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Discussion Starter · #1 ·
My engine is (or was) externally balanced. Meaning there's counterweights on the flywheel to balance the engine components and prevent vibrations etc. Of course this isn't needed with an electric motor since there's no combustion.

Should I grind off these tiny weights? They can't possibly weigh more than a few hundred grams. Also if I were to keep them would it create issues?

Would like to hear what you think.
 

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Absolutely yes, remove them, if they are really balance weights (which are different from a harmonic balancer). They may be easier to machine off on a lathe than to manually grind off, and after removal the flywheel will need to be checked and corrected for balance. The weights that balance the unbalanced engine will unbalance your nicely balanced motor. They may not look big, but keep them and you're building a paint shaker. Aside from discomfort, this can kill bearings.

Balance has nothing to do with combustion. An externally balanced engine has rotating parts which are not balanced by themselves, and would shake if turned whether there's any combustion going on or not.

A "harmonic balancer" (really a torsional damper) is a different thing, and is likely harmless, but that's usually mounted on the front of the engine and I assume that you're not talking about that.

I'm a little surprised that an Escape engine would be externally balanced - I believe you, I just wasn't familiar with that combination. Can you post a photo of the flywheel, showing the counterweights?
 

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Discussion Starter · #3 ·
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I believe the two copper-looking pieces are the balance weights.

If I were to just cut/grind/sand them off, what would be the best way to ensure it's balanced? Bring it to a shop?
 

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Thanks for the photo.

I believe the two copper-looking pieces are the balance weights.
Those are definitely balancing weights to be removed. Some balancing weights are attached by screws, especially with aluminum flywheels, but I can't tell how these are held on; if they are spot-welded, it might work to chisel them off.

If I were to just cut/grind/sand them off, what would be the best way to ensure it's balanced? Bring it to a shop?
Yes, an automotive machine shop should have no problem balancing the de-weighted flywheel, and I doubt that it's practical to do yourself.
 

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Discussion Starter · #5 · (Edited)
Thank you brian.

Calling around to a bunch of machine shops and it doesn't seem like any of them do flywheel balancing.

My alternative idea is this: I cut off the protruding counterweights gradually, and just do a test spin to high RPMs with the motor out of the car (and secured in place of course, there's a lot of rotational force) until there's no noticeable vibrations.

How does this sound?
 

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Discussion Starter · #6 ·
I still have the old flywheel around so I whipped out the angle grinder and oscillating saw and had some fun with it.
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This above picture is using a sanding attachment. Went kind of fast so I shaved off a little of the rest of it accidentally. But I left a bit of the counterweight to maybe offset it (who knows?)

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This one is with a oscillating saw. Also not pretty, but the only deep cuts are where they need to be. With the saw I cut under it and ended up with this piece of metal:
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I'll have access to a scientific scale tomorrow so I'm going to weight it to get an idea of how heavy it is. Because another way I could do this is to weld a few more of these on and keep them evenly spaced apart to make it balanced by addition instead of subtraction.
 

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Calling around to a bunch of machine shops and it doesn't seem like any of them do flywheel balancing.
That's unfortunate; I guess people just buy factory-balanced flywheels now. You could just buy a new flywheel which would come balanced without counterweights, but that shouldn't be necessary.

My alternative idea is this: I cut off the protruding counterweights gradually, and just do a test spin to high RPMs with the motor out of the car (and secured in place of course, there's a lot of rotational force) until there's no noticeable vibrations.
The whole counterweights will need to come off. The usual way to adjust balance is to drill small shallow goes in the heavy side to remove a bit of mass. Although that's not trivial, the more difficult task is probably determining where the heavy point is and by how much; I can see judging if there is still vibration by just trying it, but that won't tell you where mass needs to be added or removed.

The removal experiments show that there are no bolts, and suggest to me that they were spot-welded.
 

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Discussion Starter · #10 ·
It all depends on if the only counterweights are the two pieces that are visual. I can grind those off and have it decently close to balanced if that's it. But if there's an internal imbalance as well I think it's safe to say I won't be able to balance the clutch on my own.

If that's the case, I'll probably go clutchless.

I'll do some more research but assuming I won't be able to find any definitive information I might just give it a shot. The weight is far from the center (more leverage), hence why it's so small. So it would make sense for those two weights to be all there is.

Essentially I'm operating under the assumption that if those two counterweights were not welded on, it would be a balanced flywheel.
 

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It all depends on if the only counterweights are the two pieces that are visual. I can grind those off and have it decently close to balanced if that's it. But if there's an internal imbalance as well I think it's safe to say I won't be able to balance the clutch on my own.
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The weight is far from the center (more leverage), hence why it's so small. So it would make sense for those two weights to be all there is.

Essentially I'm operating under the assumption that if those two counterweights were not welded on, it would be a balanced flywheel.
I agree - the rest of the flywheel will be axially symmetric and thus balanced; any imbalance would only be the effects of removing the counterweights (grinding too far, etc) and manufacturing imperfections. The other imbalance in the engine (which these weights existed to counteract) was in the crankshaft.
 

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Discussion Starter · #12 ·
Yep. I think as long as I take my time I can get it pretty precise, within a few grams. It won't be perfect, but it's a diy project-- nothing of the sort is.

