Whats double clutching & whats the reason to use it

raja_ys · 20th September 2005, 19:43

sorry guys i have no idea regarding this, pls getr bac with info

Gurkha · 22nd September 2005, 14:40

Quote:

Originally Posted by hrag

I'd have thought it was the other way around, like on the Premier Padmini - synchro on all gears except 1st.

Yep, got it wrong, my Jonga is the same, Ist is no syncro, 2nd and 3rd are syncro.

MalluDude · 22nd September 2005, 16:36

I believe double clutch is still there in old Ashok Leyland vehicles, i.e. the ones that came out before the power steering/ sync gear version which was introduced 5 years back. When the driver up-shifts, you can see him closing the accelerator, bringing gear to neutral, releasing clutch, and again depressing clutch to shift to the higher gear. Some guys even race the engine while the position is in 'neutral' claiming to avoid gear-grinding.

BTW I didn't know Jonga had this...Gurkha, you do mean the ones that came from Jabalpur, right?

Gurkha · 22nd September 2005, 17:08

One of the reasons that is done in buses and trucks is because their syncros are shot so they have no choice or they are trying to preserve the syncro rings, otherwise the Leyland with the HINO/ZF power-train is smoother than most cars.

mithun · 9th January 2007, 06:00

I've heard that double-clutching is a better option even in cars which is having a synchromesh transmission because the actual gears are always in constant mesh, and the synchronizers only decide which pair of gears to connect to their shaft. Is that true ?

Also double-clutching is the right way to operate the clutch. Because it saves wear and tear on the synchronizers in the long run or if you're planning to run your car for over 3 lakhs KMS.

ex670c · 9th January 2007, 11:41

When we engage the Clutch it slows down the Flywheel, thereby the engine.

Imagine DDC to be like cadence braking, It can rapidly slow down the engine while without heating up the clutch.

In High Performance engines (Hi-Speed & Hi-Torque) DDC Prevents the Clutch plate from heating up or coming under torsional stress.

It aligns the synchroniser rings/cones better.

There by preventing a lot of wear and tear and harshness.

In Off-Road and Towing situations it prevents the clutch from burning out.

Regards,

Arka.

mithun · 11th January 2007, 05:25

Is it a wise idea to use double clutching on our new-age synchromesh transmissions ?

Will double clutching cause damage to the new-age synchromesh transmissions ?

chetanhanda · 11th January 2007, 06:38

Quote:

Originally Posted by Shan2nu

Ajmats. that's not double cluthing but it's similar to toe-heeling which is done to match the revs of the engine to the lower gear to make for a smoother deceleration.
While the heel blips the throttle, the toe is used to brake.
Watch any of the best motoring videos and you'll get a clear pic of it.
Regards...
Shan2nu

"heel-n-toe" or "toe-heeling" is not done to match the revs of the engine to the lower gear.
its done in order to keep the spooling turbo from dropping revs to lower speeds..to reduce turbo lag to a certain extent, another option to heel-n-toe is using a ALS to keep the turbo revving at the same speed even when the foot is lifted off the throttle.

When the foot is lifted of the throttle during braking the pressure/velocity of exhaust gasses drops, which causes the turbo to lose some rpm. so when the throttle is floored again (after gear shift or braking)there will be some lag for the turbo to reach the same speed.

So to prevent this the driver presses the brake with his heel to slow down and the throttle with his toe to keep the engine revving andd turbo spooling.

This creates heavy load on the brakes, engine etc but when u cant afford to lose speed at apex etc and suffer turbo lag .. u have to do this.

As mentioned earlier the other option is ALS .. but ALS comes with its
drawbacks.. loud sound and killer load on the exhust system as well as the blades of the turbo..
but nothing beats the sound of ALS on the overrun..

Rehaan · 11th January 2007, 17:22

Quote:

Originally Posted by mithun

Is it a wise idea to use double clutching on our new-age synchromesh transmissions ?

Wise.....im not sure. More like rather pointless.

Quote:

Will double clutching cause damage to the new-age synchromesh transmissions ?

Nope.

cya
R

rks · 11th January 2007, 19:41

Quote:

Originally Posted by mithun

Is it a wise idea to use double clutching on our new-age synchromesh transmissions ?

Will double clutching cause damage to the new-age synchromesh transmissions ?

If it is not required, then it is not wise to do it. Unnecessary wear and tear on your clutch, unnecessary revving on your engine, loss in fuel economy. Also I am wondering if the ECU, say of an MPFI engine, will get (at least momentarily) confused by the double declutching procedure, resulting in lower-than-optimal performance/FE?

Desert fox · 16th January 2007, 14:27

I think Constant-mesh Gearbox's are the ones who may require double clutch sift for smoother shift's.

These are the one's used in the bus's and car's of yore.they required a lot of smoothness and technique,once mastered,i have seen many KSRTC and BMTC Driver's shift without clutch!!!!

Minus points are far too many of course rendering it obsolete and un-reliable.

In syncromesh i resort to double clutch changes to car' who have a wide-gate between 2nd and 3rd gear and when iam changing at full-rev's.

vichu_zen · 18th January 2007, 10:45

yaeh... i've seen that process in many KSRTC busses but didnt quite understood that until now. thanks for that piece of enlightenment provided for us... reehan.

rranjith_kum · 10th February 2007, 00:22

Quote:

Originally Posted by Rehaan

Hey Shan2nu,

the noise you hear is because reverese gear is a "straight-cut" gear and not a "helical cut" gear.

the straight cut gears are actually called as spur gear...

rider60 · 3rd April 2007, 15:54

awesome explanation dude i never knew about anything like this........

