j30 diff question

[final act]

I heard the j30 diff is nice for turbo cars, because of the taller gearing,47
but how is it in a na ka24de 240sx?

and what does taller gearing mean, thanks in advance!

[underd0g]

"taller gearing" means that the gear is longer. you get a small decrease in acceleration, but an increase in top speed.

[Tricky1980]

i have the j30 in my 95.. and its fine, i guess i kinda noticed it alittle but having a lsd over open made up for it 10times over... so regardless im happy with it.

[projectRDM]

What does '47' mean?

S13/S14 is 4.08, the J30t is a 3.92. Very negligable difference.

[final act]

bump whos running a j30 diff?

[Agent_S13]

bump whos running a j30 diff?

I am. Put it in this weekend.... No noticeable difference in daily driving but there is an acceleration issue. I don't get that same "pick up" as I get onto a freeway like I used to. Like it was previous said before... the fact that I have a VLSD makes up for that fact. I know I'll get used to it in a week or so.

I didvnotice during my install:

I had to swap the diff covers (I have an S13) and the J30/S14 diff cover sticks out much further than my S13 one. This doesn't include the mounting bolts there. My cover is shorter but I think compensates for the fact that I didn't need to use the "supposed ABS driveshaft" I was given when I bought the J30 diff -- I ended up using my old driveshaft and everything bolted up perfectly with no extra play or tightness. The differential was the same size as my open one, even with the ABS sensor. It ended up being the same length as my open diff because the ABS sensor length was negated by the smaller/shorter differential cover.

Anyways, you won't noticed the difference in gearing at all... its too small to make a big difference.

-Aaron
'91 240sx coupe

[orion::S14]

What does '47' mean?

47 tooth ring gear I'd bet...pinion is 12 tooth on both.

47/12 = 3.91 ratio

49/12 = 4.08 ratio

- Brian

[final act]

can you just swap the open diff ring gear onto the vlsd and put it into the open diff, then have the lower gearing?

[orion::S14]

No...the ring and pinion must remain as a set, they are worn together. Plus, you'd have to set and check backlash and gear mesh, a buch of stuff you don;t have the tools for, I assure you.

You could swap the whole viscous unit into the stock housing with the stock gears, but it's a pain and a waste of time and energy for the 4% change.

- Brian