SoloRacer

I'm confident I can pull redline in all gears. However, the highest I have had mine is in the 260 km/h range as I ran out of room and didn't want to go to jail. They really have cracked down around here which puts a damper on the occaisional burst of speed.

odurandina

i've been talking about adding these gears for some time... was never sure if they were the 01e gears or not, but they had mentioned the same thing about "notching out" a little bit of extra clearance in the box.

this was three years ago that i spoke with them about it. being able to alter the transmission was a deciding factor in choosing the 968 instead of getting another 928... it confirms they were doing the exact same thing as the shop sourcing your gears is talking about.





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JDS968

I guess the real question is...do you ever hit redline in 5th gear, shift hard into 6th, and continue accelerating at WOT? Because if you don't, you're really not losing anything by leaving the FD the same and swapping out 6th for a taller gear.

Redline in 5th gear pretty fast...I WISH there were somewhere around here, where I could hit that speed and STILL have the opportunity to keep accelerating as hard as I can...Montana would be great for that...

Fox944

JDS, i have done so a few times. I would like a a 3.91 or 4.10 fd. Would make the car accel much quicker. My car isnt a DD, so i don't care for a taller 6th. Its a toy.

StewHatch

Dino - please explain how I am slowing my car down?

odurandina

Stew,

the answer is simple. your top speed will no longer occur in top gear... and from there things actually get worse..

you will see a top speed of about 125-133 mph depending on what tire size you're running - in 5th gear.


reason:

our engines are pretty dull until you start getting them past 4,000 rpm or so.

your rpms will be cut so drastically, that the engine will simply not make enough power to get the car much past 90-95 mph once you drop it into your new, long, "highway" gear... the engine will "dog" long before you see any kind of speed. especially if you run a 25 1/2" tire.



had some time to think this out for your particular application: originally, i had made the natrual assumption that you were going to turbocharge or supercharge your engine at some point,


you're not going to want to hear this - but,


1. your fuel consumption isn't going to improve.

2. you'll not be saving much wear and tear on the engine at normal highway speeds, either,

since excessive rpm over very long distances isn't really happening until you're going past about 90 mph.


3. you will place a significant burden on your engine bearings in 6th gear.

4. you will constantly be doing "switchbacks" into 5th gear, with the car constantly ******* out in 6th,

the moment you turn up from any level grade.



verdict:

don't install this gear unless you're going to run one of Carl's superchargers,

you plan on turbocharging, or installing a V8 chevy.

Fox944

Stew, there are many superchargers systems out there for our cars. If thats a route you plan to take...i wouldnt limit myself to Carl's SC, i'd look into all the options and pick what you feel is best for you. There are at least 4 different major units out there you can buy today. Personally, i know which charger i would buy.

Same deal with Turbochargers.

As for slowing your car down, it would be slower in 6th gear if you swap for a taller gear. Your car wont accel as quickly. many people, incuding yourself have expressed that they wish 6th gear is taller for more relaxed highway driving as the RPM's are too high once your around 75mph.

Personally, i don't mind the high rpm and wish the FD was shorter. I drive my 968 2-2.5K a year......and when i do....its spirited driving, so a shorter final drive would be ideal for me.

Fox944

Our cars don't use a G-46 gearbox. They have a G44/00 Gearbox

rdhayward

A year or two ago, one of my clients (who shall remain unnamed, but is a former Indy car driver and now runs a Porsche shop in Ohio) told me about a weekend trip up to Michigan for a Porsche 356 get-together. He didn't have one of his 356-series cars ready, so he drove his Ferrari Testarossa. After the trip, his wife downloaded the GPS tracking data onto her computer and learned that he had been reached 167 mph while she was taking a nap.

odurandina

today was the big day, (as i took delivery on my top speed xmission box)... i owe a huge thanks to Roger at CMS for educating me about the possibilities of setting up one of theses boxes for the bigger engine.. and especially pointing out how important it would be to get the taller 5th gear installed as well. this includes the long 5th (.729/160 mph/6000 rpm) and 6th (.600/190 mph/5880 rpm).... huge thanks so Scott Dewitt at Advanced Automotion for locating these gears...


transmission with 48 k miles; $1,800
purchase 5th and 6th gearsets; $1,730
labor to install/(4 hours)/misc parts/(local Getrag specialist); $620

total; $4,150 ... yes, i think i got off easy, and i've got my spare transmission (in the car).




/

sydneyman

congrats!

notthd

You go girl... er ...a .dude. Your avitars always kill me.

Cheers, Mike

notthd

Reading about ratios and TP speed I thought I'd post a pick of going down the straight during at New Hampshire motor sppedway if memory serves me right ...

Check out the RPM vs Speed- over 175 with more rpm but not track.....Cheers, Mike

RajDatta

Stock 968 speedometer is inaccurate at those speeds. I would send the speedo to Hollywood speedometers to have it recalibrated if you are into this thing.

odb812

How's it goin', Mike? That's in an '89, right? What turbo/ems/hp are you working with to get up that fast? When was that picture taken?

You're pretty conservative on the boost there, too.