I read about this stuff all the time. Why don't people do the obvious, which is what I did once when the throttle cable got caught after the mechanic had done something incorrectly. You put it in neutral. No acceleration at all.
Ah, the DSG gearbox. This is effectively two manual gearboxes, one for the odd-numbered gears and one for the even-numbered ones, with twin clutches so one can be disengaged from the engine at the same moment that the other is engaged. When it engages one gear in one box, it pre-selects the next gear on the other box in anticipation that if you have just changed from 2-3 then you'll next want to change from 3-4; this is fine in most cases but if road conditions change and you have to go back to 2, then it can be wrong-footed and then it takes longer than normal to change gear.
This system is coupled with an auto-throttle which sets the engine rpm at the exact speed required for the new gear, based on the road speed and the new ratio, so you get a smooth gearchange. It can be driven either as fully-automatic (gearbox chooses when to change gear and then performs it) or automated manual (driver chooses when to change gear and gearbox system performs the gearchange and engine rpm adjustment).
I imagine that it doesn't have any of the fine-tune adjustment of a torque converter, so you don't have the "in exactly the right ratio" advantage, though I'm not sure how critical that is: is there a fairly sharp fall-off in efficiency if the engine isn't at exactly the right rpm,. or is there a fairly broad range of rpms that give (to all practical purposes) the same fuel efficiency? I'm not sure.
I think the DSG is slightly less efficient than a manual, simply because it is heavier and so the engine is having to lug around a slightly heavier car.
I don't think so. I nay be wrong but I think "all" (most?) cars have the handbrake on the rear wheels, irrespective of whether they are RWD or FWD. The normal advice for any wheel (front or back) is to loosen the wheel nuts slightly while the wheel is still on the ground (and therefore friction with the road stops it turning) and then jack up the wheel and remove the nuts and the wheel. I tried loosening the wheelnuts on the rear wheel of my FWD car with the handbrake applied and with the wheel raised, forgetting what I'd been told. I managed to make the wheel turn slightly despite the handbrake - and that was on a car that had just passed its MOT so it wasn't just a dodgy handbrake.
As regards the car rolling because the front wheels aren't braked, the fact that the other rear wheel is on the ground and the car is in gear will (should...) stop that happening. No harm in chocking the wheels just in case, though :-)
Some modern torque converter autos lock the TC after every gear change under light demand.
A TC isn't the most efficient of devices, but acts to smooth out gearchanges etc. So you pay a bit in MPG for refinement.
Well, there is the robotised synchromesh box. Effectively a manual with 'solenoids' doing the gear changing and a servo operated clutch. The most basic of those should be as efficient at transmitting the motion as a manual. However, the best of these now have twin layshafts and twin clutches, so I'd guess more friction.
Very true. I was tempted to do it, but something in my brain made me realise in that split second that it would be a Bad Idea. If the throttle is jammed wide open and you release all mechanical load on the engine by pressing the clutch and disengaging the gearbox, it will over-speed, greatly exceeding its redline, putting great stresses on the con rods. Not good news if one of those breaks...
Hence the need to bring the car to rest in gear (where the brakes provide mechanic load to slow down both the car *and* the engine) and either stall the engine that way or else turn off the ignition as long as there's no danger of locking the steering.
On the occasion that I experienced this, I was still learning to drive and my dad was supervising me. We jammed the throttle at a reasonable setting (so we could drive home at a realistic speed rather than a crawl) and Dad drove back, varying the speed slightly by making use of the slow-running adjustment that a choke provides. All went well until we were about to turn into the drive, when Dad instinctively pressed the accelerator as he was changing down (he'd managed to resist the instinct to do this for all gearchanges up to then) and the engine started racing again. He had to bring the car back under control in the remaining distance of the drive so we didn't go through the house wall :-) We made quite a spectacular entrance :-)
In message , "Dave Plowman (News)" writes
But driving is thought to become an automatic function. How else can you watch the road, listen to the radio and sat nav.?
For 5 days driving around West coast America, left foot on the floor was safer for all!
I can see the hand brake benefit: ignoring the annoyance of your brake lights on following queued drivers. However, BSM taught me to use the hand brake, so I do.
>
Most cars are, yes. It's just easier that way. Citroens with hydraulic suspension and (some?) Saabs are notable exceptions.
I am talking about using both feet on the brake pedal. I don't see the possibility of leaving the right foot on the throttle at the same time, you wouldn't do it in a manual car, so you wouldn't do it in an automatic.
The original SMG single clutch boxes were pretty clunky on a gear change when driving normally in auto mode. Where a decent conventional auto would be silky smooth. They were good at hammering through a change, though, when being a boy racer.
The twin layshaft/clutch DSG allows a very smooth change since there is no disengagement of drive on the change. Ie, the same as an epicyclic box.
In a manual or an auto, I only ever use low gear for braking on a very long descent, like the French Alps. Never needed it in the UK. Just as easy to select low gear in an auto as a manual, actually easier - no clutch needed, and just select 1st if you want, it'll take the lowest feasible option. I also did this once when I saw a pig behind me and wanted to slow down without using the brake lights. It worked.
I've driven autos made in 1988, 1998, and 1999, and all were brilliant.
And a satnav for the pigs.
This has already been discussed, do try to keep up.
This has already been discussed, do try to keep up.
I prefer to use the handbrake, it's easier, with a shorter overall movement than taking the shifter from D to P and back to D. Your car may differ.
Useless information if there are cars at both sides of the pump.
It was broken. I don't blame the pedestrians, your car was faulty.
To move up to a stationary object more carefully.
Bad by design.
Most don't, too awkward.
Most don't, too much farting around.
Nope.
Only the stupid jack up the both back wheels at once.
You expect me to read all 100 relies before replying to one of them?
You expect me to read all 100 relies before replying to one of them?
All cars I've had have the standard handbrake, more force required than an auto gearshifter, and further movement, especially to release when you have to push the button on the end.
Most people here are stupid enough to use only the nearest side to their filler cap. And most people seem to have them all on the same side.
It didn't seem to damage it doing it many times. The only "fault" was allowing me to do something odd. Nobody would do that by accident.
Interlocks requiring you to apply the footbrake before you can select drive are a relatively recent thing. My SD1 (1985) doesn't have one.
What purpose do they serve? Apart from stopping you from accidentally engaging reverse when driving at 70mph forwards. But the the little thing you press on the side of the lever stops that from happening by knocking it. Anyway, the lever is just a command to the computer, it's not a physical link to the gearbox, so no harm can occur.
If you don't want to look like a willy who can't read REPLIES, yes. Just keep up as the conversation progresses.
If you don't want to look like a willy who can't read, yes.
I don't think it's the owner's choice which side of the car the filler is on, that's the manufacturer?s, and here there seems to be no bias to one side or the other. And to pull the hose at my local filling station to the opposite side is possible, but not easy, with my car. For small cars and hatchbacks, no problem, for my estate car, it is awkward, as it has to go over the roof.
I think they are on the near side in the counntry of origin.
In article , Davey writes
In a manual you would instinctively move your right foot to the brake with your left foot following to the clutch fractionally afterwards.
Don't you understand the difference between P and N?
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