Austin 7 Around the Americas
The Specification of the ‘bespk’ Austin 7 Special to travel 25,000 miles.
This article is based on the version published in the Bristol Austin 7 Magazine, June 2013
I travelled to London to meet up with John Sutton (he of the Maclachlan Special) at his ‘works’; Camco Solutions in Greenwich during August of 2009. John’s original notes are in italic.
Acknowledging that John Coleman’s 1925 Chummy had broken its chassis during his epic adventure in 1959/60 the obvious choice was to either use a modified (strengthened) early chassis or a shortened later chassis.
Having received John’s document by email within a few days I sent it to a number of my Austin 7 Friends for their thoughts and comments. Within a few weeks all had replied with their interpretation of the ideal specification. Vince Leek went further and suggested he’d found a very suitable car. Following negotiations VJ 9212 arrived in the workshop during October, so the story begins.
A short chassis will be modified by boxing in the front forging, adding a plate at the rear of the chassis to tie in the rear spring mountings and an additional flange on the fore and aft chassis member. It will also be modified to take a Ruby brake cross shaft.
VJ 9212 arrived as a 1936 ‘short chassis’; (6’9” modified in the 1980’s to 6’3”); probably following a very serious accident. (See below). The chassis member supporting the brake cross shaft has a fabricated additional fixing at the front to minimise distortion during braking.
The stub axles, steering arms and the drop arm of the steering box were crack tested and the steering arms were shot peened.
These will be standard Chummy type but with zinc interleaves and bound with cord after fitting additional spring clamps.
The 3 springs are remanufactured to 1936 specification. All 3 springs required resetting after it was found that the rear axle bottomed out against the chassis/body in initial unloaded testing. Additionally spare main front and rear leaf were also manufactured and carried within the chassis rails, under the car. They are heavily greased and wrapped with ‘Denso’ tape.
The initial road tests after the rebuild were very disappointing: the handling was very wayward. This I learnt later was as a result of increasing the ‘set’ of the front and rear springs. This effectively eliminated the castor angle of the king pins. The radius arm ball joint was lowered with a bracket by approximately 1” to restore the castor angle.
The shock absorbers (S/A’s) are standard Austin 7 modified by seam welding the rear blades for strength; the friction discs were assembled with grease and set up to a tension of 25 lb/ft (measured with a spring balance). This gives stiction rather than friction. It also prevents moisture affecting the performance of the S/A discs
An additional pair of star washers were placed under the coil spring on each of the rear S/As to give a more ‘gradual’ response.
A late semi-Girling axle and radius arms to be fitted with oversize king pins (rather than closing down the axle eyes) if required. Hubs will be the late Ruby type and the bearings will be the sealed type.
+10 thou oversize king pins are fitted. The bearings are standard size and sealed, the small front hub bearings were not available in sealed form.
A three piece narrow axle with 5.125 axle ratio. New half shafts and bearings with late Ruby hubs for additional strength. The outer casings to be machined to take semi-Girling brake back plates. The prop shaft flange will be modified to take a Hardy Spicer type.
A D type rear axle is fitted modified for a short chassis by a welded 1” block to the axle case inside of the backplates and outboard of the rear spring with a re-welded inner fixing point.
A new 5.125 crown wheel and pinion was used with new manufactured long half shafts featuring long tapers and a square key (A7 Components). During the rebuild it was found that the O/S axle tube and the torque tube were both bent beyond reclamation (due to the aforementioned accident damage).
There is a hypothesis that the trouble with the multiple broken spokes was due to the N/S axle tube being bent.
A Chummy type short column with a dished steering wheel for preference. The control levers to incorporate the horn button.
A Chummy type column was rebuilt, including a ‘top of the tube’ bronze bush rather than the felt originally fitted . A splined 1929 type steering wheel with hand throttle and advance/retard levers were fitted with only the throttle lever connected.
These will be semi-Girling modified to Girling specification.
The cross shaft is modified with a rear facing grease nipple to allow greasing and reduce the chances of seizure
The standard semi-Girling brakes were modified by making the adjusters in each backplate able to float in the backplate and the brake shoes are able to ‘self centre.’ Long levers are fitted.
Wheels and tyres:
The wheels will be 17 inch Austin 7 rebuilt and not powder coated and the tyres will be 400 x 17 Armstrong.
