Changing ring and pinion gears

[Dave Mann]

I have three RN saloons two with the standard 5.25 cw&p on one with a regent 5.375 cw&p, the latter is the fastest car.this is particularly noticeable on gradual inclines.

[Bob Culver]

It occurred to me that to many using this Forum the car types quoted would be even less familiar than say the Model T or Chev 4 was to me!
On trips I always put cotton wool in my ears. Good for another 500 rpm in 3rd (I still do the same for 360 mile forays in my 1964 car). In their day (to about 1952 when new cars became more available) few Sevens owned by mature persons would have been driven hard as many are today. My father drove our Seven quite spiritedly but only once took it up to its full 50 mph. Many Sevens chugged around with very retarded spark and would seldom reach 40. The city Wellington was divided by a few miles of waterfront road, motorway style (now is). My father reckoned that just post war 45mph was the typical speed of the fast lane. To the 60s main roads had many corners, bridges, rail crossings where 30 mph was not slow. Even in the moderns of the time to maintain 50 mph was quite taxing. My father bought a replacement "modern"" in 1957. My father discussed various smaller cars, A40s Minx etc with various owners and many stated that they normally drove at about 45 mph.

[Reckless Rat]

I went for a run out in my RP yesterday and thought about the original post. With a 5.25 diff, which is standard in the saloons, a true 45mph is very close to what was originally quoted as the car's maximum speed, ie 48mph. The ideal cruising speed is between 40 and 45mph where the engine is quite happy, but only turning at about 3000rpm. Personally I think it would be better just to leave things as they are and wear some ear plugs. It's an easier option. Those of us that do lots of miles in our cars don't have a problem with the gearing. Changing to a 4.9 rear train in a heavy Ruby is likely to render top gear pretty damn near useless.

[Ivor Hawkins]

Another option is to apply Dynomat to the bulkhead and perhaps the floors.

I have to admit, that driving my open Austin Sevens noise was never an issue and I accepted that my Ruby Saloon was a little bit noisy...the box saloon might get a touch of Dynomat as I’m planning some long trips!

[Steve kay]

After open Sevening, the noise levels in a Ruby were a bit of a surprise. A quick visit to Mountain Warehouse produced a roll of sleeping bag pad, which made a considerable improvement. It’s advantage as under mat insulation is that it does not absorb water, though no doubt everyone else has wholly watertight saloons.

[Charles Levien]

How easy would it be to change the differential ratio for a slight lower over all gearing, 1st gear seems very short in a seven and useless 2nd gear hill starts are easily possible so I was looking at getting a bit more top end speed, just being able to sit at 45mph with a lower engine speed than what feels like a million rpm.

I'm not looking for any more speed just lower revs when I travel long journeys.

Hope to hear your thoughts

Have to admit I’m a little confused by your question — you are not looking for more ( road ) speed, just lower revs on long journeys. In which case you would want to raise overall gearing, not lower it. 
The Ruby is arguably over geared in standard form and back in the sixties etc the answer was to build a relatively lightweight special which solved a lot of problems. This, is probably not what you want to do so you’re options are, use correct 400 tyres on your 17” wheels, fit a four speed close ratio box ( as has already been mentioned), get your engine sorted, wear ear plugs and practice meditation. 
I havnt mentioned going on a diet of lettuce leaves but you could look at any unnecessary weight you are carrying in the car eg use a light weight Jack in place of original etc.
Hope this is helpful!

Charles

[AustinWood]

I believe that the Nippy transmission with 5.625 back axle and close ratio gearbox gives the best performance. When I had a Nippy it would cruise at 60mph comfortably.
In standard form the Austin Seven is overgeared and benefits from lower final drive. Our car is very comfortable at 45-50 mph.
The engine should not be that noisy.

[Reckless Rat]

The point of the original post is that he wanted to reduce the back axle ratio so that the engine was revving lower for a given speed. With the Nippy diff it might go a bit better but it will of course have to rev harder for the same road speed. I think we are trying to plait fog here.

[AustinWood]

I suppose the point is that the engine should be much quieter. Raising the final drive would probably make it worse, needing 3rd gear a lot more.
An engine in good condition revs freely and sounds OK.
We have 4.9 final drive & the car is a 1929 saloon.

[Bob Culver]

It is worth remembering that many engine stresses increase as the square of revs so at 4 thousand (16) are near double at 3 thousand (9). (Also proportional to CR, which factors especially together hasten broken cranks in old age)