this might be a very n00b question

[JosiahP]

ok so i always hear of people upgrading the gears in the diff for somthing larger or smaller, like a s13 have 4.0 gears how would upgrading those to say 4.6 2 what does it really do ?
what kind of difference does that make lol i know its a pretty n00b question. just trying to learn all i can

[Bruizer]

ok so i always hear of people upgrading the gears in the diff for somthing larger or smaller, like a s13 have 4.0 gears how would upgrading those to say 4.6 2 what does it really do ?
what kind of difference does that make lol i know its a pretty n00b question. just trying to learn all i can

Well, the higher the number the shorter the ratio so you lose top end speed but gain low end. It's a nice upgrade but you end up having to get into 5th instead of only 4th in the quarter, so 1 more shift. Also, it's a bit of work to do the front and rear final drive. Some ratios fetch up to $800 to buy, then labour! there are better mods out there.

[BRN32]

As Bruiser said, higher numeric value = more low end and opposite for top end. Ratio's are the value of the number of teeth on the crown divided by pinion count, 4.10=82/20.

[aN4rk1]

So what's an optimal ratio for say a street / very light track car, with basic bolt ons and some flow mods?

[Bruizer]

So what's an optimal ratio for say a street / very light track car, with basic bolt ons and some flow mods?

Factory ratio.

[JosiahP]

thanks for clearing that up guys my friend told it backwards lol the higher the number the more top end you get lol was a bit confused but thanks for the quick responses

[falcon]

I run a 4.1 with 13'' wheels on my Miata. It's not ideal for anything but the track. 4000RPM at 100kph on the street. But the gearing is perfect for Mission.

The idea is, if you have big turbo power, you want a lower final drive because it will keep you in the boost area longer. The more you shift, you loose boost. I run a supercharger so it dosen't matter for me. I like banging off the limiter at 8000RPM diving into corners. The same can't be said for others.