Is it possible to fit a shorter final drive to a 981?
Discussion
Mario149 said:
....a bit like you can do with say a 997 GT3? I'm sure it is, but has anyone actually done it or knows anyone who has?
Jack Baldwin ran a 4.222 final drive last year in his car in the Pirelli World Challenge and it is homologated for this years series. It is made by EMCO. fioran0 believes it has reliability issues - and Baldwin has had one "transmission" failure already this year in the series - but whether that was the final drive I don't know. Whether it would be reliable for road use or quiet enough I don't know.The better option is to regear. There are good reliable gears you can install to change the box to your preference that are a no brainier over the final drive.
Do your LSD too if you are looking for projects. That will improve things no end. The as delivered unit is a low lock up, zero preload unit.
Do your LSD too if you are looking for projects. That will improve things no end. The as delivered unit is a low lock up, zero preload unit.
Edited by fioran0 on Sunday 14th June 21:22
fioran0 said:
The better option is to regear. There are good reliable gears you can install to change the box to your preference that are a no brainier over the final drive.
Do your LSD too if you are looking for projects. That will improve things no end. The as delivered unit is a low lock up, zero preload unit.
Any more details? Supplier etc? Do your LSD too if you are looking for projects. That will improve things no end. The as delivered unit is a low lock up, zero preload unit.
fioran0 said:
The better option is to regear. There are good reliable gears you can install to change the box to your preference that are a no brainier over the final drive.
Do your LSD too if you are looking for projects. That will improve things no end. The as delivered unit is a low lock up, zero preload unit.
Would that apply to PDK also?Do your LSD too if you are looking for projects. That will improve things no end. The as delivered unit is a low lock up, zero preload unit.
Edited by fioran0 on Sunday 14th June 21:22
GT gears made gear sets for BGB Motorsports for use in Grand Am with their Cayman. The gears showed themselves to be highly robust - no surprise given that they came from GT.
I would recommend contacting BGB for info and details on what is available, pricing etc. The ideal would be to let them do the work but for those in the UK that's not really an option. They may be able to supply parts though and you can find a more local source for the work. Worth considering given the potential.
Regarding PDK, I have no idea is the short answer. BGB again would be the people who would know. While the PDK has shorter gearing the jumps between some of the gears are still rather large. 2-3, 3-4 and 5-6 being the obvious ones that aren't great. The jump from 6-7 is of course horrendous but I don't suspect that is anything that anyone needs told.
On the manual gearbox side, the gearbox itself is pretty long though fairly in keeping with the usual approach taken by Porsche. Certainly room for improvement both in length and gaps.
Heres a quick table showing the gearing on a bunch of recent cars for comparison. The 997.2 GT3 RS uses the same gears as the other GT3s but has a 3.89 final drive rather than the 3.44 used previously. You can see it does a good job of shortening the box but doesn't do anything about the gaps between gears.
edit to add for the 987.2 cars
I would recommend contacting BGB for info and details on what is available, pricing etc. The ideal would be to let them do the work but for those in the UK that's not really an option. They may be able to supply parts though and you can find a more local source for the work. Worth considering given the potential.
Regarding PDK, I have no idea is the short answer. BGB again would be the people who would know. While the PDK has shorter gearing the jumps between some of the gears are still rather large. 2-3, 3-4 and 5-6 being the obvious ones that aren't great. The jump from 6-7 is of course horrendous but I don't suspect that is anything that anyone needs told.
On the manual gearbox side, the gearbox itself is pretty long though fairly in keeping with the usual approach taken by Porsche. Certainly room for improvement both in length and gaps.
Heres a quick table showing the gearing on a bunch of recent cars for comparison. The 997.2 GT3 RS uses the same gears as the other GT3s but has a 3.89 final drive rather than the 3.44 used previously. You can see it does a good job of shortening the box but doesn't do anything about the gaps between gears.
edit to add for the 987.2 cars
Edited by fioran0 on Monday 15th June 11:08
You will need to talk with BGB.
Last I heard it was circa $4500 for a set of gears versus $2500 for the final drive. No idea what a proper diff runs for these car or how accurate the pricing mentioned remains.
Worth keeping in mind that the self same issue with gearing in the GT3 will rear its head too eventually. By the time you have re-geared and/or added a final drive to that car and done its diff you are right back where you started.
As for the general sentiment; define "fun" in an absolute sense and we can maybe have a conversation. Without it it is just discussing what colour of sauce we like on our chips.
Last I heard it was circa $4500 for a set of gears versus $2500 for the final drive. No idea what a proper diff runs for these car or how accurate the pricing mentioned remains.
Worth keeping in mind that the self same issue with gearing in the GT3 will rear its head too eventually. By the time you have re-geared and/or added a final drive to that car and done its diff you are right back where you started.
As for the general sentiment; define "fun" in an absolute sense and we can maybe have a conversation. Without it it is just discussing what colour of sauce we like on our chips.
Edited by fioran0 on Monday 15th June 11:26
Interesting to see that the 987 ratios were similarish as between PDK and manual, whereas they are quite different in the 981.
