RE: Megane Renaultsport 275 Trophy: Driven
Discussion
philmots said:
epom said:
Whilst I appreciate the last figure on a car like this that I should be looking at is the top speed, I can't believe a Megane will make it all the way to 158mph ?
Why? It's not that far short of 300hp!iloveboost said:
That's impressive but I can't understand why an electrical diff would take more time to lock than a mechanical diff and that's why I interpreted the quote wrongly. For example here's a quote about the BMW active M-diff compared to the previous mechanical diff:
'The Active M Differential is the next step in giving the rear wheel drive chassis more control and stability. Rather than requiring slip, like a viscous differential, the new system can be proactive thanks to the use of electronics. It interprets data from the Dynamic Stability Control to provide the optimum locking force to each wheel all before a wheel breaks free.' The VAQ diff seems like a FWD version of this diff from what I can tell from photos, etc so why is it slower to lock than a mechanical diff when that quote is saying active diffs are faster? It's confusing me.
VAQ in the Golf and SEAT is much misunderstood but is not a diff like the M one or, indeed, others like Jag's - it operates independently of the differential cage and (as was explained to me) it is an electronically controlled Haldex clutch unit that can distribute up to 100 per cent of the drive torque to one wheel or the other. As such it works with the ESP and can provide torque vectoring too. From driving it there certainly feels to be a 'lag' between throttle input and it deciding where the torque is going to go. It IS effective and feels really spooky as it pulls the front end into the turn under power but you have to have swallowed a brave pill and driven through what feels like terminal power understeer for it to do that. 'The Active M Differential is the next step in giving the rear wheel drive chassis more control and stability. Rather than requiring slip, like a viscous differential, the new system can be proactive thanks to the use of electronics. It interprets data from the Dynamic Stability Control to provide the optimum locking force to each wheel all before a wheel breaks free.' The VAQ diff seems like a FWD version of this diff from what I can tell from photos, etc so why is it slower to lock than a mechanical diff when that quote is saying active diffs are faster? It's confusing me.
So effective and very advanced, not to mention a real USP by VW for a FWD car, but not as intuitive and readable as the Megane's mechanical set-up. VW has muddied the water slightly in its press pack description but the blame really lies with my esteemed colleagues who haven't made the distinction about how VAQ differs from conventional locking diff set-ups and just varyingly referred to it as a limited-slip diff or 'active diff'. Further compounded by the fact the latter seems a catch-all description/confusion between electronically controlled locking diffs and ESP-based 'faux' LSDs.
Rant, rant, rant!
Cheers,
Dan
Dan Trent said:
and can provide torque vectoring too.
Would be genuinely interested to understand if this were the case. Surely to do this it requires a clutch on each driveshaft? VW need to update the Wiki pagehttp://en.wikipedia.org/wiki/Torque_vectoring
Dan Trent said:
VAQ in the Golf and SEAT is much misunderstood but is not a diff like the M one or, indeed, others like Jag's - it operates independently of the differential cage and (as was explained to me) it is an electronically controlled Haldex clutch unit that can distribute up to 100 per cent of the drive torque to one wheel or the other. As such it works with the ESP and can provide torque vectoring too. From driving it there certainly feels to be a 'lag' between throttle input and it deciding where the torque is going to go. It IS effective and feels really spooky as it pulls the front end into the turn under power but you have to have swallowed a brave pill and driven through what feels like terminal power understeer for it to do that.
So effective and very advanced, not to mention a real USP by VW for a FWD car, but not as intuitive and readable as the Megane's mechanical set-up. VW has muddied the water slightly in its press pack description but the blame really lies with my esteemed colleagues who haven't made the distinction about how VAQ differs from conventional locking diff set-ups and just varyingly referred to it as a limited-slip diff or 'active diff'. Further compounded by the fact the latter seems a catch-all description/confusion between electronically controlled locking diffs and ESP-based 'faux' LSDs.
Rant, rant, rant!