AkMar · 7th April 2007, 23:08

All BEST buses before 2002/3 have non syncro gearboxes & hence require double clutch. But many drivers do not use clutch at all in these buses.

Sometime in 2002/3, buses with ZF gearboxes started arriving into their fleet. These buses had a special notice for the driver saying "ZF G.box. Single clutch" The board also indicated the shift pattern!!. But these notices have vanished in some buses due to repainting.

About automatic buses, I know one AC bus of BEST which has rear engine & automatic transmission. The recently acquired Starbuses have manual transmission.

20th September 2005, 19:43	#31
raja_ys BHPian Join Date: Aug 2005 Location: Delhi Posts: 177 Thanked: 225 Times	sorry guys i have no idea regarding this, pls getr bac with info
	() Thanks

22nd September 2005, 16:36	#33
MalluDude BHPian Join Date: Aug 2005 Location: Kochi Posts: 397 Thanked: 56 Times View My Garage	I believe double clutch is still there in old Ashok Leyland vehicles, i.e. the ones that came out before the power steering/ sync gear version which was introduced 5 years back. When the driver up-shifts, you can see him closing the accelerator, bringing gear to neutral, releasing clutch, and again depressing clutch to shift to the higher gear. Some guys even race the engine while the position is in 'neutral' claiming to avoid gear-grinding. BTW I didn't know Jonga had this...Gurkha, you do mean the ones that came from Jabalpur, right? Last edited by MalluDude : 22nd September 2005 at 16:39.
	() Thanks

22nd September 2005, 17:08	#34
Gurkha BANNED Join Date: Aug 2005 Location: Kalyani, West Bengal Posts: 444 Thanked: 10 Times	One of the reasons that is done in buses and trucks is because their syncros are shot so they have no choice or they are trying to preserve the syncro rings, otherwise the Leyland with the HINO/ZF power-train is smoother than most cars.
	() Thanks

9th January 2007, 06:00	#35
mithun BANNED Join Date: Jan 2006 Location: Cochin Posts: 2,195 Thanked: 268 Times	I've heard that double-clutching is a better option even in cars which is having a synchromesh transmission because the actual gears are always in constant mesh, and the synchronizers only decide which pair of gears to connect to their shaft. Is that true ? Also double-clutching is the right way to operate the clutch. Because it saves wear and tear on the synchronizers in the long run or if you're planning to run your car for over 3 lakhs KMS.
	() Thanks

9th January 2007, 11:41	#36
ex670c Senior - BHPian Join Date: Nov 2004 Location: Chennai Posts: 2,470 Thanked: 1,937 Times View My Garage	Advantages of Double De-Clutching (DDC) When we engage the Clutch it slows down the Flywheel, thereby the engine. Imagine DDC to be like cadence braking, It can rapidly slow down the engine while without heating up the clutch. In High Performance engines (Hi-Speed & Hi-Torque) DDC Prevents the Clutch plate from heating up or coming under torsional stress. It aligns the synchroniser rings/cones better. There by preventing a lot of wear and tear and harshness. In Off-Road and Towing situations it prevents the clutch from burning out. Regards, Arka.
	() Thanks

11th January 2007, 05:25	#37
mithun BANNED Join Date: Jan 2006 Location: Cochin Posts: 2,195 Thanked: 268 Times	Is it a wise idea to use double clutching on our new-age synchromesh transmissions ? Will double clutching cause damage to the new-age synchromesh transmissions ?
	() Thanks

16th January 2007, 14:27	#41
Desert fox BHPian Join Date: Jan 2007 Location: bangalore Posts: 228 Thanked: Once	I think Constant-mesh Gearbox's are the ones who may require double clutch sift for smoother shift's. These are the one's used in the bus's and car's of yore.they required a lot of smoothness and technique,once mastered,i have seen many KSRTC and BMTC Driver's shift without clutch!!!! Minus points are far too many of course rendering it obsolete and un-reliable. In syncromesh i resort to double clutch changes to car' who have a wide-gate between 2nd and 3rd gear and when iam changing at full-rev's.
	() Thanks

18th January 2007, 10:45	#42
vichu_zen Newbie Join Date: Jan 2007 Location: Aleppey Posts: 18 Thanked: Once	yaeh... i've seen that process in many KSRTC busses but didnt quite understood that until now. thanks for that piece of enlightenment provided for us... reehan.
	() Thanks

3rd April 2007, 15:54	#44
rider60 Senior - BHPian Join Date: Mar 2007 Location: Bhagyanagaram. (A.K.A. Hyderabad) Posts: 1,620 Thanked: 56 Times View My Garage	awesome explanation dude i never knew about anything like this........
	() Thanks

7th April 2007, 23:08	#45
AkMar Senior - BHPian Join Date: Apr 2007 Location: Mumbai Posts: 1,183 Thanked: 2,604 Times	All BEST buses before 2002/3 have non syncro gearboxes & hence require double clutch. But many drivers do not use clutch at all in these buses. Sometime in 2002/3, buses with ZF gearboxes started arriving into their fleet. These buses had a special notice for the driver saying "ZF G.box. Single clutch" The board also indicated the shift pattern!!. But these notices have vanished in some buses due to repainting. About automatic buses, I know one AC bus of BEST which has rear engine & automatic transmission. The recently acquired Starbuses have manual transmission.
	() Thanks