Is it important to have a flywheel balanced?

[robroy]

Hello!

Today I took my flywheel to a local machine shop and heard that they didn't have the machine to balance it. I also heard that flywheels are normally balanced only in combination with the engine itself (balanced while attached to the engine).

Is this true? Or are flywheels often balanced separately from an engine?

There have never been problems with my flywheel that I've been aware of, but I'd like to have it made as perfect as it can be before re-installing it.

Thanks very much!
-Robroy

[Jake11]

Depends, what motor? It's not a bad idea to get the flywheel&pressureplate balanced together. At least it will run
smoother. Some motors like a 428 or a 454 have a big counterweight on one side of the flywheel. Most shops that
do balancing can still get the balance right. It's worth the $$. Jake

[robroy]

Depends, what motor? It's not a bad idea to get the flywheel&pressureplate balanced together. At least it will run
smoother. Some motors like a 428 or a 454 have a big counterweight on one side of the flywheel. Most shops that
do balancing can still get the balance right. It's worth the $$. Jake

Hi Jake! Thanks for your reply. This is for my new Proformanceunlimited 400HP 390. The flywheel is from my old 360 setup.

Thanks for the tip of getting the pressure plate balanced with the wheel! I may go this route.

I hired the local shop to resurface the flywheel despite their inability to balance it; hopefully this effort won't be in vain.

Thank you!
-Robroy

[Faithful Old Road Dog]

My machinist balances the pistons/rods, crankshaft, flywheel and pressure plate separately. He says the Centerforce pressure plates are hard to balance. Some types of engine get balanced as a unit.

[My427stang]

Have it balanced to zero, or don't, at this point its not a big deal.

When the builder balanced the motor, he either spun it with a good zero balanced wheel, or no wheel at all. The bobweights used for balancing a crank dont change with or without the wheel bolted to it, they are a function of the piston, bearing, ring package, a little oil, and rod weights.

A 390 is zero balanced, so your wheel should be close to zero anyway off the 360, and if it isnt now, its easily done and you dont need to know anything about the balance of the motor.

If it was an externally balanced 410 or 428, that'd be a different story.

Bottom line though, I lean toward getting the wheel and pressure plate to true zero, but honestly, if you didnt, you probably wont ever know the difference.

[robroy]

Good morning! Thanks for the great advice. I see what you mean about the 390 being internally balanced--that makes it easy for me.

I think I'll find a place to balance this thing.

Faithful Old Road Dog, thanks for the tip on Centerforce pressure plates. Is this a good coincidence or did you use your psychic power to determine that that's my pressure plate?

Thanks again for the great advice,
-Robroy

[robroy]

I just got the flywheel back from a local machine shop that resurfaced it. Now I just need to find a place that'll balance it!

It sure looks nicer than it did.



Thanks for the advice folks!
-Robroy

[robroy]

On Friday I dropped the flywheel off at GMP Speed and Machine in Santa Cruz. They said they'd balance it for $100, which may seem a little expensive, but I had a hard time finding a place that would do it at all! So I'm happy about it.

I heard from the guy that he could balance my Centerforce pressure plate with the wheel, but that the Centerforce plates are very good right from the factory so there was no point (in his opinion). He said he's tried to balance flywheels with those plates before and the plate made no difference at all.

He added that in order to balance the Centerforce pressure plate he'd need to remove the UFO-like weights on the ring (special feature of these pressure plates), which makes them in a pain.

Here's the place I dropped it off at: http://www.gmpauto.com/

Thanks for the advice!
-Robroy