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Discussion Starter #1
Basicly getting ready to swap my j30 rear diff, I want to swap the entire j30 pumkin and internals out with my old open diff from my s14, but I need to know if it will make my MPH gauge not accurate because thej30 rear diff has a 3.9 gear ratio... anybody have this problem?
 

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i think they have speed sensors with different teeth that will correct it after you swap. i dont know which sensor you would need though.
 

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if hes wanting the 3.9 gears though theres always the option to swap speed sensors.
 

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Discussion Starter #5
ok speed sensor, Im gonna search to find out where and how to switch it out. if anybodys got any info on it please fill me in. 95 240sx se model... but as of right now Im going to swap the j30 vlsd and use my stock gearing. hope it does not need the backlash set again.. Ill wait for the turbo to throw the j30 gearing in...
 

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240-kid
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To my under standing the only Speed sensors that fit are the KA and SR ones, none of which I dont believe are gonna give you correct readings...
 

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they used to offer a variety of speed sensors with different teeth to correct the changed speed from their final drive kits.
 

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240-kid
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Yeah I believe they discontinued those when they took away some of the FD kits, IIRC I could be wrong
 

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Discussion Starter #9
Update......switched my open diff with a j30 vlsd and kept my stock gearing.. no backlashing no noise, just slaped it in and drove.. everythings good.. my mph gauge is still the same.. but i wish i would of saved up for a clutch diff.. cuz the vlsd is so temermental.. you have to warm it up and still some times it fails at the beggining of a drift..
 

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just remember your speed sensor is attached to your transmission, the speed sensor on the Diff is used for the ABS system, since all 240's with an LSD had ABS and J30's. But yes it does add up to approximately a 5mph difference when you chage your diff without swapping the ring and pinion gears. That difference might chage depensing on your wheel and tire setup.
 

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Sorry for the late repply, but no i dont.
 

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i run a j30 diff in my s13 the final drive ratio isn't enough to throw off the speedo and you will be amazed by the difference in performance comeing out of tight corners and launching the car.
 

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240-kid
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if i remember corectly the j30 has the same gearing as the 240 so you shoudl be fine even if it is off it woudl only be 1or 2MPH
No, 240 is 4.083, J30 is 3.916

i run a j30 diff in my s13 the final drive ratio isn't enough to throw off the speedo and you will be amazed by the difference in performance comeing out of tight corners and launching the car.
Remember tire size also plays a factor. It may not throw it off as much as you were thinking but it does...
 

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i dont feel like making a new thread, and in my search i saw scoots thread and what not

so basically this is the deal
i got a j30 diff with a nissmo 2way that has 4.364 gears in it.
options slap that bitch in as is.
change the gears beck to factory ratio
or stay welded (leaning towards this)
used for drift, as you all know
opinions

All Euro 180SX Manual Trans Model's had a FD of 3.916 (Also J30's)
- Gear Count: 47/12
All JDM 180SX CA Manual Trans Model's had a FD of 4.364 (Also Skyline GTS-T's)
- Gear Count: 48/11
ALL 240SX FD's are 4.083
 
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