Haldex Sport controller = increased wear & tear?

[AmRando]

Hi all-

-more freeforming for what to burn my money on underway. I'm debating the configurable Haldex controller. I do like the ability to reconfigure the torque split front-to-rear, but given the design of the .:R drivetrain from the factory, are the mechanicals really designed to endure a 60/40 or 55/45 torque-split permanently? How do they compare to an A3 or A4 which has this setup by default? I'd love to drive my car in Sport or Race mode all the time, but I have this creeping suspicion that 6 months or a year down the road I'll be suffering some sort of horrendous repair bill that the dealer will blame on aftermarket modifications..

[LoyalSage]

Hi all-

-more freeforming for what to burn my money on underway. I'm debating the configurable Haldex controller. I do like the ability to reconfigure the torque split front-to-rear, but given the design of the .:R drivetrain from the factory, are the mechanicals really designed to endure a 60/40 or 55/45 torque-split permanently? How do they compare to an A3 or A4 which has this setup by default? I'd love to drive my car in Sport or Race mode all the time, but I have this creeping suspicion that 6 months or a year down the road I'll be suffering some sort of horrendous repair bill that the dealer will blame on aftermarket modifications..

this is a fantastic question and was wondering myself. watching thread.

[sixteen10]

I think the answer is no.

The .:R stock form is inherently a FWD car , only at the point where traction is lost does the Haldex step in and distribute torque to the rear wheels.

By having the Haldex Gen2 in race mode you are not doing anything other than making the vehicle distribute this torque more quickly and with more of it. that means when you are driving normally you wont have any additional wear and tear than normal.

At least that's how I understood it.

[AmRando]

I think the answer is no.

The .:R stock form is inherently a FWD car , only at the point where traction is lost does the Haldex step in and distribute torque to the rear wheels.

By having the Haldex Gen2 in race mode you are not doing anything other than making the vehicle distribute this torque more quickly and with more of it. that means when you are driving normally you wont have any additional wear and tear than normal.

At least that's how I understood it.

My understanding was that besides the higher RPM to maintain torque and quicker throttle response, DSG Sport mode also keeps the rear differential engaged full-time, whereas in Drive it is disengaged unless traction is lost at the front. So the Haldex controller is only changing the speed or sensitivity of the torque distribution and not overriding or enhancing the behavior of the transmission?

I guess this question really is dependent on how much time you spend in D or S on the tranny then as well. IF I interpret this correctly so far- daily driving in DSG-D mode, the Haldex should have no negative effect at all, but in DSG-S it very well could, by constantly piping 2x or 3x more torque as usual to the rear.

[Slave IV]

I think it must cause additional wear but how much is the question...A good way to look into it would be to see the haldex and differential oil that people with the mod have changed and see if it looks dirtier than normal. If so, there could be an easy solution with more frequent fluid changes and possibly getting higher grade fluids. Which leads to the question...What aftermarket options are there for oil and anyone here have experience using any of them..or are we stuck with OEM?

[RedRain]

I have 35,000 miles with this setting and no complaints. Just had my 40k service done and there was nothing mentioned. It is pretty nice to be able to make a u-turn within one lane with the backside sliding around! No snowplow effect into steep turns either. One of the best mods I have done...

[AmRando]

I think it must cause additional wear but how much is the question...A good way to look into it would be to see the haldex and differential oil that people with the mod have changed and see if it looks dirtier than normal. If so, there could be an easy solution with more frequent fluid changes and possibly getting higher grade fluids. Which leads to the question...What aftermarket options are there for oil and anyone here have experience using any of them..or are we stuck with OEM?

Do we have any dealer service techs around who can comment on drivetrain component durability or compatibility between the A3 and .:R? Obviously the control is different; Haldex vs Torsen but what about the mechanicals? Is the .:R engineered with cheaper parts because it's expected to see less stress and use in the rear drivetrain over its operating lifetime?

[Mr_Peach]

My understanding was that besides the higher RPM to maintain torque and quicker throttle response, DSG Sport mode also keeps the rear differential engaged full-time, whereas in Drive it is disengaged unless traction is lost at the front. So the Haldex controller is only changing the speed or sensitivity of the torque distribution and not overriding or enhancing the behavior of the transmission?

