Is it necessary to have a new flywheel and pressure plate balanced before install?
05-29-2003, 08:47 AM
#1
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Is it necessary to have a new flywheel and pressure plate balanced before install?
I have read on old threads that some people have them balanced and some people don't. I have a McLeod Street Twin sitting at my house. Someone told me that there is no need to have them balanced, he also added there is no need to have a motor balanced after building it. Just wanted to get some input from others. If it does need balanced, approximately how long does that take? I was going to install it at a friends house and don't want to tie up his garage too long.
05-29-2003, 09:05 AM
#2
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Location: Palm Bay, Florida
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It wouldn't hurt anything to balance it, but it's not necessary unless you have a high RPM racing engine.
Assuming it's for your Z28 and the engine is still internally balanced and you have a neutral balanced flywheel, then you can just put it on and you'll be fine.
When you rebuild the motor, if you use all your same rods/pistons/crank then you do not have to have the engine re-balanced. I'd still weigh the rings to make sure they are not way out, but they shouldnt be.
If you change the rods and/or pistons, and certainly if you change the crank, you need to balance the rotating assembly. Sometimes you get lucky if you're just changing the pistons and they're the same diameter (ie you didn't bore the cylinders out, such as changing to blower pistons) you'll sometimes find that they weigh the same as the stock ones so you don't have to balance them. but if they're different by more than about 5 grams then you should balance them.
One problem is that normally when you switch to a forged piston is that the piston inevitably weighs more than the stock ones (especially if thier 0.030" over), which means alot of times you have to add weight to the crank. When you have to do that the balancing job becomes more expensive than just having to drill out more metal.
But I'm rambling.....the answer to your original question is that you can just use the flywheel and clutch as-is without balancing them.
-Dave C. '97 Z28
PS: I'm sure there will be those who have other opinions.
Assuming it's for your Z28 and the engine is still internally balanced and you have a neutral balanced flywheel, then you can just put it on and you'll be fine.
When you rebuild the motor, if you use all your same rods/pistons/crank then you do not have to have the engine re-balanced. I'd still weigh the rings to make sure they are not way out, but they shouldnt be.
If you change the rods and/or pistons, and certainly if you change the crank, you need to balance the rotating assembly. Sometimes you get lucky if you're just changing the pistons and they're the same diameter (ie you didn't bore the cylinders out, such as changing to blower pistons) you'll sometimes find that they weigh the same as the stock ones so you don't have to balance them. but if they're different by more than about 5 grams then you should balance them.
One problem is that normally when you switch to a forged piston is that the piston inevitably weighs more than the stock ones (especially if thier 0.030" over), which means alot of times you have to add weight to the crank. When you have to do that the balancing job becomes more expensive than just having to drill out more metal.
But I'm rambling.....the answer to your original question is that you can just use the flywheel and clutch as-is without balancing them.
-Dave C. '97 Z28
PS: I'm sure there will be those who have other opinions.
. This winter I'm hoping to pull the cash for a 355 with the LT4 on top.
05-29-2003, 09:14 AM
#4
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Cool.
I actually have freshly rebuilt 355 LT-1 in my garage on a stand as we speak! (type?)
I'm not sure what to do with it yet, but it'll probably find it's way into my Corvette sooner or later. I rebuilt it with the stock cam, but now I'm thinking of putting a different one in before I put it i the car. It's the engine I took out of my Camaro when I put the big block in it.
Good luck!
-Dave C. '97 Z28
454 cid Gen VI big block
I actually have freshly rebuilt 355 LT-1 in my garage on a stand as we speak! (type?)
I'm not sure what to do with it yet, but it'll probably find it's way into my Corvette sooner or later. I rebuilt it with the stock cam, but now I'm thinking of putting a different one in before I put it i the car. It's the engine I took out of my Camaro when I put the big block in it.
Good luck!
-Dave C. '97 Z28
454 cid Gen VI big block
05-29-2003, 09:37 AM
#7
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I'm just sure that '86 and later small block Chevy engines are external balance. Requiring specific balancer and flexplate/flywheel. The cranks are neutral and the balancer and flywheel/flexplates are balanced for THAT crankshaft.
05-29-2003, 10:00 AM
#8
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You should have that new flywheel match balanced to your old fly wheel. it very cheap on like 25 bucks to have it done. Good luck with trying to get your transmission in I hate this damn street twin clutch my car has been down for over a month now!!! I wish i would of just bought a Star stage III and been done with it. I cant get my f'in transmissin back in and im about to just take this damn thing to a shop and let them fight this mother *****er im about done with it this is the one thing that i have bought for my car that i wished i wouldnt of wasted my money on!!!!!!
sorry to rant on your thread good luck getting that tranny in with this clutch
Steve
sorry to rant on your thread good luck getting that tranny in with this clutch
Steve
05-29-2003, 10:27 AM
#9
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hmmm....
Interestingly,
I just went out and looked at a flex plate that came off an LT-1 I had that had an automatic attached to it and there IS a counterbalance weight on the thing.
