Different final drive for high power guys

[turtl631]

Based on reading about severe traction issues with 300+ whp on most street tires, I was wondering if anyone has resorted to a different final drive. I believe the S15 has a taller final drive that might be a reasonable increase from the stock ka diff. Is this a reasonable way to use turbo power or is my thinking way off here?

[fiznat]

I was thinking about it, but there are just so many other things that I need to get out of the way first: wheels with nicer tires (some ET street radials), better brakes, etc etc etc..

I would def be interested in beefing up the driveline in general though... transmission/driveshaft/rear end

[LEMHEAD16]

What about a Z32tt rear end. It should swap in and have a taller final drive right. I don't think that would be too expensive and it would br great for 400 hp Fiz.

[cdlong]

the r230 doesn't fit right in like the r200. if you were so compelled, you could probably get it to work. but it would be a whole lot cheaper to use an S15 ring and pinion.

i haven't heard of anybody breaking drivetrain components with 300hp. our drivelines are pretty strong.

[turtl631]

I wasn't referring to breakage at all; mostly I was referring to limitations with tire traction on street tires. transmission/input shaft breakage is a whole other ballgame, and frankly it doesnt concern me.

[cdlong]

you're right, though a lower rear end would technically make the car accelerate slower. i say technically because a longer final drive would solve some traction issues and you would have to shift less, often making the car faster.

the Spec R 6-speed is the only one with the 3.69 FD BTW.

[skatanic28]

yeah i was looking at swapping in an s15 hlsd as well, both for the lower gearing and helical gearset. the j30 r200v also uses a 3.9 gear, so that would be a bit longer as well.

[blubottlemax]

You would have to get one that still comes with the gear. I have an HLSD on the way, but it did not include the gear, I'll just swap mine over from my open diff.

[turtl631]

I understand that it woudl reduce acceleration, but if you can't accelerate in the first place b/c you're just roasting tires...I'd imagine there is a level at which a taller final drive would work well, and a level at which it would just cause you to accelerate way too slowly for your power output.

[cdlong]

I understand that it woudl reduce acceleration, but if you can't accelerate in the first place b/c you're just roasting tires...I'd imagine there is a level at which a taller final drive would work well, and a level at which it would just cause you to accelerate way too slowly for your power output.

my point exactly.

[:: orion ::]

It's recently come to my attention that DESPITE what my VLSD page says...the early Q45 have an R200, with a 3.69 ratio.

Now, the output shafts are a larger 5-bolt style (don't think J30 axles will work), and the front flange on the diff (what the driveshaft bolts to) is too large...but that's an easy switch.

But the case looks externally idenical to a stock S13/S14 open diff...and would probably work fine if you already had a J30 or S13/S14 VLSD to swap the output shafts and the front flange off of.

Anyway, I have pics, and will post them to my VLSD page at some point, whenb I get time.

For now, consider this good info, but untested by yours truly.

- Brian

[hannibal]

I have heard that the Q45 diff would fit, but I told them they were wrong cause Orion said so...

Courtesy parts used to carry lower ring and pinion gears (3.7 and 3.917=J30), but the page now says 'no longer available'.

[DRIFTEADOR]

kind of off topic but what are the tallest slicks you can fit on a stock height s14? not for street driving of course

If you have the money to spend, race logic makes a cool electronic traction control system that uses your stock abs sensors. this is their website http://www.racelogic.co.uk/traction/

[cyrus240sx]

man that traction control setup looks awesome..... i think ill add that to my list of future mods lol

[:: orion ::]

I have heard that the Q45 diff would fit, but I told them they were wrong cause Orion said so...

Hehehe...sorry. Things changes as people actually try setups, and not trust what's posted online (I've read on several sites that it's an R230...and car-part.com used to list the whole Q45 subframe as an interchange for an R230!).

Anyway, it looks like the output shafts may STILL prevent you form using aa Q45 diff, and the guys who's testingit and ofrwarding info to me tried S13/S14 6-bolt output shafts, and the spline count is wrong.

