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I just bought a used 5 speed 03 civic si. It has manual overdrive, is my 5th gear considered the overdrive or is there some other way to get it to kick in. I hit 3k rpm goin 60 on the highway in 5th that doesn't seem right.

 
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Yes 5th gear is overdrive I believe... it doesn't really do much though as the gear ratios are so short.

Those RPMs are normal.

 
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I guess you misunderstood the term overdrive... It's the gear ratio itself, not something you can turn on-off. It's not a truck with reduced gearing, FYI...
Si's a sport type, so they have short gearing, higher RPM - wasn't that the reason you got a Si anyway? Or did you not know what the Si trim is?...

 
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Why are you concerened? Are you getting crappy MPGs?

 
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Im getting pretty good MPGs it was just a knowledge question.... i knew what the si trim was long before i got it i just didn't expect 5th gear to rev as high going 60 thanks for the info.

 
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yeah, any gear ratio where the transmission input shaft spins slower than the transmission output shaft is overdrive. that's 5 gear on your '03 si.

 
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oh, btw, did you know that in 4th, your civic's gear ratio is 0.92. 4th is supposed to be close to 1:1 but technically, on most cars, it is also an "overdrive".
just in case you're wondering your 5th gear ratio is 0.74.