The Automatic Gearbox And Its Failings

[Clivey]

ORD said:

Classic PH - two people who own or have recently driven a car say it understeers at perfectly safe speeds; others come on and say they must have been driving really fast!

ORD said:

As the OP says, a current model 3 with the basic suspension will understeer at well below NSL on moderate bends (i.e. the kind of bends for which none of us would lift off, let alone brake).

We're not talking leave-the-road-trough-a-hedge understeer. It just fails slightly to hold its line as the fronts run wide by a foot or two. It's very noticeable if you are used to cars that corner more neutrally. Old 3s were a lot more neutral, in my experience.

Sadly, that does not bode well for the future for those of us that aren't typical PH goateed, powerfully built, Red Bull swigging company directors. I must say that increasingly, when I hear words like "progress", I take it to mean "dilution". Progress is not removing the temp. gauge or fitting stupidly tall gearing. Progress would be if I could buy a robot that would do the housework and be sent to work in my place (whilst allowing me to keep the salary of course ).

[lufbramatt]

jsp56 said:

Would you mind my asking if there are any really quite small cars with good automatic gear boxes in them? Something about the size of a KA?

Thanks!

Avoid anything with a single clutch robotised manual (eg Toyota Aygo). They are horrid. Did this recently for my mother in law after the horror that was the Aygo died, she ended up with a BMW Mini, more recent ones have a traditional automatic gearbox (early ones have a bork-prone CVT). Not many small cars around any more that don't either have a CVT (fine if you don't mind the "rubber band" effect as you accelerate and tend to last longer in light, small cars) or some sort of dual-clutch gearbox, like VW's DSG 'box in the Polo and Skoda Fabia. Expensive though.

Emissions legislation and getting the cars into lower tax brackets has all but killed off torque-converter based auto transmissions in the small car end of the market.

[E65Ross]

What's wrong with removing the temp gauge? Movable red line so you know when it's up to temp (and if you're into temps you'll get a good idea anyway) and sensors to tell you when it overheats. Can't see why you need a gauge. I've had my E65 for a while now without a temp gauge and it doesn't bother me at all. Not sure why it should really.

[jsp56]

Thanks for your helpful replies. May I ask if anyone has tried the current new corsa automatic to see if it is any good? I'd be using it mainly for stop-start city driving and almost all of our roads have a 20mph limit. We'd also have approx twice annual motorway trips about 40 minute each way.

Thanks!

Jsp

[Clivey]

E65Ross said:

What's wrong with removing the temp gauge? Movable red line so you know when it's up to temp (and if you're into temps you'll get a good idea anyway) and sensors to tell you when it overheats. Can't see why you need a gauge. I've had my E65 for a while now without a temp gauge and it doesn't bother me at all. Not sure why it should really.

I would want to know as soon as the temperature starts to climb above normal, not when it's already too late and further damage is being done. The movable redline is a good idea but (as with some cars that already have this) should be in addition to a regular gauge.

[E65Ross]

Clivey said:

I would want to know as soon as the temperature starts to climb above normal, not when it's already too late and further damage is being done. The movable redline is a good idea but (as with some cars that already have this) should be in addition to a regular gauge.

Well if you're that interested then you can have a digital temperature read out which gives the temperature in degrees Celsius.

You are aware that modern temp gauges are calibrated so that the midway point can be 75-110degrees so the period of time from "start to rise before its too late" is very, very short. By the time you'll notice it on the gauge, the warning from the obc will be going off already.

[Fox-]

E65Ross said:

Well if you're that interested then you can have a digital temperature read out which gives the temperature in degrees Celsius.

You are aware that modern temp gauges are calibrated so that the midway point can be 75-110degrees so the period of time from "start to rise before its too late" is very, very short. By the time you'll notice it on the gauge, the warning from the obc will be going off already.

I caught my E39 cooling system failure years ago simply from the fact that in traffic, the guage would creep ever so slightly. Not high enough to trigger the over-temp warning, but the fact it moved when it's a damped guage was enough to get me to check and find it was leaking.

