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Old 10th February 2005, 11:11   #16
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Well, even if you are on the first gear, in a high density traffic situation, you cannot just release the clutch and drive in the first gear as you still have to use the clutch because you may have to slowdown and that again may stall the engine if you dont use the clutch. Using the neutral may solve but that would result in a lot of gear changes..again it is a question of relative clutch wear..

Can anybody give a practical example as to how much fuel is used relatively in gears..like how much more does first gear use than second and second than third and on.

I think for a given acceleration( depressin the accelerator pedal same amount of fuel is released into the combustion chambers)

example..

if i drive 1 km in:
1) 1st gear, the vehicle may consume 150 ml of fuel
2) 2nd gear, the vehicle may consume 135 ml of fuel
3) 3rd gear, the vehicle may consume 125 ml of fuel
4) 4th Gear, the vehicle may cosume 110 ml of fuel
5)5th Gear,the vehicle may cosume 100 ml of fuel

The point i am trying to make is it depends upon the gear ratios which again are set relatively to each other based upon a lot of factors. Higher the gear say fourth, smaller is the actual gear which translates to longer distance traversed by the vehicle..I may be wrong guys as i havent revisited/understood clearly wht i learnt in my engineering days

Last edited by muni : 10th February 2005 at 11:13.
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Old 10th February 2005, 12:12   #17
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Quote:
Originally Posted by Deeps
So if you are in a stop-go traffic jam, what is more harmful for the drivetrain? Riding the clutch in 1st gear or shfting between neutral and 1st very often? manish has provided a different reasoning for not riding the clutch. But i think that even if u r riding the clutch rather than shifting into neutral, it is almost just as bad in case of getting rear-ended if the handbrake isn't pulled up.
Dude, Why don't you try it out?? Take your car in an open ground, Mark the current position of your vehicle, make sure no body is nearby, engage in the first gear, and remove the clutch all of a sudden. Note the vehicle behavior and distance your vehicle travels.. In all probability your vehicle will jump from its place and cover atleast a few yards.. Now imagine that happening to you when you are first car stopped at an intersection. or in heavy traffic jam.. In case of neutral, even if somebody hits you from behind, your vehicle will atleast have some resistance of its own since it is not in the gear..

Moreover as Rehaan mentioned, If you have your brakes clutch pressed and if you remove your leg from the clutch, your brake-pads are likely to get worn out more since there will be a constant engine power applied to your brakes. Besides if someone hits you, you are more than likely to remove your leg from the brakes as well..

Be careful, and shift to the neutral especially during the rains..

If there is a heavy traffic, i would recommend you to park your car somewhere and catch a bus or train from the nearest commuting station.. Heh Heh..
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Old 10th February 2005, 12:18   #18
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Quote:
Originally Posted by muni
The point i am trying to make is it depends upon the gear ratios which again are set relatively to each other based upon a lot of factors. Higher the gear say fourth, smaller is the actual gear which translates to longer distance traversed by the vehicle..I may be wrong guys as i havent revisited/understood clearly wht i learnt in my engineering days
Muni,

Although i am not a mechanical engineer, i can tell you that the distance you travel in your 5th gear is much more than what you travel in your 1st gear. So fuel consumption vis-a-vis gear position should also consider the gear-ratio as well.

e.g. imagine travelling 1 kilometer in the 1st gear for 150 ml and travelling 2.5 km in the 1st gear for 100 ml. So in effect, the fuel efficiency in the 1st gear is 1/150 Vs 2.5/100. I guess you can figure out which one is more.

I'll advise the right use of the clutch. The wear and tear of the clutch is not more important than preventing an accident and your life.

Manish.
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Old 10th February 2005, 12:42   #19
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Quote:
Originally Posted by man23ish
Moreover as Rehaan mentioned, If you have your brakes clutch pressed and if you remove your leg from the clutch, your brake-pads are likely to get worn out more since there will be a constant engine power applied to your brakes.
Hey Manish,

This isnt what i said

If the car is not moving there is virtually no wear happening to the brakepads no matter how much power is being applied!

Also, i cant quite figure what you have said to Muni.
Munis example was for a fixed distance of 1km in each of the 5 gears. And the basic layout he expected the results to follow (showing ml (milliliters) of fuel that would be used in each gear...)

