17 inch wheels 981 S - will they fit?
Discussion
LunarOne said:
Considering that the 718's internal name is 981 and that many parts are shared between the two cars, I think there's a strong chance of success. Having said that, parts might need to be coded to the car and software locking is likely to be the biggest stumbling block...
718 internal code is 982, not 981. It is a facelift of the 981 - really a 981.2. But I think your problem is going to be software. A lot of the 'feel' is in the code, it's not real road feel, it's coded force feedback. And in any case, the rack would certainly need to be coded to the car. Can a 981 run 982 steering rack code? It'll need to, to work.
Moreover, on the 987.2, I believe to fit a used rack (believe it or not, even on a 987.2 the rack needs to be coded to the car), you also need to replace the main ECU and the steering column ECU as a trio. And then recode the lot. So, it's a nightmare.
Using a brand new rack I [i]think{/i] may allow the fitting of just the rack on a 987.2. Not sure about the 981/982. But my guess is that you'll find it's either a nightmare or impossible. Good luck, report back if you succeed!
MA121C said:
LunarOne said:
Considering that the 718's internal name is 981 and that many parts are shared between the two cars, I think there's a strong chance of success. Having said that, parts might need to be coded to the car and software locking is likely to be the biggest stumbling block...
718 internal code is 982, not 981. It is a facelift of the 981 - really a 981.2. But I think your problem is going to be software. A lot of the 'feel' is in the code, it's not real road feel, it's coded force feedback. And in any case, the rack would certainly need to be coded to the car. Can a 981 run 982 steering rack code? It'll need to, to work.
Moreover, on the 987.2, I believe to fit a used rack (believe it or not, even on a 987.2 the rack needs to be coded to the car), you also need to replace the main ECU and the steering column ECU as a trio. And then recode the lot. So, it's a nightmare.
Using a brand new rack I [i]think{/i] may allow the fitting of just the rack on a 987.2. Not sure about the 981/982. But my guess is that you'll find it's either a nightmare or impossible. Good luck, report back if you succeed!
The point re the 987.2 is that to fit a used rack, you need to fit the main ECU and steering column ECU with the rack, all sourced from the same car. You apparently can't just recode a used rack to a car on its own.
So, you'll find breakers flogging the set - rack, main ECU and steering column key switch with the ECU - as a job lot.
It seems unlikely the 981/982 will be less complex...
As an alternative, what rack does the 991.1 GT3 use? Might be the same rack as the 981. In which case you'd then only need to see if you can use the GT3 steering map. Been a while since I drove a 991.1 GT3, but pretty sure it has better feel than a 981.
I did once dig around to see if you could use GT3 steering mapping on a 981, but couldn't find anything. Would be simpler than swapping the rack out AND doing the recoding, anyway. But I suspect you'll find either option is super hard or impossible.
So, you'll find breakers flogging the set - rack, main ECU and steering column key switch with the ECU - as a job lot.
It seems unlikely the 981/982 will be less complex...
As an alternative, what rack does the 991.1 GT3 use? Might be the same rack as the 981. In which case you'd then only need to see if you can use the GT3 steering map. Been a while since I drove a 991.1 GT3, but pretty sure it has better feel than a 981.
I did once dig around to see if you could use GT3 steering mapping on a 981, but couldn't find anything. Would be simpler than swapping the rack out AND doing the recoding, anyway. But I suspect you'll find either option is super hard or impossible.
MA121C said:
As an alternative, what rack does the 991.1 GT3 use? Might be the same rack as the 981. In which case you'd then only need to see if you can use the GT3 steering map. Been a while since I drove a 991.1 GT3, but pretty sure it has better feel than a 981.
I'm not convinced that all of the feel of an ePAS system comes from software. After all, forces are still transmitted through the wheels, the tie rods, the rack, up the steering column and to the steering wheel even when powered assistance isn't working, either because it's failed or because there's no power to make it work, for example in the case of a failed alternator and flat battery. There is still the same mechanical connection as there is in a traditional hydraulic system, it's just that the assistance is provided differently. Since the mechanical connection is still there, why does it feel different? Is it because the electrical system's software is damping out forces transmitted from the road? Possibly. But I'm sure the hardware is different, because the steering weighting and feel is so markedly different between the 981 and 982. Given all the criticism of the 981's less than stellar steering, you'd have thought that Porsche would have fixed it with a software update if they could have. That's why I'm convinced that a large component of the feel comes from the hardware, and the only hardware factors that could markedly affect it are steering geometry such as wheel size and offsets, distance from the wheel turning centres to the steering ball joint, and relative position and length of the rack, and the rack ratio itself.
I'm pretty sure the GT3 cars use double-wishbone suspension rather than the MacPherson struts seen on lower 991s, GT4s and all other Caysters, so the geometry is going to be different (at least at most front suspension travel positions). Double wishbones keep the camber angles much more precisely under control, whereas it varies much more as the wheel travels up and down relative to the car with MacPherson struts. Also, the GT cars have user-adjustable suspension whereas the lower cars don't.
No, double wishbone front first appeared on the 992 GT3. 991 GT3 is strut. GT4 uses the 991 GT3 front struts.
The 982 has a different rack from the 981. But the question remains re 991.1 GT3. If it uses the same rack as the 981, that might be a much easier route to better feel.
Wasn't saying all the feel is in the map. But a lot of it is. And like I said, if you could put the GT3 map onto your car, that might well be the most effective way to improve things. Changing the rack itself to one from a later generation of car I suspect will only be harder in terms of the software problem. Which may be insoluble in any case whichever way you go at it.
The 982 has a different rack from the 981. But the question remains re 991.1 GT3. If it uses the same rack as the 981, that might be a much easier route to better feel.
Wasn't saying all the feel is in the map. But a lot of it is. And like I said, if you could put the GT3 map onto your car, that might well be the most effective way to improve things. Changing the rack itself to one from a later generation of car I suspect will only be harder in terms of the software problem. Which may be insoluble in any case whichever way you go at it.
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