Balance flywheel/pressure plate yourself

[Eljaro]

Now that I have to order a new shortblock to replace my busted Pond sideoiler by courtesy of Eagle Cranks I have to separately balance the flywheel with the pressure plate attached, and also the harmonic balancer. Rotating assembly will be shipped internally balanced
I bought one of these balancer rigs to equilibrate motorcycle wheels, made myself an adapter and got the 22 grams off balance on the flywheel fixed.

[tboneheller]

I would send ALL of it to a good machine shop & have it balanced together as a unit.

[tboneheller]

Looks like you are missing some bolts.

[CHANMADD]

Yea,.....you have to have everything that rotates including the washers and bolts and..and...and send it to the shop and watch them balance it with the crank and all the parts attached to the crank. Another broken crank would suck!!

[Jaydee]

That's only good for static balance. It needs to be spun up and dynamically balanced. engine side and face side. Same as a tyre.
JD

[Eljaro]

Yea,.....you have to have everything that rotates including the washers and bolts and..and...and send it to the shop and watch them balance it with the crank and all the parts attached to the crank. Another broken crank would suck!!

Shortblock comes balanced from builder and it is not very practical to send flywheels and pressures plate from Spain to the US.
Of course all the bolts and washers were on it when I did the balance.I am not that stupid. The whole thing was set up again just to make the picture.

That's only good for static balance. It needs to be spun up and dynamically balanced. engine side and face side. Same as a tyre.
JD

Of course this is a static balance.But with such a narrow piece there is no place to put weights all over. Either you weld a piece of steel to the pressure plate or you screw a bolt into en empty hole on flywheel.

The POINT IS that if you have to change the flywheel or the pressure plate or both or if you get a new rotating assembly and want to reuse the the old parts you CAN balance them this way without having to take them to a machine shop. If you happen to have one close to where you live who can do a dynamic balance.
In my case there is none.

[RICK LAKE]

I have used a tire balance machine to balance my setup. They have adapters that will allow you to balance anything if the center hole is clean without burrs. Static is a good place to start but spinning the assembly is better also if you have the clutch plate centered in the assembly. off centered off balance.

[CHANMADD]

The clutch plate/disc does not get balanced with the assembly. If I was you, I would get the short block, take the crank out , at least ,( you should do the pistons too), and find a balance shop. There has to be one somewhere. Broken cranks, cracked bell housings, are all a result of out of balance. Do it right once or continue paying...............its an easy choice really!!

[Jaydee]

To balance it, you would drill holes, not weld or bolt anything to the flywheel.
JD

[Eljaro]

Originally Posted by CHANMADD

The clutch plate/disc does not get balanced with the assembly. If I was you, I would get the short block, take the crank out , at least ,( you should do the pistons too), and find a balance shop. There has to be one somewhere. Broken cranks, cracked bell housings, are all a result of out of balance. Do it right once or continue paying...............its an easy choice really!!

If the engine builder delivers an internal balanced rotating assembly, it is by itself absolutely neutral or zero balance. Anything you add front or back like harmonic damper at one end and pressure plate and flywheel can be balanced individually to give neutralor zero balance. If all these parts are 0 balance, 0+0+0+0 makes 0, right?
You may want to fit a lighter flywheel or a different clutch without having to take the crankshaft out every time. Cliutches are wear items and get replaced often, and the flywheel may have to be resurfaced same as the pressure plate. It is basically a swap job, and the only thing you want to do is to make sure those parts are checked for proper neutral balance.
Be it a static balance, like I propose, where you first balance the flywheel (in my case it was resurfaced) and it is also an aluminum flywheel, very light allready. I needed 5 grams on one end to keep it from stopping always in the same position.
Then I added the pressure plate with all the bolts fitted and balanced it again, having to add another 17 gramm in order to get it to be neutral. I will have to weld a small steel plate on the outside of the PP since drilling it will probably affect the mechanical integrity.
So there will be a small weight on the FW, a small screw in one of the empty holes and a plate on the outside of the PP.
I will anyway take it to a tire shop and see if they can fit it to their balancing machines they use and double check. Unfortunately there are no shops who do dynamic balancing here, so I have to make do with what is available.

[CHANMADD]

Every piece also needs to be indexed so that you get back in the exact place that it was balanced. A centre punch works pretty well to mark the parts. Who balanced your previous motor?

[Eljaro]

Every piece also needs to be indexed so that you get back in the exact place that it was balanced. A centre punch works pretty well to mark the parts. Who balanced your previous motor?

everything indexed , of course. The former engine was done by Keithcraft.

[Gaz64]

A device like that will show the heavy spot at 6 o'clock but it doesn't tell you how much to take off, bit of "hit and miss".

Before you know it, you have holes everywhere and it may be not correctly balanced. A small "true" imbalance of 5 grams may not allow the unit to rotate due to friction in the bearings.

Personally I wouldn't trust a device like that, I value my feet too much.

I would still get the flywheel/pressure plate balanced as an assembly including the pressure plate fasteners, with indexing marks for future disassembly.

[CHANMADD]

I think that bolt in the back of the Flywheel may hit the block anyways. Have you tried to spin it with the presure plate moved around one hole at a time untill you find the best spot first? You may not need much weight then to balance. Once you've indexed the pressure plate you can drill some holes in the casing to remove metal.

[Gaz64]

Originally Posted by CHANMADD

I think that bolt in the back of the Flywheel may hit the block anyways.

That's a good point, why have you done that?

Take it to a balancing shop and do it the right way.

[Jerry Clayton]

so how many engines have you guys balanced?????

[patrickt]

Originally Posted by Jerry Clayton

so how many engines have you guys balanced?????

A lot of the guys on here can't even balance their checkbook.

[CHANMADD]

Jerry I am just trying to help.....I also did some learning the hard way..

[tirod]

Balancing doesn't "have" to be done, and race builders also alter the balance to allow for some positive benefits by overbalancing. It's actually done with bob weights on the journals, with harmonic, flywheel, and clutch installed - and a fudge factor thrown in for the oil that might be on the rods, pistons, etc. Which means it's an approximate guess even in the most stringent shops - and they play with it.

Internally balanced, just get a matching harmonic and flywheel, call it done. The clutch, etc is always neutral. About all the harmonic and flywheel do is add the oz per factory standards because they left it off the crank. Get ones without, its already done. Exactly why racers use internal balance, so they don't have that problem when reassembling stuff. They bolt on whatever neutral parts they need, engine in car, car on track, done.

[CHANMADD]

Any imbalance will be felt , like a road wheel out of balance. If you have a zero balance motor it means that you need a flywheel balanced to zero. If you put a 28 oz flywheel, one that has a 28 oz weight tacked on somewhere on the outer circumference of the flywheel , the motor will vibrate like mad, eventually breaking something. The balancing machine in the picture is supposed to have the piece being balanced spun , not too fast maybe 800 - 1000 rpm . The posts are mounted to the plate base which should be on rubber mounts to the feet. When spinning the slowly the posts will rock side to side. If you hold a chalk to the side of the flywheel by a fixed mount, it will leave a mark at the same spot as it rotates. This is the heavy spot. Drill at this spot or put a weight opposite. By the same method one could balance , theoretically one could balance the complete motor in place. Fifty tonne power station turbines are balanced this way.