Can I downshift from D to 3 (or 2) on car (say Camry) with automatic transmission? Never tried before but would like to do it while driving down long hill. It's not practical to stop the car (in the middle of the hill, for example) to do it. Will this cause any damage (or side effect, excessive wear for example) to the transmission?
Not damage, assuming you've done all the recommended maintenance on the transmission. But, it *will* speed up wear, obviously. Every mechanic I've ever asked about this has said "Use the brakes judiciously. Brakes are cheaper than a transmission".
Brakes linings are less costly to replace than transmission friction material, so on short downhill stretches, it is less expensive to use the brakes. On long downhill stretches, the brakes may overheat and lose effectiveness, so manually downshifting is the safer option. The slower you are going when downshifting, the less wear and tear on the transmission, and it would be better to downshift one gear at a time, i.e., OD off, then 3, then 2, then low if necessary.
Downshit? I think you'd better stop the car and put in park. And preferably run into the woods. ;-)
You can safely downshift. Cars and trucks automatically downshift when you push the gas pedal harder. In fact, the shifter and transmission is made so that you can do that as well as put the transmission into a lower gear when go up hill so that the transmission won't change gears when going uphill when you lift your foot off the accelerator (like when you're going uphill and there is a crosstreet for which you slow down).
Transmission friction material? Never thought of that. Would this be the same for manual trannies? For example, keeping it in 3rd vs. shifting to
4th. Or keeping it in 4th vs. shifting to 5th. I've always used a lower gear and watch the car in front of me constantly hitting their brakes, when driving a stick.
Strange observation - lately I've been running into more women than men driving a manual transmission.
On long downhill stretches, the brakes may overheat and lose
I learned this hard way while driving our loaded Sienna in Yellowstone few years ago. When reaching the bottom of the mountain, Burned rubber smell was all around my car in the parking lot. Lucky it didn't catch on fire.
In a manual transmission, the friction material is the clutch and the synchronizer rings and cones. In an automatic transmission, there is friction material for the torque converter lockup mechanism, clutch packs, and brake bands. In either transmission, greater wear occurs when downshifting than when upshifting, and little or no wear occurs when holding a gear.
In a manual transmission, the 'friction material' is the clutch. In an AT, there are clutches and brakes inside the transmission. In a manual, YOU have control over how fast the 'friction material' contacts the friction surface (the flywheel). the faster you get your foot off the clutch, the less wear there is on the friction plate.
Driving in 3rd or 4th around town will not shorten the life of the clutch. Driving with one foot resting on the clutch pedal ("riding the clutch") may cause slipping between the friction plate and the flywheel, reducing the clutch life.
I have a Corolla GTS in my backyard with 259,000 miles...all on the original clutch...
"Ray O" wrote > > Also, the electronically controlled transmission will not allow downshifts
On my '91 Previa, the wiper blades caught together and were doing their best to rip themselves apart. In my haste to turn off the wipers, I accidentally hit the shift lever and slapped it all the way into park. This while I was going about 70 MPH. In a panic I started to pull onto the shoulder, figuring that I had just trashed the transmission, and maybe a lot more, but I noticed that the vehicle was running the same as before, so I just pulled it back into drive and continued on. I guess that there is some lockout that saved me from my own folly. I shudder to think what would have happened if I had only made it to Reverse, instead of park. Anyway, there was no discernible damage to the tranny, or anything else, except for bent wiper blades.
I do not recommend trying this, but if you put the transmission in reverse at 70 MPH, the experience would be the same as you had when you put it in park.
I was taught by my father when I was first learning how to drive that the correct "gear" for descending a hill is the same one you would use ascending the hill. Good advice that has gotten me through 47 years of driving in all kinds of conditions on all kinds of roads with sticks and automatics. Key is to select the proper gear before you start down the hill...
Do as you please, you will not damage the tranny. The tranny has built in protection that prevents damage if an improper range, or gear change, is selected. You can even select reverse accidentally, it will not engage.
Gotcha. I know there's wear whenever I shift. When I downshift, hopefully it helps when I tap the gas to bring the engine up to speed before sliding it into gear! When I know a downhill is coming up I would often leave it in gear instead of upshifting.
I know exactly what you mean by riding the clutch and no, I'm not one of those guys. It's like watching certain people shift - you see the tach go up and hear the engine rev higher, but the car doesn't move any quicker until they get their foot off the clutch. Then you hear about it when they need to replace the clutch at 60k...
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