Team-BHP > Technical Stuff


Reply
  Search this Thread
45,367 views
Old 24th July 2008, 10:27   #1
Senior - BHPian
 
Join Date: Jul 2006
Location: Bombay
Posts: 1,430
Thanked: 2,339 Times
Changing gears without using the clutch

Hey guys,

Yesterday, was reading one of the supplements with the Hindustan Times, and saw this article on how to prolong your clutch life. The article said that you could change gears without using the clutch in order to prolong clutch life. Caveat was that you should know how to do so, but there were no instructions on how to do so.

I used to think that pressing the clutch was essential to be able to change gears, since that was the only way of disengaging the engine from the driveshaft, and then you could change the gear. I guess I was wrong.

Anyways, am curious to know how does one change gears without using the clutch? How does it work and are there any issues that might arise as a result of this?

Thanks!
Lalvaz is offline  
Old 24th July 2008, 10:36   #2
Senior - BHPian
 
Join Date: Dec 2006
Location: pune
Posts: 2,392
Thanked: 2,681 Times

Don't believe in non-usage of clutch while changing gears to prolong clutch life, but I could be wrong.

Not sure about technicalities involved in this, but this is similar to the saying 'Most secure computer/system is the one which is not connected to any other computer/Internet'.
sukiwa is offline  
Old 24th July 2008, 10:39   #3
Senior - BHPian
 
Join Date: May 2007
Location: Bangalore
Posts: 3,803
Thanked: 463 Times

You can , ppl used to before the syncromesh was invented. I dont know exactly how its done but I guess you will have to listen to the engine and match the speed with the vehicle before changing.

Its probably an art to listen and then change the gears without the clutch but can do a lot of damage in todays setup, if not done properly.
dadu is offline  
Old 24th July 2008, 10:52   #4
Distinguished - BHPian
 
Thad E Ginathom's Avatar
 
Join Date: Jun 2007
Location: Chennai
Posts: 11,271
Thanked: 28,725 Times

We have talked about this one before.

Suggesting it to prolong clutch life is utter nonsense. There are many drivers who have never had to replace a clutch; it depends on good usage.

It is not changing gear that wears your clutch out: it is slipping the clutch, holding the car on the clutch on an incline --- stuff where friction is happening between the clutch plates for more than a few moments. Even resting the foot on the pedal.

The combination of syncro-mesh and clutch means we don't have to be too fussy about engine speed when changing gear, although, of course major mistakes lead to uncomfortable jerks and stress on the poor car. Equalise the speed of the two gear cogs that are coming together by getting the engine speed right and --- no clutch needed!

Certainly it can be done. I don't claim to be able to, but I have seen it.

Engine speed is what it is all about. This was a Thad's-Dad trick; driving, even on hilly, winding roads, without using the clutch --- but he only did it as an occasional show-off trick. I'm sure that if it had any financial benefit, he would have done it more often!

Probably many of actually come close much of the time. Consider that the text-book method is to fully disengage the clutch, pressing the pedal to the floor, while changing gear. The realise that what we actually do, many times, is just a quick dab on the pedal as we change.

In my opinion, the guy who wrote this has shares in a gearbox company. If people take it as serious day-to-day advise, many cogs are going to be damaged as people try it. I guess most people, after the initial graunching noise just won't ever try again, and will spend the rest of their lives stating that it is impossible.

As general advice, it is stupid and irresponsible. Gear boxes are a lot more expensive than clutch plates!

<cross-posted> Dadu, yes you are partly right. The clutch was used in the days before syncromesh. When changing down it was necessary to "double de-clutch". This involves de-clutching, changing to neutral, taking foot off clutch, reving engine to speed up the cogs on the engine side of the box, pressing the clutch again and engaging the lower gear. Have to say that I tried this only once, and it is harder than it sounds! But only a real non-syncro gearbox would test you out: a syncromesh gearbox would absorb the mistakes.

I suspect there may be stuff llike old trucks on our roads that still don't have syncromesh?

