BMW better than TT in deep rain ?
03-26-2005, 05:15 AM
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BMW better than TT in deep rain ?
I am surprised by the reaction of my TT in bad roads and bad weather.
I have allways thought that a 4WD TT will show an evident advantage when raining but in "B" spanish roads ( irregular bumps, puddles of water ), when seriously pushing the car my feeling is that it's handling becomes somehow erratic. The truth is that in those occasions, surprisingly, I feel much better driving a big ,slow and "old" 2WD 528 BMW than my TT. I woud even say that I am a faster driver with the BMW.... (??!!).
What surprises me is not that the handling changes in those opportunities, but that I do not find the advantage of the 4WD .
I have been driving my TT since a year and a half, occasionally tracking since...twenty years , attending slidding courses, this is my 4th Porsche and my second 4WD but ONLY in those particular conditions, since the very first day, I still have the feeiling that the car is continuously loosing it's front line and then the rear and...back again. It feels like if it was shifting from rear to front traction. The strange thing is that if you keep going at the same pace the car finally keeps the road but it is not at all a reassuring feeling.
I have checked my alignment, the thread of the tires is ok, my suspension is an untouched ROW. Has anybody else experienced the same thing ? Could this be due to the tires width ? Is this a typical feeling?
I have allways thought that a 4WD TT will show an evident advantage when raining but in "B" spanish roads ( irregular bumps, puddles of water ), when seriously pushing the car my feeling is that it's handling becomes somehow erratic. The truth is that in those occasions, surprisingly, I feel much better driving a big ,slow and "old" 2WD 528 BMW than my TT. I woud even say that I am a faster driver with the BMW.... (??!!).
What surprises me is not that the handling changes in those opportunities, but that I do not find the advantage of the 4WD .
I have been driving my TT since a year and a half, occasionally tracking since...twenty years , attending slidding courses, this is my 4th Porsche and my second 4WD but ONLY in those particular conditions, since the very first day, I still have the feeiling that the car is continuously loosing it's front line and then the rear and...back again. It feels like if it was shifting from rear to front traction. The strange thing is that if you keep going at the same pace the car finally keeps the road but it is not at all a reassuring feeling.
I have checked my alignment, the thread of the tires is ok, my suspension is an untouched ROW. Has anybody else experienced the same thing ? Could this be due to the tires width ? Is this a typical feeling?
03-26-2005, 09:20 AM
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Sorry I'm not familiar with the details of the AWD system in the TT, but do know other AWD systems intimately (I'm working with a number of them at the moment in the day job) - it is possible that it is the AWD system moving the torque around (front-to-rear) as the car's moving, sort of hunting for that ideal proportioning but not finding it (or the surface/driving conditions are changing too rapidly for it to keep pace)... The BMW is easier since it's 100% consistent, the driveline bias is constant, and you don't have to adapt to it.
Lesser AWD systems (FWD-based ones like Lexus RS330, Acura MDX, Nissan Murano) are really bad at this, with rather sudden massive torque transfers to the rear only on occasion, making the car go from a bad understeer to a sudden tail-happy slide... but you only see this in the slippery stuff.
Being as how you're driving a Porsche... I really hope this isn't the case!
Actually, now that I think of it - I got to do some laps of Mid-O in a Cayenne (can you tell I play with Stupid Useless Vehicles a lot?) and a few laps were in the wet... and I noticed some similar odd torque distribution changes, didn't seem well coordinated. I was slightly purturbed by them, but didn't get a chance to re-try in the dry...
Lesser AWD systems (FWD-based ones like Lexus RS330, Acura MDX, Nissan Murano) are really bad at this, with rather sudden massive torque transfers to the rear only on occasion, making the car go from a bad understeer to a sudden tail-happy slide... but you only see this in the slippery stuff.
Being as how you're driving a Porsche... I really hope this isn't the case!
Actually, now that I think of it - I got to do some laps of Mid-O in a Cayenne (can you tell I play with Stupid Useless Vehicles a lot?) and a few laps were in the wet... and I noticed some similar odd torque distribution changes, didn't seem well coordinated. I was slightly purturbed by them, but didn't get a chance to re-try in the dry...
03-26-2005, 10:23 AM
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Your issue is dominated by the width of the tire for the weight of the car. The BMW has a narrower tire/weight ratio. Beyond that, if you are in the power in these conditions, it is easy to slip the rear tires. The TT is not really full time AWD, rather it tranfers power to the front when the rears spin. If you are doing this, then the power balance is changing quite a bit.
03-26-2005, 11:39 AM
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A lot depends on whether your TT has Haldex Mk I or Mk II. Mk I is open loop and unpredictable in its behaviour, ie it won't always behave the same way under the same conditions. Mk II is much better and is 'closed loop' in nature so it is predictable.
