Shifting from R to D while still rolling backwards.

[twinrider1]

Someone I know does this and it drives me nuts. She backs down the driveway and, before she comes to a complete stop, she shifts from Reverse to Drive.
In the name of all things mechanical, I know that it's wrong. But I have to admit, it doesn't seem to hurt the vehicle. It doesn't seem to jerk or make a horrible grinding cry for help.
So is there something in their design that allows for this sort of thing? It almost seems like it free wheels, like when you stop pedaling a bike with a coaster brake.

 

[silicon]

Someone I know does this and it drives me nuts. She backs down the driveway and, before she comes to a complete stop, she shifts from Reverse to Drive.
In the name of all things mechanical, I know that it's wrong. But I have to admit, it doesn't seem to hurt the vehicle. It doesn't seem to jerk or make a horrible grinding cry for help.
So is there something in their design that allows for this sort of thing? It almost seems like it free wheels, like when you stop pedaling a bike with a coaster brake.

i was always told to come to a complete halt before going from reverse to drive. At the worst there is more wear and tear on the CV joints and the transmission internals namely the differential. if there is no clunk or other noise then perhaps the transmission can tolerate this for a period of time but one day she may forget and be going a little too fast when shifting and, "BANG", it will be too late for that poor transmission or the CV joints.

 

[phucheneh]

I would think that a modern car would wait for the VSS to reach zero before actually applying a reverse band or clutch pack. But, a traditional analog, voltage-generating speed sensor is not terribly accurate/sensitive at very low speeds.

As far as driveline shock is concerned, you will probably not hurt anything. But there will be some degree of additional wear to the mentioned band or clutch pack (traditionally, application of reverse is done by a band holding a clutch drum in place). They are meant to HOLD a part in place- they are not designed to stop a component that is being rotated by the drive wheels.

 

[DougK62]

A LOT of people do this, and it's definitely not good for the car. But wear is probably minimal as long as they're going very slow and don't get immediately aggressive on the gas.

 

[unokitty]

Someone I know does this and it drives me nuts. She backs down the driveway and, before she comes to a complete stop, she shifts from Reverse to Drive.

Can't speak about modern cars.

But I can tell you from experience that on a '61 Rambler Convertible, you can break a universal joint doing that ... And after you break the universal, the drive shaft can fall out ...

Uno

 

[boomhower]

Work car is an 06 or 07 Charger and it has a three second delay when shifting. I don't know what kind of damage it does but I have no doubt it will need a new one before I'm done with it, have no clue the logic behind that one.

 

[LTC8K6]

I have always gotten the car moving in reverse, then shifted to neutral. I come to a stop in neutral, then shift to drive. Most of my backwards movement occurs in neutral.

I developed the habit a long time ago. I do it so smoothly and fast that most people riding with me are unaware that I'm doing it.

 

[dbcooper1]

I think some transmissions tolerate it better than others; my GS300 doesn't like it at all compared to other cars I've had. I don't do it intentionally but sometimes I come to a stop and the car rolls a bit as I'm going from reverse to drive.

 

[thescreensavers]

Transmissions are designed to do this to a point (ie normal use) I wouldn't lose sleep about it.

The way it will apply torque knowing that it was just in reverse will be greatly reduced until some other sensors check in.

Lots of cars that I have driven have very crappy throttle response when switching out of R

 

[Kelvrick]

I have always gotten the car moving in reverse, then shifted to neutral. I come to a stop in neutral, then shift to drive. Most of my backwards movement occurs in neutral.

I developed the habit a long time ago. I do it so smoothly and fast that most people riding with me are unaware that I'm doing it.

Why would you do that? It eliminates your reverse lights which warns other people.

Side note, I HATE cars that activate their reverse lights when people park.

 

[nitrous9200]

I also know someone who does this and it's probably not harming anything, but it just bugs me for me some reason.

Why would you do that? It eliminates your reverse lights which warns other people.

Side note, I HATE cars that activate their reverse lights when people park.

I do the same thing - start backing out in reverse, but a second or two before I want to stop reversing, I brake and put it in neutral, then after the car is completely stopped, put it in drive.
The reverse lights are only off for a very short time and since the car is almost stopped anyway, I don't think it's dangerous.

I do it because -
a) I have to get into drive anyway, so I might as well start getting closer to it
b) The car stops faster than just stepping on the brakes while in reverse
c) It stops me shifting into D before the car has stopped rolling

 

[deadken]

When I worked for Dodge (2 different dealerships) from 90?-94 one of the jobs I used to do was to rebuild transmissions. You could always tell someone who did that or neutral drops based on one of the 'pistons' being hammered down. Please note: the 'piston' I'm referring to is just the aluminum piece that presses down to apply a clutch pack. That being said, it wasn't always the reason for the transmission failures. So, while it might not cause a failure, it can still have an effect inside the transmission. In those Dodge transmissions with the piston hammered down, it would take just a little longer for the transmission to engage a forward gear because it needed a slightly larger volume of fluid to apply that clutch pack.

The reason you don't hear a 'cry', grind, or feel a jerk that is because the torque converter is picking up some of the slack. IOW: you have a viscous coupling in the drivetrain instead of a solid / mechanical coupling. So, that acts a bit like a shock absorber. It won't eliminate the condition, but will soften the transition.

On the older cars when things were more / all mechanical drive would be called for as soon as the gear selector was put in drive. Since the newer transmissions use electrical solenoids the manufacturer can build in a delay. I believe that some cars will monitor the vehicle speed sensor and hold off engaging a forward gear if the car is still moving in reverse. IOW: certain criteria have to be met in the logic circuit before the drive solenoid is engaged.

 

[LTC8K6]

Why would you do that? It eliminates your reverse lights which warns other people.

