HELP REQUESTED -- Piston swap resulted in vibrations (condensed version)
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Joined: Jul 2004
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From: Jacksonville FL
HELP REQUESTED -- Piston swap resulted in vibrations (condensed version)
Hi everyone,
Here is the condensed version of my questions. For complete background, see the link at the bottom. Thanks.
Is there a weight difference between the 2001 and 2002 spec pistons? My research has led me to believe that if they are different that will cause the motor to be unbalanced because the lobs on the crank are intended to balance out a different weight.
What is the factory procedure for balancing a motor and what is GM's procedure to rebalance a motor?I have seen threads that say GM spins the motor at the factory and then does any balancing via weights onto the Harmonic Balancer and/or Flywheel. Well, which one do you start with first? What is the limit to what you can balace out with each one? I have talked to my Uncle who works for Chrysler and he explained they have a very sophisticated test stand the spin the motors on to balance them as they come down the line. How do you do this if you are at the dealer and not the factory or where would the dealer need to send the car and/or engine too?
Is there or is there not info in the Sevice Manual about tuning Hamonic Balancers and/or Flywheels?
If we have to start messing with the Flywheel, did anyone ever find a difinitive answer about what to do with the weights if swapping an old one out for a new one?Also, did anyone find out difinitively if the weights are to balance the clutch/flywheel/pressure plate assembly or if they are to balance internal imperfections found at the factory for that particular engine? I don't know if my flywheel had any weights on it but will try to find out from the dealer tomorrow. Assuming my "new" motor is now out of balance due to differnt weight pistons, and assuming the flywheel was tuned at the factory for that engine (i.e. zero balance flywheel assmebly had weights added to internally balance the engine), I think I should still be able to "retune" my current flywheel by adding or subtracting weight to my "new" motor without having to use a whole new zero balanced assembly and starting from there. I have found other threads where guys have done clutch jobs and then were having vibes at nearly the same rpms as mine, but the same clutch/flywheel/pressure plate is in my car and the dealer tells me they double checked its reinstallation.
http://forums.corvetteforum.com/show...ferrerid=65336
Here is the condensed version of my questions. For complete background, see the link at the bottom. Thanks.
Is there a weight difference between the 2001 and 2002 spec pistons? My research has led me to believe that if they are different that will cause the motor to be unbalanced because the lobs on the crank are intended to balance out a different weight.
What is the factory procedure for balancing a motor and what is GM's procedure to rebalance a motor?I have seen threads that say GM spins the motor at the factory and then does any balancing via weights onto the Harmonic Balancer and/or Flywheel. Well, which one do you start with first? What is the limit to what you can balace out with each one? I have talked to my Uncle who works for Chrysler and he explained they have a very sophisticated test stand the spin the motors on to balance them as they come down the line. How do you do this if you are at the dealer and not the factory or where would the dealer need to send the car and/or engine too?
Is there or is there not info in the Sevice Manual about tuning Hamonic Balancers and/or Flywheels?
If we have to start messing with the Flywheel, did anyone ever find a difinitive answer about what to do with the weights if swapping an old one out for a new one?Also, did anyone find out difinitively if the weights are to balance the clutch/flywheel/pressure plate assembly or if they are to balance internal imperfections found at the factory for that particular engine? I don't know if my flywheel had any weights on it but will try to find out from the dealer tomorrow. Assuming my "new" motor is now out of balance due to differnt weight pistons, and assuming the flywheel was tuned at the factory for that engine (i.e. zero balance flywheel assmebly had weights added to internally balance the engine), I think I should still be able to "retune" my current flywheel by adding or subtracting weight to my "new" motor without having to use a whole new zero balanced assembly and starting from there. I have found other threads where guys have done clutch jobs and then were having vibes at nearly the same rpms as mine, but the same clutch/flywheel/pressure plate is in my car and the dealer tells me they double checked its reinstallation.
http://forums.corvetteforum.com/show...ferrerid=65336
Burning Brakes
Joined: May 2003
Posts: 1,058
Likes: 0
From: Roswell New Mexico
St. Jude Donor '07-'08
From what i understand, the flywheel and balancer are zero weight. Meaning they are balanced independent of anything else. You don't need to have the balancer when balancing the rotating assembly. All pistons weigh a little different. The crank offsets are drilled, or weight is added to balance it out. Pistons can be done the same way. It sounds to me like you need to have it balanced.
