Potential Transmission Damage? - Fuel Economy, Hypermiling, EcoModding News and Forum

ermarccio · 04-22-2011, 10:51 PM

I've been learning some great driving techniques here to improve mpg, but I'm curious if there's potential to damage my auto transmission when shifting back in drive after EIC. Has anyone experienced transmission problems from repeated neutral - drive - neutral -drive shifting with the vehicle in constant motion?

Thanks,
Eric

Angmaar · 04-22-2011, 11:05 PM

No it should not cause an issue as long as you aren't shutting your car off. This is because some cars don't circulate the fluid in the transmission when it's off.

ermarccio · 04-23-2011, 09:51 AM

Good to know. The few times I've shifted back into drive have been pretty smooth, however, I usually shift back into drive at low speeds. I tried shifting back into drive once at about 45 mph (usually 4th gear) and the transmission was in 3rd gear. This made for an abrupt slowdown before the self induced up-shift and it didn't feel or sound very good to me.

Anyone else encounter a similar situation with Fords/Foci? P&G seems pretty impossible in this situation. It could be this was a fluke and next time it will work fine, but I'm hesitant now.

Christ · 04-23-2011, 01:43 PM

45 is a bit too high to worry about coasting, for the most part, especially if you're trying pulse and coast. I'd focus (lol) more on driving with load at those Speeds.

Thymeclock · 04-23-2011, 03:16 PM

Quote:

Originally Posted by ermarccio

Good to know. The few times I've shifted back into drive have been pretty smooth, however, I usually shift back into drive at low speeds. I tried shifting back into drive once at about 45 mph (usually 4th gear) and the transmission was in 3rd gear. This made for an abrupt slowdown before the self induced up-shift and it didn't feel or sound very good to me.

Anyone else encounter a similar situation with Fords/Foci? P&G seems pretty impossible in this situation. It could be this was a fluke and next time it will work fine, but I'm hesitant now.

I've warned about this before. On some transmissions you can get away with doing it, and on others you can't - but it's often impossible to tell which ones until you ruin it. Considering that a tranny rebuild is a very costly repair, it's not a risk I'm willing to take to save a few dollars on gas.

I suggest you go to at least one or several local transmission shops and ask them whether it's feasible. In other words, get some expert advice and tell us what they say about it. The fact that your transmission doesn't know what gear to go into is not unusual, as it wasn't meant to be re-engaged from neutral to drive while in motion.

Phantom · 04-26-2011, 06:47 PM

If you have the jerking issue what you should try is to slightly push the gas in so the engine rpm will be closer to the in gear speed at the change. That way only the torque converter has to catch up a little.

womprat · 04-26-2011, 09:19 PM

I rev match with my auto when shifting back into drive. Don't need to be too accurate as the torque converter absorbs a lot of shock. More critical if you've coasted down a steep hill and got up alot of speed.

Also I assume you are shifting into neutral when stopped, if you take your foot of brake before shifting into drive (you should) you'll feel the kick as first gear kicks in - ironically going neutral to drive in coasting shouldn't be any worse than this. Your tranny is built for a bit of driveline shock, nothing to worry about.

mcrews · 04-27-2011, 07:48 AM

My Q45 shifts in and uot of neutral at any speed with no problem, same for my car, a toyota avalon.
I have had the 02 Q45 since 2005 w/40k. It has 233,000 on it today and there have been no problems.
However, I had a ford taurus for about a month ( selling it for a friend) and it did not shift into neutral. It seem to stay engaged. I didn't explore the issue since I wasn't going to keep the car.

SoobieOut · 04-27-2011, 10:16 AM

I was also wondering about damaging my CV transmission. And if shutting off the engine during coast introduced more possibility of damage to the CV transmission.

HyperAccord · 08-18-2015, 03:44 PM

Curious to know people's thoughts on why we would shift out of drive after the car is max normal operating temp....almost all new cars or newer cars have automatic fuel shut off upon letting off the pedal. This must be something I'm not up to speed on, because I see this a lot around the site.

The SGII suggests the same thing. Why lose your steering or shift into neutral at all, again, AFTER the car is "room temp"? Seems like the 9th gen Accord-2.4L-CVT needs to be 150* and higher to 0GPH out on the gauge. Honda's instant mpg gauge says the same thing.

Does shutting the car off AFTER the car is room temp actually save gas on coasts?

In my 9th gen Accord, shifting into neutral from drive when the car is 175*, MPG's actually decrease. When coasting from a normal speed (say 35-55 or above), the 9th gen will 9out (instant mpg on SGII) or 0 out (GPH on SGII), all the way to roughly 10mph. What I like to do upon hitting 10mph is then shift into neutral or **** the car off and coast to my parking spot. Doing this in the 9th gen shows me 5-10mpg rolling increase (neutral after hitting 10mph) vs staying in Drive.