180sx or usdm s13... gear ratios

[madwilly240]

which nissan VLSD's had the best gear ratio's? apparently the 180SX type x, the 97-98 180sx had improved ratios... and so did the s14. but if you were me, would you pay a little more for a 180sx vlsd over a s13 usdm vlsd?

[AKADriver]

All SR20DET/5 speed 180SXs used the same 4.083:1 ratio as the 240SX, including the kouki 180SX. The S14 Silvia SR20DET/5 speed used that ratio also.

If you want taller (numerically lower) gears, the J30 and auto-trans JDM SR20DET cars came with 3.916:1 gears. The S15 6 speed gears are 3.692:1, even lower.

If you want shorter (numerically higher) gears, the CA18DET Silvia K's and 180SX had 4.363:1 gears.

I think dousan is using the CA18DET gears in his KA car if you want impressions.

[Dousan_PG]

hmmm maybe your right, AKA, i never thought of that. when the LSD comes in i'll pop my old one open and check it out. im considering keeping the final gear, i love it for drift.

[N1ceDrgn]

When I did my conversion I left the diff off my car. Everything else I essentially changed out. I left it off because I was told that the gears were too low for driving on the highways here in the states. Was that bum scoop or what? I still have my CA diff but I had no intentions of using it off track. I would love to have the power back it gave me but I was more concerned about keeping my engine alive. Would things be alright with that diff for normal and highway driving? ( I'm sorry about invading the thread like this but I was going to start another thread about almost the same thing.)

[AKADriver]

It depends what you consider "too high".

Couple the CA18DET's shorter 5th gear with the 4.363:1 final drive... revs at cruise will be 18% higher than with a stock KA or 7% higher than what you have now. It works out to about 3100rpm at 60mph.. 4100rpm at 80mph.. depending on your tire size, of course, but figuring you've got something close to stock.

[Dousan_PG]

Originally posted by AKADriver
It depends what you consider "too high".

Couple the CA18DET's shorter 5th gear with the 4.363:1 final drive... revs at cruise will be 18% higher than with a stock KA or 7% higher than what you have now. It works out to about 3100rpm at 60mph.. 4100rpm at 80mph.. depending on your tire size, of course, but figuring you've got something close to stock.

you a smart mofo

im at about 4100 at 80ish MPH. 205/55/15 tires too

[AKADriver]

hmmm... that shouldn't happen with a KA trans! even with those short tires you should be at more like 3800-3900.

this is assuming:
4.363:1 final drive
0.759:1 fifth gear (KA)
205/55-15's turn 870 revs/mile...

The numbers I put above were based on a 205/60-15 or a 205/55-16 (840 revs/mile) and a CA trans (0.838:1 5th).

Maybe you've got something even shorter than 4.363? Nismo sells a 4.636:1 gear set... that could be what you have.

[N1ceDrgn]

I fried my CA mission a couple of months after I got everything in. I'm actually in the middle of getting replacement gears and bearings right now. I am using a KA mission that has a synchro problem with second. Anyhow, the diff is the question. Where I'm at and what I usually do is a lot of highway driving. Of course lower rpm's, things will last longer, so that's preferred. If the CA diff is no good, then I plan on finding a OS Giken or something relative for my rear end.

[madwilly240]

what are higher or lower gear ratios gonna do for the cars performance?

[Steeles]

Madwilly - the (numerically higher) gears will give you quicker acceleration, (numerically lower) will give you more top end. I've got the 4.36 in my car. first gear is damn near pointless but i love it. gas mileage drops somewhat on the highway but over all I love it. (this is in an S14 with SR swap with 225/50/16) I'll have to double check my RPMs at 80 but yeah its up around that 4grand mark... I dont think over it. I think my tire size offsets it enough to keep it under. but again I'll double check later today.

[Dousan_PG]

Originally posted by AKADriver
hmmm... that shouldn't happen with a KA trans! even with those short tires you should be at more like 3800-3900.

this is assuming:
4.363:1 final drive
0.759:1 fifth gear (KA)
205/55-15's turn 870 revs/mile...

The numbers I put above were based on a 205/60-15 or a 205/55-16 (840 revs/mile) and a CA trans (0.838:1 5th).

Maybe you've got something even shorter than 4.363? Nismo sells a 4.636:1 gear set... that could be what you have.

whoops. ok here's what it was
5th gear
80mph
3800 rpm
205/55/15 tires all around

so it looks like i've go CA final gear?


ill know for sure when i put in my LSD, because i'll open up this one and check it out.

thx

[AKADriver]

yeah, that's CA final gear.

[Dousan_PG]

Thanks AKADriver!

[uiuc240]

Originally posted by AKADriver
yeah, that's CA final gear.

.838 is also an SR 5th gear...not that you didn't know that, you just didn't write it. ;)

I would HATE to have a 4.363:1 final. But then again, I don't drift. I want the 3.916:1 rear end for better cruising and better/longer 1st gear. :D

Eric

[Steeles]

Originally posted by uiuc240
.838 is also an SR 5th gear...not that you didn't know that, you just didn't write it. ;)

I would HATE to have a 4.363:1 final. But then again, I don't drift. I want the 3.916:1 rear end for better cruising and better/longer 1st gear. :D

Eric

the 4.36 isnt that bad! hehe I dont drift and have a 20 minute commute up the highway and it works fine for me :) I do need to get my speedo fixed though... ;)

[madwilly240]

Originally posted by Steeles
I do need to get my speedo fixed though... ;)

getting a different gear ratio would mess up my speedo?

[Dousan_PG]

Originally posted by madwilly240
getting a different gear ratio would mess up my speedo?

yep.
after 50mph mine is off
my RSM stays accurate though, so i am converting from KPH to MPH

[Steeles]

yeah mines off by about 5mph sucks cause the speed cut comes on that much quicker. I wanna get rid of the whole cluster eventually. half the dummy lights dont work and when I get my PFC everything will be monitered there do a tach and boost guage in there and a defi HUD for the speedo.

checked my RPMs at 80 tis morning turning aout 3600 in fifth. (speedo actually reads 85 but like i said its about 5mph off at 80 according to the speedo it's turning like 3400)

[hurleyboi514]

they have alot of new stuff on the courtesy nissan site since ive been there... they have speedometer pinions to correct speedometers. cool, huh? i plan on gettin that 4.636 rear gear myself when i get an LSD. ill need it since im going w/ NA KA... you SR guys dont need it to much, you have boost as your acceleration aid.