Quote:
Originally Posted by Septor
Thank you everyone for the help!
Is there a particular/"tried and tested" method to do the FD changing? and how do I select to which ratio I change?
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Some diy / cheap methods in forums on here if you search. But weir performance or rhdjapan have Fd kits. Should have everything but shims. Pull the pumpkin take FD kit to trans shop have them do install, and put pumpkin back in. Maybe 400-600$ labor and 650$ or less for kit.
As for what FD to choose. This is somewhat complicated. Kind of like hitting a moving target. But I’ll try to explain a few things. First in a perfect “vacuum” (not factoring traction limitations, rolling and wind resistance, and other variables) the percentage increase of acceleration should match the percentage increase of FD to the new top speed of each gear but each gear will top out at the same percentage less.
For example theoretically say 4.1 FD makes 2nd top at 60 and reach 54mph in 6seconds. 4.51 Fd (10%) will make 2nd top out at 54mph and in 5.4seconds but now you have to shift into 3rd to hit 60.
Another example when I switched FD to 4.56 before 2nd would top at 63 and do 60 in 7.3sec. After 2nd topped at 57 and hit 60 in 7.0sec flat bcs I needed an extra shift and had to accelerate at the bottom of third. But I hit 57mph about .6sec faster then before. The main difference I noticed was before the car would stop pulling once I shifted to 4th at 93mph, after it shifts to 4th at 82 but pulls all the way to the top to 114mph.
With all the being said. For tracking
The easiest method of choosing is picking a FD that tops you out in a gear just before optimal shift point on the longest and or most frequent straights for fastest acceleratetions and least shifting.
The most optimal is choosing a FD that puts you at optimal shift points just after turn out on the most frequent turns.
Now why it’s hitting a moving target is those speeds while always change not only on different tracks but as you beecome more skilled and or modify car to be faster those speeds should slowly be increasing. And then a less aggressive or maybe much more aggressive FD will be optimal.
For regular DD, street driving, canyons just decide how fast you want to go and choose a FD that makes the top of 4th max at that speed.
For tracking/auto cross maybe hold off until you have more
Mods and skills and a better idea of what speeds and FD ratio would be best accordingly.