GolfGTIforum.co.uk
Model specific boards => Golf mk7 => Topic started by: Jackie Treehorn on 23 August 2014, 07:21
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Hi
I wondered if someone could answer a couple of questions on the PP Diff. I am waiting for my car (another 4 weeks approx) and the PP diff seems to raise some questions that i haven't seen answers to on forums.
1:Does it need any maintenance long term? I have seen how it works, but not sure if the gearbox oil lubricates it, and whether the gearbox oil is different to non PP because of this LSD system? Is it wise to change at 30k intervals for example?
2:Also, this may seem stupid but if I permanently leave the diff in "sport" or "on" does this mean it will effectively wear out as it is a clutch based diff that may require long term rebuilds? (bit alarmist but just asking)
3: like #2 - What are you thoughts on whether it should be used sparingly instead of on the daily commute? Not that it will be driven hard on the commute, but should it be switched off when not having fun?
I know its a lot of questions, thanks in advance... :smiley:
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Hi
1. Not sure sorry
2. The diff is always on and sport mode just does the dampers and changes the gear box to sport if dsg box.
I think they are pretty robust as I have driven my one hard and love it..just enjoy.
Mike
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3. Same as 2 really
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Hi
1. Not sure sorry
2. The diff is always on and sport mode just does the dampers and changes the gear box to sport if dsg box.
I think they are pretty robust as I have driven my one hard and love it..just enjoy.
Mike
Gotta be honest i'm not sure what difference it makes but the diff has it's own "sport" setting in individual mode separate to the dampers and engine.
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Ok was not aware of that..thanks
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thanks all, I thought it might be tough to answer something that seems pretty new to the VW market, but like clutch plate diffs on other cars I have read, some need maintenance, also some BMW cars with LSD need a different oil to open diff models, so wondered whether it might be the same on the VW?
I planned to replaced the diff oil on my BMW every 3 years or 25K so just wondered what might be a suitable long term process to follow for this type of Diff, without any online handbook i'm not sure...
I thought the diff is off when in normal mode and the car uses the XDS system, but when nt "Sport" mode, or the individual "sport" mode for the diff, the diff becomes active? Either way i guess it will be fine for long term active use
See below. @ 1.05 for diff setting
https://www.youtube.com/watch?v=dIETxZLoA_Y
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Mines stayed in sport mode pretty much from when I've bought it and been driven hard for many of it's 9000 miles. I can't imagine any issues arising with the LSD.
VW would certainly make a point to tell you if this was the case.
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Not sure VW would tell you that its going to wear out if used hard. Hardly a selling point is it?
As a guide, read up on TSi cam chain tensioners....
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I Understand things wear out, just not sure if this is an item that i should leave on all the time. If its hydraulically controlled, is the hydraulic fluid changeable? if separate from gearbox?
BMW diffs on some models are "lifetime fill" but that only means life time of the available warranty, and as they have a fill plug, i have drained and refilled before to change out the old fluid after 25K. Same with PS fluid after 60k on the last couple of cars (Porsche,Audi) , nothing is lifetime fill with the amount of abuse hydraulic, diff or gearbox fluid takes (IMO of course)
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I doubt the diff is going to be worked that hard in every day driving unless your driving like an idiot round corners at 90mph every where you go.
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Hi
1. Not sure sorry
2. The diff is always on and sport mode just does the dampers and changes the gear box to sport if dsg box.
I think they are pretty robust as I have driven my one hard and love it..just enjoy.
Mike
Gotta be honest i'm not sure what difference it makes but the diff has it's own "sport" setting in individual mode separate to the dampers and engine.
As fair as i am aware the diff in sport mode allows a little more 'play' in the corners, if you want the diff to work most 'effectively' then leave it in normal
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As fair as i am aware the diff in sport mode allows a little more 'play' in the corners, if you want the diff to work most 'effectively' then leave it in normal
I'm not saying you're wrong... but on a front wheel drive car that seems odd...
If it is a plate type diff, then it will, over time, wear the plates and become less effective.
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As fair as i am aware the diff in sport mode allows a little more 'play' in the corners, if you want the diff to work most 'effectively' then leave it in normal
As far as i understand (but happy to be proved wrong).
In Sport: It will be open (off) on deceleration for added stability, and locking (on) on throttle to distribute the power 0-100% to either wheel. It also acts to vary yaw movement through sharp left right turns if oversteer is detected to reduce the need for input from the ESC system.