That's strange, because on my flywheel from my 6-speed car there was no weight that I recall. I need to do some research to see why this is.
But for now it seems that there certainly is a weight on the auto flex plate.
This is confusing....
-Dave C. '97 Z28
I just went out and looked at a flex plate that came off an LT-1 I had that had an automatic attached to it and there IS a counterbalance weight on the thing.
That's strange, because on my flywheel from my 6-speed car there was no weight that I recall. I need to do some research to see why this is.
But for now it seems that there certainly is a weight on the auto flex plate.
This is confusing....
-Dave C. '97 Z28
05-29-2003, 11:03 AM
#10
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Join Date: Mar 2003
Location: Northern California
Posts: 424
Balance, balance, balance!!!
Yes, you need to have the flywheel balanced correctly otherwise you'll end up throwing your engines balance out of wack. Think of the harmonic balancer in the front. In most LT1 Camaros (although not all of them) the balancer is weighted so as to balance the engine. That's why the LT1 engine is both internally and externally balanced.
If either the harmonic balancer or flywheel is off it'll feel like your engine is about to fall out of your car.
Yes, you need to have the flywheel balanced correctly otherwise you'll end up throwing your engines balance out of wack. Think of the harmonic balancer in the front. In most LT1 Camaros (although not all of them) the balancer is weighted so as to balance the engine. That's why the LT1 engine is both internally and externally balanced.
If either the harmonic balancer or flywheel is off it'll feel like your engine is about to fall out of your car.
05-29-2003, 04:12 PM
#12
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Originally posted by MrBigXL
jeez, i don't think they balanced my SLP set up w/ lightweight flywheel. they only charged $245 for the install
but no problems 6,000 miles later
jeez, i don't think they balanced my SLP set up w/ lightweight flywheel. they only charged $245 for the install
but no problems 6,000 miles later
Does that make sense to anyone else or am I talking out my ***?
05-29-2003, 09:09 PM
#13
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LT1s are externally balanced. You can just put another flywheel on it and might not even notice a thing. But over time the added vibration will slowly, but surely, eat up your bearings. Unless you get REALLY lucky and the new one just happens to have the same counterbalance as the old one.
I'm in the process of converting to a M6 and will take both my stock flywheel and the M6 flywheel to the shop so they can put the same counterbalance on the M6 one that the A4 has. It's not that expensive and will make much more sense to do it while you're in a good position to. Just my $.02
I'm in the process of converting to a M6 and will take both my stock flywheel and the M6 flywheel to the shop so they can put the same counterbalance on the M6 one that the A4 has. It's not that expensive and will make much more sense to do it while you're in a good position to. Just my $.02
09-30-2004, 09:02 PM
#14
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Re: Is it necessary to have a new flywheel and pressure plate balanced before install?
someone explain to me why the stock Lt1 t56 flywheel has a weight on it and the SLP billet one has nothing. Does this mean that anyone who buys a LP flywheel HAS to get it balanced? I ask because I have a 91z28 and just put an internally balanced 383 setup in it and I am having a bad vibration problem. I have a t56 hooked up to it and I have both the stock and SLP flyhweels. My balancer is zero balanced so I take it that my flywheel must be zero balanced right? That would mean I HAVE to use the SLP flywheel since it has no weights on it at all right?
09-30-2004, 09:48 PM
#15
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Re: Is it necessary to have a new flywheel and pressure plate balanced before install?
This has been discussed many times here. The stock LT1 is externally balanced with a weight on the flywheel/flexplate. Period. Take it to the bank.
With that out of the way, a little elaboration: As they come from the factory, each flywheel/flexplate is NOT individually balanced with the rotating assembly in that specific motor. The amount of weight used to balance the rotating assembly is the same on all of the motors. The idea is that the facory rotating assemblies are close enough to each other that the same counterweight can be used on all of them. And that appears to be so as stock LT1's seem to run plenty smooth and last a long time.
So, if you have stock motor and you are replacing the flywheel/flexplate all you need to do is to be sure it has the standard external counterweight for an LT1. If you are doing a rebuild with non-stock parts, your flywheel/flexplate will need to be balanced against the your rotating assy. Alternatively, you can have the RA neutral balanced and use a neutral balance flywheel/flexplate.
AFAIK, all harmonic balancers for Chevys are neutral balance.
Rich
With that out of the way, a little elaboration: As they come from the factory, each flywheel/flexplate is NOT individually balanced with the rotating assembly in that specific motor. The amount of weight used to balance the rotating assembly is the same on all of the motors. The idea is that the facory rotating assemblies are close enough to each other that the same counterweight can be used on all of them. And that appears to be so as stock LT1's seem to run plenty smooth and last a long time.
So, if you have stock motor and you are replacing the flywheel/flexplate all you need to do is to be sure it has the standard external counterweight for an LT1. If you are doing a rebuild with non-stock parts, your flywheel/flexplate will need to be balanced against the your rotating assy. Alternatively, you can have the RA neutral balanced and use a neutral balance flywheel/flexplate.
AFAIK, all harmonic balancers for Chevys are neutral balance.
Rich