Side note, I HATE cars that activate their reverse lights when people park.

I don't back up if a warning would be required to other people. I back up when it's clear to back up.

My reverse lights are there so I can see behind me when it's dark. :biggrin:

We're only talking about 2 or 3 seconds, max.

 

[Kelvrick]

I don't back up if a warning would be required to other people. I back up when it's clear to back up.

My reverse lights are there so I can see behind me when it's dark. :biggrin:

We're only talking about 2 or 3 seconds, max.

Ok. I guess I read it like you got in reverse to get you going (for a few seconds), then went the rest of the way without reverse lights. I'm guilty of not being in reverse the whole way too, then.

 

[shortylickens]

When I saw the thread title I thought I was in P&N.
It actually kinda works.


Anyway, I've never done it. Been too scared.

 

[Raduque]

My dad did that once in my parents Aerostar van back in 97. $2800 and 5 weeks later (transmission had to be shipped from the lower 48 - we lived in Alaska at the time) it was fixed, and he hasn't done that since to any vehicle.

 

[Jeff7181]

When I worked for Dodge (2 different dealerships) from 90?-94 one of the jobs I used to do was to rebuild transmissions. You could always tell someone who did that or neutral drops based on one of the 'pistons' being hammered down. Please note: the 'piston' I'm referring to is just the aluminum piece that presses down to apply a clutch pack. That being said, it wasn't always the reason for the transmission failures. So, while it might not cause a failure, it can still have an effect inside the transmission. In those Dodge transmissions with the piston hammered down, it would take just a little longer for the transmission to engage a forward gear because it needed a slightly larger volume of fluid to apply that clutch pack.

The reason you don't hear a 'cry', grind, or feel a jerk that is because the torque converter is picking up some of the slack. IOW: you have a viscous coupling in the drivetrain instead of a solid / mechanical coupling. So, that acts a bit like a shock absorber. It won't eliminate the condition, but will soften the transition.

On the older cars when things were more / all mechanical drive would be called for as soon as the gear selector was put in drive. Since the newer transmissions use electrical solenoids the manufacturer can build in a delay. I believe that some cars will monitor the vehicle speed sensor and hold off engaging a forward gear if the car is still moving in reverse. IOW: certain criteria have to be met in the logic circuit before the drive solenoid is engaged.

Why would the piston show any additional wear due to this... "technique?" I can't think of how any additional forces would be applied to the piston in this situation. Sure there's additional load on all load bearing components when doing this, but the piston in this case is not really a load bearing part - the load on the clutch pack which the piston actuates is a torsional friction load and would not transfer to an impact load at the piston.

If it were a band... then MAYBE a shock load could be transferred back to the piston seeing as how the band would be anchored to the transmission housing at one end and actuated at the other end. But, depending on design, the load generated by this could actually decrease load on the actuator. Even so, you said clutch pack, and typically that term refers to circular frictions and steels... not a band and drum.

 

[killster1]

its a girl thing.. they seem to do it all the time, i always have them come to complete stop first in my cars just incase it matters.. also on hills / slight incline i put parking break so its not that hard of a shift into gear when first going from park to drive.. i know my ex and her mom had no idea if they should use drive or overdrive in a car they had and had been using it in drive the whole time.. i was laughing so hard..

On side note.. how about cars with shift tronic thing.. where can shift up and down or be in automatic mode.. is going down hill in neutral then going into gear a bad thing? something about gear spinning real fast then going into gear being bad? really would like to know that one since i love to put it in neutral and coast for long time down hill..

 

[Blackjack200]

The reason you don't hear a 'cry', grind, or feel a jerk that is because the torque converter is picking up some of the slack. IOW: you have a viscous coupling in the drivetrain instead of a solid / mechanical coupling. So, that acts a bit like a shock absorber. It won't eliminate the condition, but will soften the transition.

I do this all the time for this reason. I always assumed that as long as I wasn't going that fast, the viscous coupling just absorbes the energy (I'm going < 1 MPH when I do this) without any excess wear and tear.

I would never do this with a clutch.

Should I stop doing this? (I probably won't stop doing this.)

 

[thescreensavers]

Side note, I HATE cars that activate their reverse lights when people park.

So today I experienced exactly this, I was in a parking lot and got on my brakes guy was just getting out of his car and looked at me like an idiot

 

[HeXen]

My car's computer puts it into neutral until it nearly stops moving then shifts into D.
So if I reverse fast then slam it into D, the car just keeps rolling in neutral until it's almst completely stopped. I can even press on the accelerator and the rpms go up but it just rolls backward freely. I noticed once before if I rev up the motor as it reaches that nearly stopped point, it'll grab 1st gear just the same and jerk my neck back so apparently the RPM's alone don't keep it in N during that moment and obviously can't be good on the transmission.

Now old cars I know it can screw up a trans and break the shaft. Seen a few when I took automatics class in mechanic school.

On side note.. how about cars with shift tronic thing.. where can shift up and down or be in automatic mode.. is going down hill in neutral then going into gear a bad thing? something about gear spinning real fast then going into gear being bad? really would like to know that one since i love to put it in neutral and coast for long time down hill..

Mine's like that. I have to put it in "S" mode to manually use the shift paddles except for downshifting, oddly I can still downshift in D. If I roll downhill in N then put it in "S" mode it automatically puts it into an appropriate gear but of course it's usually down shifting so my RPM's go up just as it would a stick.
It is still an automatic after all, no different than rolling downhill in N and going into D, it'll run up the RPM's as if it's downshifting but seems to find the appropriate gear the same.

No clue if all cars do that or not. Either way paddle shifters are weird, I can't stand them and only use mine to downshift as I'm coming to a stop.