By S. Calhoun Smith

THE "go kart" has taken the U. S. bystorm. A happy wedding of lawn

mower engine and steel tubing on fourlittle wheels, it has become a crazeamong kids and adults with a yen forracing or just plain driving fun.

Kart racing originated in Californiaand has spread eastward since 1956.Now the GKCA (Go Kart Club ofAmerica) is firmly established and hasset up sensible rules governing designand power for stable, safe "karting."Even the lowest powered Class A, 2.5

102

hp karts are capable of 30 to 35 mphwith an adult aboard and more whendriven by a lightweight 10-year-old.Races are run on paved parking lots andsmall dirt ovals and regular sports cartype raceways have been built withtracks four-tenths of a mile in lengthand 20 feet wide. Such tracks incorpor-ate eleven turns, both banked and flat.

The MI Kart was designed and builtby Bob Peru of Red Bank, N. J. andcan be considered a basic Class A kart.It complies in all respects with GKCA

Mechanix Illustrated

A 2-1/2,-hp lawn mower engine drives this kart atmore than 30 mph. It's Class A fun for anyone.

specifications. Cost runs from $100 to$110 complete with an A-400 Clintonengine. Peru did the welding himselfbut anyone not equipped to do it wouldhave to spend $20 to $30 extra. Thebuilding time was about 25 hours andthe tools required were a square, hack

saw, tin snips, files, hammer, large viseand an electric hand drill or drill press.To help hold cost down, the frame ismade of thin-wall conduit, but more ex-pensive chrome-moly tubing could besubstituted throughout. Some parts,the seat and steering hoops, steering

COMPLETED FRAME with axles installed;a thin-wall conduit is used to reduce cost

BELLY PAN and seat back are sheet steel;they're spot-welded to the conduit frame.

January, 1960 103

FRONT END view shows brake and throttlepedals and the simple steering mechanism.

SPOT BRAKE pivots flush against insideface of sprocket. Note engine mount plate.

104 Mecha.nlx Illustrated

yoke, front wheel spindlebracke t s and enginemount plate, can be pur-chased ready-formed fromvar ious kart manufac-turers. Their use willspeed building consider-ably-

Begin construction bydrawing a side frame out-line on a piece of scraplumber. Cut and flare thetubing required and heatthe lower piece to makethe bend. Fit the piecesover the outline and clampthem. Then tack weld alljoints and remove theframing from the board.Using the first side as apattern, clamp the parts ofthe second to it and tackweld them together. Thiswill insure uniformity.

Next fabricate the frontand rear axles. Bendthe front wheel spindlebrackets to shape and drillthem for the kingpin bolts.Then weld them to thefront axle tube. Alignthem carefully, square onthe tube ends and parallelto each other. The rearaxle tube ends are bushed

CLINTON 2-1/2-hp engine drives MI kart at more than 30mph with adult load; note throttle crank on seat hoop.

SPANKING NEW kart is ready to go. You can upholsterseat but boat cushion from marine supplier does nicely.

with a length of pipe to reduce theinside diameter for the 5/8-inchround stock axles. The axles areheld in the tube with a quarter-inch bolt near each inner end.They can be tapped for short boltsor holes [Continued on page 150]

RECOIL STARTER is pulled as youthful driversits with his left foot depressing brake pedal.

Build MI's Kart[Continued from page 106]

can be drilled all the way through for boltsand nuts.

The side frames, axles and crosspiecescan now be assembled. Cut and flare thepieces and tack weld them, using a trysquare to make sure they're aligned. Addthe axles to the frame ends, squaring upthe assembly as it progresses. Note thatthe front axle is rotated slightly in the sideframe ends so that the kingpin axis has a7° rearward slant. The frame-axle assem-bly can now be completely welded at alljoints. As the last step, add the diagonalcrosspiece at the rear.

The front wheel spindle units are madeup next. Cut the kingpin bushing tubes tofit snug inside the brackets. Then weld thewheel spindle bolts to the sides of the bush-ings. Follow this by welding the spindlesteering arm pieces to the bushings. Notethat right- and left-hand units are requiredsince the steering arm pieces slant inward.