I guess this question really is dependent on how much time you spend in D or S on the tranny then as well. IF I interpret this correctly so far- daily driving in DSG-D mode, the Haldex should have no negative effect at all, but in DSG-S it very well could, by constantly piping 2x or 3x more torque as usual to the rear.

This would be news to me. Which is not to say that it is wrong, I've just never ran across it before. I was not aware that the Haldex performance had anything at all to do with which "mode" the transmission is in.

Here's my story -

My car has 83K original miles on it, bought new by me back in August of 2007. I put the upgraded haldex controller in in my first year of ownership.

I added the cable / switch in July 08. It's been on 'race' full time ever since.

I drive in 'M' mode full time (statistically, anyways - switch to 'D' or 'S' less than 1%).

I track my car on average 2-3 times a year.

My Haldex would seem to be in fine shape. I've had the routine service done at 40K and 80K.

My rear diff is starting to howl just a bit. It's particularly noticeable with new tires all around; less so if the rears are more worn than the fronts (i.e. when I rotate my tires to put the the best ones on the front, the howl goes away).

Has my ill behavior contributed to my diff making noise? Hell if I know. The howl isn't bad, it's just loud enough to take note of. I'll probably drive it another 80K without replacing it.

[JRutter]

The A3 has the same Haldex system. (A3 ~= 4 door R32) Other "quattro" Audis are Torsen.

HPA recommends more frequent Fluid changes. I'm not FI, so I just went to 25K mile service schedule for the Haldex and DSG. No unusual fluid characteristics reported by my tech on a 25K mile interval with the new unit in place (I asked him to take note, but did not send for analysis).

[BlixaBargeld]

I think this tread has a lot of questionable info. DSG influence on Haldex....

[KurtCav]

In for a converged answer to exactly how the system works.

Everything I have read to date has been vague. I was under the assumption that a certain percentage of power is always sent to the rear and that percentage may increase up to a higher percentage, never to exceed a set value.

I also assumed the HPA controller would ALWAYS put a certain percentage of power to the rear wheels in sport and race mode.

I also assumed this works independent of DSG selection. If not, haldex programming would need to be different for MT and DSG vehicles.

[Ripdubski]

My understanding was that besides the higher RPM to maintain torque and quicker throttle response, DSG Sport mode also keeps the rear differential engaged full-time, whereas in Drive it is disengaged unless traction is lost at the front. .

I keep reading it is engaged in Sport and it isnt. I dont know for sure what the truth is, but I suspect Sport keeps it engaged far more than drive. I can hear more whine when in Sport mode and virtually none in Drive mode. I wish I knew exactly when the rear is and is not engaged.

[CF3018]

The A3 has the same Haldex system. (A3 ~= 4 door R32) Other "quattro" Audis are Torsen.

+ This. The A3 and TT both use the Haldex system

[rhcp4life]

http://www.awdwiki.com/en/haldex/

just some info and some interesting cutaways and pictures

[Mr_Peach]

I keep reading it is engaged in Sport and it isnt. I dont know for sure what the truth is, but I suspect Sport keeps it engaged far more than drive. I can hear more whine when in Sport mode and virtually none in Drive mode. I wish I knew exactly when the rear is and is not engaged.

I wonder if the root of the confusion is 'sport' mode on the Haldex vs 'sport' mode on the transmission.

Just a thought.

[TeamZleep]

I want something to completely replace haldex and leave the car permanently 50/50.

[Slave IV]

I wonder if the root of the confusion is 'sport' mode on the Haldex vs 'sport' mode on the transmission.

Just a thought.

Yeah, I always thought power distribution was based on RPM and throttle, not what mode you are in.

I want something to completely replace haldex and leave the car permanently 50/50.

Buy a jeep I'd rather have Haldex over a 4WD system personally. But "real" quattro or Subaru AWD is definitely better than Haldex. Then again, not as easy to tune with just a chip..all mechanical in torsen at least.

[LWNY]

aside from getting mixed up with the term power split and torque split. it is likely that sport or race mode causes more wear to the clutch given that they apply pressure to the clutch over a much shorter period of time. Driving in normal mode would be like slowly releasing your clutch in a stick shift vs race mode's popping the clutch all the time. Also note, the haldex clutch has to handle alot more torque than than a transmission's clutch since most of the lower gears, the gear ratio means more torque comes out of the transmission than goes in.