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Old 10th February 2005, 14:08   #20
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Quote:
Originally Posted by Rehaan
If the car is not moving there is virtually no wear happening to the brakepads no matter how much power is being applied!
Rehaan, look at it this way, the car is not moving, and the first gear is engaged with brakes pressed fully. If someone tonks to the vehicle from the back, and if a person lifts his left foot from the clutch, the car will move due to the impact of the collission.. Under such a scenario, its likely that the brake-pads may get some wear and tear. Right??

Quote:
Originally Posted by Rehaan
Also, i cant quite figure what you have said to Muni.
Munis example was for a fixed distance of 1km in each of the 5 gears. And the basic layout he expected the results to follow (showing ml (milliliters) of fuel that would be used in each gear...)
Okay i must confess here that i didn't read the last part of Muni's message. Muni is quite right as far as F.E is concerned.
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Old 10th February 2005, 14:12   #21
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Red face

Also have you noticed the increase in RPM on your tacho, when you engage in the first gear, vis-a-vis when in neutral, without pressing on the gas. eh??

BTW, Rehaan, i just noticed that you are from providence. Is it providence in Rhode Island, USA or providence in UK?? I used to live in Warwick RI..
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Old 10th February 2005, 14:19   #22
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On a slightly different note, Assume you are driving a vehicle in the 4th or the 5th gear. Now say, When you approach a traffic light, you apply the brakes and press the clutch.

My question is if it is a good idea to shift all the way from 5-N-4-N-3-N-2-N gears or can you directly shift from the 4th to the Neutral gear and then take off the vehicle by shifting to 1-N-2. I normally shift from the 3rd or the 4th gear into the neutral and then start on the 1st gear. Is it a good practice??

Gear-Box experts!! your comments please..

Manish.
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Old 10th February 2005, 14:59   #23
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Quote:
Rehaan, look at it this way, the car is not moving, and the first gear is engaged with brakes pressed fully. If someone tonks to the vehicle from the back, and if a person lifts his left foot from the clutch, the car will move due to the impact of the collission.. Under such a scenario, its likely that the brake-pads may get some wear and tear. Right??
Makes no sense, if the brakes are presseed fully, the wheels will never turn (even when you come off the clutch). The only way that car can move is if the tyres start losing traction. In that case it's the tyres that will xperience frictional wear and tear, more than any other part in the car.

When the clutch is released at idling rpm with the brakes pressed, there is no way the car will move. If it does, then you better get your brakes checked.

Quote:
Also have you noticed the increase in RPM on your tacho, when you engage in the first gear, vis-a-vis when in neutral, without pressing on the gas. eh??
Yup, it sure does happen, but not everytime and not on all types of engines. This is usually found in MPFi cars where the onboard computer raises the idling rpm (e-specially during a cold start) to get it warmed up and prevent it from stalling.

Quote:
My question is if it is a good idea to shift all the way from 5-N-4-N-3-N-2-N gears or can you directly shift from the 4th to the Neutral gear and then take off the vehicle by shifting to 1-N-2. I normally shift from the 3rd or the 4th gear into the neutral and then start on the 1st gear. Is it a good practice??
This again depends on your gear ratios. If im doing 60kmph in 5th gear and need to brake in an emergecy shedding speed at a great rate, i wont need to down shift in order, i will shift to whatever gear suits the speed my car is doing at that point.

But again, this also depends on the driving environment. On a normal drive i might down shift from 5th to 4th if i am to slow down from 100kmph to 50kmph, but if i'm in a race, i'll have to shift into probably 2nd gear to get the best out of my car.

Shan2nu

Last edited by Shan2nu : 10th February 2005 at 15:01.
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Old 11th February 2005, 03:46   #24
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Quote:
Originally Posted by man23ish
look at it this way, the car is not moving, and the first gear is engaged with brakes pressed fully. If someone tonks to the vehicle from the back, and if a person lifts his left foot from the clutch, the car will move due to the impact of the collission.. Under such a scenario, its likely that the brake-pads may get some wear and tear. Right??
Man23ish,

I see your point in terms of the safety of shifting into neutral, no argurments with that.
As Shan2nu said, if the brakes are pressed "fully" then the car will not jump forward. However, chances are that most people do not press the brakes fully at a stop. They just apply enough braking force to keep the car in place, in which case dropping the clutch can result in the car jerking forward.

Yes! Providence RI -USA. What did you do in Warwick and how long did you live there?

