Hi John, There is no final drive gearing changes for your trans axle. As for changing the gears for 1st, 2nd, 3rd, and 4th Porsche did just that in the 997s models, they spaced them out for the increased power of the 3.8 motor. I would try to go that route. With a S/C in the mix it is a must. The supercharged cars really start to pull in 4th gear. I will update the gear ratios Monday.
Tim

 

Don't claim to know anything about either company's product. But this is a simple thing as to why/why not.

The stock setup uses a unsprung clutch and a dual mass flywheel. The dual mass flywheel absorbs the driveline chatter.

If you replace the dual mass flywheel with a lwfw that is single mass (unsprung) then there is nothing absorbing the chatter anymore... unless you replace the clutch with a sprung unit.

Perhaps that is the difference in GMG?? dunno.

 

The SC will pull in every gear. It is engine speed dependent and not gear dependent. I would install the SC first as you may find no gearing changes are necessary with the increased power. You definately won't have to change out 1st or 2nd gear unless you want to go taller.

 

That's exactly my problem. Logically, I would wait to SC the car then determine which gearing mods would be appropriate. I was hoping to find someone who already went this route and figured out the best way to go. I'd like to only have to drop the transaxle one time - get it all done: clutch, fly wheel, LSD, syncros, and gearing all in one shot now in anticipation of the SC.

Out of all the SCed cars out there someone must have dealt with gearing. Anyone?

 

Hi, The more power you make the longer your gears should be. The longer gear lets the power be used. Short gears feel fast but will be slower if the longer gear are sized correct.
02 C2 05 C2S
1st 3.82 1st 3.91
2nd 2.20 2nd 2.32
3rd 1.52 3rd 1.61
4th 1.22 4th 1.28
5th 1.02 5th 1.08
6th 0.84 6th 0.88
Final 3.55 Final 3.55
also the S runs a 305/30/19 vs the 285/30/18 witch effects the overall drive number. In 4th gear the car has time to use its power so it really starts to move(watching the speedo not the tach). Also my turbo ran a 139.9 trap speed top of 4th instead of shifting 5th and losing momentum( no room for 5th gear shift in the 1/4) I will increase my tire roll out to increase my final drive number and go faster at the top of 4th.
Tim

 

GMG has a specially designed clutch made by Sachs....this clutch and flywheels combo they guarantee not to chatter.

 

Overall. you are talking about speed, not acceleration, right? I'm really concerned more with drivability in the environment in which I spend most of my driving time. I don't have much opportunity, nor the desire, to go 180. But pinning my head back in the seat during short blasts to the other side of 100 interests me. Wouldn't shortening 2nd - 4th bring on harder acceleration with added power of forced induction, or are you saying that the lower gearing will make the motor just run out of revs faster but not accelerate as hard?

 

Shortening any of the first 3 gears with an SC will make the car very uncomfortable to drive and as I stated before, will slow the car down on it's way to 100 mph. There is plenty of neck stressing power with the stock gears if you shift at the right points.

Any gain from shortening the gears will be more than offset by the additional shifting you will have to do. If changing gears is in your blood, make the first 4 gears taller.

 

Interesting. Thank you. It makes sense now. I often see this term "shift points." I'm assuming this is the point where the torque curve levels off? I have the worst time up shifting smoothly from 1st to 2nd. Winding out in first seems to last about 1 second and the rev limiter is right there. I can't seem to find that point where 2nd just takes over from 1st. I usually get this kind of double jerk happening and then the car settles back in to accelerating. 2nd gear lasts much longer and my up shift from 2nd to 3rd is nearly seamless, as are the following shifts. Is the "shift point" from 1st to 2nd lower in the rev range because the gearing is so low? I'm wondering if 1st will even be usable with another 150 HP. What am I doing wrong?

 

my experience is in 3rd and 4th is where the car seems fastest and by the time you hit 5th, your deep into 3 digits. 3rd and 4th is where you'll feel the pull the most.

 

With a centrifuge compressor on the car, your best shift points are at or near redline in each gear. With the blower, you must be very focused while at WOT in 1st gear. If you blink, you hit the rev limiter. Remember that your tach does not reflect the actually engine speed while accelerating so quickly. Learn to shift from the sound of your engine in all gears.

 

Vortech blowers typically kick in around 4K to redline.So think about where you want your power and how you drive.Like 1999 said get the blower first or drive someones car and get a feel for it.