Is it possible to do rev-match on automatic transmissioned cars?

[leon200608]

We all know that on manual tranny cars, when downshifting from a higher gear to a lower gear while maintaining the same speed, a rev-match is necessary: because to maintain the same speed the engine runs faster in low gears than in high gears, so while downshifting the driver has to give a little gas to boost up the engine rev and then clutch into the wanted gear, this way you won't feel the sudden shake of the car.

So my question: in certain cases in auto-tranny cars you have to downshift from D to 3 or 2 (though not recommended sometimes), can you do a rev-match as well and how? Since the layout is P R N D 3 2 1, you can't go to N and rev up the engine and go to 3 or 2; but you also cannot step on the gas and then downshifting because that will just increase the speed and make the shifting worse.

[phiLLy11]

I don't think it's possible to "rev-match" with a convential automatic.

The only way I could think about it possibly happening, is say you were in D, shift it into N, rev it, and if your tranny allows, immediately shift it into 3, or whatever gear you want.

[leon200608]

I don't think it's possible to "rev-match" with a convential automatic.

The only way I could think about it possibly happening, is say you were in D, shift it into N, rev it, and if your tranny allows, immediately shift it into 3, or whatever gear you want.

Let's say on a blizzard day you are going downhill at 90km/h and you want to engine brake into gear 2 (well you can just slam on the brake but without ABS and ESP your car might slide), you shift into N and boost up the throttle, but then when you shift into 2 you have to go through D and 3, won't the higher gears just engage before you going to 2?

[Anonymouse]

If you want to slow down, use the freaking brakes. Unless you're descending a mountain, engine braking is for eejits who like to change transmissions and clutches rather than brake pads.

[ShadowVlican]

u have to time your throttle and downshift.. it's possible

try giving it some gas when you shove it down to D3 (delay the gas giving maybe 0.8sec cuz manual shifting automatics is SLOW)

[potato]

short answer is no.

you don't have a clutch, how would you double clutch.

it is an automatic, unless your brakes failed and you needed some way to slow down your car, i can not think of one reason you would ever need to do that.

if you want an automatic that rev matches get the nissan gtr. it has paddle shifting and computer controlled rev matching when you need to downshift.

if you are using a several thousand dollar transmission to slow down your car instead of hundred dollar brakes, your wallet is screaming at you to stop.

[mr_raider]

No need to get the GTR. The g35/37 tranny will blip the throttle for you when downshifting.

[leon200608]

GT-R? G35/G37?? Man.....I can't afford that. :(

[z24driver1986]

stop watching fast and furious lol

double clutching and rev-matching is intended for big Transport Trucks due to the fact that they don't have syncros in the manual transmission. The automatic and manual transmission are different. One could double clutch a manual car but it would b e pointless.

[Sepiraph]

With a CVT in manual mode, you can just downshift and ease off gas if you don't want the car to accelerate.

[leon200608]

With a CVT in manual mode, you can just downshift and ease off gas if you don't want the car to accelerate.

But CVT trannies have no gears aren't they? Just two pulleys with a belt??

[HBP]

stop watching fast and furious lol

double clutching and rev-matching is intended for big Transport Trucks due to the fact that they don't have syncros in the manual transmission. The automatic and manual transmission are different. One could double clutch a manual car but it would b e pointless.

uhhh... wtf? have you ever downshifted? i dont double clutch, but a rev-match is necessary to keep my spine straight.

[D-3vil]

But CVT trannies have no gears aren't they? Just two pulleys with a belt??

"Downshifting" in this case is approximated by selecting a higher gear ratio, so engine breaking has a more pronounced effect.

[D-3vil]

If you want to slow down, use the freaking brakes. Unless you're descending a mountain, engine braking is for eejits who like to change transmissions and clutches rather than brake pads.

Downshifting with a standard transmission is especially handy during the winter, whether you're an "eejit" or not.

[Tijuana]

With an auto tranny, if your in neutral and revving it, once you put it in any gear, wont you basically break the transmission, especially if you are revving it 4+k?

[jason9945]

Let's say on a blizzard day you are going downhill at 90km/h and you want to engine brake into gear 2 (well you can just slam on the brake but without ABS and ESP your car might slide), you shift into N and boost up the throttle, but then when you shift into 2 you have to go through D and 3, won't the higher gears just engage before you going to 2?

Your not supposed to be compression braking in bad weather. Everyone knows that.
Let alone shifting between drive and neutral while moving. Just leave the shifter alone and use the brakes.