RPM increasing when you have the clutch all the way pressed and simply shift the lever from N > 1st..... never heard of that, and it doesnt seem to happen in my car. Also, i dont think MT indian cars have any input to the ECU about which gear you are in (can anyone confirm?).

Quote:
My question is if it is a good idea to shift all the way from 5-N-4-N-3-N-2-N gears or can you directly shift from the 4th to the Neutral gear
Well the correct way to break is using engine breaking. Which means you would want to downshift a bit from 4th or 5th gear as opposed to going 4or5th to N.

If i was in 5th gear and had ample time to stop i would probably do a 5-3-2-(1)-N (1st= optional, as getting it into first might be more of a pain for your sycnros and clutch.... since we are being really picky about "wear&tear" here )

So to conclude, yes i ususally go down to atleast 2nd before stopping, even in short city drives.

Everything has a balance, this wears the clutch and sychos a bit more than just pressing the brakes in 3rd/4th, but saves the brake pads a bit.

Downshifting low would DEFINITELY be the choice if i was on a long highway trip or something however, as you do not want to overheat your brakes (which causes them to be less effective as they get hotter and hotter until complete brake fade)

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Old 11th February 2005, 12:53   #25
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Quote :

Well the correct way to break is using engine breaking.

Yeah, that's for sure :-). That way there would be no
further worries about wear & tear of clutch, tyres, brakepads
etc ... :-) :-) :-) . But I'd rather try it on someone else's car :-)
(no offense please).

(Hey, how do you use the nifty smilies in your posts ? )

Last edited by meerkat : 11th February 2005 at 12:57.
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Old 11th February 2005, 13:05   #26
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Well engine braking only works well when the revvs are slightly higher. At 100-1500 rpm you wont gain any help from the engine.

While braking normally, even i don't use engine braking. I only use it when i have to shed a lot of speed within a short time without stressing my brakes. Or when i have to descend a ghat section or slope, using your brakes for a long period of time can cause brake fade.

Shan2nu

Last edited by Shan2nu : 11th February 2005 at 14:58.
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Old 11th February 2005, 13:12   #27
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Quote:
Originally Posted by meerkat

Yeah, that's for sure :-). That way there would be no
further worries about wear & tear of clutch, tyres, brakepads
etc ... :-) :-) :-) . But I'd rather try it on someone else's car :-)
You mean to say you do not use engine breaking? Tell me you are kidding
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Old 11th February 2005, 14:14   #28
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Quote:
Originally Posted by Rehaan
Yes! Providence RI -USA. What did you do in Warwick and how long did you live there?
Yes, Warwick, near T.F.Green Airport RI USA. I used to work for GTECH. But returned back to India to settle down here man. I had a lot of fun with my Camry on the I-95..

What are you doing there??
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Old 11th February 2005, 15:01   #29
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Quote:
You mean to say you do not use engine breaking? Tell me you are kidding
Well technically, engine braking is not a "must". It's just a way, most people preffer to brake. There's nothing wrong in not doing it, provided you're ok with the brake wear and don't mind replacing them once every 20-25K kms.

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Old 11th February 2005, 16:10   #30
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Quote:
Originally Posted by Shan2nu
While braking normally, even i don't use engine braking. I only use it when i have to shed a lot of speed within a short time without stressing my brakes.
Quote:
Originally Posted by Shan2nu
On a normal drive i might down shift from 5th to 4th if i am to slow down from 100kmph to 50kmph, but if i'm in a race, i'll have to shift into probably 2nd gear to get the best out of my car.
Engine braking prevents the wear and tear of brake-pads and i think it is a good technique to have. But then engine braking needs a bit of skills, You can't shift from the 5th gear at 70-80 kmpl to the 2nd gear and take your legs of the accelerator. In all probability you'll lose your gear-box, and also maybe your engine valves.. Again depends on the speed at which you are travelling.. If i were travelling at 100+ kmpl i'd rather shift down to the 4th gear before shifting to the 3rd. But if at 60-70 kmpl i'd rather shift from the 5th to the 3rd directly.

I think shifting to the 3rd gear from the 4th or the 5th makes a lot more sense for slowing down the vehicle. And after the vehicle stabilizes in the 3rd gear go ahead and move to the 2nd gear right??

My question is whether engine braking is detrimental to your gear-box and the engine valves?? Of-course, i'd rather change my brake-pads every 20K kms rather than change the transmission and the engine valves.
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