New 396...bad vibration...can DM flywheel be turned?
09-05-2006, 10:24 PM
#1
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New 396...bad vibration...can DM flywheel be turned?
I finally got my 396 started on the weekend. But got a bad vibration above 3000 RPM in gear or neutral.
My car is a 92 LT1 with a ZF M6. The shortblock is internally balanced front and rear. So I took my stock DM flywheel to a shop and asked them to remove the weight and make it neutral balanced. However, I still got a nasty vibration.
I called the shop and asked them if they properly zero balanced it and they said they did but I then found out he also machined the flywheel to resurface it.
Would a resurfaced DM flywheel cause a vibration? Or do you think my flywheel is still out of balance?
If I do need a new flywheel I am thinking of going with a single mass...the price of a dual mass is insane. Any suggestions on a flywheel/clutch combo?
With a proper tune my car should make around 400RWHP and RWTQ. I also plan to run a 150 shot of nitrous.
My car is a 92 LT1 with a ZF M6. The shortblock is internally balanced front and rear. So I took my stock DM flywheel to a shop and asked them to remove the weight and make it neutral balanced. However, I still got a nasty vibration.
I called the shop and asked them if they properly zero balanced it and they said they did but I then found out he also machined the flywheel to resurface it.
Would a resurfaced DM flywheel cause a vibration? Or do you think my flywheel is still out of balance?
If I do need a new flywheel I am thinking of going with a single mass...the price of a dual mass is insane. Any suggestions on a flywheel/clutch combo?
With a proper tune my car should make around 400RWHP and RWTQ. I also plan to run a 150 shot of nitrous.
09-05-2006, 10:28 PM
#2
Burning Brakes
A machined flywheel will not cause an imbalance, at least not a bad one. The other possibility is the clutch cover - did you have that balanced also?
Last edited by danno85; 09-05-2006 at 10:33 PM.
09-05-2006, 10:49 PM
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No, just the flywheel. The vibration is so bad I can't imagine it being any thing other than the flywheel.
What I was getting at is, I think they may have damaged the flywheel while machining it and that is what is causing the vibration. I am planning on taking it out and attempting to rebalance it but I am afraid it is now toast.
What I was getting at is, I think they may have damaged the flywheel while machining it and that is what is causing the vibration. I am planning on taking it out and attempting to rebalance it but I am afraid it is now toast.
09-05-2006, 11:23 PM
#4
Burning Brakes
Well, that could be. If it's really that bad then I'd have to wonder if they really neutral balanced it, or if they did, if the crank is really internally balanced. On the clutch cover you can always remove that and run the engine to verify it's not that.
09-05-2006, 11:45 PM
#6
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Originally Posted by danno85
Well, that could be. If it's really that bad then I'd have to wonder if they really neutral balanced it, or if they did, if the crank is really internally balanced. On the clutch cover you can always remove that and run the engine to verify it's not that.
Is the crank internally balanced? was the flywheel neutral balanced?
Were the the two parts balanced together?
09-06-2006, 06:50 AM
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Originally Posted by bogus
that's is where I am.
Is the crank internally balanced? was the flywheel neutral balanced?
Were the the two parts balanced together?
Is the crank internally balanced? was the flywheel neutral balanced?
Were the the two parts balanced together?
The flywheel was brought to an engine builder up here in Toronto. He said he neutral balanced it. But I am starting to think he is full of sh**. I am going to pull it and find out but I was hoping someone could confirm that machining a DM is or is not possible.
09-06-2006, 08:48 AM
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Bring it back to the shop and have him spin it in front of you. That's what I did. I brought my SM Centerforce FW to a shop in the morning. He called me back that afternoon. I made him spin it in front of me to show me he did the work he claimed. If they really did neutral it, they should have no problem spinning it in front of you.
-DM
-DM
09-06-2006, 12:55 PM
#9
Safety Car
Just because Golen INTERNALLY balance your 396, does NOT mean that it uses a NEUTRAL balance flywheel (unless Golen cut the weight off the flywheel or flex plate they used to balance your crankshaft and that is very unlikely). There would be no reason for them to make your engine require a flywheel that you have to modify. I am sure they used a regular one peice rear seal SBC COUNTERWEIGHTED flywheel or flex plate.
Every one peice rear seal SBC flywheel has a counterweight on it. GM used those little slug weights you had the machine shop take out of your DM Flywheel to fine tune the balance of stock LT1s on the assy line at the factory if the tollerance stacked up wrong and they had a vibration...
If your machine shop neutral balanced your old DM they would have had to mill the big counterweight off that is cast into the back of it in addition to removing all the little slug weights. The big counterweight is shown here:
http://forums.corvetteforum.com/show...light=flywheel
But like I said you probally didn't need a NEUTRAL balance flywheel you need one that exacly matches the flywheel used at Golen to balance your crankshaft. If you have a NEUTRAL balance flywheel, your engine would and should vibrate like hell. So I would call Golen and ask them what flywheel they used to balance with (ie stock DM, Fidanza, Pioneer flex plate, ect) then buy one and put it on your car.
Will
Every one peice rear seal SBC flywheel has a counterweight on it. GM used those little slug weights you had the machine shop take out of your DM Flywheel to fine tune the balance of stock LT1s on the assy line at the factory if the tollerance stacked up wrong and they had a vibration...
