shifting gears while in motion

[blackhawk777]

this question is for auto transmissions...

ive seen a lot of people do this without damaging anything yet people still say it shouldnt be done.

Shifting from R to D while still moving backwards at a SLOW speed, 2-4 mph aka 4-8km/h (ive seen a few people doing it at 7-11km/h)

here are the car specs and situation when this type of shifting was happening..

2001 Toyota Corolla with 200000km
shifting from R to D at 5-8 km/h
person has been doing this for all of the 200000km that he owned the car. no repairs needed so far.

2003 Ford Crown Vic Police Interceptor (real police car, real police officer)
with a Heavy Duty transmission
Shifted from R to D at around 8-13km/h
..to be honest i dont remember the cop ever touching the brakes.
Vehicle repair history: None

so can someone tell me why people keep condemning this type of behavior yet i have seen no proof that doing this will damage your transmission?

[Kenny McCormick]

Doing that will stress the shifting bands, planetaries and flexplate tremendously. If enough throttle is applied, you could outright shatter something(Usually the flexplate). With the front-drive, and especially considering the mileage on it, you can also snap axles at the joints.


The cop has a decent reason to do it, tho. He may be in a pursuit at the time, and any time spent coming to a stop means the perp is getting that much farther away.


Even if it doesn't outright break something, it will speed up the wear of the bands and clutches inside the automatic, and it will speed the wear of the other driveline components.

[wierdo124]

Basically my stance is that it's not necessarily great for it but it's not a big deal if you do it; i can't see it hurting much unless you're moving at a decent pace.

[cluffenstein]

I did it all the time in my old car, had some nice burnouts.. Don't do it in my new one.

Even doing it a lot my trans was still in tip top shape.

[TwIsTeDbOi]

I've noticed both my dad's '96 Silverado and my '99 Grand Prix, when we go from R to D, the vehicle slows down enough to the point where the shift doesn't seem like it's stressing anything. I mean yeah if you're doing it at 5+ MPH it can be detrimental, but slower than 2-3MPH? I think it's fine.

I think I got it from him because he ALWAYS does it. Then again he's had a manual in every car/truck he's had up until he got that truck in '96.

[Retrospekt]

I go from R to D while moving sometimes..but we're talking 2mph max. I would NEVER shift while driving any faster.

Also, I've heard a lot of people say that even shifting from D to N while moving at higher speeds is very bad for the transmission.

Edit: I should mention that the reason I'm so terribly careful with my transmission is that it's an original automatic tranny from a 96 Camry with 150k miles. They're notorious for failing around this mileage, and I am not about to replace a transmission.

[wierdo124]

Also, I've heard a lot of people say that even shifting from D to N while moving at higher speeds is very bad for the transmission.

Never heard that.

[TwIsTeDbOi]

I think it's just a lot of rumor and hearsay because automatics really have never been as reliable as manuals up until the recent years. That's just me though. But then again my sister would probably be the one to say stuff like this and then call me one day saying a mechanic is telling her her "muffler bearing" and "taillight gasket" are failing.

[cluffenstein]

LOL. but my 3rd brake light does have a gasket.. the only thing making it water tight!

[KSIMP88]

Doing that will stress the shifting bands, planetaries and flexplate tremendously. If enough throttle is applied, you could outright shatter something(Usually the flexplate). With the front-drive, and especially considering the mileage on it, you can also snap axles at the joints.


The cop has a decent reason to do it, tho. He may be in a pursuit at the time, and any time spent coming to a stop means the perp is getting that much farther away.


Even if it doesn't outright break something, it will speed up the wear of the bands and clutches inside the automatic, and it will speed the wear of the other driveline components.

All new Police Interceptors and Dodge Charger Pursuit Rated, and all other pursuit cars have a mechanism that forces the car to wait until speed is 0, before it transitions to D from R, or vice-versa. They will get you either way.

[cluffenstein]

my manual trans has something that prevents the shifter into reverse even at a roll (can't be moving at all.), and prevents you from going to gear if your moving in reverse (a slight roll seems to be ok though.)

[blackhawk777]

i just read the driver's manual for my mazda protege, it says shifting the car from R to anything below it (N, D, 2, 1) is dangerous if the engine is spinning faster than the idle speed. so i guess you can do it only at the speed your car goes when you dont press the brakes down?

[KSIMP88]

i just read the driver's manual for my mazda protege, it says shifting the car from R to anything below it (N, D, 2, 1) is dangerous if the engine is spinning faster than the idle speed. so i guess you can do it only at the speed your car goes when you dont press the brakes down?
yes-ish. Always best to stop completely.

[StreetRacingTechno]

Shifting from Drive to Neutral or Reverse to Neutral at speed will not damage the transmission at all and is actually the recommended procedure for driving when it is icy/slick out and you are trying to bring the car to a stop or slow down suddenly.

[cluffenstein]

just whatever you do DON'T go from reverse or drive to Park.. unless you'd like an easy way to remove your transmission :)

[gearcruncher]

Yikes !!

