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Flywheel decision time used OEM vs Used Fidanza advice

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1greyawdtsi

10+ Year Contributor
80
10
Sep 18, 2009
Seattle, Washington
Hi. I have recently removed my 2G AWD manual transmission to replace TOB, clutch, etc.. I have done some research, but many of the posts were from 2015 or earlier. I am planning on using a new ACT 2100 clutch kit & OEM TOB.
The car is a street car under but likely approaching 300hp. I’m contemplating resurfacing the OEM fly wheel or using the used Fidanza flywheel (that came with but not actually on the car) and replacing the Fidanza friction surface. So I have both flywheels already and I’m genuinely curious which flywheel would you use if you were in my situation? Thanks.
 
I would run OEM flywheels (resurfaced properly for new clutch kits of course) most of the time. I would only look at aftermarket (lighter) flywheels if I will be taking my whole rotating assembly to get rebalanced, which is not something you do for every rebuild let alone a standard street/daily build.
 
The flywheel is not balanced to your rotating assembly. Ford actually holds patents around using an unbalanced flywheel to offset inherent imbalances in the engine, but the first application of that idea came out in 2012. On the Eclipse it's balanced on its own and any properly balanced flywheel wouldn't have any impact on first or second order vibrations from the rotating assembly.

The goal of the flywheel is to smooth the rotational acceleration that comes from each power stroke. Lighter ones are technically harder on the drivetrain as the impact from each power stroke has a higher impulse over a shorter duration but in practice this doesn't have a noticeable effect on either the transmission or engine in terms of longevity. Pressure plate choice the big player in that field.

I have a Competition Clutch steel flywheel and while I certainly appreciate it over the factory flywheel, I would like to go lighter. I have no personal experience with the Fidanza or any aluminum flywheel in the Eclipse, but aluminum flywheels in other applications have been very unpleasantly noisy and that's why I ended up with a lightweight steel unit. How comfortable are you with pulling the transmission? I've done a clutch job in a short weekend and if it were me I'd throw the Fidanza unit in there to see how I like it, keeping the OE just in case. Worst case I pull the transmission out again to swap it back.

Any idea why a used Fidanza flywheel came with the car but not installed? Maybe a previous owner installed it and didn't like it?
 
As I just commented on your other thread, I have to do something about my 1G AWD's flywheel too, either resurface the OEM or buy a new one, which if I do will most likely be an ACT Streetlite. I'm leaning towards the latter but if the OEM still has enough surface for another cutting then I might save the money for now, especially since I'm overbudget on other things. Then again, a decent resurface is pricey around here, over $100 with some shops, so it might be a false economy. I did find one shop that does it for around $60, but they don't use dial indicators so I'd have to do the measurements myself and hope I get it right.
 
The OE flywheel/clutch is already relatively light compared to other engines. Our clutches are tiny.

On a street car, I would resurface the OEM one.

But the OP's clutch (like mine) isn't OEM, but aftermarket. Does your advice still apply?

He has an ACT 2100, I have an SBC Stage 2 DD, which I believe is comparable.
 
But the OP's clutch (like mine) isn't OEM, but aftermarket. Does your advice still apply?

He has an ACT 2100, I have an SBC Stage 2 DD, which I believe is comparable.

An aftermarket clutch and pressure plate will not be significantly more heavy than the stock parts. I am running an OEM flywheel with an ACT 2600 PP & street disc and the flywheel effect is comparable to the stock setup. Unless you feel you NEED the revs to drop faster for fast, high rpm shifts, stock is better IMO.
 
I was told the aluminum Fidanza flywheel was purchased by the PO from a friend and at some point, he was planning to put it in the car at a later date - but decided to sell the car to go back to college. Which checks out b/c the clutch I just pulled was shot.
I honestly hate that I have this decision to make. For now I am going to compare & weigh: resurfacing oem flywheel vs new friction surface for the Fidanza. I’d really like to get the car back together first and foremost. For now I’m starting to lean toward the idea that I could try the lighter flywheel and keep the OEM as a backup. Then if I hate the lighter flywheel I could swap back in the OEM (resurfaced of course) at a future date (which is not awesome). Thanks!
 
i don't like light weight flywheels on the street & DD. Stop & go is a pain & you have to rev higher & the clutch disengagement is noticeably more touchy to keep from stalling & have to be slipped more. I went back to a heavier flywheel. Light weight flywheels are fun for reving & dumping the clutch situations.
 
As I just commented on your other thread ... Then again, a decent resurface is pricey around here, over $100 with some shops, so it might be a false economy. I did find one shop that does it for around $60, but they don't use dial indicators so I'd have to do the measurements myself and hope I get it right.
All great points and things I’ll def have to take into account!
 
I like the fidanza flywheels. It might take a week of driving to get adjusted to it but then its not even an issue.
when it comes time to replace your clutch, you just buy a new friction disk and replace the old one. The step is all ways correct and you don't have to worry about the machine shop f***ing it up.

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https://www.roadraceengineering.com/clutchandflywheeltech.htm
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I would agree with @Mello and @motomattx as I have both an ACT Lightweight flywheel and a stock flywheel car. The lightweight unit is coming back out and a stock, heavier flywheel going back in (White GSX is stock, Red Talon is gong back together, but with a stock flywheel now). The inertia you loose in the light setup, in my opinion, isn't worth the trade off for being able to spin the motor up quicker. Also leaving a light is much easier with the stored energy in the heavier unit.
I ran an 11" TRUCK flywheel in my 71 Camaro SS and I could still turn that 350 to 8k and launching was a breeze with the bigger unit.
Just some of my experiences.
 
i don't like light weight flywheels on the street & DD. Stop & go is a pain & you have to rev higher & the clutch disengagement is noticeably more touchy to keep from stalling & have to be slipped more. I went back to a heavier flywheel. Light weight flywheels are fun for reving & dumping the clutch situations.

Appreciate the tips. I was set to replace my stock OEM flywheel with an ACT Streetlite but this is making me reconsider it. If it's going to make stop & go, which realistically represents a large part of the driving I do these days, a lot harder, it might be a bad idea for me. I'm not exactly the world's smoothest shifter and my clutch pedal action isn't optimal. It also sounds like I'm more likely to wear out the clutch faster, something I really want to avoid.

I just hope that my stock flywheel still has enough surface to endure another resurfacing (assuming that the shops that replaced my clutch in the past even did this). Do you know what the minimal thickness of the flywheel friction area should be? I couldn't find it in the FSM, just the runout. And even if it's a bit too thin, can it be shimmed on the crank side?

Also, some flywheels get slightly thinner from the outside to the inside. Is that bad?
 
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Yes that is bad if it is tapered. It needs to be flat. :thumb:
I am going to run this flywheel as is except for a wire wheel cleanup and a step height check.
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Back in the day I would have said go with the lighter weight option, but as others have pointed out, that can have effects that you may or may not like. These days, I say go with the one that is better condition and has the least chance of causing you problems later. Unless I knew for sure how many miles that used flywheel had on it, and what type of miles, I wouldn't put it in. I'd go with a new one. But that's just me, and I don't enjoy pulling the transmission as much as I used to. :)
 
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