The steering and seat hoops are nowformed and cut to fit onto the frame. Tomake the curves, apply heat and bend alittle at a time so that the tubing will notdeform. Tack weld the hoops in positionafter clamping them at the proper angles;then complete the welds. Next cut thebelly pan and seat back to shape, checkingthe pieces against the frame for correct di-mensions. Tack weld the belly pan in placeon the bottom of the frame and then skipweld the pan edges to the frame. Weldsshould be about one inch long and twoinches apart. Where the pan touches thecrosspiece at the steering hoop rosette,welds can be used or the sheet and tubingcan be drilled for self-tapping sheet metalscrews. To prevent the sheet steel frombuckling during welding, use a chill blockclamped about a quarter-inch from theedge along the area to be welded. The chillblock can be a piece of 1/2xlx24-inchsteel bar stock. The seat back is skipwelded to the front of the seat hoop in thesame manner as the belly pan. Make half-round cuts to clear the side frame tubes.Sissy rails can now be bent to shape, fittedto the sides and seat hoop and welded inplace.

The steering assembly is made next. Cutand drill the steering shaft support

brackets of 1/4xl-in strip steel. Bend thesteering shaft front end and drill it for thetie-rod bolt. Then bend the yoke to shape.Put brackets and collars on the steeringshaft and weld the yoke to the shaft end.Next slide the shaft through the topbracket to spread out the collars and weldthe bracket to the underside of the hoopcurve. Hold the lower end of the shaft atthe proper angle to align the top bracketwhile welding. Finish by sliding the shaftinto position and welding the front bracketto the top of the front axle.

The tie-rod ends are threaded for aboutone inch to match the Heim ball end fit-tings. Clevis end or Ford brake rod endscould be substituted if the ball ends arenot readily available. Adjust the rod endsat the center to align the wheel spindlesat zero degrees. Toe-in or toe-out can beadjusted later when the kart's runningqualities have been checked. While work-ing on the front end, weld the pedal pivotbolts to the side frames.

Drive and engine mount parts are nexton the list. The wheel hub is first fittedwith a large washer for bolting on thelarge sprocket. This permits removal of thesprocket if different sizes are to be fitted.(If you do not wish to bother with removal,the sprocket can be welded flush to thewheel hub inside face.) The large washerand sprocket are drilled for mountingbolts. Disassemble the wheel to makewelding on the hub easier. The largewasher is welded to the hub 3/16-in fromthe inside face so that the hub forms ashoulder for centering the sprocket. Weldthe washer from behind, aligning it care-fully so that it and the sprocket will trackwithout any wobble. After assembly,mount the drive wheel and sprocket on theaxle. Next bolt the engine to the mountplate, install the clutch (if used) and thechain. Now carefully align the chain andsprockets, moving the engine and mounton the frame. When set, mark the positionand clamp the mount plate to the frame.Then remove the engine and wheel andweld the mount plate to the frame. Theengine mounting bolts should be in thecenter of the slots so that the engine canbe shifted to correct for wear on the chain

150 January, 1960

Build MI's Kartand sprocket.

The spot brake is made and installednext. Detail drawings are self-explanatory,but follow this procedure for mounting onthe axle: mount drive wheel on axle;mount brake on pivot bolt and tube; clampbrake firmly to sprocket in "brake" posi-tion (this will position pivot tube on bot-tom of axle tube); then clamp and weldpivot tube to axle.

The throttle linkage is made next. Cutout and drill all parts shown on the detaildrawing. Then put the engine in place onthe mount so that the upper linkage partscan be aligned with the engine throttle.The brackets, rods and cranks can be as-sembled by brazing. Complete the throttleand brake linkage by making the pedalsand push rods. Note that there are right-and left-hand pedals. Remember to slidethe fairleads and stop tubes onto the pushrods before bending the S ends. Rods canbe fitted with clevis ends if desired so thatadjustments can be made. Fit one end ofthe rod to the brake at the rear and put thepedal on the other end. Next put the pedalon the pivot bolt at the front, clamp thefairleads to the side frames and braze themin place. Braze the stop to the rod ahead ofthe fairlead with the brake off and clear ofthe sprocket. The throttle push rod andpedal are assembled in a similar manner.Last, make and install return springs onboth pedals.

This completes the metal work on thekart. All welds should be wire brushed.Welding splatters and braze flux should bechipped off all metal surfaces and themetal cleaned before painting. It's a goodidea to clean up the welds during fabrica-tion for easy access to the tight corners.

The Clinton engine, of course, is not theonly one which can be used; West Bend,Briggs & Stratton, Continental, PowerProducts and McCulloch engines fill thebill with slight mount modifications. Thebuilder who wishes to customize his kartwill find such items as mufflers, drumbrakes, chromed tanks, steering wheelsand racing slicks available from the manykart manufacturers. You can add what-ever your pocketbook will allow—but sim-ple or dressed up, the MI kart is a kartloadof fun. •