Last edited by Thad E Ginathom : 24th July 2008 at 10:59. Reason: added comment to Dadu
Thad E Ginathom is offline   (1) Thanks
Old 24th July 2008, 11:06   #5
Distinguished - BHPian
 
androdev's Avatar
 
Join Date: May 2007
Location: bangalore
Posts: 3,212
Thanked: 24,432 Times

it is like catching a fast cricket ball with your teeth. one can do this in theory, by making the relative speed = 0, and then decelerating to rest slowly. any small mistake can hurt real bad.

btw, it is safe to get the car out of gear to neutral without using the clutch but engaging into gear is risky. just apply gentle pressure on the gear knob to slot into neutral (but not enough to actually slot into neutral) and hold it under this pressure and let go off the accelerator. as the car begins to slow down, at some point the RPM match happens and the stress on the tranny will be zero, then it will slot into neutral without clutch.
androdev is online now  
Old 24th July 2008, 11:16   #6
Senior - BHPian
 
ashthedivx's Avatar
 
Join Date: Feb 2007
Location: Delhi
Posts: 1,357
Thanked: 24 Times

Quote:
Originally Posted by Thad E Ginathom View Post
It is not changing gear that wears your clutch out: it is slipping the clutch, holding the car on the clutch on an incline --- stuff where friction is happening between the clutch plates for more than a few moments. Even resting the foot on the pedal.
Oh god... I have been holding clutch on inclines and straight lines to get better fuel economy, so as i'll not need to revv my engine and car flows in usual speed and once pickup is required i can release clutch and come back to previous gear easily. Didn't knew that it will wear clutch faster then normal circumstances.

But, I am still confused how come clutch will wear fastly when practically we ain't using the clutch. Can you clarify the doubt ???
ashthedivx is offline  
Old 24th July 2008, 11:21   #7
BANNED
 
Join Date: Jun 2007
Location: Bengalooru
Posts: 1,480
Thanked: 17 Times

Is this same as Heel n Toe, which is discussed to death here?
diabloo is offline  
Old 24th July 2008, 11:24   #8
BHPian
 
watashi75's Avatar
 
Join Date: Jan 2008
Location: Hyderabad
Posts: 518
Thanked: 13 Times

This technique is called speed shifting and is sometimes used in car racing to shift without using the clutch. There is some information here on this and other such advanced techniques -

http://www.team-bhp.com/forum/collec...e-driving.html

However contrary to popular belief there is no significant gain in time and there is a greater risk of damaging your gears.

I am not sure if this technique can be used for both downshifting as well as upshifting. Can somebody calrify?

Last edited by watashi75 : 24th July 2008 at 11:27.
watashi75 is offline  
Old 24th July 2008, 11:26   #9
BHPian
 
Mr.Bangalore's Avatar
 
Join Date: Jul 2006
Location: Bengalooru
Posts: 369
Thanked: 56 Times

well i have tried changing the gears without clutch in my bike, but never tried it on Car. One financial benefit is that FE increases defently if you dont use clutch and dont know about the clutch life though.
Mr.Bangalore is offline  
Old 24th July 2008, 11:27   #10
Senior - BHPian
 
supremeBaleno's Avatar
 
Join Date: Dec 2005
Location: Chennai / Kochi
Posts: 5,666
Thanked: 2,860 Times

Not tried it with cars (and don't really plan to), but many a time with my bike and yes possible to do it by listening to the engine. This was not to prolong clutch life or anything, but just for the heck of it. Curiousity factor being the introduction of the geared, clutchless bike Street by HeroHonda many years ago.
supremeBaleno is online now  
Old 24th July 2008, 11:55   #11
Distinguished - BHPian
 
Thad E Ginathom's Avatar
 
Join Date: Jun 2007
Location: Chennai
Posts: 11,271
Thanked: 28,725 Times

Quote:
Originally Posted by watashi75 View Post
I am not sure if this technique can be used for both downshifting as well as upshifting. Can somebody calrify?
Yes, it can. You have to increase engine speed to match geerbox.

Quote:
Originally Posted by ashthedivx View Post
Oh god... I have been holding clutch on inclines and straight lines to get better fuel economy, so as i'll not need to revv my engine and car flows in usual speed and once pickup is required i can release clutch and come back to previous gear easily. Didn't knew that it will wear clutch faster then normal circumstances.

But, I am still confused how come clutch will wear fastly when practically we ain't using the clutch. Can you clarify the doubt ???
Any situation in which the clutch is neither fully engaged nor fully disengaged will lead to wear, as there is friction between the plates if they are not totally locked together and thus rotating at the same speed.

On an incline the car should be held on the brake until ready to move.

