KahnBB6

iTrader: (5)

^^ A well made one piece is a good option indeed but it is more expensive. Also from what I've learned... at high rotational speeds of one-piece driveshafts (getting into 70mph+ and much higher extra-legal speeds) they're said to not deal with driveline harmonic vibrations as well as factory configuration two-piece driveshafts are. Perhaps it depends on the one-piece design, alloy used, etc.?

A one piece driveshaft gets to be a requirement at extremely high horsepower and torque outputs depending on the type of abuse the car sees but the factory driveshafts on SC's can take a LOT of power before that is ever a concern.

joewitafro

I think the only benefit of the two piece is to absorb vibrations through the central insulator and the rubber insulators on either side (for GS's atleast.. I think you mentioned the SC auto is slip yolk like R154). I've ran a steel one piece for 7 years with many high RPM, high speed runs with no issues and they've balanced it to exceed anything it would see rotational speed wise. The big thing after balancing would be weight, which is why the steel is the least sought after and many do aluminum and high HP drag cars run carbon fiber. All that rotational mass will decrease/increase speed of rev.

So running an OEM lexus quality mindset, the two piece with the central bearing and rear rubber insulator will be ideal to reduce drive-line vibration in the cabin. You will probably destroy the rear insulator or central bearing with high HP builds.

KahnBB6

iTrader: (5)

This clarifies a lot for me and I hope for the OP as well, thank you. As I suspected, the ultimate power limits of the factory two-piece design and isolator rubber may be high but they are there if the build is powerful enough. Your explanation also addresses why aluminum and carbon fiber are preferred (but more expensive) with one-piece designs. The slip-yoke design for the R154 and other Toyota RWD transmissions must make a difference to this end.

sc3hundo

Has anyone here measured the length for a 1pc drive shaft in an sc300 with an R154 swap?

aice

so will I need a front shaft of mk3 + rear shaft of my sc300 then it’ll fit an mk3 r154?

KahnBB6

iTrader: (5)

Honestly? What I would recommend is to pick up (if you don't already have one) a 1992-2000 SC300 Automatic front driveshaft. Its front yoke is exactly the same as is an OEM JDM Z30 Soarer R154 front driveshaft. It is however FAR too short as it is, but this can be rectified.

Take that in to a driveline/driveshaft machine shop that specializes in length changes and which has a two-piece driveshaft re-balancing machine.

Have them modify your SC300 A/T front driveshaft by lengthening it *approximately* +50mm (aka +1.96 inches). Have them re-balance it afterward. They may need your SC300's rear driveshaft brought in with the front driveshaft you are having modified in order to achieve a good balance as a full set.

Now you will have what is a near identical clone of a genuine OEM Soarer JZZ30 R154 front driveshaft.

Using your newly modified SC300 A/T front driveshaft and your stock unmodified SC300/400 rear driveshaft you can now enjoy a truly bolt-in solution for your R-series transmission swap.

...

(Further Info Alert!)

And yes you *can* use a 1986-1992 Supra MKIII Turbo 5-speed M/T front driveshaft... BUT... even though it will fit and work it is TIGHT. Just a bit too tight. You will find that the R154's rear transmission dust shield will have to be removed in order to use it... which is not ideal. Further, to make it a truly perfect fit you would have to have it professionally shortened by *approximately 3/4". At least by 1/2" at minimum.

And the SC/Soarer center bearing needs to be swapped over of course.

Before I realized that an SC300 A/T front driveshaft could be modified to fit correctly I bought myself a Supra MKIII Turbo R154 front driveshaft and eventually had to do the above shortening at a driveline shop in order to eliminate the issue of it being too tight a fit in an SC/Soarer chassis if left at its stock length.

You might ask: Why this is even when people have said in the past that a Supra MKIII R154 front driveshaft will work in our SC's?

Well... it *pretty much* fits and works for most although it's not ideal. Some people (I was one of them) even had it working with the trans dust cup removed for a few years only to find it was too tight altogether once I changed out a rear diff sometime later. That's when I had mine modified slightly shorter to correct the issue.

The 7M-R154 bellhousing on the back of a 7M-GTE engine is slightly shorter than a 1JZ-R154 bellhousing is on the back of a 1JZ/2JZ engine. Hence the front driveshaft length is

...

Today with what we know now and due to Supra MKIII R154 front driveshafts becoming scarcer I think the better and more affordable option for an R154 manual swap into an SC is to just have an SC300 A/T front driveshaft length modified approximately +50mm (+1.96") and go with that.

Also, this driveshaft solution will work in an SC with ANY generation R154 transmission.

But if you swap an MKIII R154 into your SC300/400 you will need three additional solutions apart from the front driveshaft:

1) Buy a transmission crossmember from XCessive Manufacturing and use with it a 1986-1992 Supra MKIII transmission mount. A 1982-1985 Celica W58 crossmember will also work IF you have it mounted up, hacked off on one side and plate weld length extended once the bolt holes are all aligned. The XCessive Manufacturing crossmember is a much easier solution.

2) Buy a mechanical to electronic 3-wire Toyota style screw-on VSS adapter. This allows you to get vehicle speed signal to your speedometer. Additionally a Yellr Yellowbox V5 can correct any over-read or under-read in your speedometer (using any GPS speed real time phone app or other portable GPS navigation unit as your reference).

3) If you are starting with a 1992-1994 SC300 Factory 5-speed M/T chassis then you can get XCessive Manufacturing's cast extended shift housing which should be a replica of the 1991-1993 Soarer R154 shifter extension housing. You'd need to have the transmission rear tail housing off to get your MKIII R154's internal shift arm and then send that part in to XCessive to have modified in length to match their replica extended shifter housing. You can re-use an OEM SC300 5-speed 1992-1994 shifter in this application and everything will then fit just like a stock 1992-1994 SC300 W58 will with NO transmission tunnel modification needed.

If on the other hand you are starting with any SC300/400 A/T chassis you will need to cut a hole in the transmission tunnel and have the extension housing modified by Driftmotion or another company that performs this service.

If you are starting with a 1995-1997 SC300 original 5-speed "tripod manual W58" M/T chassis then you'd want to have the MKIII R154's top-loader extension housing length modified to fit the standard tripod W58 opening of that chassis.

Another fact is that any of the R154 tripod manual transmissions will bolt right into any 1995-1997 SC300 original 5-speed chassis using the stock SC300 W58 crossmember, stock SC300 W58 transmission mount, stock 95-97 SC300 5-speed trans tunnel opening and shifter, and a VSS sensor is already built into the transmission so it plugs right into the body harness as is. You still need to get yourself a compatible front driveshaft but the rest of it is direct bolt-in for a 1995-1997 SC300 factory 5-speed M/T if you start out with any R154 tripod transmission.

....

I know if gets a little specific and complicated but these differences in SC chassis and transmission compatibility represent revision changes that both the SC and Soarer went through throughout their respective model runs.