I have spent quite a lot of time on track with these cars. To get the best results try to be as smooth and balanced as possible, setting the car up for each corner. They do not react very well to a 'muscular' driving style, smooth is fast, very smooth is faster. With practice, and super smoothness, you can understeer or oversteer at will in these cars.
If you feed in too much steering for too long without taking steps to reduce the (usually) understeer, then the ESP will cut in before everything goes pear shaped, even if you have switched it off, correct for understeer immediately and you will feel the power transferring to the wheels which have grip and the car will track round the corner properly. These cars really do not suit the BMW driving style.
With a 'modified' flick approach, you can induce oversteer at will, bbut again be very smooth about it and wait for the tail to come out and be careful not to catch it too soon, otherwise you mwill kill it immediately.
Audi organises excellent driving courses on track at the Circuit de Catalunya in the TT. The instructors are first class and they will quickly get you familiar with the best way of driving these cars.
incidentally, try to corner in as high a gear as possible when driving fast, the ESP is less intrusive in 4th than it is in 3rd, for example.
R+C
I have spent quite a lot of time on track with these cars. To get the best results try to be as smooth and balanced as possible, setting the car up for each corner. They do not react very well to a 'muscular' driving style, smooth is fast, very smooth is faster. With practice, and super smoothness, you can understeer or oversteer at will in these cars.
If you feed in too much steering for too long without taking steps to reduce the (usually) understeer, then the ESP will cut in before everything goes pear shaped, even if you have switched it off, correct for understeer immediately and you will feel the power transferring to the wheels which have grip and the car will track round the corner properly. These cars really do not suit the BMW driving style.
With a 'modified' flick approach, you can induce oversteer at will, bbut again be very smooth about it and wait for the tail to come out and be careful not to catch it too soon, otherwise you mwill kill it immediately.
Audi organises excellent driving courses on track at the Circuit de Catalunya in the TT. The instructors are first class and they will quickly get you familiar with the best way of driving these cars.
incidentally, try to corner in as high a gear as possible when driving fast, the ESP is less intrusive in 4th than it is in 3rd, for example.
R+C
03-26-2005, 03:26 PM
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Thanks to everybody.
Nordschleife.- Thank you for your very valuable input, I will try to find and contact the Audi instructors. Anyhow, I am curious: how can I know if my car has Haldex Mk I or Mk II ?
I understand your advise on "muscular" driving but, in those very bad open roads when the car literally "jumps" from bump to bump and puddle to puddle, even when keeping the same regular (if the road allows it) pace, I feel that the behavior is a bit ( even more than a bit ) unpredictable.
I am more familiar with the TT attitude in a wet track as it is - normally - a smoother road only occasionally disturbed by some puddles that can be normally seen in advance . I have been tracking (in different occasions) in special slippery tracks together with the instructors that organize courses for Porsche and the basic advise was to induce oversteer with a somehow "brutal" ( but measured ) throttle burst in order to loose the back - once the car balance properly settled in order to avoid understeer - and when the car is sliding, keep it "feeded" with regular throttle input in order to maintain the slide all the way. I have to admit that this technique has offered reasonable good results...in those special slippery tracks. ( I have to say that the man in charge of the different slide courses that I have attended was an Ex-official BMW Rallie Driver, several times spanish rally champion ...)
I am afraid that I do not have the "courage" to do this when travelling in an open road....with cars passing by !
I will try your advise on higher gears and let you know.
924RACR.- You are describing somehow my feeling in slippery conditions. I have no complains in smooth stuff. What surprises me is that in European Rallies (WRC) which are run in very slippery and irregular roads, traditionally the 4WD where beating 2WD !!!
Nordschleife.- Thank you for your very valuable input, I will try to find and contact the Audi instructors. Anyhow, I am curious: how can I know if my car has Haldex Mk I or Mk II ?
I understand your advise on "muscular" driving but, in those very bad open roads when the car literally "jumps" from bump to bump and puddle to puddle, even when keeping the same regular (if the road allows it) pace, I feel that the behavior is a bit ( even more than a bit ) unpredictable.
I am more familiar with the TT attitude in a wet track as it is - normally - a smoother road only occasionally disturbed by some puddles that can be normally seen in advance . I have been tracking (in different occasions) in special slippery tracks together with the instructors that organize courses for Porsche and the basic advise was to induce oversteer with a somehow "brutal" ( but measured ) throttle burst in order to loose the back - once the car balance properly settled in order to avoid understeer - and when the car is sliding, keep it "feeded" with regular throttle input in order to maintain the slide all the way. I have to admit that this technique has offered reasonable good results...in those special slippery tracks. ( I have to say that the man in charge of the different slide courses that I have attended was an Ex-official BMW Rallie Driver, several times spanish rally champion ...)