In normal mode: Its off and basically reverts to the GTI without the Diff, and just uses the XDS + system.
I am trying to find the source for this info but i have read sooo much in the couple of months so far waiting that i can't find it again.
*edit: Some info
Front differential lock info http://www.vwvortex.com/news/volkswagen-news/volkswagen-golf-7-gti-press-materials/
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As fair as i am aware the diff in sport mode allows a little more 'play' in the corners, if you want the diff to work most 'effectively' then leave it in normal
In Sport: It will be open (off) on deceleration for added stability, and locking (on) on throttle to distribute the power 0-100% to either wheel.
This makes much more sense - and sounds, to me, more like a Torsen setup than a plate type LSD...
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Is anyone close to their manual doesnt it say in there? I dont often drive in sport as the potholes round here are terrible and I cannot believe that I have never had my LSD on.... I wouldnt be here if it wasnt on??
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Some more info to help/confuse me :)
I guess the book may not say much but would like to find out, although i will prob find out my self at the end of Sept
1,600 Nm maximum locking moment. If the control module detects wheel slip at one of the front wheels, the plates are actuated to redistribute the drive torque from the wheel with the lower grip level to the wheel with the higher level. The maximum locking moment is 1,600 Nm, so that if necessary all of the drive torque can be directed to just one front wheel; that corresponds to a locking value of 100 per cent. This produces maximum traction for a front-wheel drive vehicle, even under difficult roadway conditions and in turning situations.
ESC Sport
In the new Golf GTI, Volkswagen is offering the "ESC Sport" function for very experienced drivers. The system is activated by a two-stage switch on the centre console. If the driver pushes the button once briefly, it deactivates the ASR function (traction control). When the button is pressed longer than three seconds, Electronic Stability Control (ESC) switches to the "ESC Sport" mode. In very fast driving with lots of bends - such as on a race course - the ESC system reacts with a delay, which enables even greater agile handling properties. As an alternative to activation by the pushbutton on the centre console, ESC can now also be activated or deactivated by settings in the CAR menu.
[Source: Volkswagen]
Unlike the electronic EDL or XDS traction systems, which use a standard differential in conjunction with individual electronic control of the front brakes, the VAQ is an active mechanical clutch pack-based device located between the differential cage and the right-hand drive shaft. The pressure required to actuate the clutch pack is produced and regulated by an electrically-powered hydraulic pump
The car has a normal differential in the gearbox casing.
So, we have a system of variable "friction" clutches, modulated by hydraulic pressure from an electric pump, that can modify the "locking" action (the Slip) between one of the halfshafts and the crownwheel / diffcage. (exactly as in a conventional LSD)
In a turn, the different wheel paths result in a wheel speed variance, and the lateral G results in a tyre normal load difference. As such, for a conventional differential, which MUST maintain the same torque for both wheels (set by the lowest denominator), if the driver applies a drive torque higher than that set by the inside wheel (the lightly normally loaded one) that wheel will overspeed, resulting in that excess torque simply being used to speed up that wheel/tyre and not to drive the car forward.
With a locked diff, the limit becomes that of the outside wheel/tyre, which will be significantly higher due to the weight transfer onto that outside tyre (latG x CofG height x front mass). This means the car can longitudinally accelerate harder than one without an LSD.
With the locking system, the diff will act to EQUALISE the speed differential across the front axle, and as a result the inside wheel will overspeed. However, this will not result in a high longitudunal acceleration (assuming the tyre is full loaded and is at the "peak" of its slip/force curve). In fact, this will result in less longitudinal drive force on the inside wheel. However, the outside tyre can accept this higher drive torque, and produce a high longitudinal drive force, and as such the inside wheel drive force falls and the outside one rises. This is the "effective" Torque Vectoring that they are talking about.