Cheers,
Dan
looking at the VAQ cross section I really do not see how it can be a propper torque vectoring diff.. and in our test drives, on some narrow B roads we have found it grossly lacking in comparison to megane RS. So effective and very advanced, not to mention a real USP by VW for a FWD car, but not as intuitive and readable as the Megane's mechanical set-up. VW has muddied the water slightly in its press pack description but the blame really lies with my esteemed colleagues who haven't made the distinction about how VAQ differs from conventional locking diff set-ups and just varyingly referred to it as a limited-slip diff or 'active diff'. Further compounded by the fact the latter seems a catch-all description/confusion between electronically controlled locking diffs and ESP-based 'faux' LSDs.
Rant, rant, rant!
Cheers,
Dan
The reason for it's slowness might be the control mechanism. The torsen diffs work purely by applying the drive torque, so they will start locking the moment you are on the throttle. If the VAQ diff waits for the sensors to detect slip in order to lock, that is why you have such delay.
Here's the official description of VAQ and its functions from the Golf GTI press pack I don't think many other hacks bothered to read! And, yes, 'torque vectoring effect' rather than the real thing.
Cheers,
Dan
Cheers,
Dan
VW press pack said:
Front differential lock
A newly engineered electronic front differential lock is being used exclusively in the Golf GTI Performance. To date, Volkswagen is the only carmaker to utilise an electronically controlled differential lock in a front-wheel drive production model. Compared to purely mechanical locks, the front differential lock integrated in the Golf GTI Performance offers advantages such as a variable degree of locking and comprehensive interfaces to the ESC, EDS and XDS+ functions. This makes it possible to completely avoid negative effects on steering response and steering precision that otherwise occur with mechanical locks. As a result, the system realises the full potential and maximum performance of a differential lock with regard to vehicle dynamics, because comfort is not impaired under any circumstances.
Functionality of the front differential lock. The front differential lock operates without any power losses here, so that the power produced by the engine is transferred 100 per cent to the road and is fully available to propel the GTI.
The electronic front differential lock utilises a multi-plate unit located between the right side driveshaft and the differential case. The hydraulic pressure needed to actuate the plates is generated by an electric motor driven piston pump. The locking moment that is generated here is proportional to the hydraulic pressure. The hydraulic pressure is controlled by the pump speed that is prescribed by a control module. This control module takes numerous parameter inputs – such as wheel speed, vehicle speed, yaw rate and transverse acceleration – and computes the ideal locking moment.
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.
Torque vectoring effect. When accelerating out of a bend, the drive torque is increased at the wheel on the outside of the bend. This produces an asymmetrical drive torque distribution that matches the dynamic wheel load distribution. This is known as a "torque vectoring effect" which reduces acceleration-related understeer. As a result, the Golf GTI Performance handles neutrally and precisely tracks along the ideal line. The existing grip level is optimally exploited. This lets the driver apply much greater force to the accelerator pedal at the apex of a bend, which in turn results in significantly higher speed exit speeds of the Golf GTI Performance out of bends.
ESC intervenes more gently and with delay. In highly dynamic situations, such as in fast driving through alternating curves, unexpected avoidance manoeuvres or load changes, the front differential lock is used to dampen yaw movements. When oversteer occurs, the front differential lock generates a stabilising yaw moment; this means that ESC interventions can be made gentler and later or might even be avoided altogether. So, the controlled front differential lock stands for even more driving fun and better performance.
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.
A newly engineered electronic front differential lock is being used exclusively in the Golf GTI Performance. To date, Volkswagen is the only carmaker to utilise an electronically controlled differential lock in a front-wheel drive production model. Compared to purely mechanical locks, the front differential lock integrated in the Golf GTI Performance offers advantages such as a variable degree of locking and comprehensive interfaces to the ESC, EDS and XDS+ functions. This makes it possible to completely avoid negative effects on steering response and steering precision that otherwise occur with mechanical locks. As a result, the system realises the full potential and maximum performance of a differential lock with regard to vehicle dynamics, because comfort is not impaired under any circumstances.
Functionality of the front differential lock. The front differential lock operates without any power losses here, so that the power produced by the engine is transferred 100 per cent to the road and is fully available to propel the GTI.
