Austin Healy Bug Eye Sprite / MG Midget - Street Legal Go Kart -
I've always wanted to build a go kart that was a mini racecar, open wheel and with lights that in the middle of
the night I could run through the streets and no one would ever catch me. Maturity has gotten the better of
me, why not build a little racecar / go kart and be able to place ... are you ready, license plates on it.
Racecars are made to go fast through the combination increasing horsepower and decreasing vehicle
weight, HP to LBS ratio. (For reference) ... Everyone knows how fast a 2012 911 Porsche is, 4.4 second 0 to
60mph and 12.7 second 1/4 mile comes from 400HP and 3,300lbs, or 8.25lbs per HP. (A 2012 911 Turbo is
3,500lbs and 500HP or 7lbs per HP).
What would happen if I took the lightest car I could find and placed a powerful lightweight motor in it. Fast
forward to a Triumph Sprite combined with a Honda S2000 engine and trans. Combining a 1,400lbs car with
a 230hp motor would yield 6.09lbs per Horse. (15% LESS HP to LBS than a 911 Turbo) ...
Racecars of course need to stop and turn as well. Slowing a 1,400lbs car I am not worried will be a problem.
So the remaining question is what will the handling of a 80" wheelbase, 46" wide track be like? I am not sure,
but damn do I want to find out. Anyone in the NY area want to take me for a ride ... Please!
Attack Banana - http://www.attackbanana.com/index.php
Technical Information - http://pdljmpr.tripod.com/techin.htm
Parts & Repair Sources - http://pdljmpr.tripod.com/parts.htm
Racecar - http://www.britishracecar.com/ChuckPitt-Spridget.htm
EX 186 - http://www.britishracecar.com/JoeGunderson-MG-EX186.htm
Fiberglass - http://www.spridgetech.com/
DESCRIPTION OF ORIGINAL -
Austin Healey Sprite Mk I
The first Austin Healey Sprite which came out in May 1958 went on sale at £669. It had a one piece lift-up
bonnet and front wings, which gave very good access to the engine compartment, unles you were six foot
plus.It was this feature which soon gave it its nickname of 'Frog-eye' but in the USA it was called the 'Bug-eye'.
Powered by the 948 cc BMC 'A' series engine producing 42.5 bhp. It is no doubt that this vehicle was the first
post war sports car that was priced to give a new generation of drivers the opportunity to sample the thrill of
The front suspension was derived from the A35 but the rear was different in that the rear axle was located
and sprung by quarter-elliptical leaf springs, this was probable the weakest part of the design.
There was no opening boot, two possible reasons for this was an increase in tooling costs and would have
made the rear end weaker. Access to the boot space was gained by tilting the backs of the seats forward.
Date when launched late 1958 MKI
Discontinued in 1961
Total produced 48,987 all Abingdon built
948 cc 43 bhp at 5,200 rpm Max torque 52lbs/ft at 3,300 rpm
Length 11ft 5.3ins Width 4ft 5ins Height 4ft 1.8ins
Wheelbase 6ft 8ins Track front 3ft 9.8ins rear 3ft 8.8ins
BMC A-series unit as used in Morris Minor/Austin A35 except for twin HSI (1 1/8) SU carburetors set at a
slight angel from the horizontal and with individual 'pancake' type air filters, special valve springs. Stellited
exhaust valve seats and copper-lead main and big-end bearings. Cast iron block and head, pressed steel
sump, 4-cylinder in -line, overhead valve with push rods, camshaft i block. Capacity 948cc (57,87cu.in) Bore
& Stroke 62,94 x 76,2 mm (2,48x30in).
Maximum power: 43bhp (net) at 5000rpm.
Maximum torque (net): 52lb/ft at 3000rpm.
Maximum bmep (net): 136lb/sq.in at 3000rpm.
Fuel pump: A.C. mechanical type, mounted in side of block and driven by camshaft. Sump capacity: 3.34 l (6
7/8 Imp pints).
Rear wheel drive from front mounted engine. Four-speed gear box bolted to rear engine plate. Synchro mesh
on second, third and top. Overall gear ratios:
Top, 4.22 3rd, 5.96 2nd, 10,02 1st, 15,31 Final drive, 4.22 to 1 Reverse, 19,68
Hypoid bevel rear axel. Clutch of Borg and Beck manufacture, 6 1/4in diameter, hydraulic operation.
Chassis frame and bodywork
2-door, 2-seater convertible of all-steel unitary (chassis less) construction. Floor pan pressed and
constructed at John Thompson Motor Pressings Ltd in Wolverhampton, England with outer sills of 1.22 mm
and inner sills of 1.6 mm thickness.
Wheelbase: 203cm (6ft 8in).
Track: front 116cm (3ft 9 3/4in).
Track: rear 114cm (3ft 8 3/4in).
Overall length: (without front bumper) 337cm (11ft 0 5/8in).
Overall with: 135cm (4ft 5in).
Overall height: 126cm (4ft 1 1/3in) but 112cm (3ft 8 1/8in) with hood down.
Ground clearance: 13cm (5in).
Turning circle: right 9.5m (31ft 2 1/2in).
Turning circle: left 9.8m (32ft 1 1/2in).
Kerb weight: 602kg (1328lb).
Fuel tank capacity: 27.3 l (6 Imp.gal).
Suspension: Front: Standard Austin A35 coil spring and wishbone components in conjunction with Armstrong
lever-type shock absorbers which also act as upper wishbone arm.
Steering: Morris Minor-type steering rack giving 2 1/2 turn from lock-to-lock.
Brakes: Lockhead hydraulic, with 7in drums. Cable hand brake to rear.
Wheels and Tyres: Dunlop 145 x 13
Electrical Equipment: 12 volt. 43 amp hour battery. Positive earth Lucas dynamo.
Wheel Information -
Here are some typical offsets necessary to keep the wheel centered for popular British sportscars: Sprite/Midget: +20mm / MGA/MGB: +22mm / TR2-TR6: +6mm / TR7-TR8: +15mm / Spitfire: +20mm
By keeping the wheel centered in the wheel well, there is less chance of the wider tires fouling the inner fender, suspension components, or outer fender—this is most important with the narrow rear fender wells
of most British cars. For street driving where there is likely to be a lot of suspension and body movement, it is a good idea to stay conservative on width. Otherwise, the smell of burning rubber and the sounds of
tire-rub are going to accompany any spirited driving. Make it a point to do your test-driving with your spouse or significant other in the car. This way, you won’t experience the unpleasant surprise of their added
weight causing the tires to rub.
If you want that maximum rubber, road-racer look, be aware that most racecars have had some radical surgery and are often fitted with stiffer springs and panhard rods or other axle locators to ensure that
suspension movement is limited. You can’t have the same look and performance without making the same sacrifices.
What Are Some Of The Pitfalls?
Sprite/Midget: The square-arch rear-fender cars have very restricted wheel wells. Even a 165-section tire is probably going to rub on the back under hard cornering. The round wheel-arch cars have much less
of a problem, and 5.5” wheels can be fitted with wide tires as long as the springs do not allow the tire to contact the fender lip. This led to many a Bugeye that looked like it got mated to a steamroller. Perhaps
Austin moved to the square wheel arches specifically to prevent Americans from fitting Chevy Vega wheels with fat, wide-oval tires to their cars.