The answer is "yes".

I agree unambiguously.

i do it all the time, have done it in every car i've owned, even the old 4 speed column shifts autos. if my '91 accord with 380k on it's original clutch could handle it, it can't do that much to the clutch.

as long as you aren't slamming it and shocking the drive train, it's not that bad, rev match even a bit, and it'll be smooth. if you're worried about the clutch-pack in the torque converter, change your valving. firming the shifts (shorter clutch cycles) will make for much less wear on your clutch packs.
the shocks that are associated with sudden gear changes will only risk damaging the componants if you are pushing excessive power.

downshifting to decelerate is actually covered on the theory exam to get your permit here. and the correct answer is yes, it is the proper thing to do.

i don't know if you ever noticed the normal operation of an automatic transmission, if you take your foot of the gas, and decelerate to a certain point, it will downshift by itself.

and it has been proven many times that it does in fact require less fuel while coasting in gear than while coasting in neutral (there is no fuel require to keep the engine turning, the vehicles' inertia takes care of that, hence why you slow down, compressing air in the cylinders with minimal addition of fuel.

diesel rigs use the technique all the time, though it is banned in a lot of towns 'cause of the noise factors.

if they aren't worried about transmission wear with those kinds of forces (yeah, i know, much bigger, stronger transmissions, but much more massive loads involved), and knowing how important reliability is for those guys, it can't be as bad as it's made out to be.

i'll continue to do it, and if i need new clutch packs i'll let you know.

As you said, it's a forum. A discussion forum. So expect discussion. If you want a simple, quick answer then call up a transmission specialist.

Yes, the torque that the clutches are attempting to transmit is dramatically lower when the car is slowing itself. It is because the negative torque that the wheels are driving back up through the drivetrain is much lower than the torque that the engine generates.

Let's talk specific hypothetical numbers. If your engine puts out 300Nm then the trans will see about 500Nm coming through at stall in first gear. The coast load would be around -30Nm.

A fair point given some component changes and an updated logic. However the basic architecture of the transmission will remain the same until they introduce their 7 speed.

Attachment 80434

Since I have to downshift to be in the right gear to merge out of an exit ramp, i tend to downshift before entering instead of braking.

If you really wanted to know the correct, factory endorsed answer, you might try reading the section of your manual that describes 'engine braking' for yourself. But hey, why do that when you can take advice from strangers on the Internet, and then criticize them for their responses?

:rolleyes:

You might also ask yourself why Infiniti designed the tranny with 'rev-matching' downshifts if they didn't intend the manumatic mode to be used in this fashion. The rev-matching is there to decrease the load or shock as the lower gear is engaged.

From the manual:

Done within reason, there is no harm in it. Considering this tranny is used in cars heavier and more powerful than the G, I can't see the additional wear (if any) being of that much consesquence.

Of course - anything taken to an extreme can cause extreme results, and there are exceptions to every rule.

Or look in your manual. :bowrofl:

I downshift to slow down a lot. I have a good clutch and a very light flywheel which helps to make rev matching easy.

ah, no one knows what there talking about anyway.. but if you leave it in the garage & don't drive it, it'll last longer too, I think it says that in the manual too :BOUNCE:

There wouldn't be any wear perse. At least not in the manner being discussed. Unless you were slipping the clutch quite a bit.

Harmful to the tranny? Not really, but it will generate more heat and the killer of all autos is heat. The answer is downshifting to slow down will raise transmission fluid temps, but not to an alarming rates. You will also put more stress on the clutches, etc., but nothing substanial unless you're in the habit of going from 5th to 2nd at 50mph to slow down. In the end, you're probably going to need to replace the tranny fluid a little more often and you'll suck a little bit more life out of the tranny internals. That's about it. Like others have said, you won't use any additional fuel.

Now, my question is why do you want to this? There's really no purpose to it unless you're coming up to a turn and want the most control possible. I downshift on occasion to do this. But coming to a stop or as a method of slowing down, what's the point? IMO, just use the brakes. Even in my manual cars, I never used the tranny to slow down the car except when coming down from an excessive speed or going down a steep grade. Plus downshifting with a manual to slow the car is a bit more stressful to the tranny than an auto.

I downshift through school zones to help keep the idle from making me go too fast.