How Much Power Can The 5 Speed Transmission Handle?

How much power can the MkIII/MkIV Supra/Lexus SC300/IS300 5 speed transmission handle?

If you have a 5 speed manual, you can expect to break it. We don't recommend trying to get any more than 300 HP out of an N/A 5 speed W58 transmission. A friend of mine went through 3 or 4 before giving up on it in a similar scenario.

What other options do I have?

I would recommend at least considering swapping to an R154 5 speed from the 1987-1992 turbo Supras, or getting the V160 6 speed of course, which has been proven to handle 1000+ HP without issues.

There's a few other transmissions that would be good to look into as well, such as the T56 and 350Z 6 speed, though both of those would need adapters, whereas the R154 would only need a 1JZ bell housing, which we do have available. You would also need a new custom driveshaft to fit, though we can get those as well.

We are currently developing a conversion kit for the CD009 Nissan 350Z/Infiniti G35 6 speed transmission, as it has almost identical ratios to the V160 6 speed, is fairly inexpensive, plentiful, and has been proven by our friends at Sound Performance to handle over 1000rwhp without any modifications or issues. Once it is available, we will be posting it on social media, in our biweekly newsletter, and on our front page.

Why go with the R154 over the T56 or CD001 / CD002 / CD007 / CD009 then? I heard "this and that" on the internet about...

The R154 is still rather easy to get, is much easier to bolt in (less messy-work and fabrication), and is proven to do fairly well up to 500rwhp, and sometimes more. We also offer our ultimate rebuild kit to strengthen the two main weaknesses of the R154 (Ultimate R154 Kit) which are the first gear thrust washer breaking, and the shift forks cracking. A properly built R154 transmission should reliably handle at least 450 ft lbs at the rear wheels, no question. We also offer a mount kit for the SC, GS, and MkIV chassis' (R154 Mount Kit) and of course, the bellhousing (JZ-to-R154 Bellhousing).

The issue with the T56 is that there is no "one T56" that was made. The T56 was available in the 2003-2004 Ford Mustang Cobra (often referred to as the "Terminator Cobra"), Dodge Challenger, Dodge Viper, Chevy Camaro/Pontiac Firebird, Pontiac GTO, Cadillac CTS-V, Chevrolet Corvette, and even some Aston Martins. The Corvette and Aston Martin version is a rear transaxle setup instead of a traditional transmission, which gives a better weight distribution to the car.

The 10 spline input shaft of the 03/04 Cobra is a known weak point. The Viper has stronger internals than the Camaro/Firebird version, but isn't unbreakable. The Ford T56s also have a different bellhousing than the Chevy T56s, as do the Dodge cars. In most cases, the bellhousing would be swapped out anyways. Additionally, the T56 comes with various different overall lengths, shifter locations, gear ratios, and output flanges. A generic T56 kit will not work, as there would inevitably be issues depending on which transmission you end up getting. We believe the CTS-V version would be closest to the correct length on a Supra, but we are not completely certain, and you will need to verify this yourself first for your application.

The T56 was later revised into the TR6060 transmission, which is a stronger version as seen in the newer CTS-Vs, G8 GXP, Challengers, Camaros, etc. There's also the aftermarket Tremec "T56 Magnum" which uses the TR6060 stronger internals in a T56 case and offers 3 different shifter locations. That's available with this listing: T56 Magnum as well as the Quick Time Bellhousing

Expect the T56 route to also cost more than $10,000 total. We do not currently have any clutch options for this swap, as we cannot verify which setups have the correct fitment.

The issue with the CD009 is that it was only available for a few years. You would need to pull one from a 2007/2008 Nissan in order to get the latest revision, triple cone synchronizers, etc. Identification of the CD009 can also be difficult if the sticker is not on the bellhousing, as the various revisions used the same case with different internals. You may think you are getting a terrific deal on a solid transmission, but you may end up with an early version that is known to break under stock power output and have terrible shift quality with soft and grinding shifts.

You also may need to modify the shifter location. This shouldn't be too difficult, as it uses a fairly external setup (not unlike the V160). We expect to have the right one available for MkIV Supras and Lexus SC300 / SC400s once the conversion kit has completed R&D stages and is ready for retail. Just like the T56, you will need a custom driveshaft with this as well, which can be easily made from a local driveshaft shop. Because of how important the tolerances on the prop shaft length are, we may be able to supply this as part of the kit, but be aware that we cannot guarantee fitment.

Another disadvantage of the Nissan 6 speed is that the bellhousing is not removable/serviceable. In many cases, the bellhousing may need to be cut off to fit an adapter, which leaves room for error in drivetrain alignment and rigidity. A few different versions of the transmission have either an internal or external slave cylinder/hydraulic throw-out bearing as well. Additional differences between the different versions even include bellhousing bolt pattern and clutch fork pivot. Like the T56, we do not currently have clutch options available. Once we have finished R&D, like our 1UZ manual conversion options, we will offer many different choices of aftermarket clutch to fit the needs of various builds and projects. Total cost on a conversion is expected to be around $6000-8000 or so, with a great deal of modification needed.

V160 Ratios:
1st: 3.827
2nd: 2.360
3rd: 1.685
4th: 1.312
5th: 1.000
6th: .793

CD009 Ratios:
1st: 3.794
2nd: 2.324
3rd: 1.624
4th: 1.271
5th: 1.000
6th: .794

T56 Ratios:
1st: 2.66
2nd: 1.78
3rd: 1.30
4th: 1.00
5th: .80
6th: .63

T56 Ratios (also very close to the R154):
1st: 2.97
2nd: 2.10
3rd: 1.46
4th: 1.00
5th: .74
6th: .50