Automatics at traffic lights

TrickyWicky

Stooby2 wrote: »

My handbrake will happily hold the car in drive downhill. If yours doesn't it needs adjusting (or you need to workout some more and beef that left arm up )

Well we've had 4 autos and all but the latest I've noticed will move with the handbrake on when facing downhill in drive. The handbrake might *just* hold them still on a level road but not downhill. The latest we've only had for a week and used it twice so not really noticed.

RichardD1970

Walter_White wrote: »

If you're going to sit in a queue for a while then put it in park, otherwise somebody like me will eventually lose it one day and drag the brake pedal holding specimen out of their car and sort them out with a wheel brace. High level LED brake lights held on for minutes on end are as anti-social as having your for lights on and they do hurt your eyes.

Idiot.





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reeac

BeenThroughItAll wrote: »

Actually it's not *really* about engine size, is it?

The Americans, for example, are capable of achieving astonishingly small amounts of power from massive V8s, whereas the last 1.6L K-Series I rebuilt produced IRO 150BHP in a car weighing <600KG.

Yes, yes, but to use that max. power to get away from the lights you'd have to rev. the engine to 5000-6000 rpm. which would soon wear out your clutch. Torque is what gets you away from the lights and big V8s are good at that.

iolanthe07

reeac wrote: »

Yes, yes, but to use that max. power to get away from the lights you'd have to rev. the engine to 5000-6000 rpm. which would soon wear out your clutch. Torque is what gets you away from the lights and big V8s are good at that.

What's the point of racing away at lights? You only burn rubber and guzzle fuel.

Weird_Nev

Walter_White wrote: »

If you're going to sit in a queue for a while then put it in park...

Ignoring the unplesant nature of the rest of your post, no don't put it in park. Park physically locks the gears in the gearbox with pawls. If you take a shunt it could do severe damage to the auto gearbox as the wheels try and turn the locked box.

If anything, shift to neutral and put the handbrake on, like a manual.

C_Mababejive wrote: »

Previously thrashed to pieces on this forum. To digress...sitting idling for excessive lengths of time in turbo diesel vehicles,,allegedly bad for the turbo ..i.e overheats..

Err, no. Not within a stop at traffic lights, anyway. Despite which, if you have to wait, you have to wait. The engine is at idle in nutral, park or drive. Makes no odds.

BeenThroughItAll

reeac wrote: »

Yes, yes, but to use that max. power to get away from the lights you'd have to rev. the engine to 5000-6000 rpm. which would soon wear out your clutch. Torque is what gets you away from the lights and big V8s are good at that.

You clearly aren't aware that big torque is what really does the damage to a clutch. In any case, that's a massive assumption about revs - the engine I was talking about was mapped to produce maximum torque at 4400RPM as that nicely related to the gearbox ratios fitted to deliver best fast-road performance.


The fitted clutch has now done 35K miles and last time the engine was out 5K miles ago it wasn't showing significant wear - there's probably at least another 35K in it.


Also, let's not forget about mass here. Big V8s are often fitted to big, heavy cars. Doesn't matter how much power and torque you have if you're limited by the size and mass of the vehicle.


I can pretty much guarantee that in the TLGP, with the exception of things like the CLS63 AMG there's not many V8 powered cars going to dispatch the vehicle I was talking about.

missile

fannyadams wrote: »

AH!
that explains ALL the inconsiderate drivers who seem to sit at the lights with their brake lights on.
They MUST have automatics and HAVE to sit there with their foot on the brake and hence illuminating the entire front interior section of my car with their high level brake lights.
KNEW there was a reason.
Those Poor things... they have my sympathy..
Oh, and I'll STILL beat you off the lights in my manual car (into gear when other lights sequence through amber, handbrake off when we are at red & amber and I'm gone on green, I might even honk you if you're not quick enough! :rotfl:) and even quicker on my motorcycle!

You will have to go some to beat my SQ5 off the lights :j- how long does your clutch last?

reeac

BeenThroughItAll wrote: »

You clearly aren't aware that big torque is what really does the damage to a clutch. In any case, that's a massive assumption about revs - the engine I was talking about was mapped to produce maximum torque at 4400RPM as that nicely related to the gearbox ratios .

This has become somewhat muddled. The OP was talking about automatics and you then claimed that your manual g.b. 1.6 would be faster away from the lights, quoting its max. power [no mention of torque] as justification. Max. power comes [more or less] at max. revs. so I envisaged your traffic lights technique as being max. revs. and then engage clutch. When I introduced the concept of torque I was backing auto's [see also my earlier post re. the benefits of torque converters] so no clutch damage involved.

Gloomendoom

BeenThroughItAll wrote: »

I can pretty much guarantee that in the TLGP, with the exception of things like the CLS63 AMG there's not many V8 powered cars going to dispatch the vehicle I was talking about.

Which was?

BeenThroughItAll

Gloomendoom wrote: »

Which was?

A Caterham. Not mine sadly, but it's quite special, I just do the spannering.

Lots of carbon fibre, no windscreen, no heater, superlight wheels, Toyo R888s, dry sump, megasquirt, custom titanium headers, lightened flywheel, LSD, AP brakes, etc.