Shifting gears without coming to a complete stop

[Carnoobie]

On Auto trans. I need to get this out of the way once and for all. Cause this is one pet peeve thats always annoyed me.

I bring this up becauae even though I always let my car come to a complete stop before shifting from like D to R or N and vice versa. Ive noticed in my time that a lot of mechs dont do this. I see them drive their customers cars in and out of their shops all the time and they will like back up the car and while hitting the brakes but not coming to a stop, they just throw it into D again while the car is still moving! Or theyre going forward, hit the brakes, throw into R while car is still going forward!

Ive always them why they do it and they all told me its no harm to the trans.

I think thats a lie. What is the story behind this? Do you know anyone who does this?

This is what one mech told me.

"There is almost zero chance of doing any damage to the trans unless you are doing a decent rate of speed. Below about 5mph there is no way at all that you will damage the transmission. None. You may, however, put some shock loading into some of the drivetrain elements, but again you'd have to be doing a decent speed to stand more than an outside chance of doing so. That's why Neutral is in between D and R."

 

[SwampSurvivor]

It KILLS me when people do this ...

 

[Carnoobie]

Originally Posted By: Miller88
It KILLS me when people do this ...


why? do you know a lot who do this? and all the time?

 

[NateDN10]

Going from drive to neutral or reverse to neutral isn't a problem.

 

[zrxkawboy]

Originally Posted By: Carnoobie
Cause this is one pet peeve thats always annoyed me.


Yep, me too.

 

[JHZR2]

I would imagine that the fluid coupling would take up most of the stress on an AT.

 

[Carnoobie]

Originally Posted By: NateDN10
Going from drive to neutral or reverse to neutral isn't a problem.


You sure about that? Lets say you back out at 10mph, then you start to brake and while still going back you all of a sudden it into D. That puts fatal shocks on the drivetrain components no?

But as far as going from like D to N and back to D i know is ok, taking it youre not going like 40km/h.

 

[d00df00d]

Originally Posted By: JHZR2
I would imagine that the fluid coupling would take up most of the stress on an AT.

Exactly.

The question is whether doing this stresses the torque converter more than, say, getting going from a standstill up a steep hill. I suspect not.

Of course, not doing it at all would still be better.

 

[Carnoobie]

Originally Posted By: zrxkawboy
Originally Posted By: Carnoobie
Cause this is one pet peeve thats always annoyed me.


Yep, me too.


Would you ever ditch a mechanic who does this? Cause you would be surprised how many do this to customers cars all the time.

And they all say theres nothing wrong with it! Read my description in the main post, thats what one said. He said at low speeds youre fine, wont damage anything or put shock on.

 

[KrisZ]

Even mythbusters proved that throwing the transmission in reverse at high rate of speed won't damage the transmission on a modern car, as the transmission simply will not shift onto gear.

Regarding slow maneuvers and not coming to a complete stop before shifting, I don't think it's such a big deal either. The worst case scenario that I can picture is slightly more wear on the clutch packs.
Shock to the drive train argument is a non issue to me. Any hard acceleration or transmission kicking down will put far more shock or stress, which the drivetrain was obviously designed to take, than backing out of the driveway and going into D before stopping.

 

[Eddie]

Probably no problem but, that type of stuff demonstrates a lack of respect for machinery. In addition; that lack of integrity will probably show up in his work via him taking shortcuts to finish the job quick. Ed

 

[calvin1]

I accidentally put my dad's 84 t-bird (c4?, not sure) into reverse at about 40MPH when I had it out when I was 17. I was trying to bump it from D to OD and missed. I had my last will and testament put together in my head before I got to the side of the road but nothing seemed to be damaged. Electrical gremlins, rust and deer all had a hand in taking it off the road before anything showed up with the transmission so I guess no real harm done, not that I recommend stupid stuff like this.

 

[ARCOgraphite]

As a silly teen we used to beat on the Buick electra 225 455 with a bullit proof TH400. to irritate guys playing with me following me close I d throw the car into reverse going, say, 30-40MPH and silmutaneously floor it - the trans would just softly engage reverse and then start spinning the rear tires backward!
I bet you'ld drop any of today's marginally overrated auto transaxle doing that kind of hijinx at a high speed, but otw no problem seen going R to D up to 5mph on the few autos ive had. I bet it shortens the life of the clutch pack a bit - even though the torque converter is cushioning the jolt.

 

[brianl703]

Originally Posted By: KrisZ
Even mythbusters proved that throwing the transmission in reverse at high rate of speed won't damage the transmission on a modern car, as the transmission simply will not shift onto gear.


They did it wrong. The engine stalled when they put it in reverse.

You know how to keep that from happening? Give it some gas while you put it in reverse. Then it will engage reverse, and you'll have your rear tires screeching in reverse as you're still going forward.

I know this for a fact. I also know for a fact that the 4R70W transmission that this was done to has not exhibited any ill effects from this treatment, although I imagine that having the rear wheels skidding on a car might result in some body damage, especially when it's going 55MPH....

 

[Nick R]

I do this all the time, mostly when backing out of the driveway. If it caused a big jerk and noise, then I wouldn't do it, but it doesn't, it's a smooth transition from reverse to 1st, so I don't worry about it.

 

[Artem]

I agree with Nick, its such a smooth transition that it just doesn't seem to be harming anything. Of course I don't do it while rolling at 5 mph but more like simply throwing it into D while coming to a complete stop (barely rolling backward).

Now when I go from D to R, I always come to a complete stop but I still time the shift and move the shifter a split second before I come to a complete stop.

 

[TFB1]

At 2-3 mph it's a total non-issue, I've done it for 45+ years and never had a problem...

Only automatic transmission I've lost was the AODE in a '93 Grand Marquis that started slipping at 30K mi when my mom owned it(she bought it new)... I installed a B&M electronic shift improver and it lasted till 131K mi, when it finally blew the front pump to case gasket... Since it had to come out anyway, I installed a fully rebuilt unit...

BTW I also used nothing but type F in that trans(as well as a AOD in a T-Bird I raced) from 30K mi, so the tales of wrong fluid causing issues(at least in the RWD Ford trans) is unfounded as well...

 

[AVB]

I know on mid 90's Z71s the owners manual says it is ok up to around 15mph I think. But I think that was when in mud not sure about hard ground. It always scares me on a 4l60 though because thats what is always blamed when the splines on the sun shell get rung off.

 

[01rangerxl]

Originally Posted By: AVB
I know on mid 90's Z71s the owners manual says it is ok up to around 15mph I think. But I think that was when in mud not sure about hard ground. It always scares me on a 4l60 though because thats what is always blamed when the splines on the sun shell get rung off.

I've heard the same thing, that the sun shell failures had a lot to do with shifting while still moving.

I can wait a couple seconds, so I don't see a need to put any additional stress on the transmission.

 

[SteveSRT8]

Depends on the weight of the vehicle a lot.

Our 9500 pound Savanas can DESTROY the trans if slammed into drive while rolling backwards.

Never a good idea, and many mfgrs have put in programming to prevent it. My Chrysler has a pregnant pause before delay anytime you change directions no matter what.