Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 3rd October 2015, 19:50   #31
Senior - BHPian
 
arunphilip's Avatar
 
Join Date: May 2007
Location: Chennai
Posts: 1,724
Thanked: 4,686 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

Quote:
Originally Posted by Sutripta View Post
In the figure below, how is the torque being transmitted in the sloping section of the blue line?
At each point of the slope, one clutch is being progressively disengaged while the other is being engaged, resulting in continuous torque output. In reality, the sloped portion should be more vertical, since the entire shift is completed faster than a manual (i.e. the red line).

Quote:
Originally Posted by Sutripta View Post
What are the thought processes behind choosing a dry clutch vs a wet clutch?
Historically, manufacturers opted for dry clutches for low torques (typically <300 Nm), and wet for higher, since the higher torque required better heat dissipation. Further, those higher torque engines could afford some power loss in driving the plumbing required for a wet clutch.

However, while that was the theory, in practice they found that dry clutches were installed in small cars having compact engine bays, that tended not to dissipate heat well. When combined with high ambient weather (e.g. tropical areas) and severe stop-and-go traffic, this resulted in high heat soak in the dry clutch, affecting its life.

As a result, manufacturers are directing their efforts towards wet clutches. Getrag, for one, have stated that all their PowerShift transmissions will have wet clutches henceforth.
arunphilip is offline   (1) Thanks Reply With Quote
Old 3rd October 2015, 20:29   #32
Distinguished - BHPian
 
Join Date: Jul 2009
Location: Kolkata
Posts: 3,478
Thanked: 2,015 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

Quote:
Originally Posted by arunphilip View Post
At each point of the slope, one clutch is being progressively disengaged while the other is being engaged, resulting in continuous torque output. In reality, the sloped portion should be more vertical, since the entire shift is completed faster than a manual (i.e. the red line).
You mean in a DCT, there are operating modes when both clutches transmit power simultaneously to the output shaft?


Quote:
Historically, manufacturers opted for dry clutches for low torques (typically <300 Nm), and wet for higher, since the higher torque required better heat dissipation. Further, those higher torque engines could afford some power loss in driving the plumbing required for a wet clutch.
What sort of clutches did the American muscle cars and Italian exotics have? (talking wrt cars with MT, not AT obviously). And what sort of clutches on out commuter motorcycles?

Regards
Sutripta
Sutripta is offline   Reply With Quote
Old 3rd October 2015, 21:46   #33
Senior - BHPian
 
arunphilip's Avatar
 
Join Date: May 2007
Location: Chennai
Posts: 1,724
Thanked: 4,686 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

Quote:
Originally Posted by Sutripta View Post
You mean in a DCT, there are operating modes when both clutches transmit power simultaneously to the output shaft?
No - that can't happen, since the gear ratio's are different. During the sloped part, one clutch is slipping/disengaging and one is driving. However, both shafts are already running at the right speed, so there's no delay in getting the 'new' clutch or shafts up to the right speed, all that's needed is an engine rpm change to match the new gear.

I sense you're leading onto something via the Socratic method, care to share it?

Quote:
Originally Posted by Sutripta View Post
What sort of clutches did the American muscle cars and Italian exotics have? (talking wrt cars with MT, not AT obviously). And what sort of clutches on out commuter motorcycles?
I'd not made it explicit, but the part from my previous that you've quoted ("Historically, manufacturers opted...") is relevant purely to dual-clutch automated transmissions (DSG/DCTs), and has no bearing on manual transmissions in cars or motorcycles. Just to set the record straight, here's a verbatim quote from the Getag CEO:
Quote:
"So for very sporty cars with high torque you need a wet clutch, and for undersized engines in oversized vehicles you also need a wet clutch. There’s an area in the middle which works very well with dry clutch, and we have very effective ones in production today."
"I cannot speak for our competitors, but our new generation of DCTs at Getrag will be 100 percent wet clutch."
Sources:
1: http://drivelinenews.com/transmissio...ys-getrag-cto/ [Feb 2014]
2: http://drivelinenews.com/transmissio...or-dry-clutch/ [2010]
arunphilip is offline   (2) Thanks Reply With Quote
Old 4th October 2015, 20:12   #34
Distinguished - BHPian
 
Join Date: Jul 2009
Location: Kolkata
Posts: 3,478
Thanked: 2,015 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

More easily visualised in a electrical system: Multiple sources/ single load - If one has to shift from source to source. then Break before Make. If important, engineer the break time to be as low as possible.

Re: wet/ dry clutches, the opinions were expressed as truths about clutches in general, not as Getrags opinion on clutches for DCTs. Hence the confusion.

BTW, in my example,
Quote:
What sort of clutches did the American muscle cars and Italian exotics have? (talking wrt cars with MT, not AT obviously). And what sort of clutches on out commuter motorcycles?
what could be the reason for this?

