Taller 5th gear for DOHC

[tradosaurus]

I have a 2000 Mazda Protege LX 1.6L 5spd and am interested in installing a taller 5th gear.

Has anyone installed a taller 5th gear on a 1998-2002 Protege?

I'm wondering if it can be done by a novice?

[Daox]

Do you know of a transmission that has a taller 5th gear?

[cfg83]

tradosaurus -

Read this thread :

Taller top gear makes a real difference (10%)

However, his Protege is a 1994, *not* a 2000, so Daox is right, the 5th gear swap may not be available for you.

CarloSW2

[D.O.G.]

Maybe check for a possible donor gearbox here?

Protegé FAQ

I don't like the top gear ratio in my Mazda either, I'd be interested in hearing how you get on.

[CigaR007]

I have been thinking about a taller 5th gear swap too. After some research, I have come to the conclusion that swapping the 5th gear might not be an ideal mod for every car. One has to determine the final drive of the originating 5th gear and analyse/calculate the drop in RPM given you car's final drive ratio.

Keep in mind that while a taller 5th gear would be great for highway cruising (circa 55 mph), it can be problematic, torque-wise, in city driving. The last you want is lugging the engine at low speeds in 5th gear.

The way I see it, in most cases, the engineers that conceived the car and its drivetrain made the best compromise possible. If you do proceed with that mod, you will create a new compromise and it might not be an ideal one. Just make it sure that you study the torque curve of your car's engine to pinpoint the pros and cons of such transmission modification. Every car will react differently. Some engines provide more torque throughout the RPM range than others, so your mileage may vary (pun intended).

Best of luck !