[TeamZleep]

Buy a jeep I'd rather have Haldex over a 4WD system personally. But "real" quattro or Subaru AWD is definitely better than Haldex. Then again, not as easy to tune with just a chip..all mechanical in torsen at least.

Screw jeeps. I like haldex, I just question it's reliability sometimes, just like the DSG...

[motrrrpsycho]

[ZPrime]

My understanding was that besides the higher RPM to maintain torque and quicker throttle response, DSG Sport mode also keeps the rear differential engaged full-time, whereas in Drive it is disengaged unless traction is lost at the front. So the Haldex controller is only changing the speed or sensitivity of the torque distribution and not overriding or enhancing the behavior of the transmission?

This is dead wrong. The Haldex doesn't give a crap if you are in D or S, there is absolutely no communication between the DSG and the Haldex (beyond maybe a reverse/D signal or similar).

Haldex on our car doesn't apply any (or very very minimal) torque to the rear wheels until slip in the front is detected. Once there is slip, the haldex clutchpack is pressurized to a varying degree to create the "split". The pressure to actuate the clutchpack is based upon the speed differential between the input shaft (propshaft) and the clutchpack itself (which is linked to the rear diff and thus rear wheels).

People get confused about how torque works and try to compare Haldex directly to a Torsen diff, which doesn't work. If your front wheels are off the ground, they are providing zero torque - no friction, no torque. This means that the Haldex should fully lock and put 100% of the torque in the rear. (This won't actually happen in first gear because there are limits to the amount of torque the Haldex can handle, and the torque through the system is affected by the final drive, but you get the idea.)

This page from BorgWarner (who bought Haldex) gives more details than I can.

We have a Gen 2 Haldex system.

The HPA enhanced controller plays around with the amount of lockup that is applied to the clutchpack, thus changing the amount (of the possible available torque) that actually gets transmitted to the back wheels. With a lighter clutch pressure, you won't get as much torque to them.

apparently this next part is incorrect, I'm not sure where I read it but I thought it was truth. Race mode does NOT keep the rear engaged under braking.

Putting the controller in race mode also disables the safety-related feature of decoupling the clutchpack when braking. I believe the clutchpack will eventually disengage after enough time anyway (if there is no speed differential between front and rear wheels, there won't be any pressure left to keep the clutchpack closed, but this is just speculation on my part).

More good reading can be found on Vortex elsewhere. Here's a link straight to a good post, but the whole thread is informative.

This PDF from Haldex themselves is also a good read.

[ZPrime]

I keep reading it is engaged in Sport and it isnt. I dont know for sure what the truth is, but I suspect Sport keeps it engaged far more than drive. I can hear more whine when in Sport mode and virtually none in Drive mode. I wish I knew exactly when the rear is and is not engaged.

I believe this is loggable in VCDS but I'm not 100% sure of that. I will take a look next time I have the computer on the car (probably will happen again in the next few days).

[Sales@HPAmotorsports]

Putting the controller in race mode also disables the safety-related feature of decoupling the clutchpack when braking. I believe the clutchpack will eventually disengage after enough time anyway (if there is no speed differential between front and rear wheels, there won't be any pressure left to keep the clutchpack closed, but this is just speculation on my part).

This is not true.

Gen 2 units always disengage the rear end under braking.

The only units that do not are our Competition unit for the Gen 1 and Gen 4.

No availability of Comp unit for the Gen 2's as of yet.

[ZPrime]

aside from getting mixed up with the term power split and torque split. it is likely that sport or race mode causes more wear to the clutch given that they apply pressure to the clutch over a much shorter period of time. Driving in normal mode would be like slowly releasing your clutch in a stick shift vs race mode's popping the clutch all the time.

Remember that the clutch here is in hydraulic oil the whole time. There isn't a lot of actual friction happening even when there is slip. Plus, all of the wear on a clutch actually happens when it's slipping. the less slip you have, the less wear. In theory, running in Race with the clutchpack fully pressurized MORE often should mean less slip on it which I'd think would actually increase longevity... but we will never know until someone with the HPA controller rips out their clutchpack and compares it to a stock setup.

Also note, the haldex clutch has to handle alot more torque than than a transmission's clutch since most of the lower gears, the gear ratio means more torque comes out of the transmission than goes in.

Haldex themselves say the system is good for 2100-2400 N-m of torque (Depending on which document you read), which is something like 1500 ft-lbs. In theory you might be able to exceed this in 1st with the front wheels off the ground, but that is a fairly unlikely scenario.

