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The History of six

Monday, March 1st, 2010

This gives further details of the restoration I carried out on the car and mentions some of the excursions we made on the car in 2004

Published in the Rover Sports Registers Magazine ‘Freewheel’, December 2004.

The 1906 Rover 6hp of David Bliss is one of the stars of tha RSR Rover Centenary Rally Video.  Here David gives some fascinating insights into the resoration and use of this delightful car.

Hello, I am David Bliss, owner of the ‘disgustingly quick’ 1906 6hp Rover (according to Kent Robinson).  We have had a busy season with our car, attending more than sixteen events in all.  The car covered 1100 miles this year, 800 of them on our VCC runs, and travelled around 5000 miles on our truck.   The Rover Centenary was, of course one of these events and I was very pleased to take part in it, I certainly will not see another one!  I was, however, a little disappointed that there were so few of the early cars and motorcycles, and no bicycles.  There are several Edwardian Rovers active in the VCC but those owners I have spoken to since told me that they had not known about the Centenary weekend, this was a pity, given a nudge they would probably have turned up.

We took DL 126 to the Isle of Wight this year (DL was the island’s registration).  A VCC run coincided with the D-day celebrations and the Old Gaffers Festival.  We were overwhelmed by enthusiastic owners of old cars, including Rover owners, all wanting to know why they hadn’t seen our Rover before.  I now understand why first gear and the axles on the car were so badly worn, steep hills everywhere that almost made Sunrising hill seem a freewheel!  I swear the island must tilt as you drive round it so that it is up-hill all the way.  I had hoped that we might discover something about the early history of the little car but, in spite of getting into the local press, appealing for information on local radio and speaking to so many local enthusiasts nothing was forthcoming.

Compared to other single cylinder cars of the same age, the 6hp Rover had the advantage of a light chassis, which made the power to weight ratio good, a three speed gearbox, rack and pinion steering making it a speedy (28 mph), manoeuvrable car.  In fact, on our runs, we have embarrassed several much larger cars that should have been able to fend us off easily.  Had Rover made the engine with the same capacity on two cylinders it would have flown!  As an engineer of today I would, of course, have changed the design, but had I been there in 1906 I would have been very pleased with the overall result.  However, the writing was on the wall for single cylinder cars.  The Rover’s very slow running, large capacity single cylinder engine (1250 rpm maximum revs, 780 cc) meant there was always a vibration problem, although an early review by ‘The Motor Trader’ said that ‘the car…. from a comfort point of view compares favourably with the most expensive type of car ….. vibration is practically nil’.  However the state of the art was moving on rapidly, Rolls had just launched his silk-smooth Silver Ghost.  This car was beyond the dreams of most people, but from then on multi-cylinder cars were to take over and single cylinders only remained to power some light cycle cars of poor quality.

I believe that there are around forty 6hp cars still surviving after 98 years.  I know of only one other, Mr Morrison’s P 3192, which is currently being used on the road, but there are several others that have been used in the recent past.  Some of these have changed hands and most are probably now in need of restoration work.  There are several others being restored at the moment, all being well there will be a larger group on the road in the coming seasons.

Just prior to final assembly

Just prior to final assembly

A properly restored 6hp is very reliable, easy to drive and very economical.  There is very little tinwork; the chassis and body are mostly wood, strengthened by metal flitch plates.  Wheels are more of a problem; wooden artillery wheels may require a wheelwright’s attention.  The rims can be obtained from New Zealand, but tyres can be a problem, the availability is patchy and quality is very variable, I have had as little as 200 miles and at most 3000 miles from a tyre.  The combined engine and gearbox is a basic, very simple unit and easy to repair, providing that no one has butchered the internal parts.  Pistons for a 95 mm bore (intended for a 1920s Austin 20hp) can be obtained from Australia and slightly modified to suit, although, if the piston is changed the crankshaft must be re-balanced.

The gearbox layout

The gearbox layout, shown in first gear

Getting the balance right

Getting the balance right

Valves of the right size are easy to find, again the Austin 20hp can be a source for replacements.  The gearbox is simple, if a little long and skinny.  Shafts for it are easily made and as the gears are straight cut it is easy to get them made, all gears of the same size are interchangeable, there are three small, four medium and 2 large sized gears.  The ball bearings are of a very narrow, light type; the balls are uncaged so the races are completely full.  As a result each ball pushes its neighbour, this rubbing makes grooves in the balls and the bearings become noisy.  If the bearings loosen balls will usually start spitting out.  These bearings were, at one time, obsolete, but are now available from a vintage supplier. I managed to find modern bearings that I could machine down to fit, these are, of course, much more reliable and of proven quality.

