between the seat and the bolt, just enough to allow a little movement. Reinstall the seat and install the four bolts, making sure to use thick rubber washers at the contact points and washers under the bolt heads. Tighten by hand until the locknut makes contact. Do not over-tighten the seat, we want the seat to be free, not loose. Now, tighten the seat struts and the seat slides securely to the frame. Voila, one seat mounted and ready for action.

Hopefully, this sheds a bit of light and clears up some of the horror stories about mounting a seat. Just like many tasks, a little explanation with a bit of time and patience can accomplish things never before thought possible. Happy mounting, see you next month!