Transmission, rush hour traffic - 1st gear only?

transmissions

#1

I have a 2000 Corolla CE 4-spd auto and I’ve asked this question from several mechanics and they all say they same: leave it in drive.

My issue is that during my rush hour commute, I’m in a lot of bumper to bumper traffic and the maximum speed is 15mph with a lot of stops. During this time, my transmission is literally switching from 1st to 2nd and then downshifting again hundreds of times. Isn’t it better to just keep it in 1st gear? The solenoids are constantly firing and gears are switching causing more wear/tear. It’s the same as putting the gear in 1st when going down hill so why do mechanics not recommend this?


#2

As long as the revs don’t get too high leaving it in first should be fine, just be sure to shift for those rare moments when the traffic opens up. But the wear caused by leaving it in drive wouldn’t be enough for me to worry about. The mechanics are probably worried about recommending something that could cause a traffic problem if you forget to shift out of first, combined with the small savings on wear you’ll see.


#3

I don’t know why they say that.
I like to do that so I can control speed with just the accelerator pedal and maybe…just maybe …help control the traffic speed to a consistant 10 mph ( I don’t race to catch up because I know they’re just going to stop again ) instead of all the jack rabbit ‘‘hurry up and wait’’ racing to catch up to stopped traffic only to brake again.

I’d much rather snail along at a consistantly slow pace .
low gear is the way to do that.


#4

Can I change from low gear back to drive (while say moving at 10mph) when traffic start getting moving again or do I need to come to a complete stop first?

What if I accidently go past neutral and go into reverse instead of drive? Would it reverse or just not engage the gear?


#5

You can change from low to drive at any time.

Going into reverse, though, is a BIG problem. It probably would engage and damage the transmission/cause an accident/who knows. Another reason why they probably discouraged you from doing this.


#6

Well I don’t know but I’d just leave it alone. Some years ago on the interstate rain turned to ice and for about 7 miles was glare ice with about 200 cars in the ditch. I crawled along at a few miles an hour in low gear to maintain control until the next exit. It wasn’t more than a couple months after that that I needed a transmission overhaul on my Olds. Can’t say that caused it but I’ve never stayed in low for any length of time after that.


#7

On some automatics selecting 2nd gear will make the car start in second gear, I have found its perfect for situations as you describe. I have never found a problem starting in second gear when in heavy traffic, the engine doesnt seem to mind. Not all automatics are second gear starters though.

I agree the constant shifting is alot of wear.


#8

When automatic transmissions shift they do not slip the friction elements appreciably (unless the transmission is already damaged), so there is no real additional wear on them.

It’s an automatic. Let it operate automatically. Having said that, it’s pretty hard to overshoot the selector going from “D” through “N” and into “R”. There is a detent in the shift selector specifically to prevent this.


#9

If you’re only going 15 MPH, maybe it’s a good idea, but otherwise you’re just trading transmission wear for engine wear.


#10

I would use “low” because shifting is the hardest thing on a transmission.


#11

I also had a question about my transmission. When I’m going very very slow (basically rolling at 10mph), my gear is at the maximum of 1st gear and is “deciding” whether to switch to 2nd gear. At that point, I hear a click…sort of like an “electronic switch/actuator turning on”…when it clicks, the transmission switches to 2nd gear. The noise is coming from under the hood near the drivers side (maybe under the gearbox).

Is this the solenoid firing in the transmission valve body?


#12

Leave it in drive. The transmission was designed to shift up and down without damage.


#13

I drive every day in rush hour traffic…sometimes for couple of hours…

Just leave it in drive. And change your fluid regularly.


#14

I don’t even leave my manual transmission in first in the traffic you describe. I try to drive as steady a speed as possible but I do not leave it in first so I can control the speed with the accelerator using engine braking. That’s just a lot of needless engine revving and fuel consumption to produce the two or three horsepower required for cruising 15 mph.


#15

missileman, you say “The transmission was designed to shift up and down without damage”.
Well yes, tires were designed to roll on the road with minimal damage, but after 80 to 100 thousand miles, they are pretty well worn out. What is the first thing/s to wear out in an automatic transmission? A. the clutches. They don’t wear if they don’t shift.


#16

Actually, Elly, we’ve been through this before. Automatic transmissions rarely wear out from simple clutch wear. The clutches do not slip when applied. Transmissions wear out from some hydraulic failure from worn or hardened seals. Seals wear more from heat and old fluid, not from shifting. Worn seals leak pressure, and then THAT causes clutch failure.


#17

Clutches in an automatic transmission wear out a because the transmission will “power shift” every time. If you floor it and the thing is revving up to 6k up shifting,then dropping to 4 while your foot is still hamming the gas, that right there was a power shift and it just put a lot of wear on the transmission. Even when you’re just lightly touching the pedals, you’re still touching the gas while it’s shifting.

I know some modern autos when coupled with a drive by wire throttle “rev matches”, and is easier on the clutches. Modern engines will do electronic wizardry (e.g. pull timing) during shifts to lessen the wear on the transmission? An auto trans will typically last quite a long time…I dare say longer than most people will own their cars.

Then there’s dual Clutch transmissions, those clutches basically never wear. Your dual clutch system is more like a rev-matched manual. Two gears are always engaged and it switches from one to the other. There’s no synchro time or synchro grinding. That car will shift in 10 miliseconds and it has continuous power, but my truck with a 4l60e has a looooong upshift time and it’s stressing the clutches that whole time.

Most of it depends on how you drive. Your grandma’s automatic will last forever because she accelerates super slow. My auto transmission will be lucky if it lasts 10 years because every merge onto a highway or freeway is a pedal to the floor clutch burning extravaganza. Automatics really don’t like being loaded down, which is basically what I’m doing when I’m flooring it. If you buy a van or suv and it has an optional towing package, that towing package likely includes an additional cooler for the automatic transmission. Heat is caused in part by the clutches slipping.

To say that clucthes in an automatic trans never wear is absurd.


#18

WheresRick:
You make a good argument for the stress on clutches with full throttle driving conditions. I agree it causes added stress on the clutches. But don’t many autos do fine in those conditions, and the lifetime of their transmissions fall into the conditions described by JayWB?

The OP is asking a question that relates to clutch wear during low speed stop-n-go driving. There is definitely no appreciable clutch-wear savings to be had by leaving it in L/1st during stop-n-go driving.


#19

@joemario

I agree, most automatic clutches will last the life of the trans.

I still say if the car is a second gear starter, put it in second gear.


#20

The clutch packs that engage gears in automatic transmissions are very similar to the clutches used in motorcycle manual transmissions. A multiplate clutch that operates in an oil bath.
Typically, the friction plates don’t wear down like the ones in dry clutches do, instead, they become glazed and when that happens, they slip under high load and become grabby when disengaged.
In motorcycles, it’s mostly the abuse from drag strip style starts that glazes them and then once they start slipping with the clutch completely engaged, they really become glazed.
Ride gently using full power only after the clutch is locked up and you may never need to replace the clutch pack, even when you shift a lot.
A car rolling along at 15-20 mph by someone who is driving as if he cares about gas mileage is likely not doing any measurable wear to the automatic transmission’s clutches. The torque converter does most of the slipping and the torque converter is what does most of the oil heating.
Also, consider that it is the output turbine blades of the torque converter that has to suddenly change rpm when the gears change, not the engine’s flywheel, that takes a lot of the abuse out of gear changing.