ok, so i have a 97 sc400, so my final drive is 3.266, i want to switch out to a sc300 pumpkin, with a welded diff, which probably has the 4.27 cuz it's coming outta an auto trans, but he says it's a 4.08, how big of a difference would i be looking at in terms of loss of top speed, difference in gas mileage, and most importantly driveability(accidentally breaking traction on turns) and low end performance gains, i'm asking cuz i usually see people going up 0.3 or 0.5 on the final drive, but this is like a 1.0 difference, i have no idea what to expect, btw, all i have is a exhaust, h-pipe, and bfi. oh and some heavy *** 19's

 

well, maybe it wont be too bad, the 92-96 sc400's ratio was 3.92.... this is sad, i'm replying to my own post

 

i know there was a site that would tell you your new top speed, it might be in the GS forums as i know they've swapped their gs4 diffs out for sc3s.

im pretty sure the autos have 4.27, the 5 speeds have 4.08. i'd have to look again but i'm sure the sc3s have the lowest gear available.

more then likely you'll be up around 3k+ at 80mph or so, it'll def be around there, not sure where you're at now when you're going 80, but that was the consensus in the gs4 area.

do it it'll probably be the best mod you can do for accel, you'll more then likely lose a couple mpg, and you'll noticethe change more by losing the heavy 19s but it should still be noticiable.

edit- did a quick search for ya, your results may differ but there's some good info in this thread.
https://www.clublexus.com/forums/sho...=3.9+gear+swap

 

thanks, that thread helped alot, i think i'm gonna go with it, although it looks like my top speed will be limited about 120ish and i'll be doing about 3500rpm at 80mph, but the ssr professors gotsta stay