Shifting Auto trans....

[iwannadie]

Ive always wondered about this, just thought Id ask here see what kinda info/opinions I get.

My sister and her husband have this habit of shifting from Reverse to Drive while still moving. Like backing outa the drive kind of quick, say 20mph they will go from R to D while still going 15-20. To me that has got to be bad for the car right? Its odd they always have trans problems with all their cars and that is the only odd thing Ive seen going on with their cars.

 

[Merlyn]

Well, the only Auto car I drive is my friends car (which he doesn't really care about) and both him and I do this (not at 20 MPH, more like 5), but you are correct, it is not good on the transmission, however, how much damage it actually creates, that I am not sure of. Simply you are moving backwards, then you are throwing the car into a forward moving gear, simply having to tell the car, stop going backwards, and immediately go forward, more technically I can't tell you how it hurts the transmission, but I can tell you, you are basically forcing the car to stop itself from moving backwards by throwing it in a forward moving gear.

 

[Mk3Jesse]

i sometimes do this but at very low speed that doesnt even register on the speedo.
Not sure how it hurts it, but i would imagine if you are still going 5mph+ it cant be good.

 

[j3pz]

my family does this also. i dont know much about trannys but i always suspected it would wear on the torque converter

 

[IJ.]

Fluid coupling(Tq Converter) slips so there's no direct connection.

it "might" wear the clutches in the trans a little more as you're at 0 throttle so there's minimal line pressure and they'll slip as well.

 

[Merlyn]

correct me if I am wrong....

1. This will put stress on your CV Joints as your axle is spinning backwards then you are pushing X amount of torque on the CV Joint in the opposite direct that it is already traveling

2. You are putting wear on the trans itself by causing it to function in the opposite form...


Now, this is a completely BLOWN up question, from the initial, but at the same time, I am under the same impression whether large scale or small, if wear is put on an item, it just lesses on a lower scale...

traveling 20 MPH (or whatever the top of your R would be) and you shift into reverse, that would have the same effects as if you were in 1st and shifted to reverse...

at 20 MPH from R to D... that is going to cause damage (as was stated in question, 15 - 20 MPH from R to D)... you would call someone stupid for saying they went from 1st gear to Reverse at 20MPH... it is the same in reverse I would asume...

 

[IJ.]

Ummmm as I said the Tq Converter cushions the drivetrain from any shock loads.

Back in the 80's I had a fairly new car (3 yr old) that I used to routinely drop into R at 30mph....... Never had a failure just LOTS of smoke from the rears.

I don't recommend this practice but am just pointing out that it can be done (hitting P is another matter though as it's a Ratchet Lock in the trans and WILL self destruct easily)

 

[Merlyn]

Ummmm as I said the Tq Converter cushions the drivetrain from any shock loads.

Back in the 80's I had a fairly new car (3 yr old) that I used to routinely drop into R at 30mph....... Never had a failure just LOTS of smoke from the rears.

I don't recommend this practice but am just pointing out that it can be done (hitting P is another matter though as it's a Ratchet Lock in the trans and WILL self destruct easily)

Ok, I am more knowledgeable about Manuals, but I figured that would have still caused some damage.. ok then, IJ is correct

 

[IJ.]

Used to do the same thing with manual shitboxes
(Pull the e-brake to lock the rears select reverse lots of revs drop clutch and e-brake = mucho smoke and laughter)

 

[1jzdreamer]

Unfortunatly Im going to have to disagree with IJ here... yes the liquid drive cuishons it some, but the gears still abruptly change direction(point in questio if your going fast enough water can break things... not exactly a solid analogie but it works), which leads to unnecesary wear. Saying doing this doesnt hurt them is like saying Nuetral drops dont either. My family does it too, everytime I B&M at them.

 

[IJ.]

Which "gears" abruptly change direction?

 

[ArthurRitus]

Depends on the speed, think about it, if your driving a stick shift car, on a upward hill, when u have that little roll back before u progress, thats similar.

 

[iwannadie]

All good info, I think though bottom line is doing it has no Good effect. If theres is a chance of causing more wear on the vehicle and its done just out of laziness then its just that, being lazy. As I said they seem to have trans problems with Every vehicle they have so It makes ya think.

They mainly do it in their SUV, an older xterra which is pretty big and heavy. It just pains me to think about that big suv rolling backwards at speed then suddenly being thrown in D.

 

[Quin]

Depends on the speed, think about it, if your driving a stick shift car, on a upward hill, when u have that little roll back before u progress, thats similar.

That's less than five miles an hour, he's talking about slamming it into D at 20. That's completely different

 

[Merlyn]

You are also still in 1st gear, through the movement backwards and forwards, not changing directional gears

 

[iwannadie]

Depends on the speed, think about it, if your driving a stick shift car, on a upward hill, when u have that little roll back before u progress, thats similar.

Besides, you should have good enough control not to roll back at all ;p

I was with some girl who had giant platform high heels, we were on a decent hill. She went from a dead stop without rolling back at all it was impressive with those shoes lol.

 

[flight doc89]

correct me if I am wrong....

1. This will put stress on your CV Joints as your axle is spinning backwards then you are pushing X amount of torque on the CV Joint in the opposite direct that it is already traveling

well, DAMN! that SUCKS! i'm NEVER parking on an uphill EVAR (i have a manual tranny, not automatic, so my car always rolls backwards a little, and since going from backwards to forwards destroys cars.....)! Cuz the shift at idle really IS harder on CV joints than 8 psi.....

/rant

 

[Merlyn]

well, DAMN! that SUCKS! i'm NEVER parking on an uphill EVAR (i have a manual tranny, not automatic, so my car always rolls backwards a little, and since going from backwards to forwards destroys cars.....)! Cuz the shift at idle really IS harder on CV joints than 8 psi.....

/rant

Nice job quoting me out of context.....

You quoting me had to do with a R to D at 20 MPH.... not a manual on a hill rolling backwards...

I drive a manual too buddy... and as stated in the START and TITLE of this post... we are speaking about an AUTOMATIC TRANSMISSION DRIVE 20 MPH IN REVERSE THEN ABRUPTLY SHIFTING TO DRIVE AND GIVING IT GAS WHILE MOVING 20 MPH BACKWARDS

/rant