So, the roadster is geared lower than the coupe to give it the same acceleration, so... What kind of improvement would the coupe get if it had the same gearing as the roadster?

Has anyone who had their transmissoin replaced tried to get the roadster gearing instead?

 

Roadster and Coupe both have the same AT and MT.

 

nope, the roadster has a different ratio than the coupe on the 6-spd if I remember correctly (to compensate for the extra weight of the convertible)

 

ok well first off if you were gonna re-gear the tranny why do you crunch the numbers and see what kind of streetability you can keep while improving acceleration... I wouldnt use the gears from the roadster(not sayin they are different I HIGHLY doubt they are) but I could be wrong...

 

Are you guys talking about the rear end gear ratio? Cause that is different than the trannys ratios. That would be a lot more feasible to swap.

 

I believe the difference for the roadster is in the rear end (diferential). The roadster has SLIGHTLY lower gears (numerically higher) to counter the higher body weight of the roadster(240 lbs or so).

The swap is possible, but all you really need is to pick a new gear set and replace the gears in the rear end.

I am not necessarily saying this is a good idea, but it could be done. I think first gear is plenty low on the Z already. In the higher gears you can get the same effect by shifting a little later.

 

According to Nissannews.com

Roadster and Coupe have the exact same ratios for AT and MT.

 

Yeah, seems that it says that everywhere... I swear Car & Driver said the ratios were different, but I am wondering if it was on the show or in the magazine. Damnit, now I gotta go back and check. I saw someone post something about it, too

 

I"ve read about the ratios being different on the vert as well

 

Roadster
http://www.nissannews.com/nissan/200...er/specs.shtml

Coupe
http://www.nissannews.com/nissan/200...pe/specs.shtml

 

USA Today

"As a result of the extra structure, the Roadster weighs about 240 pounds more than the coupe. To prevent the soft-top from being sluggish, its drive ratio has been altered. Think of the Roadster as having slightly more leverage against inertia to get it going from a standstill. In first gear, the Roadster's overall start-up gearing is 13.423 to 1 — that is, 13.423 turns of the engine to one turn of the rear wheels — while the coupe's is 13.074. Should be a pretty even drag race."

Full Link
http://www.usatoday.com/money/autos/...roadster_x.htm

 

Thanks! I knew I hadn't made it up, lol. Well, all the other numbers I found have the same ratios as Nissan News, and I get 13.423 for the M/T, so I am not sure where he got the 13.074.

Edit: I know. Reverse gear is 3.446, time first, 3.794 = 13.074. Oops, guess he made a math error when he wrote the article, and assumed Nissan changed something.

So, mystery solved and it looks like they are the same, which would definately make the roadster slower.

 

Then what acounts for the fact that there have been time for the Roadster that are equal to the coupe? One time I saw in C&D was 5.5 how is that explaned then?

 

Lots of things. COuld have been models (with different tires/wheels). Air temps. Variations form one engine to another (you'd be surprised what kind of variations you'd get on a dyno between the same model vehicle). Driver differences (maybe they had a fat guy driving the coupe? ), corrections perofrmed on the numbers. Who knows... Lots of variables...

 

First gear seems short enough as is when your hammering it from a dead stop. I wouldn't want a shorter final drive.

 

In the fall issue of sport z mag it says this. " Interestingly enough, the Roadster's performance felt slightly stronger off the line than the Enthusiast 350z coupe that nissan was kind enough to lend us for comparison purposes. That discrepancy may be due in part to a slightly lower first gear ratio (13.423 vs. 13.074 respectively) that gives the roadster a head start."