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Old 11th July 2015, 08:41   #166
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IMHO Your dad is almost correct phamilyman. You do not need to go into neutral till engine rpm fall low to cause stall.
Downshifting equals wear on engine and transmission. This sort of braking is good only if you were anticipating quick acceleration out or were at high speed approaching a curve and want to continue at max control.

Last edited by sudev : 11th July 2015 at 08:46.
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Old 13th July 2015, 00:23   #167
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

I am in doubt whether to post this here or in How to Use Clutch, Gear, and Brakes thread.

The Owner's Manual of Elite i20 recommends not to downshift more than one gear at a time.
Does it apply even if the Rpm Resulting after Downshifting is less than 2000 rpm or so? I can understand the resulting rpm should not be in the red zone. But other than this am I missing something?

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Old 13th July 2015, 00:27   #168
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Quote:
Originally Posted by IndigoXLGrandDi View Post
I am in doubt whether to post this here or in How to Use Clutch, Gear, and Brakes thread.

The Owner's Manual of Elite i20 recommends not to downshift more than one gear at a time.
Does it apply even if the Rpm Resulting after Downshifting is less than 2000 rpm or so?
You can downshift but only thing you have to be careful us the RPM blip after the shift shouldn't be too high. The downshift should give you engine braking but too much of it. As you said resultant RPM if below 2000 then I see no harm.

Under sudden deceleration or emergency situation, one does skip a gear to be on the safe side.
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Old 13th July 2015, 00:34   #169
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

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Originally Posted by IndigoXLGrandDi View Post
The Owner's Manual of Elite i20 recommends not to downshift more than one gear at a time.
The i20 Elite has been programmed for idiots. It tells the driver when to shift up and down with an indicator on the instrument panel, but unfortunately it is in no position to read the driver's mind. My gear shift pattern on an Elite has been frequently at loggerheads with what the car suggests.

For all you know, downshifting 2 (or 3) cogs at a time might leave the ECU stressed out and developing hypertension! Nah, just joking.
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Old 21st July 2015, 14:34   #170
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

Question to the experts:

Is it better to run at lower rpm, higher gear (say 1700 at 4th gear)

or higher rpm, lower gear (2200 at 3rd)

...in each case within the 'safe zone' (1500-2500), for a petrol engine.Which is more stressful [to the car]?

Sometimes I am caught in traffic that moves at an awkward speed and wonder if there is any alternative to constantly upshifting and downshifting.
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Old 21st July 2015, 14:51   #171
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

Quote:
Originally Posted by Kumar R View Post
Question to the experts:

Is it better to run at lower rpm, higher gear (say 1700 at 4th gear)

or higher rpm, lower gear (2200 at 3rd)

...in each case within the 'safe zone' (1500-2500), for a petrol engine.Which is more stressful [to the car]?

Sometimes I am caught in traffic that moves at an awkward speed and wonder if there is any alternative to constantly upshifting and downshifting.
Depends on many things, one being your definition of what you mean by stressfull. You mean wear and tear? It's not the same as putting stress on the engine (parts) and they don't necessarily corelated easily either.

As a very generic/theoretical rule of thumb, especially petrol engine tend to have less wear at higher RPMs. Better dynamicly balanced, better lubrication between pistons/cilinder wall, better lubraction in the main bearings, lower stress on pistion rods, bearings etc.

Just to add, from a wear and tear point of view, engines rarely run at their optimum at maximum torque. If anything, during most of an engine life it only produces maximum torgue at very short durations of time.

But it really depends on the engine design. And a car engine design is such that it will work flawlessly for many thousands of kilometers under a huge variety of different loads and RPMs.

In reality it probably doesn't matter at all, as long as you dont redline it, other then it will affect the fuel usage / mileage

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Old 11th August 2015, 11:38   #172
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

I don't know whether this is the right forum for discussion on this topic but I had to refill the power steering oil in my Contessa Classic. I asked by friend who owns a auto workshop and he suggested to buy HP ATF (Auto Transmission Fluid). He says PS oil and ATF oil are one and the same!!
Is that true?
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Old 11th August 2015, 19:01   #173
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Originally Posted by KkVaidya View Post
I don't know whether this is the right forum for discussion on this topic but I had to refill the power steering oil in my Contessa Classic. I asked by friend who owns a auto workshop and he suggested to buy HP ATF (Auto Transmission Fluid). He says PS oil and ATF oil are one and the same!!
Is that true?

No they are definitely not. They can be the same to some extend, but you really need to adhere to the specification for each separately. The are both hydraulic fluids, but there can be huge difference in specification, additives, viscosity etc. etc.
Typically the AT of high powered cars such as my Jaguar require very special fluids with very specific specification. You pour some DOT4 PS fluid in it, you are looking at a very expensive overhaul very quickly indeed.

