Driving styles - automatic v70

[cjard]

Originally Posted by petey

First off, NEVER tow an automatic transmission without the driven wheels on the road.

This is the opposite of what I think you intended. I think you meant to say "Never tow an auto WITH the driven wheels on the road". If your auto Volvo is front wheel drive, it's fine to put the front wheels on a towing dolly so they're off the road, and drag it do the non driven rear wheels are rolling along the road. Indeed, this is how it should be done, if towing an auto any appreciable distance. The owners manual will probably state how far an auto may be towed without disconnecting the driveshafts or putting the driven wheels on a dolly. If in doubt assume 0 miles, or call the AA and let them decide how to tow you so they don't end up liable for wrecking your box

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.

This is doesn't make sense/is confused/contradicts the sentences you write afterwards.

In a coasting situation (disconnecting the engine from the wheels via clutch/neutral gear in a manual or putting auto gearbox in neutral, and then rolling along) the engine keeps using fuel because the ECU ensures it stays running at its tickover rpm. In an overrun situation (keeping the gearbox in gear, not pressing a clutch pedal down) if you let off the throttle so that the car's momentum, turning the wheels, is pushing the engine faster than the throttle wants it to go, then the ECU will cut fuel delivery to the engine for maximum engine braking and maximum fuel saving

[john.wigley]

I think the notion of 'coasting' to save fuel had it's origins in the days when engines were carburettor fed, before computers assumed responsibility for engine management.

My father used to do this in his Ford Popular and encouraged me to when it was safe to do so. Then again, he'd just come through the immediate post-war period when petrol was in very short supply.

Reference to 'freewheels' reminds me of the Wartburg that I owned briefly back in the '70s. That was there more in the interests of engine preservation rather than fuel economy. The engine, a 3 cylinder petroil lubricated 2-stroke, could potentially be starved of oil on a long downhill grade when on the overrun, with the attendant risk of seizure. The device, which also facilitated 'clutchless' changes, could be locked out to provide engine braking in mountainous regions.

But those days are long gone!

Regards, John.

[ANDREW54]

Originally Posted by john.wigley

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.

Good idea re indicator, never thought of that, it will be adopted.
Thanks John.

Regards, Andrew

[ThomasG]

And my opinion is somewhat different about that indicator..
But then, I spend quite a bit of my time in London's traffic.
Nothing (not even BMW drivers) more annoying than stopping behind a car, without indicator on, at a junction, only to find out that HE IS actually turning, and begins to indicate when yellow light kicks in..
Result? Stuck behind..

[ThomasG]

OK, OK.. It may look different in suburban areas..
But in the middle of rush hour down here I do get proper mad at times..

[petey]

Ah, ok, so I wrote at silly o’clock in the morning...

Towed automatics must have their wheels off the ground. As do HGVs; you’ll notice that they either disconnect the prop or pull the half shafts out of the hub as large transmissions are also lubricated by pump rather than splash.

Re coasting, my text was muddled, but the point was correct; when you coast in D, the ECU recognises that fact and doesn’t fuel the engine. When you coast in N, if has to fuel the engine. Therefore coasting in D is more fuel efficient, which is perhaps counter intuitive, but accurate nonetheless.
The systems used by Saab et al were nice and all that, right up until your brakes got hot and then they were less appealing. You’re right re the two stroke lunrication concern too. There’s a reason we don’t have those exact systems now.... in short, leave it to the computer, it knows what’s going on. Most of the time.

Re using N or P at temporary stops isn’t actually a good idea. Wear on an auto only really happens when a clutch or a brake band engages. The more times a clutch engages, the more wear on the friction material inside and it seems silly to burden the transmission with more changes than it needs.
It’s also counter to the point of an auto, where you shouldn’t have to do anything but go and stop.
In the scenario I referred to, taking the car out of D won’t actually help your brakes unless you also use the parking brake and come off the service brake (assuming the off-slip is on a hill). It is true that you treat the car behind to lots of brake lights, and whilst that’s a thoughtful consideration, beware of giving mixed messages, especially with indicators. Imagine you signal left and then cancel it; how can the driver behind determine the difference between you saving his retinas and changing your mind? Signal clearly in good time and limit the changes where possible.

P

[Gazdkw]

So what your saying is, it’s best to keep in drive all the times and use the service brakes to stop, wait etc??

What would you do if you know your going to be stopped for say 5 mins? The usual situation when the little one wants a **** at Asda or the missis wants to check every door Is locked in the house 5 times before leaving. I hate turning the engine off and on. Best to sit with the foot on the brake or put it in Park?

[petey]

If you’re going to be waiting for 5 minutes, then you’re not going to be able to creep forward for that long, of course you’d be wiser in P because that would be considered parked. But you don’t need to use P for traffic lights, slow approaches to roundabouts, that kind of thing.



(I once told my children that my wife was on “Britain’s Got Talent” as a flapper:- I would drive my car into the stage, and then shout ‘Susan, come on, hurry up’ and she would then run around the stage house, checking windows, writing 16 page missives to whomever fed out cat, washing up, changing bedsheets, choosing wallpaper etc. My children firmly believed we got to the semi final, and only failed to progress to the final because there’s a half hour time limit on all performances.)

[jasmith44]

When I am waiting at traffic lights I nearly always hold it on the handbrake,i suppose it helps to keep the handbrake useable and free.

[skippyfox]

Originally Posted by Gazdkw

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

I'ts for when you are being towed.