Why Has No One Installed a Lighter Flywheel?

[Mustang_Lou]

So I've been on here since I got my 2016 GT and don't think I've ever seen anyone post anything about installing a lighter flywheel.

I had one on my 98 SVT Contour and they were popular with other makes as well back then.

Benefits are a more responsive engine as it'll rev easier & quicker - car will feel hundreds of pounds lighter depending on how light you go on the flywheel (within reason).

Cons are you may have to increase your idle so it doesn't stall and it may engine brake more.

Can't recall any others but I'm sure there are.

Anyone thought about it? It crossed my mind when I was reading the 4.09 gears thread ... lighter flywheel should have the same effect on the driving feel.

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[PC_GUARD]

So I've been on here since I got my 2016 GT and don't think I've ever seen anyone post anything about installing a lighter flywheel.

I had one on my 98 SVT Contour and they were popular with other makes as well back then.

Benefits are a more responsive engine as it'll rev easier & quicker - car will feel hundreds of pounds lighter depending on how light you go on the flywheel (within reason).

Cons are you may have to increase your idle so it doesn't stall and it may engine brake more.

Can't recall any others but I'm sure there are.

Anyone thought about it? It crossed my mind when I was reading the 4.09 gears thread ... lighter flywheel should have the same effect on the driving feel.

Depends on application. A street dedicated car a lighter flywheel kinda sucks. Yes it can be overcome, but my sn95 had a light flywheel and it took a low powered toilet, and made it slower off the line. On a race/track car (or mostly) I definitely advocate for getting every advantage you can, especially when general street manners dont matter much. I would guess (pure speculation) the coyote/voodoo would suffer (or clutch) a lot on the street. <<<< Just opinion

 

[NGOT8R]

I just put a Ram Pro Street Twin Disc with an aluminum flywheel in my 2019 Bullitt. I’m a ways off from testing it out though.

 

[ice445]

Depends on application. A street dedicated car a lighter flywheel kinda sucks. Yes it can be overcome, but my sn95 had a light flywheel and it took a low powered toilet, and made it slower off the line. On a race/track car (or mostly) I definitely advocate for getting every advantage you can, especially when general street manners dont matter much. I would guess (pure speculation) the coyote/voodoo would suffer (or clutch) a lot on the street. <<<< Just opinion

So much this. The only reason to use one is to save money (OE dual mass is pricey), or for a dedicated track car. For street use it's kinda ass.

 

[Cobra Jet]

I just put a Ram Pro Street Twin Disc with an aluminum flywheel in my 2019 Bullitt. I’m a ways off from testing it out though.

It’s always been my understanding that if a flywheel is swapped out for a lighter flywheel, that the harmonic balancer also must be changed so that it and the flywheel imbalance matches - to keep the rotating assembly in balance.

For example:
“XYZ” Engine rotating assembly is balanced with a 50oz flywheel and 50oz harmonic balancer from the factory, as built. If the 50oz flywheel was replaced with a 28oz unit, the rotating assembly will be out of balance. The same would be true if the 50oz harmonic balancer was swapped for a 28oz unit and the flywheel remained unchanged - rotating assembly is no longer balanced.

Such a change in the above example could cause premature wear on bearings, etc. and if operated in a high RPM environment, the possibility of snapping the crank snout off or the possibility of other detrimental damages exist.

—

Does the above not apply to the Coyote rotating assembly - where a lighter flywheel can be swapped in with no concerns or need to match the harmonic balancer?

 

[NGOT8R]

I have no idea. When I spoke to the Ram Clutches employee prior to my purchase, he made no mention of this being an issue. I sure hope it’s not.

 

[Unas2k5]

The shop my car is at recommended I get a steal flywheel to go with my Mclead RXT twin disc clutch. I don't see on the invoice anywhere that says "harmonic balancer' so I hope this isn't true or that the steel Mclead weights the same as stock lol.

