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


Reply
 
Thread Tools Search this Thread
Old 17th September 2016, 11:57   #16
BHPian
 
Join Date: Feb 2008
Location: Mysore/Dharwad
Posts: 91
Thanked: 110 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by smartcat View Post
In a 2WD atleast, I think both ESP and traction control reduces the vehicle's ability of handle slush/snow. Because these systems either brake individual wheels or cut engine power when it detects wheel slip.
As far as my understanding goes, traction control works by reducing power in case of wheel spin, but ESP works by individually applying brakes to 1 or more wheels
What I understand is that say for example ( refer video posted by dhanushs in post 4 of this thread ) , in a RWD car, if Left rear wheel is slipping, ESP should apply brake to that wheel and the power then goes to rear right wheel. The vehicle should be able to move and not get stuck.
Experts, please do tell me if my understanding is correct or not.

Mods: please shift this post to relevant section if you feel that it is deviating from original discussion

Last edited by i_see : 17th September 2016 at 12:10.
i_see is offline   Reply With Quote
Old 17th September 2016, 12:11   #17
Distinguished - BHPian
 
smartcat's Avatar
 
Join Date: Jun 2007
Location: Bangalore
Posts: 2,589
Thanked: 8,373 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by i_see View Post
What I understand is that say for example ( refer video posted by dhanushs in post 4 of this thread ) , in a RWD car, if Left rear wheel is slipping, ESP should apply brake to that wheel and that power goes to rear right wheel. The vehicle should be able to move and not get stuck.
Experts, please do tell me if my understanding is correct or not.
You got the first part right, but not the second part. ESP/Traction control might cut power to the slipping wheel, but will not send power to other wheel.
smartcat is offline   (1) Thanks Reply With Quote
Old 17th September 2016, 13:17   #18
Newbie
 
Join Date: Apr 2014
Location: Kochi
Posts: 17
Thanked: 14 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by Sutripta View Post
Anyone knows what technology is used by Quaife? (The companies website gives no hard information. Or maybe I don't know where to look.)
Torsen patent still active?

Regards
Sutripta
AFAIK they use helical gears to achieve locking up of both wheels and hence known as helical LSDs.

This is a picture of the Quaife Helical differential, when we opened it up.
Limited Slip Differential on a 2WD to improve rough road ability?-img_20160804_195302.jpg


Here are a few links that I found useful:
  1. http://www.trak-life.com/basic-intro...erentials-lsd/
  2. www.gkn.com/driveline/about-us/Documents/datasheets/Helical-engl.pdf

I've also attached a Master's Thesis on "THE ANALYSIS AND TESTING OF THE QUAIFE TORQUE-BIASING DIFFERENTIAL" , which is very detailed and explains how it all works.

quaife_thesis.pdf

I hope all of this helps.

Arvind
Arvi95 is offline   (2) Thanks Reply With Quote
Old 17th September 2016, 19:20   #19
Distinguished - BHPian
 
Join Date: Jul 2009
Location: Kolkata
Posts: 3,387
Thanked: 1,842 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by smartcat View Post
cut power to the slipping wheel,
How does one cut power to an individual wheel?

Quote:
Originally Posted by Arvi95 View Post
AFAIK they use helical gears to achieve locking up of both wheels and hence known as helical LSDs.
Quaife mentions helical gears, and nothing beyond that.
So I take it that it is essentially the GKN system?

Your picture: Where did you get hold of this differential? Why was it opened up?

Thanks for the link to the phd paper.

Regards
Sutripta

Last edited by Sutripta : 17th September 2016 at 19:37.
Sutripta is offline   Reply With Quote
Old 17th September 2016, 20:42   #20
Distinguished - BHPian
 
smartcat's Avatar
 
Join Date: Jun 2007
Location: Bangalore
Posts: 2,589
Thanked: 8,373 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by Sutripta View Post
How does one cut power to an individual wheel?
What I should have said -> ESP/traction control might cut engine power to the driven wheels and/or apply brakes to individual wheels when it detects slip.
smartcat is offline   Reply With Quote
Old 17th September 2016, 20:52   #21
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,381
Thanked: 3,833 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by smartcat View Post
You got the first part right, but not the second part. ESP/Traction control might cut power to the slipping wheel, but will not send power to other wheel.
You cannot send power to each wheels independently , AFAIK, buy like the above post says, in an open diff, when you brake the slipping wheel, the amount if torque needed to overcome the brakes, is sent to the wheel with traction. Hence the vehicle moves.
dhanushs is offline   (2) Thanks Reply With Quote
Old 17th September 2016, 21:46   #22
Newbie
 
