Automatic transmissions are pretty simple by design. If you want to go forwards, put it in drive. Want to go backwards? Select reverse. If you want your vehicle to stay still, choose \u201cPark.\u201d<\/p>\n
But some gear shifters come with a few more options, namely \u201cD1, D2, and D3.\u201d If you\u2019ve ever wondered what these selections actually do, it\u2019s also pretty simple.<\/p>\n
Although an automatic transmission is designed to select the right gear at the right time, it doesn\u2019t always get it right. There are conditions where the gearbox isn\u2019t really qualified to make the right decision for you, and that\u2019s why options like D1, D2, and D3 exist.<\/p>\n
If you haven\u2019t guessed yet, these selections cap the gearbox at a particular gear, with the number indicating what gear you want your vehicle to max out at. So if you want to keep it in first, select D1. If you think you don\u2019t want to go beyond second, D2. And so on. Many gearboxes will also start in whatever gear you have selected, so D2 will skip first, and start in second for example.<\/p>\n
Most of the time, you don\u2019t really need to use anything beyond drive. Modern automatic gearboxes are pretty good, and not everywhere has particularly adverse roads and driving conditions. But there are a few circumstances when these options will come in handy.<\/p>\n
For reference, if your automatic has a \u201cmanual\u201d option, you can use that in a similar way. Just pop it in manual, then use the manual selector to pick the particular gear you need. D1 is also labeled as \u201cL\u201d or \u201cLow\u201d on some shifters.<\/p>\n
First gear has the lowest top speed, but provides the highest torque multiplication ratio to the wheels. Which means D1 is handy if your vehicle is struggling to get up a hill, or you want to roll it downhill without going too fast.<\/p>\n
Similarly, when towing heavy loads, you\u2019ll find it easier to get going or keep going on a difficult hill in a lower gear. It\u2019s often a good idea to stick to D3 when towing on hilly roads, or locking out overdrive if that\u2019s an option. This will stop the transmission from \u201chunting\u201d for the correct gear, and can avoid unnecessary damage to the expensive component.<\/p>\n
D2 and D3 are both pretty handy in snow and ice. A little less torque can help you get going in slick conditions. So while the automatic will try to get things rolling in first when left to its own devices, setting off in D2 or D3 will probably be easier if you find your wheels spinning in the snow.<\/p>\n
Then there\u2019s engine braking. Since speed is usually capped by the gear, shifting to a lower gear will slow the vehicle without requiring you to press the brakes. Again, this is handy in icy or slick conditions, where hard braking can cause a skid. It\u2019s also handy on descents as it prevents brake fade.<\/p>\n
Modern brakes are better equipped to deal with this, but it\u2019s still possible to overheat most vehicle\u2019s braking systems when putting the anchors on hard down hill. This can \u201cglaze\u201d the brake pads (causing the surface to become hard and glassy), warp brake disks, and boil the brake fluid. At best, you\u2019re damaging your braking system, at worst, your brakes could fail and you might end up in an accident.<\/p>\n
With that being said, you shouldn\u2019t just drop a vehicle into D1 without knowing what you\u2019re doing. If you force your transmission into far too low a gear for the speed you\u2019re traveling at, you\u2019re likely to put a tremendous amount of strain on the gearbox and you can cause the engine to immediately redline as well.<\/p>\n
Modern transmissions should have an automatic lockout in place to stop you doing this. Either way, for most vehicles, you should try to get to 25 before you drop it into second. You should avoid going into first if you\u2019re traveling at over 15 mph. As for third, that varies by gearbox. Your vehicle should indicate what gear it\u2019s in at any given time, so get to know your car. Find out what its limits are. And try to keep your engine below 3,000-4,000 RPM when you drop down.<\/p>\n","protected":false},"excerpt":{"rendered":"
Automatic transmissions are pretty simple by design. If you want to go forwards, put it in drive. Want to go … <\/p>\n