If your machine shop neutral balanced your old DM they would have had to mill the big counterweight off that is cast into the back of it in addition to removing all the little slug weights. The big counterweight is shown here:
http://forums.corvetteforum.com/show...light=flywheel
But like I said you probally didn't need a NEUTRAL balance flywheel you need one that exacly matches the flywheel used at Golen to balance your crankshaft. If you have a NEUTRAL balance flywheel, your engine would and should vibrate like hell. So I would call Golen and ask them what flywheel they used to balance with (ie stock DM, Fidanza, Pioneer flex plate, ect) then buy one and put it on your car.
Will
09-06-2006, 01:16 PM
#10
Melting Slicks
Originally Posted by aqualung
No, the parts were not balanced together. The shortblock is a Golen 396 with a Callies 3.875" crank.
09-06-2006, 05:44 PM
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Originally Posted by rklessdriver
Just because Golen INTERNALLY balance your 396, does NOT mean that it uses a NEUTRAL balance flywheel (unless Golen cut the weight off the flywheel or flex plate they used to balance your crankshaft and that is very unlikely). There would be no reason for them to make your engine require a flywheel that you have to modify. I am sure they used a regular one peice rear seal SBC COUNTERWEIGHTED flywheel or flex plate.
Every one peice rear seal SBC flywheel has a counterweight on it. GM used those little slug weights you had the machine shop take out of your DM Flywheel to fine tune the balance of stock LT1s on the assy line at the factory if the tollerance stacked up wrong and they had a vibration...
If your machine shop neutral balanced your old DM they would have had to mill the big counterweight off that is cast into the back of it in addition to removing all the little slug weights. The big counterweight is shown here:
http://forums.corvetteforum.com/show...light=flywheel
But like I said you probally didn't need a NEUTRAL balance flywheel you need one that exacly matches the flywheel used at Golen to balance your crankshaft. If you have a NEUTRAL balance flywheel, your engine would and should vibrate like hell. So I would call Golen and ask them what flywheel they used to balance with (ie stock DM, Fidanza, Pioneer flex plate, ect) then buy one and put it on your car.
Will
Every one peice rear seal SBC flywheel has a counterweight on it. GM used those little slug weights you had the machine shop take out of your DM Flywheel to fine tune the balance of stock LT1s on the assy line at the factory if the tollerance stacked up wrong and they had a vibration...
If your machine shop neutral balanced your old DM they would have had to mill the big counterweight off that is cast into the back of it in addition to removing all the little slug weights. The big counterweight is shown here:
http://forums.corvetteforum.com/show...light=flywheel
But like I said you probally didn't need a NEUTRAL balance flywheel you need one that exacly matches the flywheel used at Golen to balance your crankshaft. If you have a NEUTRAL balance flywheel, your engine would and should vibrate like hell. So I would call Golen and ask them what flywheel they used to balance with (ie stock DM, Fidanza, Pioneer flex plate, ect) then buy one and put it on your car.
Will
It turns out your are just about right. I called Chad Golen again and he finally figured out that my crank was actually externally balanced. He said 90% of his engines are internally balanced and require a neurtal balanced flywheel.
However, by mistake Callies sent him 5 externally balanced 3.875 cranks. Mine is one of them.
He therefore told me to send him my flywheel and he will match balalnce it to their balancing flywheel. Hopefully this will solve the problem.
Thanks for all your help.
09-06-2006, 06:06 PM
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Originally Posted by aqualung
Thanks Will,
It turns out your are just about right. I called Chad Golen again and he finally figured out that my crank was actually externally balanced. He said 90% of his engines are internally balanced and require a neurtal balanced flywheel.
However, by mistake Callies sent him 5 externally balanced 3.875 cranks. Mine is one of them.
He therefore told me to send him my flywheel and he will match balalnce it to their balancing flywheel. Hopefully this will solve the problem.
Thanks for all your help.
It turns out your are just about right. I called Chad Golen again and he finally figured out that my crank was actually externally balanced. He said 90% of his engines are internally balanced and require a neurtal balanced flywheel.
However, by mistake Callies sent him 5 externally balanced 3.875 cranks. Mine is one of them.
He therefore told me to send him my flywheel and he will match balalnce it to their balancing flywheel. Hopefully this will solve the problem.
Thanks for all your help.
09-06-2006, 07:00 PM
#13
Team Owner
Originally Posted by aqualung
Thanks Will,
It turns out your are just about right. I called Chad Golen again and he finally figured out that my crank was actually externally balanced. He said 90% of his engines are internally balanced and require a neurtal balanced flywheel.
However, by mistake Callies sent him 5 externally balanced 3.875 cranks. Mine is one of them.
He therefore told me to send him my flywheel and he will match balalnce it to their balancing flywheel. Hopefully this will solve the problem.
Thanks for all your help.
It turns out your are just about right. I called Chad Golen again and he finally figured out that my crank was actually externally balanced. He said 90% of his engines are internally balanced and require a neurtal balanced flywheel.
However, by mistake Callies sent him 5 externally balanced 3.875 cranks. Mine is one of them.
He therefore told me to send him my flywheel and he will match balalnce it to their balancing flywheel. Hopefully this will solve the problem.
Thanks for all your help.
I hope they can match it up...
09-06-2006, 08:39 PM
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Originally Posted by bogus
oh man... that's insane.
I hope they can match it up...
I hope they can match it up...
I do agree this is insane. I did all my research on match balancing etc... and I thought for sure I would not get a vibration. But vibration I got...
10-02-2006, 01:21 PM
#15
Melting Slicks
I had my DM flywheel neutral balanced and I also had a vibration. I swapped it for a single mass unit and now it's very smooth. Your tranny will be louder though. It's not he rattle at idle that bothers me, it is the gears that rattle when you slightly lug the motor.
