Shfting from Drive to Low on automatics.

[npoe1]

I would like to know if there is a problem if I change from D to L on my automatic car. I?ve been doing that to reduce speed as I get closer to intersections but I?m not sure if that could damage the transmission, because using less the brake doesn?t worth a transmission.

Thanks,

 

[mooseracing]

What gear is your low? And what gear is the transmission usually downshifting from? The higher the gear that you downshift from into L the more shock on the drivetrain itself. The transmission wear would be negligable as at a higher rpm from downshifting you would have increase fluid flow letting the clutches lock up harder, but then also as you downshift you are forcing the clutchpacks to grab quick and hard like dropping the clutch almost.

I don't downshift on a manual until I know I am out of range for the gear I am in, ie lugging the engine.

 

[Zenmervolt]

Unless you are on a long downhill grade it's not usually advisable to manually shift an automatic that was not designed to have a manual function. On a standard automatic it will cause extra wear on the clutchpacks as mooseracing said.

ZV

 

[LTC8K6]

The auto won't actually shift down unless it's safe to do so anyway.

I will often drop a gear or two manually in my autos to slow down, but not all the way to first.

I have been doing it forever and haven't had any problems.

I never do it in slippery conditions, though.

I do it more out of habit, than for any specifc reason.

 

[Shawn]

Just use the brakes.

 

[fstime]

Yup, just use the brakes, no point in putting unnecessary stress on your transmission..

 

[Zenmervolt]

Originally posted by: LTC8K6
The auto won't actually shift down unless it's safe to do so anyway.

I will often drop a gear or two manually in my autos to slow down, but not all the way to first.

I have been doing it forever and haven't had any problems.

I never do it in slippery conditions, though.

I do it more out of habit, than for any specifc reason.

What you say is true of new , electronically-controlled automatics. Older automatics (some even into the mid 1990s, though that's rare) that used hydraulics as the primary control can be forced to downshift when it is not safe to do so. Even with newer automatics, I still don't recommend it unless there is a manual-shift functionality incorporated in the design of the transmission.

ZV

 

[Pacfanweb]

I've never seen it hurt a thing. It won't wear the clutch packs anymore than upshifting will, at least on new cars. Obviously, there's some additional wear, since it's another shift, but unless you do it just all the time, it's not going to be a significant difference on most transmissions. Not like it's going to halve the life of the transmission.

Even on old non-electric transmissions, and I'll preface this by saying my experience with these are mostly with GM trannys like the Turbo 350 and 400, they wouldn't shift from Drive/3rd to Low/1st until you were slow enough for it not to make you lose control.
You can drive any car with one of those transmissions and run down the highway, drop it to Low and it'll go into Second...but not Low. If it did drop to Low at highway speeds, you'd either lock the drive tires up, or over-rev the engine.
In fact, they will actually upshift on their own if you run them too fast in Low, with the shifter still in the Low position.

 

[npoe1]

I have a Ford Fusion SEL V6 and what Low does is just switch the gears at 5,000 RPM instead of doing it at 2,000 RPM but I have got until 5th gear on Low. The Transmission just downshifts from 6th to 5th and so on.

 

[Nyati13]

Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

 

[Pacfanweb]

Originally posted by: Nyati13
Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

Now that's totally wrong. No car with an automatic will help you slow down much. You certainly will never get engine or compression (as some call it) by leaving one in D.

But if you downshift you will.

 

[yelo333]

Originally posted by: Pacfanweb

Originally posted by: Nyati13
Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

Now that's totally wrong. No car with an automatic will help you slow down much. You certainly will never get engine or compression (as some call it) by leaving one in D.

But if you downshift you will.

I think some, like current gen civic, will automatically downshift to hold your speed when you are going down a hill.

Also, don't forget about CVTs. The Dodge Caliber I drove had quite an aggressive amount of deceleration when you took your foot off the throttle.

At any rate, brakes are relatively cheap compared to transmissions ... Plus, when you brake, you get the added bonus that those fancy lights in back light up. Make it easy for the cell-phone-talking tailgater behind you.

 

[npoe1]

Originally posted by: Nyati13
Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

I bought the automatic because there was no standard on that version of the car I love standard although they are a rare breed now.

 

[thomsbrain]

Originally posted by: Pacfanweb

Originally posted by: Nyati13
Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

Now that's totally wrong. No car with an automatic will help you slow down much. You certainly will never get engine or compression (as some call it) by leaving one in D.

But if you downshift you will.

The automatic in my 2003 Accord V6 will downshift one or even two gears if you brake on a steady decline. You can then let off the brake and the transmission will hold the gear until you get on the gas lightly again or the hill levels out and your speed starts dropping significantly. Then it will upshift back to the regular cruising gear for that speed. If you get back on the gas hard for a pass, it will continue to hold the shorter gear for passing power.

After ~45,000 miles of driving it, I could count on one hand the number of times that it has been in the wrong gear at the wrong time. Even under hard driving, it seems to have E.S.P. and is downshifting before the apex.

Unfortunately, it's made of brittle glass.

OP, just leave it in "D" and use the brake if you need to do so. I know it is tempting, but my experience is that automatics are best left to their own devices (pardon the pun) unless you need to utilize 2nd-gear start functions.