Axle casing repairs

Axle casing repairs nearly complete

The rear axle of the car is a very heavy design for the weight of the car, but the quality of the cast aluminium is poor so, with age and strain, this can be dangerous as it causes the brakes to fail on the early design of axle. The brake cross- shaft anchors on the early axles, as mine is, are mounted directly in the aluminium, eventually these anchors pull out.  This had happened to the axle on my car and the poor welding that was done in an attempt to repair the damage compounded the problem.  I had to sleeve the axle ends in steel to strengthen it.  Later axles were modified to prevent the problem; they have steel castings that clamp round the aluminium casing.  A further problem is that braking and driving torque is borne by an aluminium torque tube that eventually pulls out of the casing.  As this torque tube also holds the pinion shaft and gear, the gear teeth get bent as it pulls out.  I decided to make a design change here, for safety on the road and to preserve the original axle casing. I made a very short pinion housing and shaft, fitting the original gear to this and adding a propshaft with two universal joints. This modification transferred all the torque onto the springs and should prevent further problems while the original parts that have been replaced are preserved and could easily be fitted back onto the car.

Crown wheel and differential gear

Crown wheel and differential gear

What might seem unusual to some people is the differential.  It is heavily constructed with four pinion spur gears, rather than the usual bevel gears.  This was, in fact, a system used by a few manufacturers, especially of commercial vehicles, into the late 1920s.  The wheel hubs can’t be kept tight on the half-shafts and wear.  They can be repaired using a special tapered bush, which eliminates any further wear.

Stub axles

Rough-machined new stub axles and originals

The front stub axles are also castings, in this case malleable, that have weakened with age.  They have been known to break without warning.  I had already driven my car about 800 miles when I happened to ring Mr Windsor, owner of 69 PE, who asked if I was seriously thinking of driving the car on the road.  He told me that he and his wife had had an accident in their car; she had been driving when the near side stub broke and he was thrown out onto the road.  Another owner, Mr Hudson, had a stub axle on his car, ST 54, break while it was on the trailer having just returned home after a run.  I had to have new stub axles made; I also replaced the steering rods and joints since these had suffered so much mistreatment.

The thing that took longest time and a great deal of thought to get right was the carburetion.  The engine is slow running, runs very cool and has a 20-inch long inlet pipe.  The length of this pipe causes petrol to condense out on slow running and makes the air in the system bounce at anything above a tick-over so carburettor adjustment becomes almost impossible.  Several owners have fitted the carburettor directly to the cylinder but I wanted mine where it was originally intend to go, under the floorboards.  It ran reasonably well during the first year, giving 40 mpg, but I still did not like the odd running at certain speeds and went back to the drawing board.  The result was 70 mpg even when driven hard. it could still stall occasionally at low speed, but I felt I had won.  I richened the mixture slightly and now get 50 to 60 mpg.  I knew from experience what should work and, in the end, it did, but to fine-tune the carburetion tested me to the limit.  The ignition system also has a large effect on what carburetion mixtures are going to do to the way the engine runs.  I used the original trembler coil system, this is far better than magneto ignition, because it produces a stream of sparks over several degrees of crank shaft movement, making for effortless starting and firing any peculiar mixtures encountered where a single spark would result in occasional misfires.

The finished engine

Putting the car back on the road again in safe and reliable condition was quite taxing.  Sadly, during a previous ‘restoration’ many parts had been poorly repaired, leaving them unusable.  Other parts had gone missing.  Over the four years the 6hp was in production the car evolved in mechanical specification and in bodywork.  Luckily I had worked on my car thirty years before I was able to purchase it and was able to remember, basically, what these parts looked like.  I was able to look at three other 6hp cars while working on my restoration, but found I was really on my own when it came to doing the research needed to make the correct parts.  I photographed everything I did on the car, taking over 500 photographs; I also did some engineers’ drawings and took photographs of other 6hp cars and scrap parts.  This has made a record that shows the mechanical evolution of the 6hp car, which I believe has never been done before.

Finally I would like to thank and praise the following people and firms for their high quality work and expert advice; Tom MacFadon of Coventry Museum; Mike Horlick of Llewellin’s Gears,Bristol (for gears and pins); Nick Paravani of  Competition Fabrications, Norfolk (for metal panel and pipe work); Tube Fab, New Zealand (for wheel rims); J P Pistons, Australia (for piston); Mr Knights, Norwich (for boring and sleeving cylinder); Phoenix Cranks (for connecting rod) and Trevor Hedge for, motorcycle engineer, Norwich (for balancing crank shaft).

A few more photographs:-

Big end bolts that were too long

A poor attempt had been made at making a replacement manifold

New manifold parts, copied from an original

Two rusty washers and a fibre washer had been used as a replacement bearing, my modern bearing is shown behind. on all the cars I have seen the original thrust bearing seems to have failed early on.

The new cast iron brake drum. the drum that had been put on had been nearly cut through by an unnecessary washer. The groove is clearly visible here.

The original stays had gone, and very poor replacements had been fitted (top). I made a complete set of new stays, after studying the 6hp cars at Coventry and Gaydon. .

The second silencer is held together by tie roads with springs. This is to prevent damge in the event of a backfire, which was quite a common event in the early days of motoring.

One Response to “The History of six”

  1. Lance Sheldrick says:

    I am the chap who bought the 1905 6hp Rover which was on ebay. Your article and advice makes very interesting reading, but has frightened the life out of me with regard to the stub axles and rear axle casings and bearings etc.
    Thank you for posting this. It is by far the best information I have found.

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