Question: What final drive are you guys using?

[veovius]

With all the added power of a KA-T, I would think the stock final drive would be restrictive.....have any of you guys done any drivetrain gearing mods? Or like, one of those OEM nissan LSD swaps that come with a lower final drive?

[Structure240sx]

restrictive how? top speed?

with an extended redline and stock gearing we can be at the top of 4th at the traps. why hurt acceleration?

now with auto transmission swaps a different final drive can help

[nb07bcar]

I have a 4.11 lsd. Its nice to have , but for a everyday driver its not as good as a 3.70. On the freeway I am at 3-4 grand. But I would definetly get the lsd. It helps alot.

[klattr1]

do u have a mustang or something? lol

stock 240sx vlsd's and open diff's are 4.08

[nb07bcar]

Datsun 510

[veovius]

Well, as an example....

I know a guy who drove a older bimmer, with the straight 6, custom intake mani, tons of mods, fat turbo. When he switched out his final drive for a lower gearing ( I think he went form 4.10 to a 3.73, not sure tho), he built so much more boost in first gear that the LSD ripped itself apart. Minus that, he definitely would have been faster. More boost in each gear = more power, also, less time spinning through first...

[Structure240sx]

completely different car, engine, transmission, turbo setup quite hard to compare

i see what u are saying. longer gears meaning more time to reach full boost in first.

it seems i make about 16psi (when i tested for this the other night i spun the drag radials slightly from them being a lil cold and uneven pavement) in first then reach full bosot in 2nd 22-27psi depending on my setup.

[virus77]

I rather enjoy my j30 rear end. Slightly longer gear than factory that it allows me to boost longer in each gear but doesnt sacrifice accelleration too much. In a 1/4 mile maybe finishing in 4th will help but on a downshift race or certain occasions the longer gear will yield better results at different speeds. I hit 70 in 2nd gear and a hundo in 3rd so im happy. Oh and im drunk so excuse any misspellings but I like posting after the club nights.

[Structure240sx]

if i go through with the z32 TT auto, i plan to put a 4.6 ring gear in the diff.

z32 tt guys have 3.6 stock and swap to 4.10's. so we basically have 4.10's and going to 4.6 would be about the same. i wonder how accleration would be on that

[TXCumtrensh]

as fast as you would accellerate after eating at a buffet, to a bathroom. lol

4.6:1 would leave you shifting at 6800rpms (redline)

1st :: 27mph2nd :: 49-50mph3rd :: 70mph4th :: 105mph5th :: 130mph

it would be pretty close, i forgot the formula for it.. but thats going to be a good estimate for shifting points with THAT high of a rearend

[nissanfanatic]

Taller tires help out a whole lot as well... Hence why I am going into 5th at the traps while structure and the rest are at the top of 4th.. I use stock teardrops with 205/55 tires...

[95_240sx]

Taller tires definatley rock! I was running 245/55/17 DR's and was going through the traps around 7200rpm at the top of 4th and doing around 130-135 usually. I still had another 1krpm to go.

Rick

[grimple1]

Nismo 4.36 (aka 4.4) VLSD here. (though I'm not turbo-ed yet)

[AZhitman]

4.36 with S13 5-speed and 255/40/17's....

[nismofly]

i dont drag race, ive been thinking of looking into a z32 rear, iirc theyre like 3.69 or 3.92 or something like that, give me a little better top end for the faster road courses like the glen, which is where ill be doing a lot of running...then maybe stick the 4.08 back in with an lsd for the shorter courses

[veovius]

Thanks for the info

I'm not sure if I'd like taller gears though...as it is, I'm doing 3000rpm at 110kph, in 5th gear. I'd rather be at a lower rpm for cruising for 3 hours.

Another thing, doesn't shifting in general, lower your 1/4 time? If you could make the same speed say, at the top of 3rd, why make is so that you require being at the middle of 4th?

[nissanfanatic]

Taller gearing would put you at a lower RPM for cruising...

As for your question on shifting... a shorter gear helps people who want a better ET get it without making more power. Our 240s are given a short 4.08 gear to make them feel quick/torquey. If you make say 400whp, then you can definatly throw in a taller gear, retain the quickness, but shift less, and go faster. The more use you get out of each gear, the better ET you will be.

Think of it like a tow truck...

[Structure240sx]

z32 twin turbo diffs are 3.6 but cant bolt up to a 240.

[nismofly]

it was the na i believe that was the ratio i was talking about, scc runs it on their project silvia

[Structure240sx]

NA z32's have a 4.10 final drive

the twin turbo guys have ktis to swap a NA rear end. they also have gears they can put in to go from 3.6 to 4.10

[nismofly]

well blow me down

lets put it this way, id like to run somewhere around like a 3.9, right now at the glen im constantly up around 4k - 5ks rpms, so id like it to be a little lower, plus when i get my turbo that would let me run a few mph faster on some of the straights there, plus the front stretch at pocono

i wont mind if its not bolt in, ill just get the parts needed at the same time...maybe ill work with the z32 tt unit

veovius, i guess im in the same deal youre in...i couldve sworn there was something around like a 3.9 that could be made to work, but i guess its back to the drawing board for me too

[Structure240sx]

nissan motorsports used to sell a 3.7 and a 3.9 ring gear. its now not avaible anymore for some reason

they are the ones that have the 4.6 i was talking about. they also have a 4.3 and 4.083.