Possible to change a car (Targa) from 4wd/awd to 2wd/rwd?
12-31-2012, 09:08 AM
#16
Thanks!
12-31-2012, 09:15 AM
#17
Though this is only hinted at on the turbo forum, I'm a bit worried that removing so much weight, especially from the front, would mess up the suspension behavior. So it might only make sense if I want to switch to adjustable coilovers, or maybe to (front?) C2 springs and dampers, or possibly just shorten the front springs, if that's doable (or replace them with shorter springs of the same stiffness - they are linear, no?)
Last edited by rs10; 12-31-2012 at 09:37 AM.
12-31-2012, 09:45 AM
#18
With all of this trouble, if you really have your mind set on a rear wheel drive targa, just get the 996 and don't waste your money hacking up a car (which once modified, will never drive correctly no matter how much money you throw at it).
There are so many things, software, oil lines, suspension components, etc. etc. etc. not to mention the million little things that you will be spending HOURS tackling.
NOT TO MENTION THE DOWN TIME!
Buy and drive,
Do not buy, spend more money making your car worth less money, get frustrated because it's taking months and it's still not right and then leave the car in the garage with no intention on using for the next several years only to finally sell it for peanuts just to "get it out of the garage"
There are so many things, software, oil lines, suspension components, etc. etc. etc. not to mention the million little things that you will be spending HOURS tackling.
NOT TO MENTION THE DOWN TIME!
Buy and drive,
Do not buy, spend more money making your car worth less money, get frustrated because it's taking months and it's still not right and then leave the car in the garage with no intention on using for the next several years only to finally sell it for peanuts just to "get it out of the garage"
12-31-2012, 01:21 PM
#19
Drifting
The VC doesn't "tighten up", couple a substantive level of engine torque to the front diff'l, absent a period of disparate rear vs front wheel rotation rate. Quite obviously that cannot happen with the TC function of PSM intervening.
12-31-2012, 02:44 PM
#20
Three Wheelin'
If you want to drift, not sure why in a Porsche and that is what Corvettes are for, just increase rear tire pressure to 50psi, you will break loose any day, even in the 4S.
As far as PASM, I love mine, perfect for date night, grocery shopping etc, and for going to the track. The 997 with PASM and Sport Chrono; it has dynamic engine mounts which stiffens in Sport +, throttle response is quicker, ride lowers, etc etc. Dr Jekyll and Mr Hyde for the price of one.
After 4 track events in the 4S it was so much fun I added a GT3 to my stable. Amazing car.
Last edited by tgavem; 12-31-2012 at 06:20 PM.
01-01-2013, 01:15 PM
#21
Also, which cars have VC? Is it older cars, or certain models, or was it an option (or was it an option to have the electromagnetic clutch instead of VC)?
01-01-2013, 01:24 PM
#22
With all of this trouble, if you really have your mind set on a rear wheel drive targa, just get the 996 and don't waste your money hacking up a car (which once modified, will never drive correctly no matter how much money you throw at it).
There are so many things, software, oil lines, suspension components, etc. etc. etc. not to mention the million little things that you will be spending HOURS tackling.
NOT TO MENTION THE DOWN TIME!
Buy and drive,
Do not buy, spend more money making your car worth less money, get frustrated because it's taking months and it's still not right and then leave the car in the garage with no intention on using for the next several years only to finally sell it for peanuts just to "get it out of the garage"
There are so many things, software, oil lines, suspension components, etc. etc. etc. not to mention the million little things that you will be spending HOURS tackling.
NOT TO MENTION THE DOWN TIME!
Buy and drive,
Do not buy, spend more money making your car worth less money, get frustrated because it's taking months and it's still not right and then leave the car in the garage with no intention on using for the next several years only to finally sell it for peanuts just to "get it out of the garage"
On the other hand, PASM is quite tempting :-( . And good specialists aren't that far away ... . Well, for the time being I'll keep hoping someone who has done this will notice this thread - and maybe I'll post on the 997 turbo forum.
01-02-2013, 02:15 PM
#23
Drifting
So do I understand correctly that a 4wd 997 with VC always transfers minimal power to the front.
when PSM is on?
