Help! DMF conversation nothing but issues
Thread Starter
On The Tree
Joined: Sep 2018
Posts: 116
Likes: 1
Help! DMF conversation nothing but issues Nothing but issues. I swapped my dual Mass flywheel to a single Mass flywheel when changing my clutch. I had someone local try and balance match it and after install it shook like a tank. So I took it down to zr51s guy in Phoenix Arizona and had him balance match it and it's still vibrating. Please advise. I'm out of ideas. So frustrated. Vibrations is at about 3500rpms to redline. I'm about 2k into this project and fed up. It's a spec flywheels with a Carolina stage 2 clutch. Car is stock with bolt ons
Thanks
Thanks
Vibrations after C5 clutch installs are common and I’m familiar with them, I know we’re talking a C4 here but maybe this will help.
Did your factory dual mass flywheel happen to have any balance weights on it? I ask because many C5s do and if those weights aren’t transferred to the new flywheel and the flywheel isn’t clocked same as the stock, vibrations can and in many cases do occur even with a perfectly zero balanced setup. Basically the old and new assemblies need to be match balanced, where the new pressure plate and flywheel are effectively out of balance to the same extent and in the same place as the stock setup. Again, not sure if this is applicable to a C4 as I know nothing about C4s but it’s worth mentioning.
Judging by your username I assume you have a 383? If so, was it split balanced like stock or completely neutral balanced? The answer to that may help determine root cause.
Did your factory dual mass flywheel happen to have any balance weights on it? I ask because many C5s do and if those weights aren’t transferred to the new flywheel and the flywheel isn’t clocked same as the stock, vibrations can and in many cases do occur even with a perfectly zero balanced setup. Basically the old and new assemblies need to be match balanced, where the new pressure plate and flywheel are effectively out of balance to the same extent and in the same place as the stock setup. Again, not sure if this is applicable to a C4 as I know nothing about C4s but it’s worth mentioning.
Judging by your username I assume you have a 383? If so, was it split balanced like stock or completely neutral balanced? The answer to that may help determine root cause.
Thread Starter
On The Tree
Joined: Sep 2018
Posts: 116
Likes: 1
Thanks for the quick reply. No I don't have a 383 I did in the past . I did send it out to get balanced match to the old dual-mass flywheel. Originally the guy locally did it static balance which was off and then a dynamatic balance is what they did when I sent it out. I was just told by spec that when I put the weight on it supposed to be within balance of the original so I don't know how true that is. All I know is that this thing is driving me absolutely crazy. And I'm getting conflicting information everywhere
Thanks for the quick reply. No I don't have a 383 I did in the past . I did send it out to get balanced match to the old dual-mass flywheel. Originally the guy locally did it static balance which was off and then a dynamatic balance is what they did when I sent it out. I was just told by spec that when I put the weight on it supposed to be within balance of the original so I don't know how true that is. All I know is that this thing is driving me absolutely crazy. And I'm getting conflicting information everywhere
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
OP
If you are now using a standard LT1 FW but it is a SPEC and you have a stock bottom end motor than your new FW needs to = that of a stock LT1 FW. A regular store brand one would work. It will have the weight cast in and also have various balance dimples drilled into it. You line up the 6th hole of the FW onto the dowel of the crank or the hole that dowel would be in if missing
What you need to do is have the PP "neutral" balanced. All the clutch kits regardless of brand unless its a original NOS Valeo don't have balance holes drilled in one or more of the 3 ears of the PP. Also original replacement clutches had a paint dab on them you lined up to the dowel on crank but every china clone PP no longer has that as they are not balanced.
Generally this is not much of a problem on stock bottom end motors that are neutral balanced front but external balanced rear vs fully internal balanced motors which have been rebuilt absolutely need a "neutral" aka zero balanced FW & PP
I use a machine shop to balance my FW & PP. Usually costs about $40 or $50
If you are now using a standard LT1 FW but it is a SPEC and you have a stock bottom end motor than your new FW needs to = that of a stock LT1 FW. A regular store brand one would work. It will have the weight cast in and also have various balance dimples drilled into it. You line up the 6th hole of the FW onto the dowel of the crank or the hole that dowel would be in if missing
What you need to do is have the PP "neutral" balanced. All the clutch kits regardless of brand unless its a original NOS Valeo don't have balance holes drilled in one or more of the 3 ears of the PP. Also original replacement clutches had a paint dab on them you lined up to the dowel on crank but every china clone PP no longer has that as they are not balanced.
Generally this is not much of a problem on stock bottom end motors that are neutral balanced front but external balanced rear vs fully internal balanced motors which have been rebuilt absolutely need a "neutral" aka zero balanced FW & PP
I use a machine shop to balance my FW & PP. Usually costs about $40 or $50
Thread Starter
On The Tree
Joined: Sep 2018
Posts: 116
Likes: 1
OP
If you are now using a standard LT1 FW but it is a SPEC and you have a stock bottom end motor than your new FW needs to = that of a stock LT1 FW. A regular store brand one would work. It will have the weight cast in and also have various balance dimples drilled into it. You line up the 6th hole of the FW onto the dowel of the crank or the hole that dowel would be in if missing
What you need to do is have the PP "neutral" balanced. All the clutch kits regardless of brand unless its a original NOS Valeo don't have balance holes drilled in one or more of the 3 ears of the PP. Also original replacement clutches had a paint dab on them you lined up to the dowel on crank but every china clone PP no longer has that as they are not balanced.
Generally this is not much of a problem on stock bottom end motors that are neutral balanced front but external balanced rear vs fully internal balanced motors which have been rebuilt absolutely need a "neutral" aka zero balanced FW & PP
I use a machine shop to balance my FW & PP. Usually costs about $40 or $50
If you are now using a standard LT1 FW but it is a SPEC and you have a stock bottom end motor than your new FW needs to = that of a stock LT1 FW. A regular store brand one would work. It will have the weight cast in and also have various balance dimples drilled into it. You line up the 6th hole of the FW onto the dowel of the crank or the hole that dowel would be in if missing
What you need to do is have the PP "neutral" balanced. All the clutch kits regardless of brand unless its a original NOS Valeo don't have balance holes drilled in one or more of the 3 ears of the PP. Also original replacement clutches had a paint dab on them you lined up to the dowel on crank but every china clone PP no longer has that as they are not balanced.
Generally this is not much of a problem on stock bottom end motors that are neutral balanced front but external balanced rear vs fully internal balanced motors which have been rebuilt absolutely need a "neutral" aka zero balanced FW & PP
I use a machine shop to balance my FW & PP. Usually costs about $40 or $50
Trending Topics
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
So if that is the case your FW is not balanced correctly. You would need to have that checked but the only way for a shop to know is to have a original one to compare. A cheap $100 stock replacement would work. What I have used a few times and it was plug & play
Driving the car the way it is will kill the RMS...it may even show signs of leaking now.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
