I was wondering what the numbers (ratios?) represent, and also why/how does another rearend differential make you faster off the line. Finally, what are the advantages and disadvantages of the different diffs?

 

pulled from fellow Nissan Enthusist site.

here are all the ratio's


R200, R200H, R200V, R230V, F160 are the differential models. Keep in mind this does not imply the differential housings are the same.
Z33 - MT - R200 - 3.538
Z33 - MT - R200V - 3.538
Z33 - AT - R200V - 3.357
Z32TT - R230V - 3.692
Z32 - R200V - 4.083
G35 - Sedan - AT - R200 - 3.357
G35 - Sedan - MT - R200V - 3.538
G35 - Sedan - AWD - AT - R200 - 3.357
G35 - Coupe - MT - R200V - 3.538
G35 - Coupe - AT - R200 - 3.357
G35 - Coupe - AT - R200V - 3.357
Q45 - G50 - R200V - 3.538
Q45 - FY33 - R200V - 3.692
R32 GTR - RB26DETT - MT - F160 - 4.111 - (Front Final Gear)
R32 GTR - RB26DETT - MT - R200 (Mechanical LSD) - 4.111
S15 - MT - R200H - 3.692
S15 - AT - R200V - 3.916
S14 - KA24DE - 4.083
S14 - SR20DET - MT - R200V - 3.692
S14 - SR20DET - AT - R200V - 3.915
S13 - KA24DE - 4.083 - (Both R200 and R200V)

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the way the diff works simply is...... the lower the ratio ( ring gear size ) the the quicker you get through your rpm band... however this is not a solo deal. the transmission itself is also geared in a way that effects how long you stay in a certain gear..

i could ramble but i highly suggest just googling it and learning for yourself.. after that, come back and ask any further questions. I know how gears work however im no transmisson/gearing expert lol.


ps

I do know this much also... when you see V or H.... that stands for Viscous and Helical

 

as opposed to the front diff? haha, sorry couldn't resist. I prefer wider gearing for highway driving since we have no 6th gear in our cars... which is why I still haven't found an lsd that I like.

 

what about the 4.36
Which car had that one?

Does changing the gears in a diff affect the speedometer, since the speed sensor is in the transmission?

and the transmission wouldn't know that the diff was changed?

 

the diff basically changes how long you are in a certain gear.

the gear ratio itself will not change. for example changing the diff will never change the fact that 1st gear is shorter than 5th gear..

 

so is the speedometer accurate if I used lower gears compared to stock?c

 

your speedometer will read exactly how fast the gears are spinning no matter what as its physically meshed with a gear that spins it.

 

i understand that part.

But the speed sensor is in the transmission with the transmission gears. Does changing diff gears change the accuracy of the speedometer.?

as with bigger tires?

 

no.... the speedo will simply raise faster or slower depending on what you do to your drivetrain...


Example... Lighten Flywheel.


I has nothing to do with gears... it just alleviates a bit of work from the engine therefore allowing rpms to climb more easily and as a result increasing the amount of speed you will obtain faster.


the tire stuff becomes a factor when you are dealing with digital speedometers as it takes your tiresizes and calculates them into its equations to produce your speed. Mechanical setups however are part digital as it goes though the ecu and then to the speedometer. either way, the only real way to get a an official reading of your speed would be via some sort of external source such as a cops laser gun and or at a drag track

 

i searched and I found that if you lower the gears in the differential, your speedometer will NOT read your speed accurately.

To fix this I would have to get a new speed sensor gear with another one.

The problem is i don't know which speed sensor/ speed sensor gear to use.

The LSD I recently installed is one from a 180sx, the one with 4.36 ratio.
(So i am guesssing that I would need a speed sensor from a 180sx 5sp transmission which seems to be impossible.)

Bumnah also told me that I can send the cluster to some one to correct the reading.

Can someone please ELABORATE on both of these.

I don't know what to do.

 

......i have no idea... the speed indicated is an estimate of how fast you are going anyway bro.


there is clearly law breaking speed and normal traffic speed.

its not something i looked into... ill see what i can find.

 

Anytime you change the gear ratio and use the same exact way of measuring speed whether it be via speed sensor (as in our cars) or mechanically via speedo drive gear and cable, the speed that is shown on your speedo WILL most definitely change. If your car came with 4.083:1 gear ratio and you swap a differential with lets say 4.36:1 ratio, the speedometer will read faster than your actually traveling and vice-versa. It can be a nightmare trying to match your speedo with gearsets. Not to mention, your rpms at speeds will be higher with a steeper (numerically bigger) gearset. Oh, and to make it more confusing, tire diameter will throw it all off as well.

In a situation where your speedo is read electronically as in with the 240, you may need to find a different speed sensor to read it properly. However, with how the ecu reads the speed sensor, this may not be an option as they may not be interchangeable from Nissan model to other Nissan model. In this case just like when I was a young fella with my old muscle cars, I went on the highway with a friend in a car we knew to be accurate and documented at what the speedometer read at certain speeds on the highway and documented that along with engine rpms at the same speeds. You then train yourself with the changes and even put a cheat sheet in the glove box or taped it somewhere for reference.

Did I confuse you? Haha.

 

I completely understand what you are saying. I plan on changing the gear(pinion) on the speedsensor. from 20teeth to 21 teeth. It will help by not reading as high speed.

I was planning on driving with a friend on the highway to "estimate" my speed, but increasing the accuracy would also help.

It will not increase the miles on the odometer as fast too!

FAVOR: I need some one who has a speed sensor to please count the teeth on the gear(pinion) of the sensor. Please PM me/ post a picture here.

Thanks

RickY

 

is there a way to tell what kind of diff you have w/o opening it?

well i got my shell and it had a diff in it its a stock s14 pumpkin with no vlsd sticker and i checked my vinplate numbers my car didnt come with vlsd but it does have lsd. now im wondering if i got lucky and my shell came with a clutch or helical lsd installed already is there any way to tell w/o opening?

 

no. not really you have to open it.


jack the car up

Spin one wheel

-the other wheel turns opposite=Open
-the other wheel turns same direction=VLSD, LSD etc