The TC function of PSM simply prevents any rear to front disparate rotation rate from happening. No disparate rear to front disparate rotation rate = NO VC tightening.
Also, which cars have VC? Is it older cars, or certain models, or was it an option (or was it an option to have the electromagnetic clutch instead of VC)?
when PSM is on?
The TC function of PSM simply prevents any rear to front disparate rotation rate from happening. No disparate rear to front disparate rotation rate = NO VC tightening.
Also, which cars have VC? Is it older cars, or certain models, or was it an option (or was it an option to have the electromagnetic clutch instead of VC)?
01-03-2013, 06:30 PM
#24
And coming back to my other question, you seem to be suggesting that whatever is the minimal level of power sent to the front wheels, it never increases when PSM is on, because PSM stops the rear wheels from spinning faster than the front. If this is how it works, it’s quite a shame. It means you have two wheel drive when you most want four wheel drive (for instance, when driving up a snow covered hill, when you are likely to have PSM on), and four wheel drive when you least want it (when you switch PSM off in order to play).
However, is my understanding of what you seem to be suggesting correct? And if so, are you sure more power is never sent to the front when PSM is on? I’m wondering, because my understanding is that PSM does allow some wheel slip. And also because I wouldn’t expect Porsche to equip its car with what sounds like a fairly useless 4wd system.
01-03-2013, 06:32 PM
#25
Maybe I need to talk to some good specialists / tuners to talk me out of doing this - or just maybe to do it for me. Anyone know anyone likely to be able to do a good job on the drive train, suspension, and if necessary, software aspects?
01-04-2013, 02:43 AM
#27
Drifting
Wwest, thanks for you post. Regarding which system was on which cars, I’m guessing this means that 997.1 4wd cars have VC, and 997.2 4wd cars have the e-clutch. Is this what you meant, or do you know if this is correct?
I am personally not in the "know" as to what/which year, or model designation, when the change to the e-clutch was made.
And coming back to my other question, you seem to be suggesting that whatever is the minimal level of power sent to the front wheels, it never increases when PSM is on, because PSM stops the rear wheels from spinning faster than the front.
If this is how it works, it’s quite a shame.
No, the very last thing you need to have happen, inadvertently/unawares, is to lose traction and have the car go out of control. PSM (VSC/TC combined) is a highly regarded safety aspect.
It means you have two wheel drive when you most want four wheel drive (for instance, when driving up a snow covered hill, when you are likely to have PSM on), and four wheel drive when you least want it (when you switch PSM off in order to play).
That's exactly why the switch was made to the e-clutch. Front drive will be engaged each and every time you accelerate straight ahead at/from a lower speed. The harder you accelerate the higher % of drive, up to 50%, will be automatically coupled to the front.
Add a little yaw moment, turning, in the above case and the front drive coupling will be lowered accordingly, the tighter the accelerating turn, the less is the coupling to the front. Until at some point the laws of physics prevail and PSM "steps" in, (to much or to little yaw moment) automatically de-throttling the engine and adding stability control braking to the overall equation.
However, is my understanding of what you seem to be suggesting correct? And if so, are you sure more power is never sent to the front when PSM is on?
If you were to drive a VC C4 in a tight circle continuously, creating continuous rear to front disparate wheel rotation rates, when also accelerating just below the point of rear kick-out (wherein VSC would undoubtedly activate) the VC would tighten, possibly seriously so. I
I’m wondering, because my understanding is that PSM does allow some wheel slip.
No, the TC function of will NOT allow even the slightest level of detectable wheelspin/slip. And trust me, that's exactly the way you wish it.
And also because I would’t expect Porsche to equip its car with what sounds like a fairly useless 4wd system.
I am personally not in the "know" as to what/which year, or model designation, when the change to the e-clutch was made.
And coming back to my other question, you seem to be suggesting that whatever is the minimal level of power sent to the front wheels, it never increases when PSM is on, because PSM stops the rear wheels from spinning faster than the front.
If this is how it works, it’s quite a shame.
No, the very last thing you need to have happen, inadvertently/unawares, is to lose traction and have the car go out of control. PSM (VSC/TC combined) is a highly regarded safety aspect.
