Shorter final drive?
03-09-2010, 04:13 PM
#16
Rennlist Member
This is very interesting. I never thought about this before. Thanks for the info!
Maybe they need a 8/33 or 8/31 gearset... instead of 8/32... !
Maybe they need a 8/33 or 8/31 gearset... instead of 8/32... !
On the 8 tooth pinion it divides into 32 evenly, meaning the same tooth hits the same opposite tooth every single time it spins around.
The 9 tooth pinion takes a number of cycles before it hits the same tooth on the ring gear. This creates a variance to the wear patterns and tends to make the gear pairs last longer.
The 9 tooth pinion takes a number of cycles before it hits the same tooth on the ring gear. This creates a variance to the wear patterns and tends to make the gear pairs last longer.
03-09-2010, 04:26 PM
#17
There are certainly benefits to changing out gearing, that the ring and pinion does not really offer, however in researching the gearing chart for the 997 GT3, one of the considerations should be that you really do not want to change out the 3rd gear, as this is a somewhat special gear, in so far as it is a bit beefier than the previous 996 GT2/GT3 gear. Of all of the gears running in your gearbox the 3rd gear is the one that tends to take the most abuse. For this reason Porsche made this gear larger in thickness, to help with its durability. What this means in terms of gearing is even if you space out the rest of the gearbox, say by putting in a 1.16 4th, 1.00 5th, and pushing your current 5th gear into the 6th gear position, your gearbox is still geared for a top speed of 190 MPH, which you will probably never see at most of the race tracks in the US. (This is assuming that you are running CUP 27.2 Inch tires, and a 7200 redline.)
So what is the solution to really get this gearbox to perform well on the track? Well it is actually a combination of both, ring and pinion, as well as shorter gearing as previously mentioned. Matt brought up a very good point, in saying that traditionally the Porsche Motorsport ring and pinion set has not shown itself to be overly durable. There are a couple of things that you might consider, to help offset this issue. Cryogenic Stress relief and REM Micropolish, can help increase the life of the ring and pinion by quite a bit. The other possibility would be to go with an aftermarket ring and pinion, rather than the Porsche Motorsport part. The other consideration, is that there were several different ring and pinions made up for PMS, it may simply be a particular part number that you need to go with to ensure that you do not get one of the bad ones. I know the last time I spoke with PMS about this, I was told to use a G50 part number rather then the 996 part. It is reported to be at least marginally better in terms of durability. Add in the Cyro/REM and I think you will be just fine.
Let me know if you would like to see some gearing charts for this, so that you can really see what I am talking about in terms of the difference you will see by changing out gears as well as the ring and pinion. Obviously, no matter how you look at the problem, cost is not going to be cheap, but the performance advantage is extreme.
I hope that this helps a bit.
Erik Johnson
GBox Performance Transaxles
(303) 440-8899 work
(303) 895-4828 cell
www.gboxweb.com
So what is the solution to really get this gearbox to perform well on the track? Well it is actually a combination of both, ring and pinion, as well as shorter gearing as previously mentioned. Matt brought up a very good point, in saying that traditionally the Porsche Motorsport ring and pinion set has not shown itself to be overly durable. There are a couple of things that you might consider, to help offset this issue. Cryogenic Stress relief and REM Micropolish, can help increase the life of the ring and pinion by quite a bit. The other possibility would be to go with an aftermarket ring and pinion, rather than the Porsche Motorsport part. The other consideration, is that there were several different ring and pinions made up for PMS, it may simply be a particular part number that you need to go with to ensure that you do not get one of the bad ones. I know the last time I spoke with PMS about this, I was told to use a G50 part number rather then the 996 part. It is reported to be at least marginally better in terms of durability. Add in the Cyro/REM and I think you will be just fine.
Let me know if you would like to see some gearing charts for this, so that you can really see what I am talking about in terms of the difference you will see by changing out gears as well as the ring and pinion. Obviously, no matter how you look at the problem, cost is not going to be cheap, but the performance advantage is extreme.
I hope that this helps a bit.
Erik Johnson
GBox Performance Transaxles
(303) 440-8899 work
(303) 895-4828 cell
www.gboxweb.com
03-09-2010, 04:44 PM
#18
Nordschleife Master
03-09-2010, 04:47 PM
#19
Nordschleife Master
There are certainly benefits to changing out gearing, that the ring and pinion does not really offer, however in researching the gearing chart for the 997 GT3, one of the considerations should be that you really do not want to change out the 3rd gear, as this is a somewhat special gear, in so far as it is a bit beefier than the previous 996 GT2/GT3 gear. Of all of the gears running in your gearbox the 3rd gear is the one that tends to take the most abuse. For this reason Porsche made this gear larger in thickness, to help with its durability.
