5 Spd to 6 Spd Conversion DIY

[Bluevitz-rs]

This is a DIY on how to convert the stock C150 5-Spd (Echo) to the close ratio C160 6-Spd.

Detail on this conversion would still apply to the Yaris transmission.

Unfortunately the C160 I purchased does not have the optional LSD, but the price was right, so I got it. There is also a possibility of swapping the lower ratio .815 5th gear out of the 5-Spd in place of the 6th gear's .725 in the 6-Spd. This would make the RPM even higher in 6th and would only be recommended for racing purposes only. The stock gearing in the 6-Spd has increased RPMs @ 100km/h from 2600 to 2950.

You need to make slight modifications to the frame in order to clear the end of the transmission, as it's longer for the extra gear and an extra bearing, though the modifications to the frame of the Yaris might be different, or not needed at all. I don't have a Yaris, so I can't be sure. This was relatively simple to do with a cutoff wheel on my angle grinder and MIG welder.

Here is a graph to illustrate the speed differences between the two transmissions.



The Main Gear Housing
I'll start with a side by side comparison shot.
The Echo's C150 on Left and the C160 on Right.


Inside the C150


Inside the C160
Notice the extra gusseting under 1st gear.


Slight differences in the top of the cases. There's an extra hole on the top of the C160. Its only and oil fill hole, but the shifter mechanism is slightly longer.




The Bell Housing
C160 on Left and C150 on Right
The only swap needed is to the reverse gear arms and shaft. All of the bearings are the same size. I measured both input and output shafts and they're identical.


The C160.
The only noticeable difference is the notch for oil flow to the reverse gear idler shaft hole.


The C150


The End Cover

There are major differences here. It's much longer because it contains an extra gear and bearing support.
Also, you NEED the Puller B Set from Toyota in order to properly pull the gears off, plus a steering wheel puller and studs for the No.3 clutch assy.


My Clutch after 70,000Km. Looking really good


My Fidanza Flywheel and Celica GTS clutch and cover
Also note the frame before modification.