haldex argument AGAIN! when will it end?
03-03-2001, 01:47 PM
#1
Junior Member
Thread Starter
Join Date: Jul 2000
Posts: 1,261
Likes: 0
Received 0 Likes
on
0 Posts
haldex argument AGAIN! when will it end?
the haldex quattro is under fire yet again, on vwvortex. this time even vwvortex1 himself has posted saying that the TT quattro is FWD by default and with the haldex fully engaged has 50:50 split.
i still think this is bunk, and that they are following skewed logic. what's the deal? here's the thread, anyone who's informed please feel free to join in the discussion there.
URL below.. i should note this thread starts out just plain bashing the TT, pivoting centrally on the TT's 'sub-par' AWD system.
...dave<ul><li><a href="http://forums.vwvortex.com/vwbb/Forum1/HTML/015032.html">TT under fire</a></li></ul>
i still think this is bunk, and that they are following skewed logic. what's the deal? here's the thread, anyone who's informed please feel free to join in the discussion there.
URL below.. i should note this thread starts out just plain bashing the TT, pivoting centrally on the TT's 'sub-par' AWD system.
...dave<ul><li><a href="http://forums.vwvortex.com/vwbb/Forum1/HTML/015032.html">TT under fire</a></li></ul>
03-03-2001, 02:31 PM
#2
New Member
Join Date: Oct 2000
Posts: 205
Likes: 0
Received 0 Likes
on
0 Posts
Haldex info
yes...it is true...the TT is front wheel drive until the haldex unit engages and causes torque transfer to the rear.
The haldex unit is an electronically controlled hydraulic multi-plate clutch installed between the driveshaft and the rear differential. Inside the haldex housing is a plate cluster running in an oil bath. As the clutch plates are forced together by a increase in hydrualic pressure the amount of torque transferred to the rear wheels increases. There is a small electric primer pump that maintains a base pressure to make the systems reaction times very quick and seem almost instananeous.
Two Axial piston pumps supply pressure to the pistons that operate the cluth plates. These pumps are driven by a swashplate which activates when there is a difference between the rotational speed of the input shaft and the output shaft This is all electronically controlled by a control unit that monitors wheel speed, engine speed etc. The control unit is what allows the haldex unit to disengage while abs is active, or parking brake is engaged, etc...
This is different from other Quattro systems which use a mechancial system..a Torsen differential which starts out with a 50:50 torque split and adjusts from there...our haldex system is 100:0 and adjusts from there...
Rukman
The haldex unit is an electronically controlled hydraulic multi-plate clutch installed between the driveshaft and the rear differential. Inside the haldex housing is a plate cluster running in an oil bath. As the clutch plates are forced together by a increase in hydrualic pressure the amount of torque transferred to the rear wheels increases. There is a small electric primer pump that maintains a base pressure to make the systems reaction times very quick and seem almost instananeous.
Two Axial piston pumps supply pressure to the pistons that operate the cluth plates. These pumps are driven by a swashplate which activates when there is a difference between the rotational speed of the input shaft and the output shaft This is all electronically controlled by a control unit that monitors wheel speed, engine speed etc. The control unit is what allows the haldex unit to disengage while abs is active, or parking brake is engaged, etc...
This is different from other Quattro systems which use a mechancial system..a Torsen differential which starts out with a 50:50 torque split and adjusts from there...our haldex system is 100:0 and adjusts from there...
Rukman
03-03-2001, 02:34 PM
#3
Junior Member
Thread Starter
Join Date: Jul 2000
Posts: 1,261
Likes: 0
Received 0 Likes
on
0 Posts
i know how the haldex unit itself works, i've been told it so many times.
explain *why* it cannot transfer more than 50% when the torsen system can.
nobody has been able to do that.
...dave
nobody has been able to do that.
...dave
03-03-2001, 03:09 PM
#4
AudiWorld Super User
Join Date: Apr 2000
Posts: 13,257
Likes: 0
Received 0 Likes
on
0 Posts
Couldn't just leave the battle in Vortex eh Ebb?
I've had many a discussion with AuForm - mainly for kicks. I've got lots of info on the Haldex - I just haven't shared it yet. 
03-03-2001, 03:44 PM
#5
Elder Member
Join Date: Mar 2000
Posts: 22,171
Likes: 0
Received 0 Likes
on
0 Posts
Here is some info for you . . .
This item I found is VERY interesting!
<b>Off-road</b>
Rapid activation with high torque transfer for maximum traction. Alternative separate off-road mode (switch) to lock the coupling.
