xB final drive swap thread

[cali yaris]

i guess this isn't for street cars?

Sure it is -- but it depends on your tolerance for high revs on the freeway. Otherwise, it improves the Yaris' performance value a LOT.

How do you reprogram the speedo?

You don't. As far as I can tell, it didn't change that. Aren't the speed sensors at the wheels?

any word on this? how did it go?

I haven't drag raced again since then, sorry.

[CrankyOldMan]

Originally Posted by cali yaris

Sure it is -- but it depends on your tolerance for high revs on the freeway.

And I'm working on a solution for this. If you're pulling all the gears off the output shaft anyway, you might as well replace the 5th gear set with the taller overdrive from the '03-ish Matrix/Vibe/Corolla. That drops your 70 mph revs from about 3600 down to 3200. For reference, the stock trans does about 3500@80 and 3000@70.

You can get an idea of how it would sound by finding a "closed road course" and a "professional driver" to achieve that speed.

Originally Posted by Bluevitz-rs

The output for the speed sensor is read off of the final drive assembly. But you aren't spinning the FD any faster because your wheels aren't turning any faster at the same speed. It's all the other gear before the FD that change speed. (I hope that makes sense to you all)

I think the newer models use a wheel/axle sensor instead of the internal speedo gear, but the principle is the same. Changing the internal gear ratios only modifies the torque delivered at a given wheel RPM. The trade off is that the transmission input RPMs (engine RPMs) have to change to make the same output speed.

[CTScott]

Originally Posted by cali yaris

You don't. As far as I can tell, it didn't change that. Aren't the speed sensors at the wheels?

This is correct for Yaris with ABS. For them the speedometer is fed from the ABS ECU, rather than from the transmission.