As for any other scenarios that depends on the transmission. I know my chrysler operates differently than most as all 4 speeds are available in any gear selector position (OD/3/L).

[FazerRider]

Let's say on a blizzard day you are going downhill at 90km/h and you want to engine brake into gear 2 (well you can just slam on the brake but without ABS and ESP your car might slide),

engine braking can still cause your car to slide. the reason cars slide is caused by tires losing traction due to DECELERATION. if engine braking can decelerate your car, it can still cause your car to slide.

[hytong]

in that situation you would simply speed up the locked wheel ... either by engine power or remaining traction and vehicle momentum, before things get too out of hand

everyday engine braking occurs whenever you take foot off the gas pedal, down shifting multiply this effect by the gear ratio, this compression serves as an added drag less prone to overheat other than using brakes alone

[Sepiraph]

With an auto tranny, if your in neutral and revving it, once you put it in any gear, wont you basically break the transmission, especially if you are revving it 4+k?

Yes definitely you would, and even in manual transmission your clutch can only last so long if you keep launching your car.

[DrXenon]

Your not supposed to be compression braking in bad weather. Everyone knows that.

+1
Downshifting with a standard transmission is especially handy during the winter, whether you're an "eejit" or not.

Yes, it's very handy if you like sliding half your wheels, not giving the person behind you notice that you're slowing down and abusing your drivetrain. I agree that the term "eejit" is incorrect, though. The correct word is "idjit".

[Tomy]

why would u wanna do that?


fixing a tranny is costly @_@

[ES_Revenge]

in that situation you would simply speed up the locked wheel ... either by engine power or remaining traction and vehicle momentum, before things get too out of hand
I don't think we're talking about locked wheels here though. The reason you don't downshift in poor-traction conditions is the resultant increase in engine torque output from the initial downshift and rev increase can cause you to lose control--has nothing to do with locked wheels.

And like everything else even using compression to slow the vehicle you're still "using up" traction on the tyres just as you would the brakes, so if you're doing this and turning or trying to remain in control on a low-traction surface, it might make things worse for you (just like braking).

everyday engine braking occurs whenever you take foot off the gas pedal, down shifting multiply this effect by the gear ratio, this compression serves as an added drag less prone to overheat other than using brakes alone
It does and it doesn't... With an auto trans (with a torque converter) you have two things that inhibit the effect of "normal" (throttle-closed) engine braking. One is the torque converter, the other is the fact that most autos stay in high[er] gear when coasting.

After all this though I don't think we've addressed the original question, lol.

mr_raider essentially did that in post #7. There are a few cars that have autos that rev match or at least rev match better upon downshifting, than would just downshifting using the lever in an old-skool regular auto. Most of these are cars that have a command shift mode ("tiptronic" as everyone likes to say).

Engine braking in a regular auto is permitted but don't make a habit of it. Mainly use it for descending hills, not for slowing down on a flat road. There isn't really a way to rev match so the best way is to keep your foot on the throttle (keep the throttle open a little) when going from say "3" to "2" or "D" to "2", and close the throttle just as you click the lever into position. This is how most owner's manuals say to do it anyway. Try to do it at lower speeds and, if possible, prevent the car from shifting into a higher gear to begin with; e.g. if you're at a light and there is a hill descent right after the light just put the shifter in "2" from the light and then you won't have to worry about downshifting at the top of the hill, as you'll never exceed 2nd to begin with.

[mau108]

if your car has tiptronic (or step tronic or sport shift what eve ryou wanna call it) it will rev match on down shift.


Doing this in a conventional auto (no sport shift mode) can SERIOUSLY damage your transmission.

Heck I hate even doing it in our sport shift capable cars.

[maniacshopper]

can you manually rev match auto on recent cars? no, especially cars that have drive-by-wire.

throttle controlled by cpu.

It's an automatic, unless you are using the manumatic mode, even still the shifts are smooth, so you don't have to rev match.

go to youtube watch best motoring clips. Rev match is only necessary if you're rev's are about to enter a corner, and brake. You blip the throttle to rev match and downshift to take a corner and exit at full speed. It's a racing technique, unnecessarily used in the streets.

[bionicbadger]

You shouldn't need to do engine breaking. Use your car's brakes. Brakes are cheaper to replace than a transmission is.

[hytong]

are there any production vehicle on conventional automatic (torque converter runs on auto xmission fluid) automatically blip the throttle or this features is limited to clutchless manual so far?

[KawaiiTentacleBeast]

The Mercedes 7G-TRONIC does. I'm sure the 8 speed Lexus ones do as well.