Reviewed by Unique Cars and Parts
Our Rating: 3
The advent of the Mini DeLuxe mid-way through 1967
was a significant milestone in the development of auto transmission
units for the small cars. Dare we say, almost as revolutionary as the original 1959 Mini
It was true that the Mini's transmission was based on an idea first conceived in the late 1940's by Automotive Products in England, very little detail of the ultimate and much refined transmission
leaked out until the Mini DeLuxe was finally released and available in the BMC showrooms.
There were two changes in the automatic's engine-room. Compression ratio was up to 9:1, compared with the manual's 8.3:1 rating, and a bigger 1.5 inch SU carburettor
was fitted. The net result was that power output went up 2 bhp, to 42 bhp., while revs, at maximum power dropped by 250 down to 5000 rpm.
Dubbed by many in the motoring press as the "Mini-Matic" - the clever transmission seemed to go about its work with as much flair as the manual version - so much so that few considered the slight bump in horsepower could not explain the DeLuxe's dexterity. Two bhp was, after all, a comparatively minor power increase.
The motoring press were right. But what they didn't know was that the transmission itself was a model in design efficiency. What the BMC engineers needed to do was design an automatic transmission that was as diminutive as the engine bay would allow. Simply put, underneath the Mini's bonnet there wasn't much room to spare for any additional bits and pieces.
Thes design brief was simple enough. The engineers had to come up wiith a transmission that would not increase the engine dimensions. Like the manual version, the transmission needed to be housed beneath the motor, accommodating the convertor in the space previously occupied by the clutch and flywheel.
In this location, the transmission needed to utilise the same sump oil which lubricated the rest of the engine. And in doing this, the design would make a vital contribution to transmission efficiency, because it would avoid duplicity of oil pumps, reservoir and filters - and the power loss which otherwise would have been incurred. In fact it was a basic reason why the additional 2 bhp.was put to such good effect and the overall performance for a four-cylinder automatic was so lively.
One of the brightest decisions BMC made when determining that the Mini should go automatic, was the choice of a slot type selector. I gave it the nod over all other systems because of its operational simplicity - not overlooking the fact that it was also is one of the easiest for identifying gear positions. Gear positions down the slot from front to rear were marked R, 1, 2, 3, 4 and D. Manual shifts through positions 1, 2, 3 and 4 produced gear changes as in any normal manual transmission from the time, although they could be made much faster - logical enough in that the shift movement was in a direct fore-and-aft line - which was not typical of automatics of the time.
Down-changes from position 4 back through the gear train had normal manual retardation. As in most automatics from the era, D was for drive and meshed in all four forward gears for automatic cycling. The transmission was designed without the generally incorporated free-wheeling unit. Not best practise, but to counter that a not often found feature BMC saw fit to include was over-run braking, achieved through braking bands on third and second forward gears, and on reverse. The effect was felt as road speed fell. The transmission would drop back to third, then second and finally into first. These down-changes were both audible and mechanically apparent - and took a little getting used to - each shift being accompanied by an abrupt deceleration.
When accelerating away from rest the gear changes were on the "snatchy" side. But again, it was really a case of getting used to the sensation, rather than being too critical that it was different to the norm. And when you considered the size of engine, and the normally power-sapping properties of an automatic transmission, the BMC engineers had worked wonders. It was true that timed acceleration figures were slower than for the manual Mini, but the differences were not overwhelming and in traffic the automatic had no difficulty in doing well in traffic light sprints.
On the Road
Something many owners noticed, particularly after driving a more regular atmo car, was the Mini transmission's sensitivity to changes in both road speed and throttle openings. It was a design feature fully intended and the units' ability to swap cogs to meet speed or throttle variations ensured it could avoids a lot of the sweat and driving effort that might have been expected with such a small automatic. Maximum speeds in the gears were: first - 27 mph; second - 45 mph; third - 58 mph and in top (or fourth) - 75.3 mph.
Better still, the Mini DeLuxe was equally adept in the hills. There may have been occasion to swith to manual selection of gear, but generally the unit would make the best selection for the conditions and not rob too much power when needed at the apex of a corner. Reliability was also not compromised, and after many road tests by various motoring magazines nobody could fault the setup, both engine and transmission refusing to overheat despite plenty of abuse, and not extra oil consumption. Even the fuel consumption figures remained relatively good, at around 28 mpg. In city traffic, and without a lead foot, drivers regularly achieved closer to 35 mpg.
The Mini is a popular classic car - and devotees we have met will generally prefer the manual. That is because swapping cogs yourself is more fun, and in the Mini driving really is a pleasure. But if you were to wind the clock back to 1967
, the Mini was finding favour as a 2nd car - and while undoubtedly sounding sexist, that 2nd car was driven by mum to do the shopping and take the kids to school. An automatic Mini would have put forward a very compelling argument.