thinking of the 3.9 gears, just wondering how to fix the speedo. I don't want to buy new gears and have the speedo all screwed up!

 

i've been searching quite a bit and all i can find is that no one seems to know where the speed is even measured at, some say wheels, some say transmission, some say ecu. and i can't find anything out there to correct for tire sizes or gearing. it seems hard to believe that nobody makes anything to fix this problem, hell you can buy handhelds and fix your speedo on most domestics with obd2. what kind of ecu do we have?

 

I have been asking the same question and so far the only answer I can get is. "It not worth it." When I press the question I find out they just don't know how to do it. So, it is not worth it to them I guess.

I just emailed Performance Nissan and see if they can help us answer this question.

I should hear from them by tomorrow and I will post their response here.

I'm thinking a recalibration / reflash of the CPU @ $125 or so. Hope it's not that much however.

I was going to find out in a month or so when I was ready but, since you asked maybe I can help both of us out.

$900 for LSD, $935 for 350EVO 3.971 gears, $350 to install, $125 for reflash.
This is going to cost some coin but worth it I think. Over $2300 + tax

 

The speedometer reads rear tire rpm. Modifying the drivetrain makes no difference. That’s what I think.

 

Glad to hear the thread is about gear ratios....I was scared that it would be about speedooooo'S

 

OK, so here it is .... Jason from Performance Nissan replied. He is a sponsor to this forum. He states:

"Hi There,

It does not effect your speedo...

Please let me know if you have any other questions...

Jason"

I think Davidv is correct however, I replied to Jason's email asking why. I would hate to have everyone buy this based on this thread without a tad more information.
The only way I see the speedo correcting itself is how DavidV has stated it. Now, that is with stock sized, or same diameter tires.

More later ....

 

Thank you everyone for this recognition.

 

thanks fella's, guess i'll do a little test before and after the install and i'll post for reassurance.

and you are right mecinoid this is gonna cost alot... which is what i've figured out about most mods for this car, but i love sooooooooo

 

i think their called wheelspeed sensors one on each corner. should have a toner ring and sensor, these sensors tell the pcm how fast each wheel is going so that it can decide whether to enable abs or traction control. most other cars read thru the transmission so the transmission would be going faster wouldnt it. it probably has a speedo buffer either internal or external pcm for just the speedo. vote for pedro

 

Me too !!! I also feel it is worth it. I mean by the time I get done. I will have a car that looks, handles and has more power than a Turbo Carrera for under $40K. At least those are my goals.

BTW- I'll post the response from Jason when I get it unless he chimes in here.