It does however rely on the driver applying more throttle, and hence more drive torque, themselves (unlike a proper torque vectoring system that can do this with the torque it is currently supplied with). The result of that is probably what Dan is talking about as a "slighty none intuitive" need to apply more throttle that seems normal to get the front diff to really "work" in his Gti/Meganne piece
The biggest benefit of the electronic control of slip is that your input parameter matrix become very wide indeed. For a conventional LSD using ramps or sprung plates etc the input parameter is primarily drive torque (both positive (drive) and negative (overun). With electronic control, you can apply modifications to the wheel speed split (and hence vehicle yaw authority) based on things such as vehicle speed, driving mode (Normal, sport, eco etc) and of course multiple inputs from the dynamic stability control system (for example, keeping an open diff with no handwheel feel corruption most times, but locking it hard when yaw stability (and phase lag) become critical, such as in an emergency lane change etc
[Source: Max Torque]
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Some more info to help/confuse me :)
I guess the book may not say much but would like to find out, although i will prob find out my self at the end of Sept
1,600 Nm maximum locking moment. If the control module detects wheel slip at one of the front wheels, the plates are actuated to redistribute the drive torque from the wheel with the lower grip level to the wheel with the higher level. The maximum locking moment is 1,600 Nm, so that if necessary all of the drive torque can be directed to just one front wheel; that corresponds to a locking value of 100 per cent. This produces maximum traction for a front-wheel drive vehicle, even under difficult roadway conditions and in turning situations.
ESC Sport
In the new Golf GTI, Volkswagen is offering the "ESC Sport" function for very experienced drivers. The system is activated by a two-stage switch on the centre console. If the driver pushes the button once briefly, it deactivates the ASR function (traction control). When the button is pressed longer than three seconds, Electronic Stability Control (ESC) switches to the "ESC Sport" mode. In very fast driving with lots of bends - such as on a race course - the ESC system reacts with a delay, which enables even greater agile handling properties. As an alternative to activation by the pushbutton on the centre console, ESC can now also be activated or deactivated by settings in the CAR menu.
[Source: Volkswagen]
Unlike the electronic EDL or XDS traction systems, which use a standard differential in conjunction with individual electronic control of the front brakes, the VAQ is an active mechanical clutch pack-based device located between the differential cage and the right-hand drive shaft. The pressure required to actuate the clutch pack is produced and regulated by an electrically-powered hydraulic pump
The car has a normal differential in the gearbox casing.
So, we have a system of variable "friction" clutches, modulated by hydraulic pressure from an electric pump, that can modify the "locking" action (the Slip) between one of the halfshafts and the crownwheel / diffcage. (exactly as in a conventional LSD)
In a turn, the different wheel paths result in a wheel speed variance, and the lateral G results in a tyre normal load difference. As such, for a conventional differential, which MUST maintain the same torque for both wheels (set by the lowest denominator), if the driver applies a drive torque higher than that set by the inside wheel (the lightly normally loaded one) that wheel will overspeed, resulting in that excess torque simply being used to speed up that wheel/tyre and not to drive the car forward.
With a locked diff, the limit becomes that of the outside wheel/tyre, which will be significantly higher due to the weight transfer onto that outside tyre (latG x CofG height x front mass). This means the car can longitudinally accelerate harder than one without an LSD.
With the locking system, the diff will act to EQUALISE the speed differential across the front axle, and as a result the inside wheel will overspeed. However, this will not result in a high longitudunal acceleration (assuming the tyre is full loaded and is at the "peak" of its slip/force curve). In fact, this will result in less longitudinal drive force on the inside wheel. However, the outside tyre can accept this higher drive torque, and produce a high longitudinal drive force, and as such the inside wheel drive force falls and the outside one rises. This is the "effective" Torque Vectoring that they are talking about.
It does however rely on the driver applying more throttle, and hence more drive torque, themselves (unlike a proper torque vectoring system that can do this with the torque it is currently supplied with). The result of that is probably what Dan is talking about as a "slighty none intuitive" need to apply more throttle that seems normal to get the front diff to really "work" in his Gti/Meganne piece
The biggest benefit of the electronic control of slip is that your input parameter matrix become very wide indeed. For a conventional LSD using ramps or sprung plates etc the input parameter is primarily drive torque (both positive (drive) and negative (overun). With electronic control, you can apply modifications to the wheel speed split (and hence vehicle yaw authority) based on things such as vehicle speed, driving mode (Normal, sport, eco etc) and of course multiple inputs from the dynamic stability control system (for example, keeping an open diff with no handwheel feel corruption most times, but locking it hard when yaw stability (and phase lag) become critical, such as in an emergency lane change etc
[Source: Max Torque]
Anyone understand that :embarrassed:
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Lol
tech info aside, the sport button near the gearstick doesn't appear to have any relation on the PP diff. ESC enhanced settings in sport is a separate feature. That's the way i read it anyway.
also the PP cars get the std diff in the gearbox casing and a torsion applied clutch pack diff on the side, that's hydraulically controlled.
someone must know on here, the cars have been out a while and so many people are driving them. I want to make sure i understand what things do on my cars and how they wear mechanically so i can be sympathetic to them. But i guess most just drive, and look at the next car purchase at the end of the lease.
