How to Set Up Your Vector DO Kart
Position the front hub on the front spindle in the narrowest tracking, that is, with as few spacers as needed for tire clearance at the steering arms. Place the remaining spacers and castle nut on the outside of the hub, starting with the nut slightly snug as the spacers tend to seat in very quickly when they are new - Continually check and readjust the nut for bearing preload - especially after the first couple of races.
As with any new kart, contiually check each bolt on the kart for proper tightness.
Using a 34 inch length axle, set the face of the left rear hub 4 inches from the end of the axle; the right rear hub 2 1/2 inches from the end of the axle. The "face" is the part that the wheel center mounts to.
The front end kingpins are adjustable, and should be set in a neutral position (not one side higher than the other to begin with), and with the front end fairly low - You will raise the nose of the kart as the track gets more slick, or as additional front end bite is needed. It is important to not exceed 5/8 inch in difference in spindle heights as this will put the chassis in a bind during cornering. Stagger on the front of our karts should not exceed 1 1/2" in extreme situations to gain more cross weight. Typically 1/2"stagger across the front is adequate for our DO model chassis. Some racers prefer to use more ackerman on the left front - If you feel this is something you would like to experiment with, there is a second 3/8 inch hole in the center of the steering arms 3/4 inch ahead of the existing location. This will help turn the car into the corner on extremely tight ovals. Camber is fixed on the Vector chassis, however it is adjustable by "shimming" the spindle hanger. By shimming the top of the spindle out, will increase "positive" camber. The left front should be set at 0* camber, while the right front is actually set at 2* "positive" camber. Yes, this is different (opposite) than some other chassis builders use, but it is the correct way it should be done on this chassis. On higher banked tracks, you can experiment with higher or lower camber. If you are going to run larger than a 6.00" tire on the right front, then decrease camber on the right front to 1/2* positive camber or even negative camber. If using an 8" or wider tire on the right fron, start with 1 1/2* negative camber. For extremely high grip tracks, go to 2 1/2* negative camber.
Set the toe-in/out to driver preference. For very short, flat tracks, we prefer 1/8-inch toe-out - this helps turn the car into the corner. For very large tracks or pavement applications, we set toe-in at 1/16-inch toe-in. Never exceed 1/8-inch toe-in or -out. Mount tires and inflate to 25 pounds each - let each set for 15 minutes, then deflate to racing pressures - For dirt slicks, we start with 6 psi left front (LF), 8 psi right fornt (RF), 6 psi left rear (LR), and 8 psi right rear (RR). - This is our recommended starting set-up. We prefer the use of 6 inch wheels, although the kart was designed with a higher ride height to accommodate 5 inch diameter wheels on the front and left sides. Always use an 8.10X6" tire on the right rear. Although some customers have had great success using the popular 11-8.10x6 tire on a 9 1/4 or 10" wheel on the RF, we prefer that you use a 6.00X6" on the left front, and, at the most a 7.10X6" on the right front. 5 inch tires will have a wider (softer) sidewall, which is preferred on loose dirt and rough track surfaces. Using 5" tires on the right side of the kart will make it tighter at corner entry, and should only be used in lighter weight classes and on particularly small and dry slick tracks. This should be avoided, if at all possible. 5" leftside tires are recommended only when the track is extremely rough. 6" tires have a stiffer sidewall which better accommodates sticky and rubber laden tracks. For high speed and momentum type tracks you will need to run 6" tires all the way around the chassis. You will want to scale your kart with the same stagger you normally race with - This varies with specific tracks and driver preference.
For an offset kart (any brand) to have proper steering geometry, it will not be comfortable for the driver's left leg during braking. Other manufacturers have sacrificed optimizing steering design for driver comfort and we felt that was an area that was too vital to the chassis' performance to cut corners on.
It makes absolutely no sense to set all your tires at equal pressures and zero stagger if you are not going to race with that set-up. -Scale it the way you roll on to the track and you will always have a basic set-up to compare to.
Mount the engine, clutch, chain, etc. so that everything is race-ready except for the seat.
Mounting the seat is the very most important part of properly setting up and scaling the chassis. We prefer to use a plastic "lcg" (low center of gravity), or laydown, (banana) seat made by G-Man, although most fiberglass seats will also work. (We strongly reccommend against any of the very low (laydown style) seats - They are extremely dangerous, putting the driver's head just inches above the left rear tire!) Position the seat where is it the most comfortable for the driver, never compromising safety.
On some extra large seats, it will be necessary to mount the left rear seat strut on the outside of the left side frame rail. This is acceptable as this piece is a continuation of the main frame, and is not simply a nerf bar spud.
Be sure that the top rear edge of the seat does not extend behind the rear axle. Typically, it will be directly above the front edge of the axle. Keep the seat as low as possible, but not below the main frame rails. A straight edge and plumb ball will help in positioning the seat correctly. It is not uncommon to have to notch, or slot, the seat on the left rear side to enable correct positioning over the frame rails - If this can be avoided, however, the integrity of the seat itself will be stronger.
