Originally Posted by Ultra4

The SL25A, ACT disc and LUK pressure plate are working well behind the 3GR-FSE. A bit grabbier than I want, but that's the price of my laziness for not deleting the delay valve yet.

Edit: just saw the parts you hid in the title. The disc you mention is unsprung, which is generally regarded as a bad idea with the single-mass setup. 1.125", 21 spline, max OD just about 10"...I'm not sure if a 10" disc would work or not. Lots of options to choose from, from basic organic to ceramic/kevlar multidisc hybrid.

Edit2: Aisin CKT-022 appears to be sprung, organic, and relatively affordable

Edit3 since you complain of it being underpowered, I suggest a Y38 or Y58 differential swap, so you're actually applying power to both rear wheels, instead of skateboarding off all the rubber they put in the suspension. That iconic IS250 6MT "na-na-na-na-naaaaaa" start goes away with the new diff.

Originally Posted by Jeff Lange

Toyota sizes their clutches and pressure plates to match the application, either by diameter differences and/or spring strength, similar to most other manufacturers. For cars, most of their clutches are typically one of the following sizes: 180, 190, 200, 212, 224, 230, 236, 240, or 250 mm, usually with a 19- or 21-spline shaft but there are others. For trucks, sizes are usually one of the following: 212, 224, 236, 250, 255, 260, 270, 275, or 300 mm, usually with a 14- or 21-spline shaft but there are others. Vans and other utility vehicles are usually mixed somewhere between them.



The clutch on the RA62 is somewhat unique, but also somewhat common to other Toyota setups. It is a pull-type clutch which is similar to the R154 and V160/161, in fact the release bearing is the same as the V16x and the pressure plate is the almost the same design as the 2JZ-GE V161 (like the GTE's pressure plate, but without the cooling fins and with a lighter clamping force). The flywheel is unfortunately quite unique in the IS250, even though other vehicles also use the AY6 and Toyota has used dual mass flywheels in several applications. Even between the IS200d/IS220d and the IS250 which all use the AY6, the flywheel is noticeably different for the IS250. The two biggest things that are unique compared to other Toyotas is the large step between the pressure plate mounting surface and the friction surface (approximately -8 mm from memory), and the actual overall thickness of the flywheel. The only other Toyota off the top of my head that used a similar step was the 4A-GZE and its 224/230 mm flywheel, though I suspect there may be another couple out there.

Other GR/AY6 setups use a push-type clutch with a larger 275 mm disc. The crankshaft bolt pattern is different between the 1GR and 2/3/4GR. The bellhousing on the RA60/61 is also larger to accommodate the larger diameter (but much thinner) flywheel.

This is one spot where the GM 3.6L setup is somewhat similar to the Toyota setup, the GM flywheel has a similar step, but is much thinner overall.



While the size and material of the original disc is nothing special, the factory disc is unsprung (as the flywheel dampens vibrations) and not used in any other application. If you go to a dealership, they will sell you a 31250-53050, which looks like this:

Attachment 489176

The 31250-33032 is only used if they are performing TSIB L-SB-0059-11 (USA) or TSB L-TCI-2960 (Canada), which also includes replacing the transmission with updated part 33030-53370 to get rid of the abnormal noise on some vehicles when releasing the clutch. Otherwise they will just be putting the original unsprung 31250-53050 back in there. Either way, the goal was to get rid of the abnormal noise, not affect the way the car drives, hence the car will drive about the same (I've had both the original transmission with the unsprung disc, as well as the updated transmission with the rubber-damped disc.)



The GM AR5/R154 is a bit easier than the GM AY6/RA62 because the bellhousing is not integral to the transmission case, and so a Toyota bellhousing can easily be swapped onto the GM transmission. That said, you're still forced to use a non-Toyota friction disc, as the input shaft splines are different between the GM transmission and the Toyota transmission. This is also the case for the AY6, the GM version uses a 23-spline input shaft in place of the Toyota 21-spline. Additionally, it is a push-type clutch and uses a pilot bearing with an integrated slave cylinder in place of the pull-type clutch and release-fork with external slave cylinder that Toyota uses on the RA62. In short, don't look to GM for any compatible clutch components for the IS250.



The master cylinder is a 3/4" diameter, and the slave cylinder is a 15/16", which isn't a super common size for Toyota (though they have used those same sizes on other applications like the TRN2## Tacoma).



As I said earlier, the GM AY6 setup uses a very different setup which is a 255 mm 23-spline disc in place of the 236 mm 21-spline disc of the IS250.



It's interesting because GM actually doesn't sell just the clutch disc by itself, you have to get the pressure plate and clutch disc as a kit, which lists for $389.43 (2010-2012 Cadillac CTS and 2010-2015 Camaro, Part No. 19353433). Toyota lists the clutch disc for $86.18 for the original unsprung disc and $116.19 for the rubber damped disc. If you include the pressure plate (Toyota Part No. 31210-53032, lists for $354.74) it's a bit more expensive than GM by $51.49. I'm sure your 10x estimate was a bit of hyperbole, but it's really only 13% more expensive for the Lexus clutch and pressure plate than for the GM clutch and pressure plate (which won't fit anyway).

As for the original poster's question, there are a few options out there for different setups for the IS250 6MT, but not as many as other cars, that's for sure. The only other alternative options I really have to add other than what you've already listed would be the PGEAR FW1224005 flywheel (unfortunately out of stock and requires a minimum qty of 5 to run them due to lack of demand) and possibly going with a larger sprung disc. The flywheel and pressure plate can handle a larger disc up to about 250 mm.

I am running a 250 mm Aisin NVR sprung disc on a PGEAR chromoly flywheel using a higher capacity SPEC pressure plate with no clutch accumulator:





(One other clutch/flywheel setup exists and that is the setup from the GRMN Mark X, which is a stronger version designed to handle the 3.5L's higher output, but it's still a dual mass setup, and very expensive, so probably not worth considering.)

Jeff

Originally Posted by Ultra4

Yeah, finally talked to some folks and got my mock'n'measure all cleaned up late last night and slept on it.

Mk4 Supra flywheels typically have a .020 bump up (toward the trans/rear of vehicle) from the mounting hardware. The SL25A friction surface is 7.5mm on the nose sunken into the fly. Typical clutch disk thickness is 7.5mm. Additionally, the hardware attaching the friction surface to the SL25A is 100-degree countersunk #10-32tpi hardware. Friction surface OD is 10-3/8", inner hole is 6".

Therefore, a 5/16" thick ring with a buncha transfer-drilled .1935" holes will need to be made. 7.5mm=.2953"; 5/16=.3125"; .3125"-.2953"=.0172. Close enough to .020" proud for me.