I would think putting ATF in your power steering is less likely to do damage then the other way round though. Why risk it though?

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Old 30th August 2015, 23:04   #174
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

One of the steps which hurts your car and fuel bills is the traffic signal racing. There are plenty of drivers who consider themselves as souls of Michael Schumacher at pole position waiting for lights to go off. It is pointless red lining the engine at traffic lights when you know you have got another red light waiting for you barely 100 meters away. First you overburden your car in rapid acceleration and them jam the brakes hard to make the timely stop at next signal. You overheat your engine, gearbox, tires and brakes.
Once a while its fun but useless in maze of traffic signals.
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Old 31st August 2015, 07:59   #175
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@MSC...one in a while doing this helps in cleaning EGR valve and keep car breathing better. But agree with you. This coupled with coasting to stop for next red light also preserves brakes.
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Old 31st August 2015, 09:22   #176
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

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Originally Posted by MSC View Post
First you overburden your car in rapid acceleration and them jam the brakes hard to make the timely stop at next signal. You overheat your engine, gearbox, tires and brakes.
Once a while its fun but useless in maze of traffic signals.
[quote=sudev;3790962. This coupled with coasting to stop for next red light also preserves brakes.[/quote]

Enjoying a car and its performance does mean driving it with little consideration for wear and tear. I wouldn't worry about overheating the engine at all, or the gearbox for that matter. It does put some additional wear and tear on tires and brakes, but that's a small price to pay for having a bit of fun as far as I'm concerned.

Each to its own. My next door neighbour gets his enjoyment from his car by trying to get the maximum fuel efficiency. I'm more the opposite, I can honestly say that I rarely, if ever, get anywhere near the advertised fuel efficiency numbers for any of my cars. Pedal to the metal, that's what I enjoy most!

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Old 2nd September 2015, 11:14   #177
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

Can anyone share the caster and camber angle data for Contessa Classic. I have the workshop manual but that only details the engine.
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Old 17th February 2017, 09:56   #178
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

I was just going through the instructions for starting a car when I observed that certain manufactures insist on pressing the clutch pedal while cranking the engine. This, i believe, is to reduce the drag on transmission gears but I am not sure on how helpful it is.
Also while driving the new Tata Tiago, i noticed that without pressing on the clutch, the engine does not start. Is it that necessary?
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Old 17th February 2017, 11:16   #179
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

Quote:
Originally Posted by KkVaidya View Post
certain manufactures insist on pressing the clutch pedal while cranking the engine. This, i believe, is to reduce the drag on transmission gears but I am not sure on how helpful it is.
Also while driving the new Tata Tiago, i noticed that without pressing on the clutch, the engine does not start. Is it that necessary?
I've heard this explained as a safety feature - wherein by allowing a car to start without depressing the clutch, if the car is mistakenly kept in gear, it can jump forward unexpectedly (which could result in bumping the car ahead, or nosing into traffic, etc.).

So, manufacturers put in a bit of circuitry to detect if the clutch is pressed before triggering the starter relay.

There isn't much added drag when starting a car in neutral without pressing the clutch, compared to pressing the clutch. In cars that are marginal (weak battery, failing starter motor) it might make a difference, but in reasonably maintained cars it wouldn't matter much. I'm not sure if extremely cold climates (like Kashmir, and north of the Tropic of Cancer) might make a difference.

Out of habit, I start the car with the clutch pressed and the gearbox in neutral. The next part might seem odd (I'm not sure it makes a difference), but once started, I let go of the clutch and let the car run in neutral while I settle down, buckle up, etc., in the hope that running the input shaft of the gearbox gets the oil moving a bit in the gearbox. Once I'm ready to go, I slot the car into gear and drive away.

Last edited by arunphilip : 17th February 2017 at 11:28.
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Old 17th February 2017, 17:58   #180
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Default Re: ARTICLE: Mechanical Empathy | Preserving the Car While Driving

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Originally Posted by arunphilip View Post
Out of habit, I start the car with the clutch pressed and the gearbox in neutral. The next part might seem odd (I'm not sure it makes a difference), but once started, I let go of the clutch and let the car run in neutral while I settle down, buckle up, etc., in the hope that running the input shaft of the gearbox gets the oil moving a bit in the gearbox. Once I'm ready to go, I slot the car into gear and drive away.
I do exactly the same thing I also release the handbrake only after I am ready to roll (even with an auto transmission car). So even if in stick shift the transmission was engaged and the clutch pedal not pressed the handbrake would save the day.

And yeah, this decades old habit of mine has saved me from embarrassing outcomes several times because many people including friends (on those very rare occasion I trust them to drive my car ), technicians at the service centre etc have the irritating habit of leaving the car in gear to prevent it from moving forward or backward inadvertently.
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