quattro question -- when one wheel has no traction, others still rotating, yes?
09-01-2005, 11:31 AM
#1
AudiWorld Member
Thread Starter
Join Date: Jun 2005
Posts: 316
Likes: 0
Received 0 Likes
on
0 Posts
quattro question -- when one wheel has no traction, others still rotating, yes?
someone, talking about Torsen, said "...when one of the wheels has no traction at all... the car will not move at all."
this sounds like an urban legend to me.
any experiences/data to confirm/disprove this?
thanks, mark.
this sounds like an urban legend to me.
any experiences/data to confirm/disprove this?
thanks, mark.
09-01-2005, 11:55 AM
#2
AudiWorld Senior Member
Join Date: Jun 2004
Posts: 846
Likes: 0
Received 0 Likes
on
0 Posts
yes - the complete opposite of what your friend said.
transfers power from spinning wheel to the others. otherwise it would be a completely crap system wouldn't it? you wouldn't win many rallys with that would you?
Info here<ul><li><a href="http://www.sonic.net/garyg/zonc/TechnicalInformation/TorsenDifferential.html">http://www.sonic.net/garyg/zonc/TechnicalInformation/TorsenDifferential.html</a</li></ul>
Info here<ul><li><a href="http://www.sonic.net/garyg/zonc/TechnicalInformation/TorsenDifferential.html">http://www.sonic.net/garyg/zonc/TechnicalInformation/TorsenDifferential.html</a</li></ul>
09-01-2005, 12:15 PM
#3
Senior Member
Join Date: Mar 2004
Posts: 5,376
Likes: 0
Received 0 Likes
on
0 Posts
there is some truth to that theory
on quattro II without the rear diff locked you could lift a wheel and be without any traction at all.
on quattro III the center and rear diff were torsen so lifting a rear wheel wouldnt unload the driveline.
on quattro IV the center diff is a torsen unit and the rear diff is an open diff... however the car uses it's ABS system to actuate EDL (electronic differential lock) which pulsates the ABS on any of the 4 wheels *I think* to eliminate slippage which prevents the driveline from unloading and consequently prevents total loss of traction.
Now if you unplug your ABS unit or have a failed ABS controller on a quattro IV system and lift one wheel off of the ground... you wont be going anywhere.
on quattro III the center and rear diff were torsen so lifting a rear wheel wouldnt unload the driveline.
on quattro IV the center diff is a torsen unit and the rear diff is an open diff... however the car uses it's ABS system to actuate EDL (electronic differential lock) which pulsates the ABS on any of the 4 wheels *I think* to eliminate slippage which prevents the driveline from unloading and consequently prevents total loss of traction.
Now if you unplug your ABS unit or have a failed ABS controller on a quattro IV system and lift one wheel off of the ground... you wont be going anywhere.
09-01-2005, 12:21 PM
#4
Senior Member
Join Date: Mar 2004
Posts: 5,376
Likes: 0
Received 0 Likes
on
0 Posts
you are partially correct
however you are also partially incorrect, and I'm a pessimist, so you're wrong.
There are 4 or 5 versions of "quattro" not all of them use torsen differentials. Some have no differentials or locking diffs, others use a haldex electrohydraulic clutching system, and finally some use torque sensing differentials that have a natural bias while others use neutral torsens with either a 3:1 or 2:1 maximum ratio.
The early rally cars didnt have torsen, but they still won races. They had lockable diffs kinda like a 4x4, but without the transfer case.
You didnt actually think that for the last 25 years audi had been using the same quattro did you?
There are 4 or 5 versions of "quattro" not all of them use torsen differentials. Some have no differentials or locking diffs, others use a haldex electrohydraulic clutching system, and finally some use torque sensing differentials that have a natural bias while others use neutral torsens with either a 3:1 or 2:1 maximum ratio.
The early rally cars didnt have torsen, but they still won races. They had lockable diffs kinda like a 4x4, but without the transfer case.
You didnt actually think that for the last 25 years audi had been using the same quattro did you?
09-01-2005, 12:49 PM
#5
AudiWorld Senior Member
Join Date: Jun 2004
Posts: 846
Likes: 0
Received 0 Likes
on
0 Posts
Okey doke, but I though he was talking about a) Torsen b) B6's
Does that still make me wrong - assuming all the parts are working as they should?
Quite happy to be wrong - "I'm a lover not a mechanic"
and of course I bow to your superior knowledge.
Cheers
PS - What version of quattro do we have?
Quite happy to be wrong - "I'm a lover not a mechanic"
and of course I bow to your superior knowledge.Cheers
PS - What version of quattro do we have?
09-01-2005, 12:52 PM
#6
AudiWorld Super User
Join Date: Nov 2002
Location: Montreal, Canada
Posts: 18,597
Likes: 0
Received 0 Likes
on
0 Posts
You would need two wheels to be off the ground not to go anywhere...
One in the front and one in the rear. Of course this is not totally true anymore on my car.
Trending Topics
09-01-2005, 02:27 PM
#8
New Member
Join Date: Aug 2005
Posts: 158
Likes: 0
Received 0 Likes
on
0 Posts
Re: quattro question -- when one wheel has no traction, others still rotating, yes?
http://www.germantechnik.com/showthread.php?t=17118
This is a really good write up on what quattro started as and has become, along with the advantages and disadvantages of each generation of quattro (haldex,torsen)<ul><li><a href="http://www.germantechnik.com/showthread.php?t=17118">http://www.germantechnik.com/showthread.php?t=17118</a</li></ul>
This is a really good write up on what quattro started as and has become, along with the advantages and disadvantages of each generation of quattro (haldex,torsen)<ul><li><a href="http://www.germantechnik.com/showthread.php?t=17118">http://www.germantechnik.com/showthread.php?t=17118</a</li></ul>
09-01-2005, 03:06 PM
#10
AudiWorld Super User
Join Date: Mar 2000
Posts: 21,689
Likes: 0
Received 0 Likes
on
0 Posts
untill EDL kicks in, you've really got nothing.
Yes I have experienced this with my H-sport rear sway bar, there is a seccond or two of hang time where the driveline is totally unloaded and the car has no ability to accelerate for a very brief moment.
When does it happen?
In very very tight uphill turns that are cambered or if there is an uphill turn that becomes terraced suddenly enough so that my rear suspension cannot accomodate the difference in height between the rear wheels. At those points a rear wheel will lift and the driveline unloads, that wheel (off of the ground) spins and then chirps when it contacts the ground again.
A limited slip rear diff will prevent this, as does EDL when it activates about a seccond after its all over.
When does it happen?
In very very tight uphill turns that are cambered or if there is an uphill turn that becomes terraced suddenly enough so that my rear suspension cannot accomodate the difference in height between the rear wheels. At those points a rear wheel will lift and the driveline unloads, that wheel (off of the ground) spins and then chirps when it contacts the ground again.
A limited slip rear diff will prevent this, as does EDL when it activates about a seccond after its all over.