The electronic front differential lock utilises a multi-plate unit located between the right side driveshaft and the differential case. The hydraulic pressure needed to actuate the plates is generated by an electric motor driven piston pump. The locking moment that is generated here is proportional to the hydraulic pressure. The hydraulic pressure is controlled by the pump speed that is prescribed by a control module. This control module takes numerous parameter inputs – such as wheel speed, vehicle speed, yaw rate and transverse acceleration – and computes the ideal locking moment.
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.
Torque vectoring effect. When accelerating out of a bend, the drive torque is increased at the wheel on the outside of the bend. This produces an asymmetrical drive torque distribution that matches the dynamic wheel load distribution. This is known as a "torque vectoring effect" which reduces acceleration-related understeer. As a result, the Golf GTI Performance handles neutrally and precisely tracks along the ideal line. The existing grip level is optimally exploited. This lets the driver apply much greater force to the accelerator pedal at the apex of a bend, which in turn results in significantly higher speed exit speeds of the Golf GTI Performance out of bends.
ESC intervenes more gently and with delay. In highly dynamic situations, such as in fast driving through alternating curves, unexpected avoidance manoeuvres or load changes, the front differential lock is used to dampen yaw movements. When oversteer occurs, the front differential lock generates a stabilising yaw moment; this means that ESC interventions can be made gentler and later or might even be avoided altogether. So, the controlled front differential lock stands for even more driving fun and better performance.
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.
Thanks for the info Dan I think I've got it now.
The BMW M3 E46 used a mechanically controlled viscous LSD (I think like early Haldex?) so it takes a lot more time to lock than the electronically controlled viscous LSD used in the V8 M3. However even the faster diff must still take longer to lock than a geared LSD I guess it just makes more traction when there's little grip.
A geared LSD seems best overall as long as both tyres have some traction.
The BMW M3 E46 used a mechanically controlled viscous LSD (I think like early Haldex?) so it takes a lot more time to lock than the electronically controlled viscous LSD used in the V8 M3. However even the faster diff must still take longer to lock than a geared LSD I guess it just makes more traction when there's little grip.
A geared LSD seems best overall as long as both tyres have some traction.
a gear type diff... such as torsen type diffs used on the megane, RCZR, integra type R etc... are smooth in operation and imho effective enough for everything apart from racing (where one might like the adjustability and single wheel on the ground traction that you get from a plate diff.
If you try a mazda 3 MPS, which uses a plate type front diff you'll find that it is much more noticeable in operation, bordering on violent in some circumstances.
speaking about FWD cars of course.. RWD / AWD is another matter altogether.
If you try a mazda 3 MPS, which uses a plate type front diff you'll find that it is much more noticeable in operation, bordering on violent in some circumstances.
speaking about FWD cars of course.. RWD / AWD is another matter altogether.
THe 275 could well be the greatest car ever made but I discovered a small problem with it. My local RenaultSport dealer is completely hopeless! Didn't have much of a clue beyond that they'd heard of it, and that was after more than 1/2 hour waiting for sales staff to be bothered to deal with my query! Went along the road to Ford so as not to waste the afternoon, got a test in a Focus ST3 and was mightily impressed. It's one downside being the lack of a proper diff as it occasionally struggles with even the 250bhp. But a car that I'd never even considered is now on my short list. The Renault? If that's how the dealers try to sell you cars, what would they be like for aftersales! No thanks.
Ali_T said:
The Renault? If that's how the dealers try to sell you cars, what would they be like for aftersales! No thanks.
That's a shame. Pity really, think there are some competent Renault sales people on PH. I'm sure they could help with the purchasing part. But if you are not convinced about how your local shop will do regarding after sales...Just an anecdote, but my BMW place round the corner has the most arrogant sales staff on earth. Also not really competent. Not a good mix, so I avoid. But their chief tech is really good. Just saying that sales and after sales experience is not necessarily correlated.
That would be worth the price of admission alone!irish boy said:
speedjockey said:
Why even bother with the Trophy-R then if this is essentially the better package when spec'd up? Don't think I'd bother with the R at all frankly..
Rarity, residuals, and you can be guaranteed the boys in renaultsport will put a 'little extra something' in the r.Based on that sort of demand they won't drop much.
Think BMW 1M kind of residuals
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