mikeho

I know that there are other threads out there regarding this combo, but I wanted to create a review thread for myself and for those who wanted to give their impressions on this modification.

My installation may be different than others because my Spec Stage 2 clutch has an UNSPRUNG disc. I had my mechanic install both pieces for me. My original problem was that the engine was throwing cylinder misfire codes. My mechanic (Dan of Ministry of Transport in San Jose, CA) checked the engine and determined that the issue was not the engine itself or the ports, but that my flywheel and clutch were causing vibrations through the drivetrain, causing the engine timing to skip and tripping the computer.

Notes about purchasing:
- Don't believe it when other places say they have it in stock. It seems like only Assaultech has it and Dan was great about getting it shipped out quickly. Might as well buy the clutch from them too.
- Fidanza Aluminum Flywheel: $425 shipped
- Spec Stage 2 unsprung clutch: $637.39 shipped
- Labor (includes my 100K oil change): $802.50

Notes about installation:
- The Fidanza Aluminum flywheel comes with bolts that are too long (I believe my mechanic told the Fidanza engineer that it was about 1/4" too long). It is acceptable by Fidanza to have them cut to the correct length.
- The Fidanza flywheel is 19lbs and is single-mass. The Lexus OEM flywheel is dual-mass and weighs about 60lbs.
- The Lexus OEM clutch is a solid (unsprung) disc. The Fidanza engineer stated that the flywheel was designed to replace the OEM flywheel, so there is no special requirement to have a sprung disc.
- From what I've been reading, if you can install a unsprung disc, it's preferable since it has no moving parts and is therefore less likely to break.

Notes about break-in:
- Mechanic recommends driving easy for 500 miles to let it break in.

First impressions driving 17.2 miles from mechanic's shop to work. Mix of streets and highway.
- Transmission feels the same, as far as I can tell (it's been about a month since I've driven it and the Subaru Outback I've been driving in the meantime has a MUCH smoother transmission, despite being half the price).
- Clutch engagement is MUCH higher and is pretty instant (short clutch point). I would have to say that the clutch point is pretty much within 2 inches of pedal travel.
- Despite it being an unsprung clutch and no dampening in the flywheel, the drive is smooth. No issues so far. I still need to get a better feel for it though.
- Idle is smooth, no roughness or excess noise. Idle seems to be higher. It used to be at about 700RPM; now it's at about 1200RPM. I think the computer is trying to adjust the throttle/mix because of the lightened flywheel, so it might settle lower.


That's all the impression I have so far. I'll report more as I drive it more, but to be honest, I'm not sure if it's the world of difference that many claim that it is.

lobuxracer

iTrader: (2)

Don't expect your synchros to last as long as they should with an unsprung disc replacing a sprung flywheel. There are only two dampers in the driveline - the flywheel from the factory and the rubber doughnut between the driveshaft and the differential. The transmission and driveshaft are isolated by these two dampers so the shock loads are lower.

I ran both sprung and unsprung discs in my Supra (similar set up to the IS250 MTM from a design perspective). Unsprung does mean things to the gearbox, and your synchros don't like the extra loading. Just be aware your choice is not without consequence.

mikeho

Probably. I figured that there might be issues down the line, but Fidanza was adamant that there would be no issues and my mechanic (whom I wholly trust) is comfortable with the install, so we'll see.

Speaking of the transmission, my mechanic mentioned that he was impressed with it. Most cars around the same size, he said, have transmissions that are about half the size and usually break down faster. He thinks this one will last quite a long time.

Jeff Lange

iTrader: (1)

The IS250 doesn't have dampers on the driveshaft actually. The driveshaft is splined and slides onto the output shaft, and it is bolted directly to the rear diff without the damper.

The IS350/IS-F RWD driveshaft is damped at both ends of the driveshaft, the IS350 AWD driveshaft is damped at the rear but not at the front.

Jeff

mikeho

Some more notes:
- Idle has dropped back to 700-800RPM (normal levels).
- Still getting used to the super short engagement point.
- Getting a weird noise on acceleration in 3rd and 4th. Not sure what it is.

lobuxracer

iTrader: (2)

I disagree, especially because we've heard so many of them making marbles in a coffee can noises. The internal design is really poor from a longevity perspective - everything depends on a pair of opposed Timken bearings at the tailshaft, and there is no middle support. Probably OK for stock power, but nothing like a really stout design.

Wow. Even worse. No damping at all now. This would not be my first choice at all.

mikeho

A quick update:
- As the clutch is breaking in, I'm noticing the noise disappearing more quickly. Again, the noise only happens during acceleration.

I'm hoping that it's the clutch breaking in and not the synchros. I might have screwed them up with the old setup; the springs in the flywheel seemed to have lost their springiness and I might have been driving hard on the synchros...


You say that's ok for stock power, but there's been evidence in this forum that a supercharged engine putting out 271 bhp and an IS350 engine mated to this transmission seems to work fine.