A set of 17” wheels were rebuilt and (?) powder coated 4.00/4.25 17” Excelsior tyres were used. (11 covers used over 20,000 miles).
After fitting the new tyres in Tulare; the ride was very lumpy and on the advice of Nate Jones (Long Beach, CA) he removed all the covers, balanced the wheels which made a vast difference to the amount of ‘faceting’. He also advised using talcum powder as a lubricant between the tube and cover.
(The two front tyres were too worn to pass an MOT on our return).
An early Chummy type steel cowl painted black. The radiator to be re-cored.
A four bladed fan (mag type) for cooling.
The radiator core was replaced during the rebuild. During the testing of the spare top fan pulley, before departure, it collapsed and the four bladed fan damaged the core, destroying itself. This required another replacement core. I decided to use a thermostatically controlled electric fan with a switched override. Using this was found to be necessary only when climbing long hills and when moving slowly in traffic. VJ 9212 had an overflow tank (?from Morris 1100) this was refitted during the rebuild.
To be built using a Magneto crankcase with a 11/2” Phoenix splash fed crankshaft and conrods. This will involve some machining internally to gain clearance for the big ends.
The camshaft will be modified to give an output of approx. 25bhp. Cam followers to be standard radius. Various camshaft designs are available but the manufacture or re–profiling needs to be of a high standard.
Timing gears to of standard type but carefully checked for mesh.
Cylinder block to be 10 studded for extra security.
Pistons to be decided but the new slipper pistons as used in the Maclachlan Special are recommended.
The valves to be standard size with the inlets made with 30 degree seats.
Oil pump to be standard size.
The sump to be decided on during the rebuild but it is important to make sure it is baffled. A possible option is to make a steel plate to replace the sump gauze as this has the advantage of stiffening the crankcase.
The engine was built by Alex Myall (Pigsty Racing) essentially as outlined above to his ‘Trials specification’ with 11/8th” inlet valves, an alloy cylinder head (similar to a 1937 type), a high volume oil pump, oversize oil jets (for greater flow rather than pressure) and an Alan Raeburn type alloy sump, a full flow spin off oil filter is fitted.
The starter dog was modified to support/drive the bottom pulley machined to accept a polyV belt for the alternator drive. The housing for the dynamo was blanked off. The top fan pulley, similarly modified for the PolyV belt, was fitted with a pair of sealed ball bearings held in place by Allen grub screws.
Clutch; It is recommended that cast iron linings are fitted with standard clutch springs. A reconditioned clutch withdrawal bearing to be fitted and attention to toggle arms. Pressure plate to have a good starter ring.
A standard Austin clutch was fitted using a late type release bearing and clutch release arms.
It is proposed to fit a 3 branch exhaust manifold under the bonnet. The inlet manifold to be designed to take an SU carburettor.
A custom built 4 branch exhaust manifold is fitted. A John Barlow semi downdraft inlet manifold is fitted with an 11/4” SU (Mini type). This is actuated by a Bowden cable with a modified bulkhead accelerator/hand throttle arrangement. A custom made KN air filter is fitted
The silencer is a standard Chummy type.
This will be an ML magneto rebuilt to the highest standard with a spare for security to be carried in the car.
The original engine set up used the rebuilt ML magneto (Magneto Magician). Once the coil conversion was available and modified by Willie McKenzie to overcome lubrication problems this was fitted and used throughout the trip. One magneto was carried.
A “bacon slicer” type with a starter button attached.
A 12v ‘soft start’ motor was developed by ARK Racing and fitted after advice that the original type 6v motor run off 12v wrecked the flywheel ring gear in about 10,000 miles.
A three speed with a high second gear and vertical speedometer drive.
The output shaft to have a flange to convert to a Hardy Spicer prop shaft.
A late 4 speed gearbox (2 SYN) was rebuilt and fitted with a vertical (3 speed type) speedometer drive. A new manufacture Hardy Spicer prop shaft was fitted.
An approach to be made to Rod Yates for a Chummy type body to incorporate the proposed scuttle fuel tank. Failing this Keith Roach will almost certainly be able to make one to our specification. The body should also have reinforcement in the rear section to allow for carrying the additional weight.
