Driving styles - automatic v70

[jasmith44]

Originally Posted by Gazdkw

Well I’d like to know what that is as I tow quote alot

should have said FOR BEING TOWED

[Simon Jones]

Might be worth reading the owners manual so as to understand the correct use of the gearbox

[petey]

Hmmm, a couple of things here....

First off, NEVER tow an automatic transmission without the driven wheels on the road. So long as it’s out of park, the position of the gear-lever won’t make the slightest difference as the high pressure pump that engages gears via the valve body won’t be turning. And because the oil pump isn’t turning, the transmission lunrication isn’t active and your bands and clutches will quickly say goodnight without it. (most manual transmissions rely on splash lubrication, but an automatic gear cluster is orders of magnitude more complicated and has a lubrication system similar to an engine. Towing an automatic is analogous to running an engine without the oil pump running.) Neutral is there for the same it exists in a manual transmission (and also that the law requires a step between forward and reverse), that you can have the engine running without the car being driven should you ever need it. In practice you rarely do though.

Conceptually, quite apart from the needless wear on the transmission, shifting into neutral to coast will cost you fuel rather than save it. This is because the engine recognises that you are in a coast situation and no longer fuels the engine in the certain knowledge your coasting will keep it going. If in neutral, you have to provide fuel to the engine to keep it running.
The VW DSG box has a coast feature designed into it, but it only chooses this at very select times when it feels it would be beneficial. You do not have the same information as the ECU and are very unlikely to make that call correctly.

Brakes:- front discs are much more heavily loaded on an auto because if you say come flying down the off-slip from a motorway and descend to the lights at the exit roundabout only to get caught by them, you should use your handbrake to hold the car as constant pressure from the pads in one place on the discs causes a local hotspot which can lead to warping. I used to always stop short and then gently creep forward at barely perceptible speeds until the lights changed to avoid this.

In the Borg-Warner 65 days of my youth, the gear lever was connected to valve on the valve body and when you selected reverse, reverse was what you got. Nowadays, all shifts are controlled by a drive module ECU and reverse at 30 is considered an error state and is ignored. The gear lever is now a ‘request’ rather than a ‘command’. Park is usually a direct mechanical link, although that’s not the case increasingly these days. The parking pawl, where fitted, drops into a toothed wheel, but the wheel has rounded edges so that it’ll make a lot of noise at speeds over 5 mph or so, but won’t ever engage. I wouldn’t test this though.

I say where fitted, as on-manuals don’t HAVE to have a parking pawl/gear arrangement. Whilst the i3 does, Tesla instead have a simpler transmission and have a second brake calliper on the rear wheels. If you disconnect them, there’s no method to secure the vehicle when you leave it (ask me how I know)

[pookie]

Regarding coasting in neutral, back in the day some cars had a freewheel system fitted. Saab and Rover spring to mind. Very interesting to drive as with the freewheel engaged there was no engine braking whatsoever. These were fitted as a means of increasing fuel consumption.

Salut!

Pookie

[S60D5-185]

Originally Posted by pookie

Regarding coasting in neutral, back in the day some cars had a freewheel system fitted. Saab and Rover spring to mind. Very interesting to drive as with the freewheel engaged there was no engine braking whatsoever. These were fitted as a means of increasing fuel consumption.

Salut!

Pookie

Correct, in 1980 I had a Saab 95 Kombi with that feature and it worked superbly. How I wish that I still had it.

Mine was exactly like this one, even the colour.

[Gazdkw]

If I’m driving downhill and applying a very slight amount of braking the revs will drop to tick over revs. Does this mean my v70 is out of gear? If I was to apply some throttle it would then select appropriate gear and revs would increase?

As for the braking, so your saying it’s best practice to apply handbrake in D mode to keep temperarily stationary? Part of me thinks this is illogical because the car is trying to move forward and only my handbrake to stop it. Would the Park function be a better use?

[Simon Jones]

Originally Posted by pookie

These were fitted as a means of increasing fuel consumption.

Hopefully that should read 'reducing fuel consumption' or 'increasing fuel economy'

[ThomasG]

I think I read somewhere that my aisin Werner (v70 P2) has a freewheeling capability that is controlled by ETM(ETM/ECM/TEM.. just who came up with this?) I mean by gearbox controller.
This is to accommodate both coasting and engine braking, as needed

[ANDREW54]

Hi, I’ve always put the box into neutral when at lights, anticipation and patience means you don’t have to “ram” it into D when starting off. I’ve done 80,000 miles and not had any gearbox issues.

[john.wigley]

Originally Posted by ANDREW54

Hi, I’ve always put the box into neutral when at lights, anticipation and patience means you don’t have to “ram” it into D when starting off. I’ve done 80,000 miles and not had any gearbox issues.

If I anticipate remaining stationary for more than a few seconds, then so do I, 'ANDREW54'. At the very least, it avoids sitting there dazzling the car behind with one's brake lights at night! Similarly, I'll cancel the indicator if in use, switching it on again as the lights change in my favour.

Regards, John.