Coasting - Auto

[oragex]

Originally Posted by Tannaton

For me in normal driving when on the move you should not be touching the gear selector unless it is to move it sideways into manual mode. The risk of mis-shifting into reverse or Park and causing catastrophic damage (and potentially and accident) is not worth the potential minuscule benefit.

Happened once, I was in a mood while on the motorway remembering how was it driving with a shift stick (back in the days). All of a sudden my right hand (I'm in the US) that was resting on the lever knob, for some reason acted and moved the lever from D to R (I was at about 65mph). Nothing happened (except my heart stopped a little), shifted back in D and no problems. Can even find a similar video on Youtube. Not recommending trying this, but these transmissions seem to be smart enough to my liking

[Tannaton]

Originally Posted by oragex

I remember about a post on a forum, a Volvo owner who mentioned he used to wait at a traffic light with the transmission in N. He mentioned the transmission failed some time later on. Was it due to having it often times in N while the car was idling ? Who knows, but just to be safe I leave in always in D. Maybe in N with the engine idling there is not enough pressure to lubricate all bearings - but this is just a huge assumption of mine. Worth noticing that the transmission is not designed to stay in N with the engine running in any specific situation. The N is there only for some safety reason, so the R and D gears are not close to each other. Also remember the 'neutral stop shifting' problem with the 01-02 transmissions. I prefer to keep it safe when there is no clear answer.

As for 'engine breaking' with these automatic transmissions, in hilly areas I would just shift it in 4, 3 or even 2 if the car doesn't go too fast (but the 2nd gear seems a little 'rough' on these transmissions)

Volvo have modified the AW transmissions so that if you sit stationary, in "D" with your foot on the brake for more than 10 seconds or so the TCM will shift the transmission into "N" for you - this is called Neutral control. As soon as you lift off the brake it pops it back into first.

http://www.import-car.com/tech-tip-v...trol-function/

[Tannaton]

Originally Posted by oragex

Happened once, I was in a mood while on the motorway remembering how was it driving with a shift stick (back in the days). All of a sudden my right hand (I'm in the US) that was resting on the lever knob, for some reason acted and moved the lever from D to R (I was at about 65mph). Nothing happened (except my heart stopped a little), shifted back in D and no problems. Can even find a similar video on Youtube. Not recommending trying this, but these transmissions seem to be smart enough to my liking

I bet that was a huge relief.... I will take your word on that as I'm not going to try it myself...

[skippyfox]

Originally Posted by cchidzey

Thanks Skippyfox, it's the engine braking I'm trying to avoid. Big question is, is it detrimental to the actual gearbox?

Same background here, from heavy haulage to heavy recovery/wrecker work

Only just fallen on this post again after looking for something else, engine braking using the gear box if done right won't do any damage to the gear box. it's designed to take a lot of torque. Think how much grunt it takes to get 48 ton plus moving from a stand still, and you can always stamp on the exhaust brake and if fitted, flip the switch on the electronic retarder.

[BEJ]

Not sure about modern cars, but back in the day there was a section in the owners manual that said do not tow above 30mph or you could risk damaging the gearbox. It also recommended disconnecting the propshaft if towing for any distance.

[cchidzey]

Originally Posted by BEJ

Not sure about modern cars, but back in the day there was a section in the owners manual that said do not tow above 30mph or you could risk damaging the gearbox. It also recommended disconnecting the propshaft if towing for any distance.

Is that with the engine not running though, so no oil pump being driven?

[cchidzey]

Originally Posted by skippyfox

Only just fallen on this post again after looking for something else, engine braking using the gear box if done right won't do any damage to the gear box. it's designed to take a lot of torque. Think how much grunt it takes to get 48 ton plus moving from a stand still, and you can always stamp on the exhaust brake and if fitted, flip the switch on the electronic retarder.

Aye mate I get that, was wondering if it did any damage by coasting in neutral?
It's the engine braking I'm trying to avoid, want to knock it into neutral and coast further.

[BEJ]

Originally Posted by cchidzey

Is that with the engine not running though, so no oil pump being driven?

Probably engine running as no power braking if engine is off.