Gator911

After having my first 911 for a few weeks, I have come to notice that the RPMs drop pretty significantly between shifts, which I find sort of odd being equipped with a 6-speed.

Has anyone, or does anyone make a shorter gear set, tranny or diff or anything in between for the 996?

You guys know this is the "poor mans supercharger" right?

-Keith

10 GT3

Changing the axle ratio won't change the amount of rpms between gears. It will just shorter the overall ratio. You can get different gear ratios for each of the gears in your transmission. They run $300-500 per gear pair for both shafts. So figure 6x times that if you want a full set of gears plus $1-2K to have them installed.

Unless you are racing on a track and need specific gears to run the track faster, it is really pointless changing ratios. It isn't uncommon to re-gear an older 915 or G50 5-sp transmission when rebuilding since you are most likely buying gears anyways. This is particularly true for 1st and 2nd. This can help with some of the spread between gears. Except for 1st to 2nd, the gear ratios in the 996 6-sp are actually pretty good keeping the engine in the strong part of the powerband. Our gearing is optimized for 0 to 174-180 (3.4l to 3.6l). Remember that your redline is 7200 rpms and the torque peak is at 4600 rpms. As long as revs are above the torque peak after each shift, you will be on the strong side of the powerband. From 2nd-on revs drop to 5K+ for every gear when shifting at redline. Unlike other 6-sp cars like Vipers, Mustang Cobras and Vettes that have 6th gears just for fuel economy; we have a real/useable 6th gear and our gearing is optimized to top the car out in 6th gear. Try doing some shifts at redline in 4th at close to 125 mph or in 5th at close to 150 mph and you won't fell that our transmissions are tall geared.

gjb

Keith,

Powerhaus here in Boulder County has something you might consider:

996 Close/Short Ratio Gears. Ad is on page 146 of the August 06 Excellence and their url is www.powerhausII.com

They're saying 1.783:1 3rd, 1.455:1 4th, 1.200:1 5th and 1.000:1 6th.

Found it interesting but haven't called them yet. If you do, post back your experience.

Thanks,
Grant

newport996

True..I thought that when I read this post that our 6th gear isnt really an "overdrive"..Its another gear. The problem is that most people dont do redline 5th gear shifts. So moving it all down for faster acceleration (slightly faster) isnt a bad idea, but I wonder the downsides?

gjb

$$$$$$$$$$$$$$$$$$$$$$$$ ?

Gator911

Im just not familiar with working on a Rear engine car yet...

From my BMW days you could swap out the diff in-order to change the redlines, etc...

I dont really want to rebuild the whole transmission. The big sacrafice in this are fuel mileage and engine noise. Once i get used to the car more i will make a better educated judgment on the current gearing setup. I just feel like there is a little bit of "lag" on the lower gear shifts. Highway is beautifull...

-Keith

Gator911

Does anyone have the stock gearing info handy?

wross996tt

shorter...lol...I want taller! I'm in first for like 1 second.

Gator911

thats such a terrible problem to have, I'm so sorry

JimB

I'm not sure about the Powerhaus product but I love the idea. It appears that they are making 1st higher, 6th lower (same as current 5th) and sqeezing the other 4 ratios in between. This is exactly what I would do to my race car if it were legal. It would transform a street car as well.

The down side? 1) A higher 1st will be harder and slower to launch and harder on clutches. Ever hear someone take off from a dead start in a cup car? It won't be that bad but it will be different. 2) More shifting. Maybe this is an upside? 3) Top end limited to around 150 mph.

I think this would be the most significant power upgrade you could install short of a supercharger.
Jim

faris13

Had a shorter final drive ratio installed on my last car, a 350z. There was a noticable difference in acceleration throughout all the gears. The "downside" is your top speed will be reduced and a top speed of 150 would be fine with me

Ubermensch

I was thinking along the same lines as Faris. Rather than changing all of the individual gears just change the final drive to effectively improve acceleration across the board without creating "dead spots" between the gears.

JimB

Changing the final drive is nothing like changing the gears. All it does is make all your gears lower in the same proportion. You would end up with a 1st so low it would be usless. 2nd would become 1st, 3rd would be come 2nd, etc. You see some minor improvements to the acceleration line on a gear chart but it's not meaningful.

Ub, changing the gears fills the dead spots. It doesn't create them.
Jim

Gator911

Anyone have pricing info on changing the gears?

Anyone have info on adding clutches to make a non-lsd, LSD

-Keith

Ed Newman

I have the PowerHaus gears in my car and LOVE them. What a difference. The car is much more fun on the track. The upgrade with an LSD and some bearing and syncro upgrades was about $7000 total plus a few hours of labor to drop an reinstall the box. The gears only change 3-6. Top speed is 160-165 depending on the tires. There is a down side for a street car. The gears are very noisy, I believe they are straight cut.

http://www.phii.net/