 

[K4fxd]

It’s always been my understanding that if a flywheel is swapped out for a lighter flywheel, that the harmonic balancer also must be changed so that it and the flywheel imbalance matches - to keep the rotating assembly in balance.

That is only partially true with an externally balanced engine. The weight of the flywheel and harmonic don't matter. The added balance weight does.

Coyotes are internally balanced

 

[Cobra Jet]

That is only partially true with an externally balanced engine. The weight of the flywheel and harmonic don't matter. The added balance weight does.

Coyotes are internally balanced

Oh ok - so that would mean the Coyote flywheel is a 0 (zero) ounce balance, correct?

 

[K4fxd]

Yes

 

[Rick#7]

It’s always been my understanding that if a flywheel is swapped out for a lighter flywheel, that the harmonic balancer also must be changed so that it and the flywheel imbalance matches - to keep the rotating assembly in balance.

For example:
“XYZ” Engine rotating assembly is balanced with a 50oz flywheel and 50oz harmonic balancer from the factory, as built. If the 50oz flywheel was replaced with a 28oz unit, the rotating assembly will be out of balance. The same would be true if the 50oz harmonic balancer was swapped for a 28oz unit and the flywheel remained unchanged - rotating assembly is no longer balanced.

Such a change in the above example could cause premature wear on bearings, etc. and if operated in a high RPM environment, the possibility of snapping the crank snout off or the possibility of other detrimental damages exist.

—

Does the above not apply to the Coyote rotating assembly - where a lighter flywheel can be swapped in with no concerns or need to match the harmonic balancer?

Your example is specific to the pushrod era 302/5.0. That engine family (often referred to as Windsors, but technically is simply the small block Ford) was externally balanced as previously mentioned, meaning the rotating assembly was manufactured with an imbalance and required external weights on the flywheel and harmonic balancer to balance the engine. Earlier versions from the 60's and 70's used a 28oz external balance weight, later versions (from sometime in the early 80's, I can't remember the exact year tho) used a 50oz external weight. In that specific case, the harmonic balancer and the flywheel both had to have the correct balance weight to match the crankshaft that was in the engine. In the 80's and 90's the 302/5.0 gained power and efficiency with technology like EFI and hydraulic roller cams, so It was common practice to swap a later model 5.0 into an older car in place of a 289 or 302 with the early 28oz balance weights, and people ran into problems when switching the balancer and/or flywheel on the newer engine to the earlier parts to get it hooked up to the trans or fit the front pulleys, causing a wicked vibration. The balance weight in question is completely irrelevant to the overall flywheel weight. Strictly in terms of engine balance, it doesn't matter if the flywheel weighs 10 lbs, 15 lbs, or 50 lbs, as long as the balance is correct for the engine.

 

[mustang_puppy]

Reading this dampens my thoughts on having a lighter flywheel installed along with a new clutch and disc, carbon fiber driveshaft, lighter brake discs and GT350R wheels. It would be a waste or overkill in the weight savings department as I mostly drive my car daily with very seldom (these days) joyrides on twisty backroads (blasted gas prices!) but possibly a track day or 2 in the future. This crazy idea of mine could really do a number on my car with regard to NVH or just everyday performance right?

 

[Mustang_Lou]

I'm reading the negatives about daily driving but a small drop in flywheel weight I assume would be less of an issue than a larger drop. As always, finding that happy medium is the trick.

 

[boB]

I had a car with a light flywheel, it was fine for everything except taking off from a stop. That involved higher revs and slipping the clutch. It is probably not for the street unless you don't have many stops.

 

[Radiation Joe]

I never found the light flywheels to be much of a problem starting off. I think it's a matter of technique. Once you're used to it, you don't much notice it. The quick rpm drops during shifting and the easy double clutching are what I like.
In my opinion, the main negative is the increased noise from the transmission at idle when you have it in neutral with the clutch out. All of my cars have been the same. Sounds like someone threw a bag of nickels into your transmission.

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