Join Date: Apr 2014
Location: Kochi
Posts: 17
Thanked: 14 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by Sutripta View Post
Your picture: Where did you get hold of this differential? Why was it opened up?
I'm a part of NITKRacing, the formula student team of NITK, Surathkal. This is the diff we were using on our previous car. We opened it up one fine evening, just out of curiosity.
Arvi95 is offline   (3) Thanks Reply With Quote
Old 18th September 2016, 00:22   #23
Distinguished - BHPian
 
SS-Traveller's Avatar
 
Join Date: Jan 2009
Location: New Delhi
Posts: 6,525
Thanked: 10,249 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

A very well-written article that clears a lot of misconceptions about what is being discussed here: https://practicalmotoring.com.au/car...years-edition/
SS-Traveller is offline   (5) Thanks Reply With Quote
Old 18th September 2016, 09:30   #24
Distinguished - BHPian
 
smartcat's Avatar
 
Join Date: Jun 2007
Location: Bangalore
Posts: 2,589
Thanked: 8,373 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by SS-Traveller View Post
A very well-written article that clears a lot of misconceptions about what is being discussed here:
Very clearly explained, I agree. What I liked most about that page was an unrelated video "Can a 2WD Drive Offroad?"



The Suzuki Vitara FWD even managed to get across a section with left side wheels in a ditch filled with water

Limited Slip Differential on a 2WD to improve rough road ability?-20160918.png

Article explaining the performance of Vitara FWD off-road -
https://practicalmotoring.com.au/car...i-vitara-rt-s/

The following helped -

- Low weight (1 ton)
- FWD (engine weight on front wheels for traction)
- Electronics (traction control)
- High ground clearance

Quote:
Originally Posted by i_see View Post
in a RWD car, if Left rear wheel is slipping, ESP should apply brake to that wheel and the power then goes to rear right wheel. The vehicle should be able to move and not get stuck.
Quote:
Originally Posted by dhanushs View Post
You cannot send power to each wheels independently , AFAIK, buy like the above post says, in an open diff, when you brake the slipping wheel, the amount if torque needed to overcome the brakes, is sent to the wheel with traction. Hence the vehicle moves.
You two are right, I was wrong. Quoting the above article -

Quote:
Electronics also helped and hindered. As with many modern cars, the Suzuki has brake traction control, engine traction control and stability control. The brake traction control always helped the car by braking a single spinning wheel. But a couple of times the engine traction control just didn’t let us have any more power, even though the vehicle wasn’t out of clearance.

The solution was to disable the both of them plus stability control by a long press of the stability control switch, and then there was unlimited power… but then the benefit of brake traction control was lost. Ideally, you’d want brake traction control active with engine traction control and stability control disabled. As ever, how to set a car up to tackle any given obstacle is a judgement call every time based on the car and the situation at hand. You can see in the video where we could only ascend one hill with the electronics fully off, as otherwise engine traction control would cut the power just when we needed it.
Basically, traction control is good for rough-roading, ESC is not. Article explaining the differences between ESC and traction control from Practicalmotoring.com -

https://practicalmotoring.com.au/car...ility-control/
smartcat is offline   (1) Thanks Reply With Quote
Old 18th September 2016, 20:22   #25
Distinguished - BHPian
 
Join Date: Jul 2009
Location: Kolkata
Posts: 3,387
Thanked: 1,842 Times
Default Re: Limited Slip Differential on a 2WD to improve rough road ability?

Quote:
Originally Posted by Arvi95 View Post
We opened it up one fine evening, just out of curiosity.
Anything you learned which you would like to share?

Regards
Sutripta
Sutripta is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Torque vectoring twin clutch system by GKN - Goodbye to Limited Slip Diff? shyn Technical Stuff 2 20th September 2015 15:18
Strange loss of braking ability. What happened? msdivy Technical Stuff 86 30th August 2015 01:00
Question about safari Limited Slip Diffrential (LSD) tsk1979 4x4 Technical 44 1st March 2008 19:31
We need search ability in BHP garage Samurai Shifting gears 4 23rd December 2005 16:52


All times are GMT +5.5. The time now is 07:06.

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