I'm going for it: GTS ring & pinion replacement with an S4 unit
05-13-2009, 02:16 AM
#47
Rennlist Member
Im not sure about that, Ill have to see what the GTS auto has as ratios.
Actually, for racing, and 400rwhp, you are right, that would be the best gear box available . 1st through 3rd, and redline to 3rd at the long straights. However, since most tracks have a few more 120mph straigths, the advantage might be lost. But, it would be interesting, but having to use the awkward 1st gear might not be that fun. 2nd through 4th is more desirable as far as gear shifting positions.
Anyyway, a GTS with a 2.2. man, those first 3 gears are going to be way tall, right? thats a 17% difference up to the final gear shift!!
mk
Actually, for racing, and 400rwhp, you are right, that would be the best gear box available . 1st through 3rd, and redline to 3rd at the long straights. However, since most tracks have a few more 120mph straigths, the advantage might be lost. But, it would be interesting, but having to use the awkward 1st gear might not be that fun. 2nd through 4th is more desirable as far as gear shifting positions.
Anyyway, a GTS with a 2.2. man, those first 3 gears are going to be way tall, right? thats a 17% difference up to the final gear shift!!
mk
475hp/460lb.ft
09-26-2009, 04:02 AM
#48
Rennlist Member
Thread Starter
Quick update before my summer driving season is over and the GTs is going into hibernation.
The R&P performs very good and is still quiet, no noise at city cruising speeds. Slightly noticeable put nothing close to the old 2.538 R&P.
Fuel consumption has improved a lot. 23 MPG is no problem at constant 62 MPH. I can average about 19 MPG when I "go with the flow" on the Autobahn (about 80 MPH).
The only downside is slow accelleration after about 149 MPH. The car still accellerates but it slow to go faster. However, I was able to go up to 162 MPH (GPS) yesterday. But you need a lot of Autobahn...
Overall: For you guys in the US the 2.2 R&P is the better choice if you use your car as a daily driver (my personal opinion).
The R&P performs very good and is still quiet, no noise at city cruising speeds. Slightly noticeable put nothing close to the old 2.538 R&P.
Fuel consumption has improved a lot. 23 MPG is no problem at constant 62 MPH. I can average about 19 MPG when I "go with the flow" on the Autobahn (about 80 MPH).
The only downside is slow accelleration after about 149 MPH. The car still accellerates but it slow to go faster. However, I was able to go up to 162 MPH (GPS) yesterday. But you need a lot of Autobahn...
Overall: For you guys in the US the 2.2 R&P is the better choice if you use your car as a daily driver (my personal opinion).
09-26-2009, 07:21 AM
#50
Addict
Rennlist Member
Rennlist Member
I plan on doing same change during winter to Amethyst GTS. Any problems due to torque converter stall speed changing from 83-102kph to 95-117kph on 4th gear? I'm thinking about how much converter slips on long 80-100kph drive. I quess its not a problem.
Plan is to swap GTS ring and pinion into one local ext US S4 diff and its R&P into GTS.
GTS gearing before and after
US S4 gearing before and after
We both get what we want. S4 should loose few tenths off from 0-100kph time and GTS gets loooooong 4th for fast motorway cruising and slightly better fuel economy. I'm not too worried about 0-100 time as there should be some extra hp in engine soon and it should more than compensate longer 1st gear.
Plan is to swap GTS ring and pinion into one local ext US S4 diff and its R&P into GTS.
GTS gearing before and after
US S4 gearing before and after
We both get what we want. S4 should loose few tenths off from 0-100kph time and GTS gets loooooong 4th for fast motorway cruising and slightly better fuel economy. I'm not too worried about 0-100 time as there should be some extra hp in engine soon and it should more than compensate longer 1st gear.
09-26-2009, 11:37 AM
#51
Rennlist Member
Thread Starter
Erkka,
there is really not a big difference beteween 80-100 km/h.
