Impreza/XV Crosstrek 6-Speed Conversion

This is my experience in swapping from a 5-speed trans in my '16 Crosstrek to a 6-speed manual from an '18 Crosstrek. This generation Crosstrek was actually offered with a 6-speed manual in overseas markets, but as usual, North America got the short end of the stick. And although I am the first person that I'm aware of that has done this swap using a '18-'23 Crosstrek transmission, I need to give credit to user 95wrc on subaruxvforum.com for being probably the first in the U.S. to do a 6-speed swap, in his case using a Forester transmission.

I should mention here that this is not an in depth how-to, but I'll touch on some of the important parts of the swap that may be a bit of a mystery. Also, the infomation listed is written with '12-'16 Imprezas and '13-'17 XV/Crosstreks (GJ/GP chassis) in mind, but some info may also apply to other Subaru models.

First, the transmission - it's a 100% bolt in. Same bellhousing bolt pattern, clutch, mounts, length, driveshafts/prop shaft, starter, and input shaft diameter/spline count (1", 24 spline). The only thing that I did find is different is the slave cylinder (not sure how, but it is a different part number). And of course, the shifter.

The original 5-speed trans uses a rod shifter. On the '18+ Crosstrek (as well as the Forester, WRX, and maybe others), the transmission is cable shifted. For my car, I ended up buying a complete shifter and cable assembly from a 2019 WRX. It all bolts up with no mods as long as you have all the mounting hardware (which I didn't, had to hunt some down). You'll also have to replace your shift boot (can keep your original shifter bezel) and get a 6-speed shift knob.

Old rod shifter assembly vs. new cable shifter

Top and side views of new cable shifter assembly

New WRX shifter bezel vs. old Crosstrek bezel

All in all, it's a pretty easy swap. If you can remove and reinstall the original transmission for a clutch job, you can do this swap. Again, the biggest change that needs to be made to the chassis when going to a 6-speed is the new cable shifter. But even that all bolts in.

New 6-speed transmission ready to go in

Driving impressions - first gear is a bit shorter, 6th is a bit taller than the old 5th. The ratios are fairly well matched to the 2.0 liter engine. Again, this is with a Crosstrek trans that uses a .74 6th, compared to a Forester 6-speed that uses 1-5 gear ratios identical to the 5-speed but with a fairly tall .69 6th gear. With a 2.5 liter swap, either transmission would work well, I'd imagine.

That being said, the trans is definitely not what I would call close geared. The ratios are still pretty far apart from each other, especially compared to the C60 in my 2ZZ Corolla. But the shifter action is a lot more satisfying than the old 5-speed rod shifter, which felt pretty rubbery.

For my swap, I splurged on a Group N transmission mount

Worm's eye view of cable shifter assembly

Was the conversion worth the $1,500 or so I spent? Probably not, as it's not really any quicker and fuel economy is about the same. But it sure is cool from a bragging rights standpoint, though.

This swap might really wake up an Impreza though, especially since you have to swap in a 4.44 rear diff. It would also make more sense if you had to replace a broken 5-speed or convert from a CVT.

No need to pull the engine on this swap, but I ran into a bit of trouble...

Miscelaneous Notes:

• Suitable transmission donors include 6-speed equipped '14-'18 Foresters and '18-'23 Crosstreks; '15-'21 WRX should also work.
• The same applies for cable shifter assemblies. The above donors should all work. Make sure you get a complete shifter assembly and both cables.
• WRX STI transmissions are different. The info here will likely not apply to those.
• Don't forget to match your rear differential to the transmission you'll be using. Manual Crosstreks and Foresters use 4.44 axle ratios, manual Impreza and WRX are 4.11. Forget this and you'll break expensive parts.
• Many Subarus suffer from worn clutch release bearing surfaces, which cause chatter and other issues. Consider buying an oversize release bearing, which usually comes with a stainless steel sleeve that goes over the wear-prone bearing surface on the transmission.

Gear Ratios: