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A responder in another thread suggested I get my new flywheel balanced with a new clutch. I've changed several clutches in my lifetime, never had the pair balanced.
Can anybody share the reasons for doing this? This is a stock 70 LS5, nothing special. I have no plans to modify for high rpms. On the other hand I very much want to do the job right, hope to never take this apart again, so I'm asking for input.
A responder in another thread suggested I get my new flywheel balanced with a new clutch. I've changed several clutches in my lifetime, never had the pair balanced.
Can anybody share the reasons for doing this? This is a stock 70 LS5, nothing special. I have no plans to modify for high rpms. On the other hand I very much want to do the job right, hope to never take this apart again, so I'm asking for input.
A flywheel would be balanced already when purchased. Never heard about a clutch being balanced to a flywheel. I guess in theory it would make sense, but under normal street car use I doubt you would notice the difference. Buy your new parts, install and get out and drive that car!
Yes, you can balance the new flywheel and pressure plate to the rest of the rotating assembly. However, I think in order to do the job right you need to take your whole rotating assembly to the machine shop. Crank, balancer, connecting rods and pistons.
As far as the clutch disk itself I don't think you balance those. There's just not enough heavy mass there to make much difference IMO.
Your engine (unlike the predecessor 427) is not internally balanced- where as the flywheel is used to balance the rotating assembly-AKA "externally balanced."
So- having the flywheel balanced w/ the clutch won't work in your case.
You'll be fine w/ a quality clutch AND the correct flywheel.
Here's a LS5 flywheel- notice the added weight at the top of the flywheel.
I highly recommend you ask the guys like Duke and Joe L over at NCRS.
GM marked the flywheel and pressure plate with an X. It notes in the service manual to align the X when reassembling.
GM neutral balanced all the parts separately when new.
I would never assume a well balanced part off the shelf.
I will say that the LUK flywheel was balanced well when I did mine. The pressure plate not so much. I considered the balance cheap insurance against unwanted vibration.
I highly recommend you ask the guys like Duke and Joe L over at NCRS.
GM marked the flywheel and pressure plate with an X. It notes in the service manual to align the X when reassembling.
GM neutral balanced all the parts separately when new.
I would never assume a well balanced part off the shelf.
I will say that the LUK flywheel was balanced well when I did mine. The pressure plate not so much. I considered the balance cheap insurance against unwanted vibration.
Your call.
Bill
I've been getting mixed signals on whether or not to balance the flywheel and clutch assembly. Today I checked with a local Corvette shop whom I trust. They recommend getting the clutch and flywheel balanced. This adds a bit of expense and hassle having to travel a bit to a recommended machine shop but in the end best to do it right. Hope this doesn't drag out over a long period.
Thanks to all of you who provided input. appreciate it.
I have never balanced any clutch assembly. It might be a good idea for a race car. But on a daily driver it's a waste of time and money. If those parts need to be balanced then your new clutch set is a piece of junk.
I have never balanced any clutch assembly. It might be a good idea for a race car. But on a daily driver it's a waste of time and money. If those parts need to be balanced then your new clutch set is a piece of junk.
I remain a bit skeptical but considering how much work is involved removing the transmission I figure I'll spend a bit more to eliminate balance being a possible issue. With global manufacturing, difficulty knowing where a part was actually made or to what quality standards they were held, I'll have it checked.
Something I'm not understanding here; if the crankshaft is externally balanced -meaning the crankshaft's balance is achieved by weight added external to the shaft. In the case of your 454, the weighted items are the flywheel and the damper- what exactly are they balancing and what are they balancing it to?
If you have the crankshaft balanced, you have to take the flywheel and damper you're using with that crank. The shop mounts them to the shaft and spins them up, finds and adjusts balance on the crank. The imbalance remains on the flywheel and damper. You don't balance the crank by removing or adding weight to the flywheel or damper. If you do modify the balance on the flywheel post crankshaft balancing, you no longer have a balanced assembly. And if they neutral balance the flywheel, then you are really screwed.
I can see a tiny bit of merit in doing this to an internal balance assembly but I'm not clear at all for an external assembly. But then, I don't know everything.
Something I'm not understanding here; if the crankshaft is externally balanced -meaning the crankshaft's balance is achieved by weight added external to the shaft. In the case of your 454, the weighted items are the flywheel and the damper- what exactly are they balancing and what are they balancing it to?
If you have the crankshaft balanced, you have to take the flywheel and damper you're using with that crank. The shop mounts them to the shaft and spins them up, finds and adjusts balance on the crank. The imbalance remains on the flywheel and damper. You don't balance the crank by removing or adding weight to the flywheel or damper. If you do modify the balance on the flywheel post crankshaft balancing, you no longer have a balanced assembly. And if they neutral balance the flywheel, then you are really screwed.
I can see a tiny bit of merit in doing this to an internal balance assembly but I'm not clear at all for an external assembly. But then, I don't know everything.
Pretty much what I thought. The Corvette shop which advised having the balance checked knows it's a 454, external balance. I gather the thought is to be sure the pressure plate is neutral balanced. I don't know how you would balance the flywheel without the rest of the rotating assembly unless there is some spec to work towards, not neutral. See what the machine shop has to say next week.
I came full circle on this topic, had the flywheel resurfaced by a recommended machine shop. The operator said the flywheel was actually in pretty good condition, cleaned up easily. Less risk of being out of balance, keeping the original vs taking my chances with a replacement. Cost me $45, not $80. Did the resurfacing while I waited.
If I modify the pressure plate I bought, have it balanced, the clutch will be non returnable should there be any issues I may find upon installation. Pretty much pushes me toward a clutch which I should not need to have balanced. My last two pressure plates have weights attached which I assume are for balance. The new pressure plate does not which makes me suspicious. I can take my chances and install as is or return it and buy another...
I've replaced several clutches over the years, never had a balance problem. Last time I did so was twenty years ago so I'm not sure I can make the same assumptions about quality.
If I modify the pressure plate I bought, have it balanced, the clutch will be non returnable should there be any issues I may find upon installation. Pretty much pushes me toward a clutch which I should not need to have balanced. My last two pressure plates have weights attached which I assume are for balance. The new pressure plate does not which makes me suspicious. I can take my chances and install as is or return it and buy another...
I've replaced several clutches over the years, never had a balance problem. Last time I did so was twenty years ago so I'm not sure I can make the same assumptions about quality.
The only time you would normally see weights attached to a pressure plate is if it were like this...
The purpose of these weights is to increase clamping force without increasing the pedal effort. It is referred to as a centrifugal weight design pressure plate. As RPM increases the clamping force is increased. Otherwise the Pressure Plate would normally be neutrally balanced when sold.
The only time you would normally see weights attached to a pressure plate is if it were like this...
The purpose of these weights is to increase clamping force without increasing the pedal effort. It is referred to as a centrifugal weight design pressure plate. As RPM increases the clamping force is increased. Otherwise the Pressure Plate would normally be neutrally balanced when sold.
Good luck... GUSTO
The weights I refer to are small washers rivetted to the pressure plate (Hays) or some small pieces of steel spot welded on one side (unknown brand). They appear to be for balance.
I'm aware of the Centerforce clutch which uses weights to increase clamping pressure. In this case the pattern would be symmetrical to stay in balance.
I just rebuilt my L-82 355 and the engine was internally balanced and the flywheel, pressure plate, and clutch were balanced separately as one rotating mass after the flywheel was resurfaced. The charge was $60 for the flywheel, clutch, pressure plate balancing and the motor is smooth as glass at 6K RPM.
Last edited by jb78L-82; Sep 25, 2014 at 01:34 PM.
I just rebuilt my L-82 355 and the engine was balanced and the flywheel, pressure plate, and clutch were balanced separately as one rotating mass after the flywheel was resurfaced. The charge was $60 for the flywheel, clutch, pressure plate balancing and the motor is smooth as glass at 6K RPM.
There are two issues as I understand this. First is if I modify the pressure plate by having it balanced I am going on faith there are no defects or other issues with the pressure plate. It will be non returnable.
The other problem is this is for a 454, external balance, which means the flywheel is not neutral balanced by design. My understanding is that I'd want the new clutch to be neutral balanced? I doubt I'd want to throw off what ever the flywheel is balanced for. A shop may be able to do this, haven't really explored this deeply. How can the flywheel and clutch be balanced without removing the entire rotating system from the engine?
My general feeling is I'd prefer to buy a quality clutch which I may have faith is balanced well enough for street use on a stock LS5.
There are two issues as I understand this. First is if I modify the pressure plate by having it balanced I am going on faith there are no defects or other issues with the pressure plate. It will be non returnable.
The other problem is this is for a 454, external balance, which means the flywheel is not neutral balanced by design. My understanding is that I'd want the new clutch to be neutral balanced? I doubt I'd want to throw off what ever the flywheel is balanced for. A shop may be able to do this, haven't really explored this deeply. How can the flywheel and clutch be balanced without removing the entire rotating system from the engine?
My general feeling is I'd prefer to buy a quality clutch which I may have faith is balanced well enough for street use on a stock LS5.
Yes and Yes. I think that if I was in your situation I would leave it alone and go with the hope that a quality clutch will be balanced correctly for your externally balanced 454.
...a quality clutch will be balanced correctly for your externally balanced 454.
The pressure plate is neutral balance so ,in that regard it would be correctly balanced for a 454's external balance as well as a 427's internal balance as well as any smallblock using an 11" clutch. The 454's imbalance is in the flywheel and the damper. That there are no balance weights on the pressure plate means only that it didn't require any weight adjustments. Balancing might have occurred on the plate itself ahead of assembly.
Balance Clutch/Flywheel?