It means you have two wheel drive when you most want four wheel drive (for instance, when driving up a snow covered hill, when you are likely to have PSM on), and four wheel drive when you least want it (when you switch PSM off in order to play).
That's exactly why the switch was made to the e-clutch. Front drive will be engaged each and every time you accelerate straight ahead at/from a lower speed. The harder you accelerate the higher % of drive, up to 50%, will be automatically coupled to the front.
Add a little yaw moment, turning, in the above case and the front drive coupling will be lowered accordingly, the tighter the accelerating turn, the less is the coupling to the front. Until at some point the laws of physics prevail and PSM "steps" in, (to much or to little yaw moment) automatically de-throttling the engine and adding stability control braking to the overall equation.
However, is my understanding of what you seem to be suggesting correct? And if so, are you sure more power is never sent to the front when PSM is on?
If you were to drive a VC C4 in a tight circle continuously, creating continuous rear to front disparate wheel rotation rates, when also accelerating just below the point of rear kick-out (wherein VSC would undoubtedly activate) the VC would tighten, possibly seriously so. I
I’m wondering, because my understanding is that PSM does allow some wheel slip.
No, the TC function of will NOT allow even the slightest level of detectable wheelspin/slip. And trust me, that's exactly the way you wish it.
And also because I would’t expect Porsche to equip its car with what sounds like a fairly useless 4wd system.
Same story with Subaru's newest WRX, and my '01 RX300 F/awd. When the RX adopted VSC/TC the VC fluid formulation was changed to prevent the fluid from densifying. While Lexus sales and marketing stated otherwise the factory shop manuals indicated there was NO VC at all in the RX330, RX350(***), nor the Highlander, Sienna, etc.
*** the Toyota Venza and 2010 RX350 uses the very same e-clutch a the 997.
01-04-2013, 02:52 AM
#28
Race Director
OP, buying an AWD drive Targa and converting it to 2WD is a really bad idea and I'm still unclear as to why you think you want to do it. If you don't want AWD, and must have a Porsche, pick a different model.....
01-06-2013, 12:11 PM
#29
However, while I'm willing to bear the weight penalty of the Targa's roof and hatchback, I would rather not bear the weight penalty of the 4wd in exchange for what are to me limited benefits. Indeed, I'm not sure there would be net benefits for me at all. What I know is that the 997.1 4wd is consistently criticized because it offers nothing in between big-time sideways and neutral/understeer. What I don't know is which is more fun to drive at, say, 7/10s (one would generally expect a rwd car to be more fun, and also a lighter car, but the 4wd may counter with quicker turn in); nor which is faster on track (though I'd guess 2wd - otherwise GT3s would be 4wd). In any case, even if 4wd is more fun at 7/10s and faster on track, I doubt the difference would matter enough to me to overcome the other disadvantages.
Alas, even if 2wd is much better than 4wd, the conversion may still be a very bad idea. I looked at the 997 turbo forum on 6speed, and the conversion is consistently said to be either a bad idea or impossible. Though no one reported trying it until quite recently, and they made it sound easy. But no mention of touching the suspension to compensate for the changes in weight, nor whether they tried it on roads where the suspension matters, much less on track ...
01-08-2013, 08:08 PM
#30
VC was in use, and undoubtedly worked quite well, by Porsche before TC and/or PSM was adopted. VSC/TC is of much greater value as a safety matter than a mostly "flaccid" (REQUIREMENT) actual VC could ever become.
Same story with Subaru's newest WRX, and my '01 RX300 F/awd. When the RX adopted VSC/TC the VC fluid formulation was changed to prevent the fluid from densifying. While Lexus sales and marketing stated otherwise the factory shop manuals indicated there was NO VC at all in the RX330, RX350(***), nor the Highlander, Sienna, etc.
*** the Toyota Venza and 2010 RX350 uses the very same e-clutch a the 997.
Same story with Subaru's newest WRX, and my '01 RX300 F/awd. When the RX adopted VSC/TC the VC fluid formulation was changed to prevent the fluid from densifying. While Lexus sales and marketing stated otherwise the factory shop manuals indicated there was NO VC at all in the RX330, RX350(***), nor the Highlander, Sienna, etc.