VJ 9212 came with a Keith Roach Chummy body built in the 1980’s (flat floor) This was modified; the woodwork was bonded to the aluminium skin with Sikaflex to create a stressed skin structure. A false floor was created to enclose the space under the rear seat which was removed/not fitted. Additional lockers were created to support the rear of the driver and passenger seats. All the trim panelling was discarded and replaced by high density polyurethane foam covered with aircraft quality aluminium (0.20” thick)
A formed, hinged, lockable aluminium cover was made behind the seats for security and to provide a platform for our day to day luggage which was held in place using an elasticated net with fixed ‘hooking points’.
Seats:- These are standard Chummy pattern upholstered in leather.
The hood was remade and fixed to the body at the rear using ‘Lift the Dot Fasteners’ which allowed us to roll up the vertical panel whilst keeping the hood up and with the front screen held open, the thickness of a cork, to have a through flow of air; ‘air-conditioning’.
An alternator (Kubota digger; 40A below 4,000 revs) driven by a poly V belt).
Voltage regulator is integral to the alternator.
Batteries Two 6 volt MGB type batteries one fitted as per Chummy and the second fitted under the driver’s seat. These can then be used for 12 volts or tapped off for 6 volts if required.
Two 12 volt batteries (that fit into a standard A7 battery box) are fitted. The engine battery is under the driver’s seat. The other, under the passenger seat, was for running the sat nav. and the iPad. A split charging unit is used.
A 12v CAV windscreen wiper motor, driving a single blade, is fitted.
Scuttle lamps are fitted with LED lamps as indicators/hazard warning lights. The rear lamps are Model A Ford type fitted with LED indicators, conventional stop and tail lamps. Additionally high intensity rear lights are fitted for higher visibility on Freeways and for hill climbing in poor visibility at high altitude.
Headlamps:- To be decided.
VJ 9212 had Bosch type 51/2” headlamps with quartz halogen bulbs mounted on the front wings.
Switch panel for coil engine (ammeter not connected)
A speedometer calibrated to suit the axle and tyre configuration.
An oil pressure gauge.
A water temperature gauge
An additional switch panel was fitted to the steering column.
The wiring used ‘switched earth’ to reduce the load on the switches.
This included direction indicators/hazard warning lights, magneto on/off,
fuel pump, alternator on/off, spare, electric fan, high intensity rear lamps.
Fuel tank pressure gauge/air pump and taps for front/rear distribution.
Taps for front/rear tank selection. See below.
This to be made full body width (similar to those on a TT car) so that it forms the scuttle onto which the Chummy bonnet sits. It should have a sump below the tank so that the tank does not run dry on steep hills.
A standard Chummy front tank is used with a ‘Nippy’ type rear tank fitted to chassis extensions. It is possible to use either tank with the electric pump (or the hand air pump in case of failure). Both tanks have separate glass bowl filters.
Alex Myall was adamant that only Castrol GP1 should be used (after 250 miles using ‘running in’ oil). This is based upon his experience and that of his father’s; Tim Myall, both of Pigsty Racing.
Having run ‘old engined cars’ since 1966, I have a conviction that oil selection can be a really cheap form of engineering if you make wise choices. Having researched oils prior to the trip I was fortunate enough to find a book; ‘Which Oils’ written by Richard Michell, an Australian Oil Engineer (who owns an Austin 7) and published by Veloce Publishing. I made contact with the author by email. We had a very interesting correspondence.
What I learnt is that oils for old engines of this type require high levels of Zinc and Phosphorus to cope with the high rubbing forces.
In extremis (when the oil of choice is not available) Richard advised the use of straight 40 grade diesel oil in the engine/gearbox and 50 grade diesel oils for the back axle.
I wrote to all the suppliers/manufacturers of ‘old car oils’ in the UK. Whilst receiving a couple of replies that were not very encouraging with my thinking; I had a visit from the local Morris Lubricants representative for Cornwall; Bruce Mccann. Extensive discussions with their technical team; Andy Brown, evolved a specification of oils; 15w50 Golden Film Motor Sport oil for the engine, Lodexol 80/90 for the gearbox and AG 140 for the back axle.
It was not long before cases of oil arrived at the workshop. Introductions were given to their agent in the USA; Robert Bauer of Classicoils and another company who supplied oils from their base in Santiago, Chile.