Whatever happened to overdrives?

[DSdriver]

I have had two cars in the past that  had an overdrive switch for the gearbox, a series 3 Sunbeam Rapier and a Rover 3 litre. 

I haven't thought about it for years but you don't hear about them on cars nowadays. When did they fade from view and why?

[Lacquer Peel]

My 1993 Volvo 940 TD manual had an overdrive. The last mass production car with a manual gearbox and overdrive?

[mercrocker]

I guess 5 speed boxes killed the need mostly, true the usual overdrive add-on gave additional ratios for 3rd, 4th and sometimes second (often not by design) but from a manufacturing point of view the 5spd box must be a no-brainer compared to what is essentially an extra gear box and the need to offer two prop lengths etc.... 

[OwdChina]

Still got it on the big pickups in the USA, coupled to auto box. It's an engaged from start-up feature with the option to disengage when towing / Hauling heavy shit up hills etc...............saves cooking /trashing the auto box.

 

[anonymous user]

Not something I'd ever thought about and I've owned and driven quite a few things with overdrive, nicest was a Volvo 240 with the button on the gearstick, my Bond 2 litre had a switch on the column, as did my father's Volvo 144, the fun ones were on my brother's early Range Rover which had a separate gearstick (which just to confuse people also had a standard 4 speed and reverse labelled gearknob) also my mates 101 Land Rover used one of the redundant winch control levers to operate the overdrive. Thinking about it another old friend had fitted one to his Vauxhall estate and the switch for that was an old ceramic and brass light switch dangling on a cable in the footwell.

[bub2006]

Regards auto boxes i think previa had them till late 90's. Manuals i think where big volvos. Xantia could do with one on motorways!

[stripped fred]

My dad's triumph 2500 had overdrive I think. That's not a car you see much now!

[gordonbennet]

My year 2000 Landcruiser has a auto/overdrive, had it nearly a year before i discovered a small switch on the side of the gearlever which when pressed turns overdrive off.

[lisbon_road]

I believe that what killed them was the ability to make gearboxes with continuously rated indirect gears.  

 

In plain English, traditionally the only gear you could use constantly was top, as it wasn't a gear at all - the output shaft was running at the same speed as the input.  Lower gears would cause damage if run constantly.  

 

To make this clear, you've got to have continuously rated gears for all speeds over say about 30mph.  But if you can only have one, it is then by definition a bit low when you go fast.  Hence the need to an overdrive box which is a sturdy item and can be used continuously.  

 

Later on, the ability to have gearboxes with gears that could be run constantly (perhaps at a reasonable price) came in.  Now seems many five speed or six speed boxes don't have a direct ratio at all.

 

I'd really like to put another gear on the Vauxhall Viva as it is ridiculously undergeared.  My Mk3 Astra could do with a sixth gear and make all the gears a bit closer together.

[dollywobbler]

Transverse engines didn't help matters, but overdrive was dying off before that - Vauxhall's FE Victor lost the overdrive option part way through its production run, but RWD Vauxhalls carried on for ages afterwards. Five-speed gearboxes removed the need, but I reckon the biggest problem was when overdrive switches moved from the dashboard/steering column to the gear lever. If you have to put your hand on the gear lever, you might as well just select another gear! Whereas, on cars with a proper finger-operated switch near the steering wheel, you can change ratios without having to let go of the steering wheel. I love TRs and Scimitars for that reason.

 

As mentioned, the Japanese have an obsession with overdrive on autos. London Taxis with the Nissan engine and auto gearbox have an overdrive. That acts on all gears though I think, and it flashes up a warning of doom to remind you that you've not got overdrive engaged. I never fully understood what the point is.

[oldford]

I had overdrive on my 1850 Dolomite, overdrive 3rd was very much like normal 4th, the advantage being that you could effectively change gear at the flick of a switch.  One disadvantage is that the inhibitor switch needs to be working, overdrives don't like being engaged and used with reverse gear.

 

As mentioned above, the Japanese like them on their automatics, I remember when the S4 auto box was introduced on the Rover 800s, no need to use kickdown  if you wanted a bit of acceleration when it was in top gear, push the button and press the pedal.

[Tamworthbay]

I love them, brilliant when used properly but also a complete hoot in very slippery/ icey conditions as you can induce rear end slippage at the flick of a switch.

[cort1977]

The 'O/D off' switch and warning on the dash in Japanese moderns just means that the top ratio is locked out and the gearbox is not in an 'overdrive' ratio, i.e. less than 1:1.   The purpose of the switch is to prevent the gearbox moving to top gear when you don't want it to for example in hilly areas or when towing.   The warning is just to remind you so you don't waste fuel.   Sadly this is nothing to do with a proper Laycock de Normanville overdrive unit.   There is no separate box, they just use the term to mean an overdrive ratio.

 

I would hazard a guess that the warning light is a US federal requirement driven by the CAFE standards hence why it is present in US trucks and Japanese vehicles.

 

The wife's minivan has it, it's handy in the mountains and also towing the camper trailer.

[DSdriver]

Great answers - it had just occurred to me to wonder whether fwd made a difference before the reply from DW so that was well timed.

It must have been a bummer for Laycock when they dropped out of fashion.

I often find myself trying to find a sixth gear on the DS as there is plenty of power at 70mph plus (on French motorways obvs) but the revs are a bit too high for comfortable cruising.

[RayMK]

The 'O/D off' switch and warning on the dash in Japanese moderns just means that the top ratio is locked out and the gearbox is not in an 'overdrive' ratio, i.e. less than 1:1.   The purpose of the switch is to prevent the gearbox moving to top gear when you don't want it to for example in hilly areas or when towing.   The warning is just to remind you so you don't waste fuel.   Sadly this is nothing to do with a proper Laycock de Normanville overdrive unit.   There is no separate box, they just use the term to mean an overdrive ratio.

 

I would hazard a guess that the warning light is a US federal requirement driven by the CAFE standards hence why it is present in US trucks and Japanese vehicles.

 

The wife's minivan has it, it's handy in the mountains and also towing the camper trailer.

 

Similarly, the 'SNOW' setting on some automatics (e.g. Nissan QX) just locks out the lower ratio or two so that traction is less likely to be lost - a bit like using 2nd or 3rd in a manual when starting on ice i.e. more gentle.  I recall that even my Volvo 66 (DAF CVT belt drive) had a switch but I think it was to force the pulleys into a lower ratio in order to improve downhill engine braking.  'Overdrive' ratio was obtained by slightly backing off on the throttle when at cruising speed.