FYI...it still looks you CANNOT use a Q45 diff. We'll see...

- Brian

[cdlong]

kind of off topic but what are the tallest slicks you can fit on a stock height s14? not for street driving of course

If you have the money to spend, race logic makes a cool electronic traction control system that uses your stock abs sensors. this is their website http://www.racelogic.co.uk/traction/

you already have something like that built into your car, it's called the gas pedal all that system does is cut engine power. it can't sense which wheel has less grip because we only have a three channel system (rears are together) and it can't actuate individual brakes to steer more torque to the other wheel because we have a passive system.

i like how the pic on page shows a car drifting, not exactly showing off their system.

[SunshineAcid]

this is exactly what i want to do2.6l stroker turboed6k redlinelower final drive2.6l stroked and turboed would have massive tq and massive wheelspinlower final drive would be a must.

[Red-KAT]

you already have something like that built into your car, it's called the gas pedal all that system does is cut engine power. it can't sense which wheel has less grip because we only have a three channel system (rears are together) and it can't actuate individual brakes to steer more torque to the other wheel because we have a passive system.

i like how the pic on page shows a car drifting, not exactly showing off their system.

If you read up on the system more. You don’t HAVE to tap into you're stock ABS system, you can install the wheel speed sensors they also sell... The system learns the acceptable wheel speeds and how much they differ from one another. Then the system just cuts HP to keep all the wheels into spec. The system also lets you dial in the amount of slip that you would like to occur. So you could set it for 0 slip... up to 100% slip... Drop it on 50% and you could have assisted drifting and not need to control the whole car yourself.

Anyways back on topic... We dont need the other R200's to fit ... Just get a good clutch type limited slip put in, and then rip the 3.7 gears out of another R200 and install it in you're own. You might be able to find a cheep open diff with the right final drive that way.

[DRIFTEADOR]

to add to what red-kat said, it doesnt work by activating the abs system, it only uses the sensors to detect wheelspin, then, like you said, takes power away. doesn't matter if its a 3 channel, that just meants the abs unit pumps both rears togethe, there are still 4 abs sensors and thats what the system reads.

[:: orion ::]

... it only uses the sensors to detect wheelspin, then, like you said, takes power away. doesn't matter if its a 3 channel, that just meants the abs unit pumps both rears togethe, there are still 4 abs sensors and thats what the system reads.

That's the thing...the 240SX and J30 have only a 3-channel system, which means (in this case) that the rear only has ONE sensor...on the nose of the diff.

It looks for a difference in speed as compared to the front tires, not compared to one-another.

Just FYI...

[/thread jack]

- Brian

[IvanAtSPRacing]

I am also seeking a taller final drive. In fourth gear, the KA tops out at about 120 mph. For a higher HP drag car, that means 5th gear will be needed to make it thru the traps. Taller tires will help but wont be enough. Even with my 28" tall tires I will still need a taller final drive.

I belive the Z31 had a 3.7x ratio R200 12mm gear set. Can any of you diff gurus check into that? Orion... a little help please

[klattr1]

http://www.az-zbum.com/informa...shtml

http://zhome.com/ZCMnL/tech/GearRatios.html

[:: orion ::]

I belive the Z31 had a 3.7x ratio R200 12mm gear set. Can any of you diff gurus check into that? Orion... a little help please

3.69:1 ratio is a 48 tooth ring gear, 13 tooth pinion (48:13).

I think the Z31's R200 48-tooth ring gear would be correct for our diffs, but the pinion IS NOT swap-able IIRC...look at a Z31 diff and you'll see why...the length difference is too great.

So you're still left with needing to find a ring/pinion set that will bolt into a 240SX case...the Q45 may be your answer (case seems to be indentical to S13/S14)...ratio is 3.69...but the output shafts may not work. Could the fix be as simple as swapping J30 or S13/S14 VLSD 'guts' onto the Q45 ring gear, and using VLSD output shafts?

Someone needs to try it!

- Brian