C series gearbox - interchangeable gears - Toyota Yaris Forums

CrankyOldMan · 05-22-2020, 12:55 PM

Weird, I swear I replied to this post.

ArmstronRacing indeed has the definitive guide for gear swaps. I've done some research as well but didn't do a very good job of documenting it. Here's a quick summary:

* The C5*/C6* family is generally interchangeable, the C15*/C16* family is generally interchangeable, but the families are not. I.e. the C15x is narrower and has shorter shafts than the C5*.

* 1st and 2nd gear are fixed to the input shaft. Most have the same 2nd gear ratio. If you want a different 1st gear ratio, you have to change the input shaft.

* The final drive is fixed to the pinion shaft.

* There a limited number of ratios that can physically fit into the gear space, and a limit to the number of combinations that make sense for the RPM and common speed limits of a given market. Fuel economy also plays into that, I suspect, so they target a certain fuel economy by matching a gear ratio to the optimum engine speed to reach a target cruising speed.

* The differentials and differential ring gears are definitely not compatible between C5* and C15*, and are not necessarily compatible inside of a family, even with the "same" model. I.e. the Yaris C50 uses the same gear ratios as the xD C50 but they use different differential bodies and gear rings.

I found a great site with USDM gearbox parts info as well: mmerlinn.com. They list the ratios, shaft diameters and all the critical info you need to figure out what can physically be swapped. This may or may not apply to you though because non-USDM gearboxes often have very different ratios for the reasons above.

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05-22-2020, 12:55 PM	#3
CrankyOldMan 2ZR swap. DO IT! Ask how! View User's Garage Drives: 09 Meteoric Metallic HB Join Date: Feb 2011 Location: West Michigan Posts: 2,333	Weird, I swear I replied to this post. ArmstronRacing indeed has the definitive guide for gear swaps. I've done some research as well but didn't do a very good job of documenting it. Here's a quick summary: * The C5/C6 family is generally interchangeable, the C15/C16 family is generally interchangeable, but the families are not. I.e. the C15x is narrower and has shorter shafts than the C5. 1st and 2nd gear are fixed to the input shaft. Most have the same 2nd gear ratio. If you want a different 1st gear ratio, you have to change the input shaft. * The final drive is fixed to the pinion shaft. * There a limited number of ratios that can physically fit into the gear space, and a limit to the number of combinations that make sense for the RPM and common speed limits of a given market. Fuel economy also plays into that, I suspect, so they target a certain fuel economy by matching a gear ratio to the optimum engine speed to reach a target cruising speed. * The differentials and differential ring gears are definitely not compatible between C5* and C15*, and are not necessarily compatible inside of a family, even with the "same" model. I.e. the Yaris C50 uses the same gear ratios as the xD C50 but they use different differential bodies and gear rings. I found a great site with USDM gearbox parts info as well: mmerlinn.com. They list the ratios, shaft diameters and all the critical info you need to figure out what can physically be swapped. This may or may not apply to you though because non-USDM gearboxes often have very different ratios for the reasons above.