I am afraid that I do not have the "courage" to do this when travelling in an open road....with cars passing by !
I will try your advise on higher gears and let you know.
924RACR.- You are describing somehow my feeling in slippery conditions. I have no complains in smooth stuff. What surprises me is that in European Rallies (WRC) which are run in very slippery and irregular roads, traditionally the 4WD where beating 2WD !!!
03-26-2005, 05:58 PM
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What Mark, Sunday driver said - weight of car to width of wheel, when dealing with big puddles or standing water, you are going to be faced with hydroplaning and it doesn't matter how many wheels or if they are driven or not.
I can tell you from experience at a few of our tracks that the difference going around a wet track in my car vs. a twin turbo on streets is phenonmenol for handling and braking alone. Rain is a great equalizer of the power advantage.
I can tell you from experience at a few of our tracks that the difference going around a wet track in my car vs. a twin turbo on streets is phenonmenol for handling and braking alone. Rain is a great equalizer of the power advantage.
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03-27-2005, 03:37 AM
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I would expect that you have Mk I.
Your point about doing all this stuff in traffic being difficult is very valid. The Audi Driving Experience Instructors teach people the techniques on left hand turns first, so people get used to the sensation of turning the steering wheel to the right (towards the oncoming traffic!), to get the car to stabilise and continue turning left. I use momentum to get the rear out and then the throttle to keep it there and adjust the angle and direction, best practiced on the track first!
When you are doing this at will, you will soon realise how controlled you are, but you do have to have better technique than in a BMW, like the Drift Challenge drivers you will be holding the car sideways with one hand out the window waving at the senoritas!
As far as Aquaplaning is concerned, you can feel the power being diverted to the wheels with the grip, which is reassuring, though I admit to feeling butterflies when it happens at over 300kph! i have found the Continental Sport Contact 2 tyre to be good in these conditions, but not with a BMW driving style.
In any event I do find the TT's rear end moves around a lot, I have learned to live with it, it mreminds me of a fidgitty child.
R+C
Your point about doing all this stuff in traffic being difficult is very valid. The Audi Driving Experience Instructors teach people the techniques on left hand turns first, so people get used to the sensation of turning the steering wheel to the right (towards the oncoming traffic!), to get the car to stabilise and continue turning left. I use momentum to get the rear out and then the throttle to keep it there and adjust the angle and direction, best practiced on the track first!
When you are doing this at will, you will soon realise how controlled you are, but you do have to have better technique than in a BMW, like the Drift Challenge drivers you will be holding the car sideways with one hand out the window waving at the senoritas!
As far as Aquaplaning is concerned, you can feel the power being diverted to the wheels with the grip, which is reassuring, though I admit to feeling butterflies when it happens at over 300kph! i have found the Continental Sport Contact 2 tyre to be good in these conditions, but not with a BMW driving style.
In any event I do find the TT's rear end moves around a lot, I have learned to live with it, it mreminds me of a fidgitty child.
R+C
03-27-2005, 04:27 AM
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Alan.- If:
, ( which I also believe ) where is the advantage of the 4WD supposed to be ? It has been said many times that the advantage is unexistant in dry conditions... and I have in mind that, before they where banned of different competitions, the 4WD where nearly always winning on 2WD in Rallies (WRC).
Does this mean that getting the 10/10th of a 4WD requires a more sophisticated technique than typically driving a 2wd ?... And less technique than in a 2WD when driven by a novice at 7/10th ?
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Rain is a great equalizer of the power advantage.
Does this mean that getting the 10/10th of a 4WD requires a more sophisticated technique than typically driving a 2wd ?... And less technique than in a 2WD when driven by a novice at 7/10th ?
03-27-2005, 04:31 AM
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Nordschleife, do you have by any chance the address or data of the team that organizes the Audi traing days? I doubt that if I contact Audi directly they will allow me to enter the courses with a Porsche !! 
03-27-2005, 07:03 AM
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Boqueron
How is your German?
here is a URL
http://www.audi.com/de/de/erlebniswe...experience.jsp
Audi provides all the cars, so you have no worries about your own car, and they can turn off the ABS and Stability Management (ESP) when required. They gave los Galacticos some driving tuition last year. I notice that the best instructors are not always the famous names, but most of the really fast ones come from Rallying.
Your assumption about getting 10/10th from a 4WD being more difficult than a 2WD is, I believe, correct. Also, what you say about the comparison with 2WD and novices. However, lots of people reach the limits early in a 4WD car if they use 2WD techniques, this is why so many journalists have problems with TTs and high performance Audis and review them so badly.
I was fortunate to spend some time on the Nordschleife with Walter Röhrl, he hardly moves his hands, perhaps turning the wheel half a hands-width, very very fast and very very smooth.
R+C
How is your German?
here is a URL
http://www.audi.com/de/de/erlebniswe...experience.jsp
Audi provides all the cars, so you have no worries about your own car, and they can turn off the ABS and Stability Management (ESP) when required. They gave los Galacticos some driving tuition last year. I notice that the best instructors are not always the famous names, but most of the really fast ones come from Rallying.
Your assumption about getting 10/10th from a 4WD being more difficult than a 2WD is, I believe, correct. Also, what you say about the comparison with 2WD and novices. However, lots of people reach the limits early in a 4WD car if they use 2WD techniques, this is why so many journalists have problems with TTs and high performance Audis and review them so badly.
I was fortunate to spend some time on the Nordschleife with Walter Röhrl, he hardly moves his hands, perhaps turning the wheel half a hands-width, very very fast and very very smooth.
R+C
03-27-2005, 07:04 AM
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03-27-2005, 07:07 AM
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Originally Posted by Nordschleife
here it is in full
http://www.audi.com/de/de/erlebniswelt/
driving_experience/driving_experience.jsp
I hope!
just append the second line to the first line when you enter it in your browser!
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03-27-2005, 07:13 AM
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this may help -
El curso deportivo es el más exigente y el que más emociones promete. Si eres propietario de un modelo de la gama S o un Audi TT, aquí tienes la oportunidad de comprobar todo el potencial de tu automóvil.
Todo el curso se desarrolla en un circuito, donde aprenderás a trazar y a dosificar el freno entre otras técnicas de conducción deportiva. Primero se estudia el circuito por sectores y luego se aborda en una serie de vueltas. Para finalizar, los asistentes pueden acompañar a los instructores en vueltas rápidas, afrontando las curvas con derrapajes.
Para finalizar, los asistentes pueden disfrutar de una vuelta rápida al circuito de la mano del piloto Jordi Gené.
Si quieres saber hasta dónde llega la potencia de tu Audi y tu capacidad al volante, rellena el formulario que aparece en esta página web o llama al 902 40 05 45 para inscribirte en una experiencia única.
El curso deportivo es el más exigente y el que más emociones promete. Si eres propietario de un modelo de la gama S o un Audi TT, aquí tienes la oportunidad de comprobar todo el potencial de tu automóvil.
Todo el curso se desarrolla en un circuito, donde aprenderás a trazar y a dosificar el freno entre otras técnicas de conducción deportiva. Primero se estudia el circuito por sectores y luego se aborda en una serie de vueltas. Para finalizar, los asistentes pueden acompañar a los instructores en vueltas rápidas, afrontando las curvas con derrapajes.
Para finalizar, los asistentes pueden disfrutar de una vuelta rápida al circuito de la mano del piloto Jordi Gené.
Si quieres saber hasta dónde llega la potencia de tu Audi y tu capacidad al volante, rellena el formulario que aparece en esta página web o llama al 902 40 05 45 para inscribirte en una experiencia única.
03-27-2005, 08:35 AM
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Thank again for the information.
Amazing: when sitting in my TT next to my trainer in ALbacete track ( near Madrid ) he moved his hands a lot !! Anyhow it looked smooth, easy and fast. I have to insist that it was a very slippery dedicated track that mimics a soiled (ash) track . As a mater of fact, when the track is wet it replicates an ice track. The trainer, an international rallye driver, has raced many years with 4WD cars the spanish off road rally championship (Campeonato de tierra ) . Twice winning the spanish championship... I have to admit that it was easier for me to slide and control the slide with the 2WD (BMW's) that with my own TT which required MUCH MUCH more speed to provoke the needed initial understeer. Also, any mistake with the TT sent inmediatly the back to spin which was not the case with the BMW's. But.... the big surprise came when the trainer admited that he had the same feeling !!! ( something that you could check just watching what happened in the track ). He was aiming at the weight distribution as the reason for this curious behaviour.. To make things clear, he loves Porsches, does not work for BMW and he told all the group that the best road car that he and his team had ever driven in a traditional circuit was the Porsche 996 TT.
By the way, it seems to me that your spanish is far beter than my, nearly unexistant, German.
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I was fortunate to spend some time on the Nordschleife with Walter Röhrl, he hardly moves his hands, perhaps turning the wheel half a hands-width, very very fast and very very smooth.
By the way, it seems to me that your spanish is far beter than my, nearly unexistant, German.