 

[npoe1]

I will resist the temptation and only use D, but the sound of a decelerating engine is one of the sweetest things in the world.

 

[bruceb]

I dp that on my GM on steep downgrades. But only from
"D" down to "3" and then to "2" if needed. In "2" I try
to keep car speed to under 35-40MPH or about 3000RPM
max. That is a fairly safe range and still gives good engine
braking. I have the 3800 V6 with the 4 speed auto transaxle..
No issues at all.

 

[DougK62]

It's an automatic, just leave it in D and use your brakes. You really want to move the shifter around as little as possible. If you like the sound of gearing down then get a car with a manual transmission.

 

[Nyati13]

Originally posted by: Pacfanweb

Originally posted by: Nyati13
Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

Now that's totally wrong. No car with an automatic will help you slow down much. You certainly will never get engine or compression (as some call it) by leaving one in D.

But if you downshift you will.

Nope, completely right. Despite my lifelong hatred of automatic transmissions, even I have to admit that recent automatic designs are almost as good as a manual transmission. The engineers have closed a lot of the gaps that autos used to suffer from.

 

[LTC8K6]

I recently rented a Grand Cherokee with the 5 speed auto manumatic. It was a lot of fun downshifting to slow down. Of course it was set up to be shifted that way.

My 1997 Z24 has been aggressively downshifted since I bought it new. Sounds wonderful and I love to do it. In fact, I'll be dropping it down into 2nd some more today. When's the tranny gonna break?

Can't recall ever having an auto transmission problem on any car I have owned save one, and that was a 1995 Taurus SE recall that was unrelated to my downshifting.

 

[Pacfanweb]

Originally posted by: Nyati13

Originally posted by: Pacfanweb

Originally posted by: Nyati13
Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

Now that's totally wrong. No car with an automatic will help you slow down much. You certainly will never get engine or compression (as some call it) by leaving one in D.

But if you downshift you will.

Nope, completely right. Despite my lifelong hatred of automatic transmissions, even I have to admit that recent automatic designs are almost as good as a manual transmission. The engineers have closed a lot of the gaps that autos used to suffer from.

Then I evidently haven't driven one, then. If they are making them like that, it's about time.

To get any REAL engine braking though, you'll still need to manually downshift.

 

[Bignate603]

Unless you're going down a LONG hill just let the transmission do what it was designed to do and use the brakes for what they were designed to do. The only reason you should consider using engine braking in an automatic is if you're going down something that threatens to overheat the brakes. There was a couple mile long hill that I had to drive pretty often. I'd downshift going down that because I'm not sure the corolla's brakes would have liked it.

 

[LTC8K6]

The shift lever was designed to be moved.

 

[2dt Drifter]

My 04' Grand Cherokee and my 94' Cherokee both have auto trans and both have Over Drive on/off buttons. I'm surprised no one has brought it up? I live in Colorado and driving in the mountains every weekend I constantly turn off O/D for going up and down hills. get a little jump on the higher RPM's before climbing a hill and using the engine to give me a constant deceleration rate so i dont lay on the the brakes for 1/4 mile going down hills.

by all means if the vehicle has an O/D on off switch use it when you need it, thats why they made it.

 

[Nyati13]

Originally posted by: Pacfanweb

Originally posted by: Nyati13

Originally posted by: Pacfanweb

Originally posted by: Nyati13
Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

Now that's totally wrong. No car with an automatic will help you slow down much. You certainly will never get engine or compression (as some call it) by leaving one in D.

But if you downshift you will.

Nope, completely right. Despite my lifelong hatred of automatic transmissions, even I have to admit that recent automatic designs are almost as good as a manual transmission. The engineers have closed a lot of the gaps that autos used to suffer from.

Then I evidently haven't driven one, then. If they are making them like that, it's about time.

To get any REAL engine braking though, you'll still need to manually downshift.

A lot of the newer designs are getting fancy with their software packages, so autos keep getting closer to manuals every year.

 

[Pacfanweb]

Originally posted by: Nyati13

Originally posted by: Pacfanweb

Originally posted by: Nyati13

Originally posted by: Pacfanweb

Originally posted by: Nyati13
Newer design automatics already have built in engine braking functions. By trying to manually control it, you would be knocking the transmission out of it's software controlled mode ( which is usually the best state the transmission can acheive already) and decreasing the engine braking effect you are trying to achieve.
You bought an automatic.... stick it in D and just leave it there.

Now that's totally wrong. No car with an automatic will help you slow down much. You certainly will never get engine or compression (as some call it) by leaving one in D.

But if you downshift you will.

Nope, completely right. Despite my lifelong hatred of automatic transmissions, even I have to admit that recent automatic designs are almost as good as a manual transmission. The engineers have closed a lot of the gaps that autos used to suffer from.

Then I evidently haven't driven one, then. If they are making them like that, it's about time.

To get any REAL engine braking though, you'll still need to manually downshift.

A lot of the newer designs are getting fancy with their software packages, so autos keep getting closer to manuals every year.

Yeah, that's why the gas mileage difference from auto to manual in the same vehicle these days is either the same or very little difference.