Regards
Sutripta

Last edited by Sutripta : 4th October 2015 at 20:19.
Sutripta is offline   Reply With Quote
Old 14th December 2015, 08:46   #35
BHPian
 
Join Date: Aug 2005
Location: Mumbai
Posts: 275
Thanked: 62 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

How does a dual clutch - dry system compare to a cvt in performance and longetivity?
an_and is offline   Reply With Quote
Old 14th December 2015, 09:05   #36
Team-BHP Support
 
ampere's Avatar
 
Join Date: Sep 2009
Location: Bangalore
Posts: 15,485
Thanked: 8,377 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

Not wanting throw a negative aspect to this brilliant article by Arun. But here is another angle which is building up

http://www.team-bhp.com/forum/intern...opularity.html (USA: Dual Clutch ATs losing popularity)

Would be great to put this in perspective.
ampere is offline   (2) Thanks Reply With Quote
Old 7th March 2016, 10:44   #37
Senior - BHPian
 
reignofchaos's Avatar
 
Join Date: Apr 2007
Location: Bangalore
Posts: 2,206
Thanked: 1,152 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

A question for all Ford Powershift owners: Do you folks shift to neutral on stop lights?

I have the Volvo version of the Getrag gearbox (MPS6 or 6DCT450) which has a wet clutch and higher torque capability and apparently much better reliability.

I have been diligently following a regime of shifting to neutral at long stop lights. Wondering what the others do?

Last edited by reignofchaos : 7th March 2016 at 10:46.
reignofchaos is offline   (1) Thanks Reply With Quote
Old 7th March 2016, 20:45   #38
BHPian
 
Join Date: Jul 2010
Location: Bangalore
Posts: 65
Thanked: 26 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

Thanks a lot for this awesome technical write up. My Ecosport AT was shuddering rather a lot these days and have dropped it off for its second free service. Gave this feedback to the service center folks. The car literally shudders when its shifting from 1 to 2 and 2 to 3. The shuddering is more when we slow down on a speed breaker and are trying to pick speed.

It even happens when am in the manual mode.

Seems like the service guys know about this issue and have to keep the vehicle for 2-3 days as they have to send diagnostics data to ford and get back next steps. AT least thats what they told me.

Kinda concerned on the overall purchase now. Love the car but worried.
sk7671 is offline   (1) Thanks Reply With Quote
Old 10th March 2016, 22:15   #39
BHPian
 
Join Date: Jul 2010
Location: Bangalore
Posts: 65
Thanked: 26 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

Team - This is an update on my AT Ecosport. When dropped off for 2nd service, service folks sent all the diags to Ford and seems like Ford has requested to change the clutch in the AT unit. It now has been replaced. I read on the internet about these problems and extended warranty given away by Ford just on the transmission. I have not yet picked up the car, but how do I go about it with Ford?

Quote:
Originally Posted by sk7671 View Post
Thanks a lot for this awesome technical write up. My Ecosport AT was shuddering rather a lot these days and have dropped it off for its second free service. Gave this feedback to the service center folks. The car literally shudders when its shifting from 1 to 2 and 2 to 3. The shuddering is more when we slow down on a speed breaker and are trying to pick speed.

It even happens when am in the manual mode.

Seems like the service guys know about this issue and have to keep the vehicle for 2-3 days as they have to send diagnostics data to ford and get back next steps. AT least thats what they told me.

Kinda concerned on the overall purchase now. Love the car but worried.
sk7671 is offline   (2) Thanks Reply With Quote
Old 20th September 2016, 10:52   #40
Senior - BHPian
 
arunphilip's Avatar
 
Join Date: May 2007
Location: Chennai
Posts: 1,724
Thanked: 4,686 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

Quote:
Originally Posted by reignofchaos View Post
A question for all Ford Powershift owners: Do you folks shift to neutral on stop lights? I have the Volvo version of the Getrag gearbox (MPS6 or 6DCT450) which has a wet clutch and higher torque capability and apparently much better reliability.
According to Jason Fenske of the Engineering Explained channel, shifting to neutral is not required, since both clutches are disengaged upon stopping. I covered the same point on page 1 of this thread: "The clutches will disengage when the brakes are applied."

There's no harm done by shifting to neutral, but its not required either.


Sorry about the delayed reply, and hope you're having fun with your Volvo V40.
arunphilip is offline   (2) Thanks Reply With Quote
Old 25th September 2016, 10:03   #41
BHPian
 
komalthecoolk's Avatar
 
Join Date: Feb 2014
Location: Hyderabad
Posts: 108
Thanked: 53 Times
Default Re: Ford PowerShift Dual-Clutch Transmission (DCT) - A Technical Overview

Quote:
Originally Posted by arunphilip View Post
There's no harm done by shifting to neutral, but its not required either.
After reading your post multiple times and after test driving the Figo AT I was very impressed with the technology. But after watching related videos, reading about the possibilities of one of the clutch wearing out with slow moving traffic and reading global grievances and issues with the DCT, I've decided not to go for it :(

For a technology that's relatively new and seeing Ford silently replace many problematic transmissions all across the globe, it did not give me enough confidence to have this as my vehicle for the next 5-6 years. May be in the near future, if budget permits, I'd like to have the Figo AT as my secondary car though
komalthecoolk is offline   (2) Thanks Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Ford Fiesta DCT Automatic: Gearbox woes Peejay Technical Stuff 57 6th August 2017 22:45
The Ford Nanny - New Ford Fiesta DCT (Automatic) Simple_car Test-Drives & Initial Ownership Reports 39 11th July 2017 20:40
Ford Fiesta: Manual or DCT? Abh1nav Sedans 14 26th September 2014 18:11
The second Ford Fiesta DCT Ownership Review dsvikki Test-Drives & Initial Ownership Reports 15 5th July 2013 12:15


All times are GMT +5.5. The time now is 06:38.

Copyright ©2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks