flywheel balancing

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Mar 3, 2005 | 09:32 AM

WESCH

Thread Starter

Melting Slicks

Joined: Feb 2001

Posts: 3,330

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From: Europe , Luxembourg

flywheel balancing

Hi

Awhile ago, I asked if it is required to balance a flywheel after resurfacing. Some thought yes, most sayed no.
Well, my 68 427 internally balanced engine flywheel was a original 6.500 RPM engine unit and was not bad, only got a slight resurfacing done due to new clutch being installed as I am installing the T56.
I asked to get it balanced and well, they had to drill 3 holes, so it was well out !!
The pic shows the 3 holes on the very outside diameter.
You figure now if balancing is required.

Günther

Mar 3, 2005 | 10:25 AM

bobs77vet

Race Director

Joined: Sep 2004

Posts: 11,874

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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod

i think balancing stuff is the only way to go.....thats the difference between a really smooth engine....and the rest.

Mar 3, 2005 | 10:35 AM

ZD75blue

Race Director

Joined: Nov 2000

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From: NC,USA

How do you balance one anyway?

Mar 3, 2005 | 10:39 AM

bobs77vet

Race Director

Joined: Sep 2004

Posts: 11,874

Likes: 263

From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod

Quote:

Originally Posted by ZD75blue

How do you balance one anyway?

take it to machine shop and they spin it....same concept like balancing a tire

Mar 3, 2005 | 02:56 PM

Surfer69

Drifting

Joined: Apr 2002

Posts: 1,720

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From: Manhattan Beach Ca

Why would the stock one be out of balance if the ring gear is new like yours looks? Slight surfacing is still symetric.

Mar 3, 2005 | 04:45 PM

stingry

Drifting

Joined: Mar 2003

Posts: 1,608

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From: Canberra AUSTRALIA

St. Jude Donor '05-'06

Quote:

Originally Posted by Surfer69

Why would the stock one be out of balance if the ring gear is new like yours looks? Slight surfacing is still symetric.

The front edge that touches the clutch is now flat after machining but the rear side may be warped (as the clucth side was before machining) hence differnent thickness around the flywheel will cause imbalance.

Think of it in terms of a one sided brake rotor. You only machine one side flat on a flywheel so the other side must still be warped.

Does that make sense?

Mar 3, 2005 | 04:52 PM

norvalwilhelm

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Joined: Nov 2000

Posts: 11,872

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From: Waterloo ontario Canada

Quote:

Originally Posted by Surfer69

Why would the stock one be out of balance if the ring gear is new like yours looks? Slight surfacing is still symetric.

I agree with that. Simpley resurfacing shouldn't affect the balance.
I also noted that the holes are almost spread out 180 degrees, not quite but one hole offsets the others being drilled too big or deep.
If you overdrill one spot you need to move to another spot to rebalance what the first hole unbalanced.
You don't need to spin the wheel to balance. Static balancing can also work for a neutral balanced flywheel.
I have a fixture in the shop that will show even a thumb tac out of balance on a neutral wheel.
For offset flywheels I have a fixture that clamps on the wheel to simulate the offset balance

Mar 4, 2005 | 06:35 AM

WESCH

Thread Starter

Melting Slicks

Joined: Feb 2001

Posts: 3,330

Likes: 13

From: Europe , Luxembourg

hI

THE REASON FOR THE ONE HOLE BEING SO FAR OFFSET IS BECAUSE THE OTHER DEEPER HOLES WOULD HAVE INTERFERED WITH THE THREDADED HOLES FOR CLUTCH ATTACHMENT. SO TO STAY AWAY FROM THOSE, THEY HAD TO COUNTERBALANCE WITH A SMALLER HOLE OFFSET. IS THIS UNDERSTANDABLE ?

GUNTHER