flywheel/pressure plate balancing

[Mike T.]

I'm putting a new NAPA flywheel and a new LUK pressure plate on a 283 for my 57. Should they be balanced at a machine shop before I put it together?
I have read in a service manual that the factory equipment has an "X" stamped in both units that are supposed to be lined up.
Thanks.

[Joe L.]

Re: flywheel/pressure plate balancing

I'm putting a new NAPA flywheel and a new LUK pressure plate on a 283 for my 57. Should they be balanced at a machine shop before I put it together?
I have read in a service manual that the factory equipment has an "X" stamped in both units that are supposed to be lined up.
Thanks.

Mike-----


You DEFINITELY want to have them balanced by a competent balancing shop.

The factory did mark the cover and flywheel for subsequent re-alignment for re-establishing original balance. However, that's only meaningful if one is re-installing the original pressure plate assembly on the original flywheel. If EITHER are replaced, the marks are meaningless.

[Mike T.]

Re: flywheel/pressure plate balancing

10/4
Thanks Joe

[Terry M.]

Re: flywheel/pressure plate balancing

I'm putting a new NAPA flywheel and a new LUK pressure plate on a 283 for my 57. Should they be balanced at a machine shop before I put it together?
I have read in a service manual that the factory equipment has an "X" stamped in both units that are supposed to be lined up.
Thanks.

The machine shop that does the balancing will "neutral balance" the flywheel/clutch assembly -- and as Joe says you definitely want to get that done.

The problem is that after assembly Flint (and later Tonawanda) balanced the entire rotating assembly by adding weight to the vibration damper and drilling the outer surface of the flywheel as needed to dynamically (while in motion) balance the whole engine. Unless the entire engine is disassembled you will not be able to duplicate that. Odds are good the neutral balance will be sufficient, but if the rest of the engine assembly was on the edge of production tolerances you may have vibration issues. I am not aware of anyplace that can balance the entire engine assembled, except engine assembly plants -- but I could be wrong.

BTW: This process has nothing at all to do with the terms “internal” and “external balance,” so don’t go there. That is a whole other issue, and in no way related to the process I explained above.

[Timothy B.]

Re: flywheel/pressure plate balancing

Terry,

I would love to see the process the factory used. I guess computers are used to perfectly balance with todays engines.

[Terry M.]

[Joe L.]

Re: flywheel/pressure plate balancing


Terry------


The entire reciprocating assembly can be custom-balanced and it will pretty much duplicate, if not exceed, a factory balance. Of course, the engine needs to be completely dis-assembled to do this.

[John H.]

Re: flywheel/pressure plate balancing

Just a guess, but John Hinkley might be able to fill in some of the detail blanks.

In the 50's-60's, the crankshaft was balanced by itself after finish-machining/grinding on equipment provided by GM Balance Engineering, and that was it; different cranks (differing counterweight sizes/weights) were specified based on rod/piston weights to be used in final assembly for specific configurations. The last time I was in Flint V-8 was in the late 60's, and any balancing operations at hot-test were added at some time later than that.

Most modern engines (ignoring the kind of stuff built at Wixom) have no final balancing operations either; the weight of the components are specified with close tolerances, the crank is dynamically balanced by itself, and the engine is simply assembled.

They aren't hot-tested any more either; final cold-test software (with sensors everywhere) focuses on variations in rotating friction while the engine is slow-motored by electric servo motors, along with variations in oil pressure, vacuum, exhaust port pressures, etc., and is sophisticated enough that the cold-test stand can detect a piece of dirt in a main bearing, and identify whether it's the upper or lower shell. Hot-testing disappeared over ten years ago.

[Timothy B.]

Re: flywheel/pressure plate balancing

Nice pics John,

Like you stated, the spec on the rods and pistons must have been close so just the crankshaft is balanced. I assume then that the front damper and rear flywheel are zero balanced when manufactured.

Was the pressure plate and flywheel actually balanced or is the X mark indication of heavy side and light side so they are put together to align.

[Clem Z.]

Re: flywheel/pressure plate balancing

NEVER let them balance the flywheel and pressure plate as a unit because if you ever have to replace the pressure plate you must balance the unit together again

[Terry M.]

Re: flywheel/pressure plate balancing

In the 50's-60's, the crankshaft was balanced by itself after finish-machining/grinding on equipment provided by GM Balance Engineering, and that was it; different cranks (differing counterweight sizes/weights) were specified based on rod/piston weights to be used in final assembly for specific configurations. The last time I was in Flint V-8 was in the late 60's, and any balancing operations at hot-test were added at some time later than that.

Most modern engines (ignoring the kind of stuff built at Wixom) have no final balancing operations either; the weight of the components are specified with close tolerances, the crank is dynamically balanced by itself, and the engine is simply assembled.

They aren't hot-tested any more either; final cold-test software (with sensors everywhere) focuses on variations in rotating friction while the engine is slow-motored by electric servo motors, along with variations in oil pressure, vacuum, exhaust port pressures, etc., and is sophisticated enough that the cold-test stand can detect a piece of dirt in a main bearing, and identify whether it's the upper or lower shell. Hot-testing disappeared over ten years ago.

"Stuff at Wixom" Yea, John some kind of "stuff." Just short a few cylinders by your standards. LoL

Shows everyone what the blind man and the elephant is all about. I don't have to try too hard to be the blind man.

I have been to Flint and Tonawanda, and Wixom, all of which did and in the case of Wixom still do hot test balancing, so I took it that was the process in general. I now remember your Connor Avenue explanation of the 588 engine there. Maybe I need a couple of more trips through there to burn it into my memory. I have a standing offer to go through Oshawa, and one of these days I should take advantage of that.

BTW: At Bowling Green when my 2008 was built the easy way to distinguish between the racks of LS7 and the LS3 engines is the color of the exhaust manifolds on the LS7. They were the only heat discolored exhaust manifolds. Of course now with the GS engines being built at Wixom, I just don't know if they are hot tested or not, so even that recent info may be dated. So it goes, moving on.

[Terry M.]

Re: flywheel/pressure plate balancing

Terry------


The entire reciprocating assembly can be custom-balanced and it will pretty much duplicate, if not exceed, a factory balance. Of course, the engine needs to be completely dis-assembled to do this.

Yea, that is sort of what I was getting at. I just wasn't sure if balancing technology had moved on at machine shops. it has been a while since I had occasion to use their services.

[John H.]

Re: flywheel/pressure plate balancing

Yea, that is sort of what I was getting at. I just wasn't sure if balancing technology had moved on at machine shops. it has been a while since I had occasion to use their services.

Terry -

It hasn't changed much - still uses shot-filled bobweights, but the electronics are more compact than they used to be.