In real life, I find city driving impossible without some clutch slipping in traffic queues (just releasing the clutch a little to edge the car forward when it would be travelling too fast in 1st with the clutch engaged) and for brief stops on inclines, like at a junction. I don't, however, drive with my foot resting on the clutch, ever --- so not all bad!
Thad E Ginathom is offline  
Old 24th July 2008, 12:11   #12
Distinguished - BHPian
 
sudev's Avatar
 
Join Date: Jan 2008
Location: Gurgaon
Posts: 3,857
Thanked: 3,232 Times

Done that and can be done shifting up or down. But not with purpose of saving clutch. Come on cost of clutch is much less than a "kaput" gaer box at worst or even " worn out synchro-gear rings.

In theory the two gears inside your gear box have to be at same revs to slot in (further helped by synchro rings) The driving gear is rotating as per engine rpm's and the driven gear (while not slotted) is rotating with wheel rpm's. If you can get both at same rpm's you can slot in the gears to lock with each other. When you press the clutch this is what is happening. The engine side gear is free wheeling because of clutch and can easily slot with driven gear.

First to do a change to neutral you need to practice slight easing off accelerator and pushing the gear to neutral. This is easy part.

Second do get in to the next gear (say second to third) just wait a second in neutral and then push the lever towards third - all the while keeping off accelerator. As soon as gear revs match the gear will slot in to place.

Problem is doing in other direction (third to second) where you need to pump accelerator to rev up the engine and then let it slow down enough so that again revs on both side match up and gear slots in.

Have driven in emergencies on plains and even in hill but it is something to be done with extreme caution and only if you have practise.

BUT again this is no way to save the clutch and if that is the intention then you may save the clutch only to land up with much bigger bill of gear box.
sudev is online now  
Old 24th July 2008, 12:31   #13
Senior - BHPian
 
alpha1's Avatar
 
Join Date: Apr 2007
Location: LandOfNoWinters
Posts: 2,161
Thanked: 2,880 Times

I used to do that on my bike whenever the clutch wire broke.

But would not advise anyone doing it - of course if you wanna screw your gear cogs - then proceed by all means.
alpha1 is offline  
Old 24th July 2008, 12:35   #14
Team-BHP Support
 
Rehaan's Avatar
 
Join Date: Feb 2004
Location: Bombay
Posts: 24,329
Thanked: 35,586 Times

Quote:
Originally Posted by androdev View Post
...by making the relative speed = 0 ....
Exactly!

Quote:
Originally Posted by ashthedivx View Post
Oh god... I have been holding clutch on inclines and straight lines to get better fuel economy, so as i'll not need to revv my engine and car flows in usual speed and once pickup is required i can release clutch and come back to previous gear easily....
Bad for many reasons.
See this post, you will find your answers :http://www.team-bhp.com/forum/techni...tml#post226145

Quote:
Originally Posted by supremeBaleno View Post
...Curiousity factor being the introduction of the geared, clutchless bike Street by HeroHonda many years ago.
...though that really doesnt work in the same way. However, some new electronic-manual transmissions found in sports cars do, if i am not mistaken.



Lalvaz,

Please search next time before creating a thread. This has been brought up many times before :

http://www.team-bhp.com/forum/techni...ut-clutch.html

http://www.team-bhp.com/forum/techni...ut-clutch.html

And redirected to other similar threads where the topic was touched upon :

http://www.team-bhp.com/forum/shifti...le-breaks.html

http://www.team-bhp.com/forum/techni...nge-gears.html

http://www.team-bhp.com/forum/collec...son-2-use.html

cya
R

Last edited by Rehaan : 24th July 2008 at 12:42.
Rehaan is offline   (1) Thanks
Old 24th July 2008, 12:36   #15
BHPian
 
Alfa_Kilo's Avatar
 
Join Date: Apr 2007
Location: Jaipur
Posts: 328
Thanked: 13 Times

I have done it a few time with my 540 when the clutch actuator failed. One has to match the engine speed with the vehicle speed and then gently shift into gear from neutral. It does not take long to get the hang of it. The problem is in moving from a standstill, which requires slotting the vehicle in 1st and cranking the engine, quite a pain in start stop city traffic.
Alfa_Kilo is offline  
Reply

Most Viewed
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Copyright ©2000 - 2024, Team-BHP.com
Proudly powered by E2E Networks