Sure, the transmission makes noises (actually, I have probably one of the first IS250 MTs and I haven't had the specific marbles noise).. it's not the smoothest shifting transmission in the world. But truck transmissions make a lot of noise, yet can be some of the most durable ones in the world (thinking utility trucks like Sprinters). FWIW, since I'm not a transmission expert by any means, so sure, if you've been on several race teams like my mechanic has or has had training in transmission design, then I trust you too.

lobuxracer

iTrader: (2)

I have very practical experience in this space. This is my Supra's gearbox. I did all the work myself after I broke the first gear synchro. As far as I know, I'm the only owner who has done this. Everyone else has had someone do it. I've been doing this kind of stuff since the early 70's.

kumquatism

iTrader: (10)

Just curious, how many miles were on the car before you changed out the clutch and flywheel? How was the clutch when they took it out? Was the clutch bad, or did you just want something different? And why did you choose to go with an unsprung clutch?

mikeho

I had 99800-ish miles. The clutch was causing enough vibrations through the drivetrain that it was causing the engine computer to record a cylinder misfire (read the OP). The clutch itself wasn't very worn down, but it and the flywheel had a lot of hot spots on it. Most likely the clutch disc would have to have been replaced anyway and the flywheel would have required machining to get rid of the hot spots.

The hot spots themselves were causing the clutch to make some really screechy noises. I chose to go with an unsprung clutch because Spec shipped it out (Clutchflywheel made a mistake when ordering the part) and Fidanza said that there should be no vibration/harmonic issues (it's very smooth on idle, no roughness whatsoever) and I was too lazy to pay shipping (there and back) to have them ship me a sprung disc.

SeanIs250

Hi all,

Im new to this forum and am based in the uk. I recently had the above installed on my vehicle

Fidanza flywheel

Spec clutch

I ordered these from the us as the uk is pretty lame for upgrades like this

Since having this combination installed im am having problems soo need your lots help if possible

Firstly i replaced the standard clutch and flywheel as was advised it was on its way out

The clutch had a very high biting point and i would get quite alot of clutch judder

I have recieved the vehicle back after the install and am still getting these problems

It is due to go back in tomoro where they are going to check their work

Anybody have any idea on what the garage may or may not have done correctly, im thinking basics like not bleeding the clutch slave cylinder but surely the judder should have been cured right?

Any help would be appreciated

Thanks

mikeho

So... after months of headache and pain, I got my car back.

DON'T GET THE UNSPRUNG CLUTCH! It will not work with the Fidanza flywheel. I had clutch lockup issues (where the clutch wouldn't disengage) which cleared up after going through the hassle of getting a sprung disc from Spec.

So I have a Spec Stage 2 Sprung Clutch.

Initial thoughts are good. The OEM clutch had a long and gradual clutch point. The new clutch has a high and short clutch point. My mechanic (who has worked on race cars) tells me that high performance clutches are like this. It takes a bit getting used to, but it's pretty nice.

Idle is pretty loud now. With less dampening (only the springs on the clutch now dampen the vibrations to the drivetrain), you can definitely hear the transmission on idle. Push the clutch in silences the chatter, but in neutral, it's pretty loud. Chatter doesn't exist while in gear.

I do get this annoying squeak when starting from a stop. My mechanic says that sometimes these high performance clutches will have this noise. I've noticed that the noise happens when the engine and the drivetrain are out of sync. Hopefully, this will fade over time. It's already gotten better.

Dampening is much less now. If you drop the clutch quickly, you'll feel a sudden force when the clutch grabs on. I honestly don't plan to dump the clutch at 4K anytime soon. If you did that with the OEM clutch, you'll hear the tires chirp and eventually you'll start moving, but there's no thump or sudden feeling. Since there's less dampening, there's a greater chance that something else will eventually break if you treat it harshly.

Notchiness is basically gone. There's still some hesitation getting into gears (it's not as silky or smooth as I'd like. My reference is the Honda 6-sp in the S2000), but it's not a notchiness per se. I don't know how to describe it.

I do notice that my mileage goes down, but I think it has to do with the flywheel not holding the RPMs like it used to, so it takes more gas to keep the engine at a given RPM.

I'll update more as I put more miles on it.

kumquatism

iTrader: (10)

How is the throttle response for revving? Our cars take a while to rev up. My friend has a lightweight flywheel in his car, and he revs up to redline in less than half the time it takes me.

mikeho

Revving is definitely faster. Considering that it's a 3x difference in weight, I'd (probably unreasonably) expect a 3x difference in revving speed. But no, it's not. It's a little bit faster. Better, but I'd like quicker still, if I could.

One thing I have noticed is that the actual throttle is pretty slow. What I define as the throttle is the time between a change in the pedal pressure and actually seeing the revs change. The change in rev response only exaggerates this difference. Considering that it's an electronic throttle, I wish it were faster. Any way to reprogram the throttle?

Jeff Lange

iTrader: (1)

Get a throttle controller to change the response curve. Most new Toyota/Lexus models are not linear, and the first bit of throttle pedal travel doesn't equate to the same amount of actual throttle plate opening. Something like a Blitz or Pivot 3Drive throttle controller will change this a lot. I had a Pivot in my old Corolla XRS and had intended on putting it in my IS250, but couldn't find a good spot to mount it, so I ended up selling it to a friend. They're pretty neat units.

Jeff