4.11 or 4.55 ratio diff for track work

[pandaah]

hey guys, thought id ask cos no doubt some of you must of gone through the same quirey..

anyway, im running a 4.55 diff and im finding it revs out abit too fast even with the mighty 1ggte.. now im worried when i throw in my 1jz and 35r and use it for circuit racing that im gunna be changing gears every 1second..

what do you guys think?.. ive got a 3.9 ratio but im think id rather a 4.11 same as my old skyline had, its a w58 5speed so not sure how the ratios would mesh up but do you guys reckon theres even much difference between 4.11 and 3.9 ??

any opinions would be apprieciated

[andrew_mx83]

jump on norbies ratio calculator thingy, punch in tyre size/gear ratios, and print out a couple of graphs with different rear end ratios. sit em next to your dyno chart and pick the most appropriate one -where you can keep it always on power, doesnt have a power "hole" anywhere and good top speed in gears. my old setup with w55 was balls, you could either come into a corner in second revving its tits off and about to hit limiter, or off-power in third.
i did as i described above and chose the gearbox that most suited what i wanted to do (settled on a J160). same would apply to diff gears if you are fixed in the 'box. i was after an upgrade anyway so this was the simplest solution for me. ive since picked up a set of 4.3's, but will prob chuck them in the daily instead as i reckon the race car will be spot on with its stock 3.9's now.