4.08 or 3.90 gear questions...

filip00 · 08-13-2023, 05:18 PM

Bringing this thread up instead of opening a new one..

Lately I am thinking that I want the Z to have more power, i.e. more low end torque. I was thinking about various supercharging options, but that seems like a handful, expensive, and a bit risky move. Then it occurred to me that a final drive swap would actually give me exactly what I want. I would get the more "lively" feel with the car, the engine would be quicker to rev up with the first 3 gears, and I wouldn't actually sacrifice a lot - losing a bit of top speed and a bit higher cruising speed. But the main gain that I see here is having a much livelier car, that would probably feel like having some extra 30-40hp within the first three gears, as the gearing between stock 3.53 final drive and the 4.08 drive is more than 15%, which makes a big difference.

So after further research online, I think I'd go with 4.08 or 4.11 final drive, whichever I find to buy.

So my questions is more for the ones who already did it....how complicated was the install? I think the biggest challenge is getting a press for handy use, as it seems like the pinion gear, bearings and preload are the most difficult thing to get right. So I'm thinking that I'd maybe even pay someone to do it.

Also, which parts do I really need? I was thinking that beside the pinion and ring gear, I'd take new bearings for the pinion, new bushings, and probably new diff oil. Last year I changed the axle bearings, so I'd keep them.

Thanks for any input or thoughts.

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08-13-2023, 05:18 PM	#40 (permalink)
filip00 Track Member Join Date: May 2021 Location: slovenia Posts: 596 Drives: 370z pack Rep Power: 125429	Bringing this thread up instead of opening a new one.. Lately I am thinking that I want the Z to have more power, i.e. more low end torque. I was thinking about various supercharging options, but that seems like a handful, expensive, and a bit risky move. Then it occurred to me that a final drive swap would actually give me exactly what I want. I would get the more "lively" feel with the car, the engine would be quicker to rev up with the first 3 gears, and I wouldn't actually sacrifice a lot - losing a bit of top speed and a bit higher cruising speed. But the main gain that I see here is having a much livelier car, that would probably feel like having some extra 30-40hp within the first three gears, as the gearing between stock 3.53 final drive and the 4.08 drive is more than 15%, which makes a big difference. So after further research online, I think I'd go with 4.08 or 4.11 final drive, whichever I find to buy. So my questions is more for the ones who already did it....how complicated was the install? I think the biggest challenge is getting a press for handy use, as it seems like the pinion gear, bearings and preload are the most difficult thing to get right. So I'm thinking that I'd maybe even pay someone to do it. Also, which parts do I really need? I was thinking that beside the pinion and ring gear, I'd take new bearings for the pinion, new bushings, and probably new diff oil. Last year I changed the axle bearings, so I'd keep them. Thanks for any input or thoughts.