I am kinda new here and dont wanna step on any toes .
I use to build transmissions for a living .
What takes the load of a 4000 pound vehicle going from forward to reverse without coming to a complete stop ? The trans rite ?
I can tell who does this just by looking at the internal parts of the trans .
I have replaced hundreds of internal automatic transmission parts for this very reason .
Domestic vehicles were the worst usually resulting in cracked transmission housings or ribs of alluminum inside the housing that hold the center support in place . I have seen sprags and roller clutches blown apart from not coming to a complete stop .
Transmissions are designed to apply gears of opposite direction from a complete stop .
I beleive 1 model ZF transmission used in the Case front end loader has built in protection in the even reverse is selected when the machine is going forward but all other transmissions have no protection .
Can it be done ? Yes
Should it be done ? No - its a bad habit and sooner or later it will sting you in the pocket book .

[lautinjr]

Good advice wasn't sure of that but a tranny guy told me once it's stupid things people do that do the most damage like this and constantly kicking the passing gear in and letting it out.

It'll be good to have a trannie guy around! Welcome!!

[slickwilly]

Yikes !!

I am kinda new here and dont wanna step on any toes .
I use to build transmissions for a living .
What takes the load of a 4000 pound vehicle going from forward to reverse without coming to a complete stop ? The trans rite ?
I can tell who does this just by looking at the internal parts of the trans .
I have replaced hundreds of internal automatic transmission parts for this very reason .
Domestic vehicles were the worst usually resulting in cracked transmission housings or ribs of alluminum inside the housing that hold the center support in place . I have seen sprags and roller clutches blown apart from not coming to a complete stop .
Transmissions are designed to apply gears of opposite direction from a complete stop .
I beleive 1 model ZF transmission used in the Case front end loader has built in protection in the even reverse is selected when the machine is going forward but all other transmissions have no protection .
Can it be done ? Yes
Should it be done ? No - its a bad habit and sooner or later it will sting you in the pocket book .

This is the direction I was going in.

In my exp. most trans. will break the Sprag (one way clutch) if it damages the clutches then they were weak already or had low hyd. pressure.

The only trans. I have ever seen do this repeatedly and survive is the old 2 speed Power glide.

In the mid 60's Ford had the Cruiseomatic, it had a built in safety feature
that would not let the trans. shift in to any gear from neutral if the engine was above idle.
My brother had one in a 65 T-bird and it would not do a neutral drop
for nothing
so out it came an in went a C-6 that did not have this safety feature
it lived a short life.

[wierdo124]

From what i've heard, the tranny they put in my blazer, the 4L60E, is a terrible tranny.

[Kenny McCormick]

I haven't heard of anything terribly bad about the 4L60E behind a V6. From what I've heard, it's quite the reliable slush-o-matic.

Then again, I also heard bad things about the input shaft on my NP 4-speed, but that hasn't shattered either. Or even cracked. So maybe I'm hearing wrong things.

[canadianshane]

what about driving and going say from the low setting on yor tranny to drive then overdrive is that bad? just since its somewhat apart of this topic

[Mr Car Guy]

Shifting up while moving forward is no problem, with the exception of 2nd gear, the trans will only shift up when it's ready.

[wierdo124]

what about driving and going say from the low setting on yor tranny to drive then overdrive is that bad? just since its somewhat apart of this topic

Won't hurt a thing. You should still let off the gas for two reasons, you could a) shift too far and hit neutral and bury the needle, damaging or blowing the engine, or b) really overshoot and hit reverse. which that is WAY too fast to go into reverse.

[KSIMP88]

Won't hurt a thing. You should still let off the gas for two reasons, you could a) shift too far and hit neutral and bury the needle, damaging or blowing the engine, or b) really overshoot and hit reverse. which that is WAY too fast to go into reverse.

You can't burry the needle in most auto's as I understand. They won't even shift down unless the lower gear isn't going to be redlining

[wierdo124]

Most have a rev limiter that you can't go past 4k. Mine doesn't at least. I can bring her right up to 6k

[cluffenstein]

the PT wouldn't allow you to rev past 4K in park or neutral.

[wierdo124]

Thanks for proving my point :D

[slickwilly]

From what i've heard, the tranny they put in my blazer, the 4L60E, is a terrible tranny.


I rebuilt the 4L60e in my wife's 94 Bravada and I can say that the 4L60 does have a weak link, it is called the sun reaction gear shell, this clutch cage is pressed out of maybe 3/16 sheet steel and has an internal spline on the back side for the out put shaft, this splined area can spread out allowing the splines to be stripped out, this is what happened to the wife's tranny.

A well built reman. unit will cost almost as much as a new unit but it is stronger
due to it having a machined splined section welded on to the Sun reaction gear shell

[lautinjr]

I rebuilt the 4L60e in my wife's 94 Bravada and I can say that the 4L60 does have a weak link, it is called the sun reaction gear shell, this clutch cage is pressed out of maybe 3/16 sheet steel and has an internal spline on the back side for the out put shaft, this splined area can spread out allowing the splines to be stripped out, this is what happened to the wife's tranny.

A well built reman. unit will cost almost as much as a new unit but it is stronger
due to it having a machined splined section welded on to the Sun reaction gear shell

Exactly the 4L60E is a great trans but like every trans there is always room for improvement after market prerebuilt units can have many upgrades over the factory ones.

[wierdo124]

I ripped one out of an Astro at the scrap yard for $400, wasn't about to drop $1300 for a rebuilt.