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Lol
tech info aside, the sport button near the gearstick doesn't appear to have any relation on the PP diff. ESC enhanced settings in sport is a separate feature. That's the way i read it anyway.
also the PP cars get the std diff in the gearbox casing and a torsion applied clutch pack diff on the side, that's hydraulically controlled.
someone must know on here, the cars have been out a while and so many people are driving them. I want to make sure i understand what things do on my cars and how they wear mechanically so i can be sympathetic to them. But i guess most just drive, and look at the next car purchase at the end of the lease.
I quite agree as I like to look after my cars even if it will be following owners who see the benefit.
Is the diff on the PP a safety feature that could help me during normal driving or in the wet or is it just something which only comes into use when driven hard or on the track. Safety is important it worries be a little when reports say you need to bury the throttle in the corner to trigger the benefit. I have an interest in road safety during to my profession :smiley:
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Best thing to do is find a big,open,empty,wet roundabout and start playing.
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Is the diff on the PP a safety feature that could help me during normal driving or in the wet or is it just something which only comes into use when driven hard or on the track. Safety is important it worries be a little when reports say you need to bury the throttle in the corner to trigger the benefit. I have an interest in road safety during to my profession :smiley:
Not really a safety feature as such, it allows you to access more of the performance without spinning away the power through the unloaded front wheel... TBH, if you're seeing regular significant benefit on the public road... then let us know where you're going to be... so we can make sure we're not there :grin:
So, my understanding is that it is a "torsen" system... In my experience (similar torsen type diff on Integra Type-R), they're very good in the dry and damp/wet conditions reducing understeer and improving traction out of corners... Counter intuitive in snow/icy conditions.
Remember they only work under load. In snow/ice/wet mud etc they tend to lock (100%) and you will find that the car is very reluctant to turn... you need to come off the throttle, turn and then get gently back on the power.
Plate type diffs tend to me more tunable in terms of locking strategy (hence why the rally car I navigate in has a plate type diff) but require much more maintenance (a rebuild every few events) to account for the wear on the plates... This is why the majority of manufacturers who fit an LSD to road cars go for the torsen type as they require much less maintenance...
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Is the diff on the PP a safety feature that could help me during normal driving or in the wet or is it just something which only comes into use when driven hard or on the track. Safety is important it worries be a little when reports say you need to bury the throttle in the corner to trigger the benefit. I have an interest in road safety during to my profession :smiley:
Not really a safety feature as such, it allows you to access more of the performance without spinning away the power through the unloaded front wheel... TBH, if you're seeing regular significant benefit on the public road... then let us know where you're going to be... so we can make sure we're not there :grin:
So, my understanding is that it is a "torsen" system... In my experience (similar torsen type diff on Integra Type-R), they're very good in the dry and damp/wet conditions reducing understeer and improving traction out of corners... Counter intuitive in snow/icy conditions.
Remember they only work under load. In snow/ice/wet mud etc they tend to lock (100%) and you will find that the car is very reluctant to turn... you need to come off the throttle, turn and then get gently back on the power.
Plate type diffs tend to me more tunable in terms of locking strategy (hence why the rally car I navigate in has a plate type diff) but require much more maintenance (a rebuild every few events) to account for the wear on the plates... This is why the majority of manufacturers who fit an LSD to road cars go for the torsen type as they require much less maintenance...
Just backs up my view that unless you drive it hard it is of little use. I shall not be doing that so little value to me should have saved the money .... I do prefer the calipers on the PP though :smiley:
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I guess a quick way to check.
If you press the Mode button and put the car in sport mode on the console near the gear stick. Then go to individual settings and see if the diff is selected as "sport". This will tell us if the diff is always on in sport mode or whether the console mode button just changes the other functions, like steering and dampers if you car has DCC. If the diff has to be manually selected then people that have the car in sport, don't have the diff active I guess. If it does select all sport features then you are using the hydraulic clutch based diff all the time, which may lead it to wear quicker, or not...