[ZPrime]

This is not true.

Gen 2 units always disengage the rear end under braking.

The only units that do not are our Competition unit for the Gen 1 and Gen 4.

No availability of Comp unit for the Gen 2's as of yet.

"Race" mode on a Gen2 unit does not keep the rear engaged under braking!?

I swear that was thrown around in several places as one of the selling points for the switch and race mode. Very good info Keir. I'm not sure where I had read this but I was convinced that was part of "race" on the Gen2, which generally only happens if I read it somewhere authoritative...

[LWNY]

Remember that the clutch here is in hydraulic oil the whole time. There isn't a lot of actual friction happening even when there is slip. Plus, all of the wear on a clutch actually happens when it's slipping. the less slip you have, the less wear. In theory, running in Race with the clutchpack fully pressurized MORE often should mean less slip on it which I'd think would actually increase longevity... but we will never know until someone with the HPA controller rips out their clutchpack and compares it to a stock setup.

Since front and rear wheels almost always turn at different rate in dry condition, there should always be slip. If the haldex locks up as you are accelerating around turns, you will be destroying your driveline.

This is not true.

Gen 2 units always disengage the rear end under braking.

The only units that do not are our Competition unit for the Gen 1 and Gen 4.

No availability of Comp unit for the Gen 2's as of yet.

I thought some Gen I only kept the clutch engaged with one's foot off the accelerator, to facilitate engine braking, but one puts their foot on the brake, it is release so as to not interfere with the ABS system.

[JRutter]

"Race" mode on a Gen2 unit does not keep the rear engaged under braking!?

I swear that was thrown around in several places as one of the selling points for the switch and race mode. Very good info Keir. I'm not sure where I had read this but I was convinced that was part of "race" on the Gen2, which generally only happens if I read it somewhere authoritative...

My understanding was that it does allow for some engine braking - and it feels that way to me.

[Saabstory02]

This is dead wrong. The Haldex doesn't give a crap if you are in D or S, there is absolutely no communication between the DSG and the Haldex (beyond maybe a reverse/D signal or similar).

Truth

Haldex on our car doesn't apply any (or very very minimal) torque to the rear wheels until slip in the front is detected. Once there is slip, the haldex clutchpack is pressurized to a varying degree to create the "split". The pressure to actuate the clutchpack is based upon the speed differential between the input shaft (propshaft) and the clutchpack itself (which is linked to the rear diff and thus rear wheels).

Also truth, although partially incomplete What Z said above is exactly right with this caveat: With the above in mind, you have to remember also that Haldex is a 100% real-time system so the actuality of a 0% engagement is rearely ever the case. There is almost always a speed differential between the front and rear so there is almost always some rear power applied while moving. The amount varies constantly according to changes in that differential (IE turning, ice patch, gravel, etc etc).

Basically, unless you are idling at a stoplight or cruising on the highway in a straight line, you have at least some Haldex clutch engagement going on.

apparently this next part is incorrect, I'm not sure where I read it but I thought it was truth. Race mode does NOT keep the rear engaged under braking.

Putting the controller in race mode also disables the safety-related feature of decoupling the clutchpack when braking. I believe the clutchpack will eventually disengage after enough time anyway (if there is no speed differential between front and rear wheels, there won't be any pressure left to keep the clutchpack closed, but this is just speculation on my part).

Yeah; it's been tossed around often on the forum here that race mode keeps the Haldex engaged during braking (I've said it as well). Sucks but what can you do

I could swear it was passed on by system experts and the whole nine yard that race mode keeps the haldex engaged under braking, but who knows. I'll ask my guy at Haldex for confirmation...

More good reading can be found on Vortex elsewhere. Here's a link straight to a good post, but the whole thread is informative.

This PDF from Haldex themselves is also a good read.

Both excellent links, and that first one is a great explanation of torque

I believe this is loggable in VCDS but I'm not 100% sure of that. I will take a look next time I have the computer on the car (probably will happen again in the next few days).

Should be, I'd love to see some numbers on it.

Since front and rear wheels almost always turn at different rate in dry condition, there should always be slip. If the haldex locks up as you are accelerating around turns, you will be destroying your driveline.

Nope; you'll just have the equivalent of a locked rear end and you'll scrub the hell out of your tires... Ask me how I know

My understanding was that it does allow for some engine braking - and it feels that way to me.