The 987 PDK ratios aren't THAT bad, at least with the 3.4 engine to plump up the power in the mid-range, whereas I found the 981 on 20 inch tyres to have simply bonkers gearing. 2nd was the only gear worth using in anger. I know I am a bit of a wimp, but I did almost all of my overtaking in that gear as I was scared that 3rd wouldn't have enough zip!
The 987 PDK ratios aren't THAT bad, at least with the 3.4 engine to plump up the power in the mid-range, whereas I found the 981 on 20 inch tyres to have simply bonkers gearing. 2nd was the only gear worth using in anger. I know I am a bit of a wimp, but I did almost all of my overtaking in that gear as I was scared that 3rd wouldn't have enough zip!
Thanks fiorano, interesting post.
Tbh, I didn't find the gaps between gears a problem when test driving the 981 GTSs in either manual or PDK form, it was simply the overall length, especially in the manual. While custom gears may be the uber optimal way forward, a shorter final drive on its own would be fine for the road for me.
All that said, given that the PDK is already a good chunk shorter for the first 6 gears (and the driving reason why I have ordered PDK instead of manual), for the cost I can't imagine changing. If I was in a 2 year old manual 981S I'd be ringing the outfit you mentioned as we speak
Tbh, I didn't find the gaps between gears a problem when test driving the 981 GTSs in either manual or PDK form, it was simply the overall length, especially in the manual. While custom gears may be the uber optimal way forward, a shorter final drive on its own would be fine for the road for me.
All that said, given that the PDK is already a good chunk shorter for the first 6 gears (and the driving reason why I have ordered PDK instead of manual), for the cost I can't imagine changing. If I was in a 2 year old manual 981S I'd be ringing the outfit you mentioned as we speak
fioran0 said:
You will need to talk with BGB.
Last I heard it was circa $4500 for a set of gears versus $2500 for the final drive. No idea what a proper diff runs for these car or how accurate the pricing mentioned remains.
Worth keeping in mind that the self same issue with gearing in the GT3 will rear its head too eventually. By the time you have re-geared and/or added a final drive to that car and done its diff you are right back where you started.
As for the general sentiment; define "fun" in an absolute sense and we can maybe have a conversation. Without it it is just discussing what colour of sauce we like on our chips.
Thanks chief, that's quite interesting, and certainly cheaper than buying a GT3! Last I heard it was circa $4500 for a set of gears versus $2500 for the final drive. No idea what a proper diff runs for these car or how accurate the pricing mentioned remains.
Worth keeping in mind that the self same issue with gearing in the GT3 will rear its head too eventually. By the time you have re-geared and/or added a final drive to that car and done its diff you are right back where you started.
As for the general sentiment; define "fun" in an absolute sense and we can maybe have a conversation. Without it it is just discussing what colour of sauce we like on our chips.
Edited by fioran0 on Monday 15th June 11:26
Seems just a final drive (like I did in the Mazda) might provide the fix I'm after.
As said before I think one of the main reasons people wanted the 997.2 RS v. the normal cat was because of the shorter final drive.
Am sure if you speak to JZM or Parr they would be able to advise whether that can also be done on a 981 car. In the GT3 I think you swapped directly for the RS part, you just didn't have a longer 6th so might lose a bit of top speed (I think?). Let us know how you get on. Have a feel all manufacturers are drawn to these super long gearing by headline CO2 numbers but would happily do without them...
Am sure if you speak to JZM or Parr they would be able to advise whether that can also be done on a 981 car. In the GT3 I think you swapped directly for the RS part, you just didn't have a longer 6th so might lose a bit of top speed (I think?). Let us know how you get on. Have a feel all manufacturers are drawn to these super long gearing by headline CO2 numbers but would happily do without them...
mollytherocker said:
I have a way of shortening the ratios considerably but you lose 1st gear. Its cheap too.
Put a sticker over the gearknob and replace the gear numbers with one number higher. Eg, 2nd is now 3rd.
Works a treat.
Agreed. If you want a lower gear, use a lower gear. With six to choose from there's usually one that suits!Put a sticker over the gearknob and replace the gear numbers with one number higher. Eg, 2nd is now 3rd.
Works a treat.
One point to remember is that if you fit a shorter final drive the range of speed available in any given gear will be reduced. So you may waste more time changing gear than you gain through enhanced acceleration.
Ozzie Osmond said:
Agreed. If you want a lower gear, use a lower gear. With six to choose from there's usually one that suits!
Except there isn't at road driving speeds where you don't want to lose your licence. You're point is only valid if you're on a track where you might use 3rd instead of 4th. But at that point it makes not difference anyway as you're not bound by a legal limit at which you can driveOzzie Osmond said:
One point to remember is that if you fit a shorter final drive the range of speed available in any given gear will be reduced. So you may waste more time changing gear than you gain through enhanced acceleration.
It's not about time, it's about being able to rev the car out more often and enjoy the full range of the engine and use the gears more, and as a brucey bonus having a little more shove in the backGassing Station | Boxster/Cayman | Top of Page | What's New | My Stuff