I need to find out about this feature and how I go about getting it installed!
The Haldex unit can be used with either a Fwd platform or a Rwd platform. If the car is Fwd, then the Haldex LSC is located at the rear avle. If on a Rwd platform the Haldex LSC is at the front axle.
On a TT and all other Fwd Haldex LSC vehicles the torque split is 100:0 F/R. On a Rwd car it is most likely 0:100.
I have read through and am reading the Haldex website to see if they mention torque split % numbers. So far they have not. They have mentioned some things that disturb me though:
1. When the ABS kicks in, the Haldex LSC turns off!
"<b>Braking/ABS</b>
Immediate deactivation on ABS signal to ensure full function of ABS system."
2. When the ESP kicks in the Haldex LSC turns off! Someone will need to find the answer out for this from Audi, if they would ever release that information!
"<b>ESP</b>
Immediate deactivation on ESP signal to ensure full function of ESP system. Alternative is to communicate with the ESP system for adding the control possibility of the Haldex LSC to the ESP System."
3. This does not make sense to me, can someone please explain why?
"<b>parking</b>
Low or zero torque transfer needed for easy and comfortable manoeuvring."
"<b>high speed driving</b>
Reduced torque transfer, to minimum, still adding dynamic stability."
Why is the system delivering low or zero torque when parking, but the system is reduced to a minimum at high speeds? What am I not understanding here? To me it is just slightly safer to have awd ON at speed than while PARKING! lol
This will explain that the Haldex LSC is 100:0 and 0:100 for Fwd and Rwd respectively:
"When both shaft are rotating at the same speed, there is no pumping action. Immediately as a speed difference occurs, the pumping and starts to generate oil pressure. As a piston pump there is virtually instant reaction with no low speed pumping loss."
The pump is the Haldex LSC unit.
Dave, go and read everything at the <a href="http://www.haldextraction.com/">Haldex Group</a> Then head on over to the Technical Information section.
Each awd (quattro) system has their advantages and disadvantages.
<b>Off-road</b>
Rapid activation with high torque transfer for maximum traction. Alternative separate off-road mode (switch) to lock the coupling.
I need to find out about this feature and how I go about getting it installed!
The Haldex unit can be used with either a Fwd platform or a Rwd platform. If the car is Fwd, then the Haldex LSC is located at the rear avle. If on a Rwd platform the Haldex LSC is at the front axle.
On a TT and all other Fwd Haldex LSC vehicles the torque split is 100:0 F/R. On a Rwd car it is most likely 0:100.
I have read through and am reading the Haldex website to see if they mention torque split % numbers. So far they have not. They have mentioned some things that disturb me though:
1. When the ABS kicks in, the Haldex LSC turns off!
"<b>Braking/ABS</b>
Immediate deactivation on ABS signal to ensure full function of ABS system."
2. When the ESP kicks in the Haldex LSC turns off! Someone will need to find the answer out for this from Audi, if they would ever release that information!
"<b>ESP</b>
Immediate deactivation on ESP signal to ensure full function of ESP system. Alternative is to communicate with the ESP system for adding the control possibility of the Haldex LSC to the ESP System."
3. This does not make sense to me, can someone please explain why?
"<b>parking</b>
Low or zero torque transfer needed for easy and comfortable manoeuvring."
"<b>high speed driving</b>
Reduced torque transfer, to minimum, still adding dynamic stability."
Why is the system delivering low or zero torque when parking, but the system is reduced to a minimum at high speeds? What am I not understanding here? To me it is just slightly safer to have awd ON at speed than while PARKING! lol
This will explain that the Haldex LSC is 100:0 and 0:100 for Fwd and Rwd respectively:
"When both shaft are rotating at the same speed, there is no pumping action. Immediately as a speed difference occurs, the pumping and starts to generate oil pressure. As a piston pump there is virtually instant reaction with no low speed pumping loss."
The pump is the Haldex LSC unit.
Dave, go and read everything at the <a href="http://www.haldextraction.com/">Haldex Group</a> Then head on over to the Technical Information section.
Each awd (quattro) system has their advantages and disadvantages.
Trending Topics
03-03-2001, 08:41 PM
#10
Elder Member
Join Date: Mar 2000
Posts: 19,796
Likes: 0
Received 0 Likes
on
0 Posts
And my favorite stat on the Haldex: It responds to 2 degrees of slip!
THat is amazing to me. 2 degrees of circumference on our wheels is somewhere in the neighborhood of 2cm. 1/2 inch. Beyond a human's ability to detect the slippage.