Put the seat and driver in the kart, in racing position, on four scales. Digital bath scales will not work. Simple dial type bath scales are better than nothing. Be sure to NOT "zero" a bath type scale. Instead, place a known weight on each scale and adjust them to read the same...ie (50# dead weight = reads 50# on all four scales). Do not be concerned if one or more scales does not go back to zero. If you need, we can scale your chassis for you, and we also offer professional digital scales for sale. Please see our online description. Make sure that the driver is in a comfortable driving position. That is, with right foot to the floor, left foot resting, arms and hands in driving position, etc. Make sure that the wheels are pointed straight ahead. The use of a "toe-lock" will help tremendously at this point. This keeps the steering wheel from moving the tires. Record each of your corner weights and do your calculations.
Total Weight (TW) = LF + RF + LR + RR
Left Side (LF) = LF + LR
Right Side (RS) = RF + RR
Rear Weight (RW) = LR + RR
Cross Weight (CW) = RF + LR
Be sure TW is the weight at which you race and is legal for your class. Out extensive testing has shown optimum weights as 57% LS and 43% RS. Cross weight (CW) should be between 53 and 54%. Typically cross needs to be 3-4% less than left side weight. Rear Weight (RW) should be between 52 and 62% depending on driver preference of a loose or tight kart, and track conditions. That is why we utilize the adjustable front seat slides to accommodate the racer's needs. We recommend starting at 55% and lowering from there until the kart is too loose to drive (then it's just about right.) These suggested percentages are given as a starting point only. Not every track and driver require the exact same set-up. Please consult the experts at Vector chassis for detailed information on setting your chassis for your situation.
A good example might be the light class with a total weight of 325#.
Typically, it is nice to have 20-25 pounds heavier on the LR than the RR; LF should be even to 5 pounds heavier than the RF. This is desirable because as the kart enters the corner, weight will be transferred to the right side due to inertia, which will neutralize the corner wieghts. Once the seat is positioned in its approximate location, fasten it securely, using rubber grommets (supplied) between the seat and the struts. After everything is secure, recheck your scales and corner weights.Another helpful scaling hint is to try to keep your left front corner weight and right rear corner weights equal. This keep the car very neutral and responsive to minor adjustments at the track.
The Vector chassis comes equipped with spuds on the rear to utilize a torsion bar. We feel that this is a band-aid fix for improper chassis set-up, and should be avoided. It is necessary though on a very (extremely) rough track, or indoor tracks that are very sticky, or tracks that are very aggressive on tire wear and are heavily laden with rubber. Install the rear torsion tube so that the kart does not flex so much that leftside unloading (commonly referred to as "hop") becomes a problem. The torsion bar, even in its softest position (flat) stiffens the rear of the kart tremendously, and greatly reduces the chassis' ability to flex and properly adhere to the racing surface. We recommend the use of dual sprocket protectors such as those offered through our shop.
Caster Adjuster: The center mark on each caster adjuster is 15 degrees. For short track, banked tracks, and high horsepower classes, 15 degrees LF, 18 degrees RF. For high speed tracks, decrease caster on each corner to decrease wheel-loading effect. Typically, 9 degrees and 12 degrees for high-speed ovals. Try not to run more than 3 degrees of split across the front. Also, if you run big tires on the right front, you will want to run less caster. As always, each customer has their personal preferences, and you will likely want to experiment. Regularly check bolts for tightness; especially while new, as the aluminum housing wears on the new paint of the plate.
Try to get in a regular program of chassis adjustments. All dirt tracks start out tacky and end up getting slick as the event goes on. Therefore, it will be necessary to make adjustments which will tighten the kart up as the day (night) goes on. Concentrate on tire pressures, compound, and stagger first - make the bulk of your adjustments at the RR. Move the RR in 1/2 inch to tighten the kart on corner entry. Decrease stagger as the track slicks off or as more left rear drive is desired upon corner exit. Only adjust the LR hub for extreme conditions. Moving the left rear out will put more weight on the right rear at corner entry, and also unload the left rear at corner exit, making the car tighter entering, and looser exiting. Moving the left rear in, will make the kart tighter from the center of the corner - out. It is more desirable to make other changes before moving the LR in or out on our DO chassis specifically. As you become more accustomed to your Vector DO chassis, you can begin experimenting with wedge across the front. - You will find running the front track width as narrow as possible to have the fastest response during cornering. If delay or slowed steering is desirable or to reduce front end grip - as in a junior restricted class or higher sped momentum oval, you may move the front wheels outward. As you have any questions, or comments, please feel free to contact us.
215 N. High St.
Linden, IN 47955
Hours: Mon-Thur 8-6 or by appt.
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