I share the concern that such gauges are removed from cars.

[bennyboysvuk]

E65Ross said:

I reckon there's something amiss, if I could get the wheels to spin on an E46 330i with an automatic gearbox, no reason the more powerful and similarly-tyred E90 wouldn't.

I finally had the opportunity to test it this morning in the wet. On decent tarmac, it wouldn't spin up. However, on that really glossy, muck coated kind of tarmac it will briefly spin up, but then get traction again as soon as the auto hits 2nd. This is with the rear tyres at nearly 40psi.

E65Ross said:

Either way, this thread has gone way, way off topic. Basically, you've tried slating an automatic gearbox for somewhat daft reasons and one could very easily write a similar thread about manuals (as per my somewhat sarcastic post a while ago).

It went way O/T, but it was mildly interesting. I still hate the auto, but can better appreciate how it works for others and how to go about living with it now. i.e. treat it like an idiot and use manual mode as often as required.

[Welshbeef]

Turn TC off

[GroundEffect]

Clivey said:

E65Ross said:

What's wrong with removing the temp gauge? Movable red line so you know when it's up to temp (and if you're into temps you'll get a good idea anyway) and sensors to tell you when it overheats. Can't see why you need a gauge. I've had my E65 for a while now without a temp gauge and it doesn't bother me at all. Not sure why it should really.

I would want to know as soon as the temperature starts to climb above normal, not when it's already too late and further damage is being done. The movable redline is a good idea but (as with some cars that already have this) should be in addition to a regular gauge.

Modern calibrations derate the engine when they read high ECT. Usually around 110C they will start to reduce torque and if ECT doesn't balance out it will keep reducing torque until you basically can't pull away.

A proper coolant leak and overheat happens faster than a person could react. If you had a top hose come off the engine is gone regardless.

And as said, the dials in current cars are so heavily damped they don't tell you anything - amusingly (well, amusing for a Powertrain cooling engineer...) when I took my Integra Type R on track, the dial did not move from the normal motorway cruising temp, i.e. around 90C. The coolant was more likely at 105-110C. They don't tell you anything.

[redtwin]

Lack of a proper ECT gauge in my car (not even a damped one) is why I fitted an OBD gauge.

[redtwin]

va1o said:

jsp56 said:

Would you mind my asking if there are any really quite small cars with good automatic gear boxes in them? Something about the size of a KA?

Thanks!

Not really, most cars that size are better suite to a manual. Best bet would be stepping up to something like a Polo DSG or Fiesta Powershift

I had a hire Focus with a 2.0 petrol mated to a Powershift box and the thing was dire. I thought the car had a serious problem just trying to get off the hire car multistorey car park when I first got it. It was OK on the open road, but light throttle, slow speed driving had the the gearbox tying itself in knots.

The ECU couldn't make up it's mind which gear it wanted to be in or whether the clutch needed to be engaged or not, so just gave up and decided to impersonate a kangaroo rather than be an automobile.

[ORD]

redtwin said:

I had a hire Focus with a 2.0 petrol mated to a Powershift box and the thing was dire. I thought the car had a serious problem just trying to get off the hire car multistorey car park when I first got it. It was OK on the open road, but light throttle, slow speed driving had the the gearbox tying itself in knots.

The ECU couldn't make up it's mind which gear it wanted to be in or whether the clutch needed to be engaged or not, so just gave up and decided to impersonate a kangaroo rather than be an automobile.

In my experience, the modern fancy auto is not usually better than an old-school auto (although that may be because a lot is being asked of the transmission as regards flattering the engine and the driver). PDK and, to a lesser extent DCT, is an improvement, but I don't think the units in Fords and BMWs are anything like as good as suggested by journos. I would choose the manual every time (unless driving a diesel, in which case I would go auto but also choose a live hand grenade).