BTW
A friend of mine has an Euro S4 and once we both went on the Autobahn in our cars and floored it as soon as there was no traffic. My GTS is still quicker in accelleration up to 120 MPH.
there is really not a big difference beteween 80-100 km/h.
BTW
A friend of mine has an Euro S4 and once we both went on the Autobahn in our cars and floored it as soon as there was no traffic. My GTS is still quicker in accelleration up to 120 MPH.
09-26-2009, 05:27 PM
#53
Addict
Rennlist Member
Rennlist Member
When speed where converter locks rises 20% it is right at the speed limit at many local rural roads. Good to know its not an issue.
I'm not worried about S4's. If engine I'm currently building works it should have more than 400hp.
A friend of mine has an Euro S4 and once we both went on the Autobahn in our cars and floored it as soon as there was no traffic. My GTS is still quicker in accelleration up to 120 MPH.
06-23-2010, 08:04 AM
#54
Nordschleife Master
BTW:
Porsche never provides backlash numbers for used ring and pinions, only new. Always increase the factory backlash by at least 20% for used pieces....more if there is significant wear. If you set up the backlash to "new" specifications, it will be too tight and can fail. This is a common problem when people rebuild gearboxes and decide to set up the ring and pinion to "new" specs. Pinion depth doesn't change, as both bearings wear at the same rate, in theory, so you can use the factory numbers for this.
Porsche never provides backlash numbers for used ring and pinions, only new. Always increase the factory backlash by at least 20% for used pieces....more if there is significant wear. If you set up the backlash to "new" specifications, it will be too tight and can fail. This is a common problem when people rebuild gearboxes and decide to set up the ring and pinion to "new" specs. Pinion depth doesn't change, as both bearings wear at the same rate, in theory, so you can use the factory numbers for this.
I measured the backlash for my factory-original 157k mile open-diff.
The specification etched on the crown wheel is 0.14mm backlash.
The averaged backlash reading (over 4 compass points) is 0.1625mm, so 16% increase on new-spec.
I'll be installing my limited slip diff and setting the backlash to the 0.16 value, so that the contact patch is in the same quiet spot as its always been.
06-23-2010, 09:22 AM
#55
Addict
Rennlist Member
Rennlist Member
Few pics from past winter.
Backslash was close to factory spec in both gearboxes before and was set slightly larger than it when R&P were changed between them. S4 has run without any issues. GTS box is still waiting to be installed.
Backslash was close to factory spec in both gearboxes before and was set slightly larger than it when R&P were changed between them. S4 has run without any issues. GTS box is still waiting to be installed.
06-23-2010, 03:34 PM
#56
Rennlist Member
Thread Starter
Quick info: My GTS still runs with no issues, quiet and very smooth. The 2.2 R&P is IMHO a very good match if you don't need to get up to top speed quickly. Lower RPM's while cruising and about 22 MPG @ constant 62 MPH is no problem.
There is nearly no difference in accelleration up to 150 MPH. Beyond 155 MPH acceleration is signifcantly reduced and takes more time.
There is nearly no difference in accelleration up to 150 MPH. Beyond 155 MPH acceleration is signifcantly reduced and takes more time.
06-27-2010, 02:53 PM
#59
Racer
Hey Schocki,
Glad to hear that you're still satisfied with the R&P replacement. As you may remember, my GTS also has a whining from 50-60km/h under moderate load. It has not gone worse over time, and I got used to keeping the radio a little louder
I have found another R&P which will ship to me shortly, and I will probably do the R&P replacement later this year. A GTS style ... not a S4.
Regards,
Theo
Glad to hear that you're still satisfied with the R&P replacement. As you may remember, my GTS also has a whining from 50-60km/h under moderate load. It has not gone worse over time, and I got used to keeping the radio a little louder
I have found another R&P which will ship to me shortly, and I will probably do the R&P replacement later this year. A GTS style ... not a S4.
Regards,
Theo