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The Imp Site

Nathan Impudence II

August 1965

Willy Griffiths runs the Nathan racing shop. He transformed the dealer's Imp into an exceedingly non-standard little surprise, with an exciting track performance.

Roger Nathan had just put in a couple of laps at 62 seconds as a demonstration for John Blunsden's track test - [Bottom Bend is Brand Hatch?]
The 1 litre saloon car time had just officially been lowered to 62 seconds.

Suspension

New all through.

Front

  Nathan Impudence II
  Lower wishbones; trailing arms; sharply angled high-mounted spring-damper units
   
    Nathan Impudence II
  Special oil and water coolers have been moved to the front. The standard radiator has been dispensed with. By canting the 1 litre engine well over to the left, a fairly straight induction path is possible. A pair of 38mm Weber downdraught carburettors.

Rear suspension

The revised suspension has left room for Herald-type front disc brakes, which use DS 11 pads, but the standard Imp drum brakes are retained at the rear, with VG 95 linings.

Wheels

The wheelbase is almost 2 inches longer than standard.

The wheel cutaways had to be extensively modified to allow the necessary clearances.

Unsprung weight has been reduced by about 20 pounds per wheel.

Engine

Cylinder head

Stage 4 of a range of head modifications marketed by Nathan

They were going to fit 1 5/16 inch inlets, which were expected to provide a further 200 to 300 revs in top gear.

Cooling

Higher oil pressure

The standard single timing chain has given no trouble, and apart from the modified sump and oil cooler, the only alteration to the lubrication system has been to put in an adjustable relief valve, enabling the engine to run with 55 to 60 psi pressure, instead of the usual 40 psi.

Steering, lock to lock, standard 2 ½ turns, now 1 ½ turns

Power

The Speedwell dynamometer has been used for all the engine development tests.

Current output is 93 bhp at 7,200 rpm
Maximum torque at about 5,500 rpm.

Close-ratio gears
Special Jack Knight close-ratio gears have been fitted inside the standard gearcase, giving reductions of 13.5, 8.0, 5.77 and 5.05 to 1.

Battery up front

Driving Impudence II

Driving Impudence II apparently took a lot of getting used to.

Roger Nathan's flying Imps

John Blunsden [Track Test 41, Motor Racing August 1965] said the complete lack of feel from the steering foxed him. He said that you had to keep your foot down all the time, that gentle finesse was useless with this Imp.

A lack of message from the front wheels.

"I only had to watch Roger Nathan at work to see how swiftly it will go through a bend on full power, but it takes quite a nerve to floor the right foot when the car feels (even though it isn't) on the point of breakaway. I found left-handers were the tricky ones, and not until near the end of the test did I manage to take Bottom Bend flat-out in third, as Nathan assured me could be done. In fact, it felt a good deal more stable that way, after all, due to the cleaner carburation! "

A useful closeness of third and top, but quite a high gap above second.
The engine can be taken up to 8,000 rpm in the gears with no trouble at all.

Gear change: lack of feel in the 'gate' on the left side.

High revs please the engine. With the throttle well open the Imp's exhaust note sounded nice & crisp. But a feathered throttle, especially on lefthand bends, caused some hesitation, which accentuated the need to really drive the car through the corners.

The brakes were superb. By braking right through the turning point at the hairpin the back end could be unstuck, and the car driven round very smoothly on a tight radius. On the faster bends, however, such as Kidney, the tail would sometimes come out quite late, but fortunately the car can be held well out of line and brought back again.

Nathan says the car has never been spun, either in a race or a test.

 



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            Impudence II, prepaired by Roger Nathan Racing Ltd. (This file)
         

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