This is the first time I've read about this. How does the cruise control stop functioning?

 

The computer knows that X speed should jive with X revs in whatever gear. The difference is recognized and the computer thinks something is out of whack or that there is a loss of traction, etc., so it turns the CC back off. That's the basics, as I understand them. There has not been a solution found that will allow the CC to work correctly with the gear swap.

 

I barely ever use the CC anyway. Too much traffic here in the Tampa area.

 

I'm working on a CC solution...may take a few more months - but looks very promising...

 

With this mod, the top speed for each gear will be reduced? So now when going 0-60 you have to shift into third to hit 60? I am assuming you also lose top speed.

 

Again this mod is really only good for those that drag race or otherwise are interested in maximizing acceleration from a stop. Once you're moving, it's a toss up for which car will accelerate more quickly (the one with the stock final drive or the new final drive) based on the starting speed.

 

with the current gearing, when i'm on the freeway and wana make a pass, i never know to go into 2 or 3, if i'm at like 65 - i can go into 2 and be right at my power peak, but most of the time i play it safe and go into 3 because i'm usually going 70-80 when i need to accelerate. but 3 is not usually in the powerband, because i have an 05 that is pretty peaky. So it seems like with the gears i would always be able to go into 3 and be at the sweetspot every time.

also, with the gears, although you won't always accelerate faster at the same SPEED, you will ALWAYS accelerate faster in the same gear at the same rpm.

 

Of course, but why does that matter? Ideally with a mod you make your car faster than it was without that mod at all speeds, and that's not the case with the gearing change. Accelerating faster at same RPM in the same gear causes the confusion that makes everybody think the car is always faster with a different final drive.

 

Thanks much for the info.

 

i don't quite understand the downside. seems to me that with a close gearbox like in the 6mt, you can keep it in its powerband at any speed, and that's gonna make the gears accelerate faster at virtually any speed.

 

All will be clear once I get off my lazy *** and generate the ground force plots.

 

The 3.9 will only install where a 6mt ring and pinion gear set has been removed. Meaning, yes your starting point has to be a 6mt diff. Of course when you also install a Nismo LSD or any other clutch type LSD at the same time, your also installing a 6mt based unit diff. The only clutch type LSD that will allow 3.3 gears to be installed would be the Cusco MZ or RS as both are offered in MT and AT versions.

Don't forget what DaveB is saying about your cruise control going by by.

 

Are you tuning the TCM, trying to find a way to modify sensor inputs to the ECM or reprogramming the ECM to update its drivetrain speed/gear mapping table? This was something I had hoped to look into, but had tabled for now because I won't be getting around to doing the gear swap until mid to late '06.

As GT-Ron had stated, cruise control turns off because the ECM is getting signals out of accordance with its programming. The automatic speed control device takes signal inputs from the ASCD brake switch (brakes), stop lamp switch (brakes), ASCD clutch switch (clutch position), ASCD steering lamp switch (steering wheel controls), Park/Neutral switch (gear), comination meter (vehicle speed) and TCM (powertrain revolution).

If a malfunction occurs in any of those sensors the system will disable. The ECM views the higher powertrain revolution than what is in allowed parameters as a failure and shuts down cruise control. In short, find a way to keep the ECM happy and you'll have cruise control. The ASCD is the only system I'm aware of that takes inputs from both the TCM and speedometer. Most of the other systems use the wheel speed sensors as a basis which is why they are not affected by the swap.

 

Nice to know you're working on a solution to one of the few drawbacks to this mod, ISM!

 

I have never used cruise control before, so I don't think I will be missing out on much.