*** the Toyota Venza and 2010 RX350 uses the very same e-clutch a the 997.
And coming back to my other question, you seem to be suggesting that whatever is the minimal level of power sent to the front wheels, it never increases when PSM is on, because PSM stops the rear wheels from spinning faster than the front. If this is how it works, it’s quite a shame.
No, the very last thing you need to have happen, inadvertently/unawares, is to lose traction and have the car go out of control. PSM (VSC/TC combined) is a highly regarded safety aspect.
I may have been a bit unclear. I meant it's a shame that the power sent to the front never increases when PSM is on. For instance, if I'm driving up a snow covered hill and the rears start to spin, I'd rather it sent more power to the front than braked the rear.
I’m wondering, because my understanding is that PSM does allow some wheel slip.
No, the TC function of will NOT allow even the slightest level of detectable wheelspin/slip. And trust me, that's exactly the way you wish it.
I perhaps shouldn't have used the word "slip". Slip is going on constantly. The car couldn't turn without it (at least without lifting several wheels). I guess the real question regards differences in speed between front and rear wheels. ("Spin" is an extreme form of both.) Here I have to disagree. Many (most/all?) stability control systems allow more than one ratio of front to rear wheel speed, particularly including PSM. (PSM was said by Porsche to allow more freedom than the stability control that was initially available on the 996.1.) If stability control gives you some choice between understeer and oversteer, as it does on my car, then it gives you some choice between the rear/front ratio (more oversteer/less understeer means a higher ratio). And that is exactly how I want it :- )
And also because I would’t expect Porsche to equip its car with what sounds like a fairly useless 4wd system.
Maybe it's not so useless. Turn off PSM (as you would when you want to have fun and/or go fast on track), and the 4wd will send power to the front, and will deliver a better lap time than the equivalent 2wd car on a slippery track (of course), but also on a short track, and maybe even a medium track. Also, whenever the PSM is turned off, whether for fun or for speed, it will be safer and easier to drive. And while the ideal would be to go up the snow covered hill using both 4wd and PSM, at least you can turn off PSM and use 4wd. You don't have that option in the 2wd car.
But I'd still be happier to know it could send a lot more power to the front with PSM on. And I still believe I'd be even happier without it ...
No, the very last thing you need to have happen, inadvertently/unawares, is to lose traction and have the car go out of control. PSM (VSC/TC combined) is a highly regarded safety aspect.
I may have been a bit unclear. I meant it's a shame that the power sent to the front never increases when PSM is on. For instance, if I'm driving up a snow covered hill and the rears start to spin, I'd rather it sent more power to the front than braked the rear.
I’m wondering, because my understanding is that PSM does allow some wheel slip.
No, the TC function of will NOT allow even the slightest level of detectable wheelspin/slip. And trust me, that's exactly the way you wish it.
I perhaps shouldn't have used the word "slip". Slip is going on constantly. The car couldn't turn without it (at least without lifting several wheels). I guess the real question regards differences in speed between front and rear wheels. ("Spin" is an extreme form of both.) Here I have to disagree. Many (most/all?) stability control systems allow more than one ratio of front to rear wheel speed, particularly including PSM. (PSM was said by Porsche to allow more freedom than the stability control that was initially available on the 996.1.) If stability control gives you some choice between understeer and oversteer, as it does on my car, then it gives you some choice between the rear/front ratio (more oversteer/less understeer means a higher ratio). And that is exactly how I want it :- )
And also because I would’t expect Porsche to equip its car with what sounds like a fairly useless 4wd system.
Maybe it's not so useless. Turn off PSM (as you would when you want to have fun and/or go fast on track), and the 4wd will send power to the front, and will deliver a better lap time than the equivalent 2wd car on a slippery track (of course), but also on a short track, and maybe even a medium track. Also, whenever the PSM is turned off, whether for fun or for speed, it will be safer and easier to drive. And while the ideal would be to go up the snow covered hill using both 4wd and PSM, at least you can turn off PSM and use 4wd. You don't have that option in the 2wd car.
But I'd still be happier to know it could send a lot more power to the front with PSM on. And I still believe I'd be even happier without it ...