03-09-2010, 04:48 PM
#20
Rennlist Member
That will be an even more aggressive reduction compare to the 8:32, but it will take out the meshing of the same teeth problem you mentioned...
I assume that it will be aftermarket effort, instead of from Porsche?
I assume that it will be aftermarket effort, instead of from Porsche?
03-09-2010, 05:03 PM
#21
Nordschleife Master
Yes on both counts. While a lot of our parts appeal to the street rod market, we really approach our R&D of things with an intent for our parts to be used in motorsports. That ring and pinion will be a GT branded part.
03-09-2010, 05:37 PM
#22
Hey not to be jerk or anything, because I learned this a slightly different way, but if you want to promote your products, yes even those not yet made, you really need to become a sponsor here. Your thoughts and opinions are certainly welcomed and while I really don't care one way or the other, there may be others here that would feel differently.
Just thought I would let you know. I have had some issues with this in the past myself.
Erik
Just thought I would let you know. I have had some issues with this in the past myself.
Erik
03-09-2010, 05:48 PM
#23
Nordschleife Master
Hey not to be jerk or anything, because I learned this a slightly different way, but if you want to promote your products, yes even those not yet made, you really need to become a sponsor here. Your thoughts and opinions are certainly welcomed and while I really don't care one way or the other, there may be others here that would feel differently.
Just thought I would let you know. I have had some issues with this in the past myself.
Erik
Just thought I would let you know. I have had some issues with this in the past myself.
Erik
Plus, I'm not even a retailer. I'm a manufacturer and wholesaler. Site sponsors, who are Guard certified resellers, like Deman Motorsports and Body Motion are the ones who will get the referrals if people want to buy any GT products.
03-09-2010, 06:34 PM
#24
Just trying to give you a heads up Matt, relax. As I said I could care less one way or the other. As to Brian Copan's post, I am afraid you have me at a loss on that one. Have a nice day.
Erik
Erik
03-09-2010, 06:50 PM
#25
Rennlist Member
Matt- I'll pm u later down the road with respect to the gearsets. I dont plan on doing nething this year but I'm gravitating towards stripping the car next year and god almighty when I have my piggy bank refilled. My wife's creative spending ie house remodel(cant argue against that) has put a huge damper on track stuff. When GT was here in California- very impressed with the knowledge and still continues on - u guys havent missed a beat- good going. MIke
03-09-2010, 07:02 PM
#26
Nordschleife Master
Mike,
I hear you on the piggybank. MY wife wants a baby and a Cayman S. There's going to come a point where she's got to choose one because we're not made of money. I've told her once she's learned to race in her Subaru we can discuss other options. I'm banking on her desire for a baby to win out before too long and then all I'm on the hook for is remodelling a bedroom and diapers...
Erik,
Given recent history, you'll pardon my skepticism that you're at all concerned about my best interests. The comments had nothing to do with the topic at hand and really didn't need saying.
I hear you on the piggybank. MY wife wants a baby and a Cayman S. There's going to come a point where she's got to choose one because we're not made of money. I've told her once she's learned to race in her Subaru we can discuss other options. I'm banking on her desire for a baby to win out before too long and then all I'm on the hook for is remodelling a bedroom and diapers...
Erik,
Given recent history, you'll pardon my skepticism that you're at all concerned about my best interests. The comments had nothing to do with the topic at hand and really didn't need saying.
03-09-2010, 07:22 PM
#27
Rennlist Member
Matt- I have a 15 yr old daughter that still loves us and still hang with us old geezers. But man 1st 3 months is HELL!!!! Just a heads up : ). Mike
03-09-2010, 07:28 PM
#28
Nordschleife Master
Boys or girls, I hope our kids like the track because they're gonna be there a lot growing up. I spent a good part of my pre-teen and teen years hanging out in the pits at Laguna Seca and Sears Point. My dad didn't race, but my best friend's dad did and he often took us out there. The hook got set in me early and I hope to pass on the disease.
03-09-2010, 07:38 PM
#29
GT3 player par excellence
Lifetime Rennlist
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Lifetime Rennlist
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