[Patrick Bateman]

Fox- said:

I caught my E39 cooling system failure years ago simply from the fact that in traffic, the guage would creep ever so slightly. Not high enough to trigger the over-temp warning, but the fact it moved when it's a damped guage was enough to get me to check and find it was leaking.

I share the concern that such gauges are removed from cars.

Likewise if the thermostat is shot, that's unlikely to be apparent without a gauge.

[lufbramatt]

Patrick Bateman said:

Fox- said:

I caught my E39 cooling system failure years ago simply from the fact that in traffic, the guage would creep ever so slightly. Not high enough to trigger the over-temp warning, but the fact it moved when it's a damped guage was enough to get me to check and find it was leaking.

I share the concern that such gauges are removed from cars.

Likewise if the thermostat is shot, that's unlikely to be apparent without a gauge.

Way off topic now but in most of the engines in a E39 the temperature varies from about 85 to 108 degrees anyway depending on load. The thermostat is controlled by the ECU to run the engine at a higher temp whilst cruising to lower emissions, but can lower it to increase power under heavy load. But the gauge always stays in the middle It's the running at such a high temp+pressure that leads to the weak cooling systems in these cars.

[E65Ross]

ORD said:

In my experience, the modern fancy auto is not usually better than an old-school auto (although that may be because a lot is being asked of the transmission as regards flattering the engine and the driver). PDK and, to a lesser extent DCT, is an improvement, but I don't think the units in Fords and BMWs are anything like as good as suggested by journos. I would choose the manual every time (unless driving a diesel, in which case I would go auto but also choose a live hand grenade).

Are you for real? The DCT box in the new M6 is every bit as smooth and good as an auto as the old 5 or 6 speed traditional autos. Only faster and more responsive. And more efficient. And they give you more control.

[FrankUnderwood]

ORD said:

redtwin said:

I had a hire Focus with a 2.0 petrol mated to a Powershift box and the thing was dire. I thought the car had a serious problem just trying to get off the hire car multistorey car park when I first got it. It was OK on the open road, but light throttle, slow speed driving had the the gearbox tying itself in knots.

The ECU couldn't make up it's mind which gear it wanted to be in or whether the clutch needed to be engaged or not, so just gave up and decided to impersonate a kangaroo rather than be an automobile.

In my experience, the modern fancy auto is not usually better than an old-school auto (although that may be because a lot is being asked of the transmission as regards flattering the engine and the driver). PDK and, to a lesser extent DCT, is an improvement, but I don't think the units in Fords and BMWs are anything like as good as suggested by journos. I would choose the manual every time (unless driving a diesel, in which case I would go auto but also choose a live hand grenade).

Sort of agree and largely disagree... Some cheap modern hatchbacks have had unbelievably bad autos, but the 8 speed in the RR sport is insanely good.

Even the current Seat Ibiza has dual clutch for an auto so on the whole they've come on a long way.

[redtwin]

That's because the RR has a conventional auto with a torque converter not an automated manual with a clutch controlled by an indecisive ECU.

A world of difference between the two.

[ORD]

E65Ross said:

Are you for real? The DCT box in the new M6 is every bit as smooth and good as an auto as the old 5 or 6 speed traditional autos. Only faster and more responsive. And more efficient. And they give you more control.

I've not driven the M6 so cant comment on that. I find the ZF's attempts to mimic a dual clutch box just make it neither one thing nor the other and a bit irritating to drive (except mated to a diesel engine, where it gets the most of the smoker, but that is mostly because of the number of ratios).

[E65Ross]

ORD said:

E65Ross said:

Are you for real? The DCT box in the new M6 is every bit as smooth and good as an auto as the old 5 or 6 speed traditional autos. Only faster and more responsive. And more efficient. And they give you more control.

I've not driven the M6 so cant comment on that. I find the ZF's attempts to mimic a dual clutch box just make it neither one thing nor the other and a bit irritating to drive (except mated to a diesel engine, where it gets the most of the smoker, but that is mostly because of the number of ratios).

You're the only person I've heard saying that you don't think the 8 speed box is any good in anything other than a diesel.