I'm gonna sand the counterweights down the next time I get a chance. I'll keep this thread updated with some nice before and after pics.

If when I finally get around to spinning the motor it vibrates like hell I'll probably ditch the clutch entirely like I was saying earlier. It would be nice to have as long as it works.
 

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2.5L Mazda Duratec inline 4 cylinder.

From a 2010 Ford Escape XLS.
I recall that all inline engines are internally balanced. Only some V engines are externally balanced. Is your FW some kind of dual mass unit? If it is, with a smooth running electric motor, maybe a simple, single mass Fw would be a more reliable choice.
 

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Discussion Starter · #14 ·
Yep it's dual mass. If there was a single mass version available for my car, I would've bought it. But I couldn't find one. The first gen escape had a single mass flywheel, but I'm not sure it would work with the 2nd gen.

I believe that a number of Ford engines are externally balanced.
 

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I recall that all inline engines are internally balanced. Only some V engines are externally balanced.
But that's clearly not true, as this is an inline-4 which is externally balanced. I note from other online discussions that it may be externally balanced only in some applications, particularly the transverse installations (and not the longitudinal rear-drive applications).

I agree that it is normally vee engines which are externally balanced (although the Mazda rotary is as well). I don't know why the variations in the Duratec, or why anyone would not internally balance an inline engine, since there should be lots of room for crankshaft counterweights; however, I will note that this is the largest-displacement variant of this engine family.

Is your FW some kind of dual mass unit? If it is, with a smooth running electric motor, maybe a simple, single mass Fw would be a more reliable choice.
Yep it's dual mass. If there was a single mass version available for my car, I would've bought it. But I couldn't find one. The first gen escape had a single mass flywheel, but I'm not sure it would work with the 2nd gen.
reiderM, I'm not sure that you understand what a "dual mass flywheel" is. You have a simple single-mass flywheel; it just has some counterweights on it.

With a synchronous or brushed DC electric motor, there would be no purpose for a dual-mass flywheel (or harmonic damper, which is usually mounted on the other end of the crankshaft). Even with the cogging of a switched relucatance motor I doubt anyone uses these devices.
 

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But that's clearly not true, as this is an inline-4 which is externally balanced. I note from other online discussions that it may be externally balanced only in some applications, particularly the transverse installations (and not the longitudinal rear-drive applications).
NIce bit of circular reasoning there, brian. The stock FW appears to be a DM unit. Because of the combination of unmachined cast, forged, or other formed parts in the DM, I'm guessing balancing this FW requires the spotweld-on weights that reiderM unfortunatly ground off. The aftermarket FWs for RWD conversion appear mostly to be single mass and made to fit different starter locations, ring gear size or other changes to adapt to RWD transmissions. None appear to have weights attached, or cast-in, as would be associated with an externally balanced engine. They only have a few drilled balancing holes to balance the FW by itself.
 

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Discussion Starter · #17 ·
reiderM, I'm not sure that you understand what a "dual mass flywheel" is. You have a simple single-mass flywheel; it just has some counterweights on it.

With a synchronous or brushed DC electric motor, there would be no purpose for a dual-mass flywheel (or harmonic damper, which is usually mounted on the other end of the crankshaft). Even with the cogging of a switched relucatance motor I doubt anyone uses these devices.
I do actually have a dual mass flywheel. The OEM flywheel was dual mass, and I bought an OEM replacement. It's frustrating, because a DMF is both less efficient and more expensive than a SMF. But I wasn't able to find a single mass replacement that I know will fit right, so I ended up just buying an OEM one.
 

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Discussion Starter · #18 ·
NIce bit of circular reasoning there, brian. The stock FW appears to be a DM unit. Because of the combination of unmachined cast, forged, or other formed parts in the DM, I'm guessing balancing this FW requires the spotweld-on weights that reiderM unfortunatly ground off. The aftermarket FWs for RWD conversion appear mostly to be single mass and made to fit different starter locations, ring gear size or other changes to adapt to RWD transmissions. None appear to have weights attached, or cast-in, as would be associated with an externally balanced engine. They only have a few drilled balancing holes to balance the FW by itself.
Just to clarify, I cut off the weights on the OLD flywheel which was destined for the dump. I haven't touched the new flywheel yet.

I am a little lost on what you're suggesting though. Are you saying that if I were to cut off the balancing weights it would still not be balanced? I know that my engine is externally balanced (did some research).

By the way, if you do manage to find a direct replacement SMF, I'll 100% jump on that. A DMF is silly for an electric motor, but it's all I could get.
 

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Just to clarify, I cut off the weights on the OLD flywheel which was destined for the dump. I haven't touched the new flywheel yet.

I am a little lost on what you're suggesting though. Are you saying that if I were to cut off the balancing weights it would still not be balanced? I know that my engine is externally balanced (did some research).

By the way, if you do manage to find a direct replacement SMF, I'll 100% jump on that. A DMF is silly for an electric motor, but it's all I could get.
Can you reference the source for the externally balanced part? I could be wrong on newer engines.
 

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Get one of these Lawn mower blade balancers at Amazon, Napa, True Value, etc.to test both FWs. Put a dab of grease on the pivot pin to minimize friction. It may be sensitive enough to show some imbalance if you can fit the FW center hole close enough to one of the diameter steps on the tool.
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