Engine braking will still keep the Haldex engaged as you haven't touched the brake pedal yet. When you tap/press on the brake pedal, this disengages the Haldex unit (apparently).

Also as a nice to know: The Haldex is (unless the performance controller changes this setting as well?) also designed to disengage at very low speed maneuvers, IE parking lots and such, to make it easier to manuever

[motrrrpsycho]

I was told BY HPA and could swear I heard elsewhere that the gen 2 in race mode would keep the rear axles engaged under braking. When I was trying to decide rather to get the switch, I called HPA and talked to them about it. I don't recall the name of who I talked to, this was a couple years back, but we were talking specifically about the MKV R and gen2 controller - there was no confusion as to what we were talking about. I also asked specifically about the dyno plot overlay and was told that regardless of that being a turbo car, the overlay represented the difference of F/R power distribution acheived by the arious controller modes. HPA telling me that race mode including this feature and the dyno overlay I posted above are what convinced me to not only get the controller but to get the switch so I could have race mode.

Now we are saying gen2 race mode does not keep the rear axles engaged under braking?

And we are saying no power goes to the rear unless the front wheels are slipping and the only thing the controller actually does re-route power more quickly? How is the dyno overlay of the different modes explained then?

HPA - PLEASE answer the OP's question AND clarify on the above.

[Fast1one]

Guys, don't forget about brake bias! Engine braking with the rears engaged is like increasing the braking power in the rear, which makes your braking less effective! You want the front and the rear to have the same braking potential, which means weight transfer, rotor diameter, pad composition, tire size and power distribution have to be considered.

http://stoptech.com/technical-suppor...alance-matters

[abeR]

you are all not high, we were given this info previously.

[Mr_Peach]

I also asked specifically about the dyno plot overlay and was told that regardless of that being a turbo car, the overlay represented the difference of F/R power distribution acheived by the arious controller modes. HPA telling me that race mode including this feature and the dyno overlay I posted above are what convinced me to not only get the controller but to get the switch so I could have race mode.

.

I really enjoy that plot, but.....

Dyno has to have real world limitations, right? After re-reading the Haldex wiki, I wondered how Haldex deals with an AWD dyno. Isn't it in perpetual rear-wheel slip mode?

[Fast1one]

I really enjoy that plot, but.....

Dyno has to have real world limitations, right? After re-reading the Haldex wiki, I wondered how Haldex deals with an AWD dyno. Isn't it in perpetual rear-wheel slip mode?

Yes it is. I think what the dyno is giving us the absolute maximum power distributed to the rear under full slip conditions. But under normal driving conditions, especially partial throttle, the distribution to the rear is minimal just like stock.

[ehhh]

On an all wheel dyno the front wheels are perpetually "slipping" (rotating faster than the rears), so the Haldex engages the rear axle. There's a pretty thorough VW technical doc on the Haldex system floating around out there.

[motrrrpsycho]

Fast1one
Originally Posted by Mr_Peach
I really enjoy that plot, but.....

Dyno has to have real world limitations, right? After re-reading the Haldex wiki, I wondered how Haldex deals with an AWD dyno. Isn't it in perpetual rear-wheel slip mode?
Yes it is. I think what the dyno is giving us the absolute maximum power distributed to the rear under full slip conditions. But under normal driving conditions, especially partial throttle, the distribution to the rear is minimal just like stock.

ehhh
On an all wheel dyno the front wheels are perpetually "slipping" (rotating faster than the rears), so the Haldex engages the rear axle. There's a pretty thorough VW technical doc on the Haldex system floating around out there.

This makes sense, and now I feel like an idiot (as far as how I interpreted the dyno plot). I feel slightly duped, but mostly just stoopid.

I still have the question regarding race mode though. My understanding of why you would want the rear axles engaged under braking is that it helps keep the car more stable under heavy braking when hitting bumps and what not. I had a couple of incidents pre haldex controller when braking hard and hitting bumps that it felt like the rear wanted kick out, maybe even try to come around on me. I -thought- I was perceiving an improvement in stability in similar conditions after getting the controller, but apparently I've been smoking peyote...

And apparently not just me, but allot of folks who have the gen 2 controllers have been smoking something when we perceive the car pushing more from the rear as we accelerate through / out of corners, or thinking we can do better donuts in a snowy parking lot, etc etc???????