I have searched this site and google and can"t find a yes or no answer to either question. I want to use the flywheel off a 6.9 4 speed parts truck I have to replace the trashed one on my daily driver and thought I would upgrade my stock 11" clutch to a 12" while I am at it. Anyone know for sure? Thanks- Scott
Are 6.9 flywheels zero balanced, and will a 12" clutch bolt up?
- Thread starter 10fords
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Dave Barbieri
Full Access Member
Yes, the 12" clutch is a direct bolt-on upgrade. Luk and Valeo are two good sources. I'm using a 12" for my new engine - it just bolts right up.
mobilemech
Full Access Member
I've used 6.9 flywheels on 7.3's and have had no problems with balance. I do beleive they are zero balance.
icanfixall
Official GMM hand model
wHEN DOING A CLUTCH FLYWHEEL REPLACEMENT ON ANY IDI BE IT AUTO TRANS OR STANDARD TRANS. aLWAYS USE A THREAD SEALANT ON THE BOLTS THAT CONNECT THE CRANK TO THE FLYWHEEL. i USE BLUE LOCTITE BECAUSE i HAVE SEEN THESE BOLTS BACKING OUT AND SHEARING OFF. tHESE BOLT HOLES GO THRU THE CRANK INTO THE OILY SIDE OF THE ENGINE.
someone is screwing with gary again, pushed the caps button.
icanfixall
Official GMM hand model
Yes they did. Anytime the wifey is useing the computer before me and this happens I easly blame her.... But this time it was my fat frigen fingers to blame... See the first letter is lower case and all the others are upper case. I found out thats what happens when you have the terminal set to caps and you ask for a cap thinking you are not set for caps... So this was my fauld.... This time...
mobilemech
Full Access Member
Caps or not, fat fin gers or not, this is good info, it's missed a lot and then when it starts leaking, people go after a rear main seal. good point Gary.
Ok- thanks for the info- I got the 12" clutch today and it appears to be a bolt up. Is there any reason not to use the 12" instead of the 11'" one? I decided to have my original flywheel resurfaced, hopefully tomorrow, instead of useing another one. I was trying to get the truck on the road for work Monday but decided to do it right the first time! I got the clutch at O'reillys and it says Valeo on it, and the throwout bearing is all metal instead of the plastic collar one that was in there originally, so hopefully that is a good thing. It also came with a pilot bushing instead of the bearing that is in there now- is that good or bad? For future reference though I still dont know if the 6.9 flywheel is zero balanced. Anyone?- Thanks- Scott
mobilemech
Full Access Member
no reason not to use the 12" clutch. yes the flywheels are zero balance.
Knuckledragger
blowing chunks and grabbing porcelain
Agreed as stated above. Most all engines have zero balance flywheels and HBs, unless a lot of stroke is used in the engine and there isn't enough mass on the crank to compensate. 454 Chevy gassers have external balancing. I don't know of many others. 6.9 and 7.3 engines both use the same crank and do not need external balancing. Until someone decides to make a stroker diesel. Let's see, special crank, special rods, special pistons...
The SMF I got from SBC for my ZF conversion on the crew cab wasn't zero balance unfortunately. I had it balanced with the roatating assembly (meaning they made it zero balance again). They had to drill three 1/2 inch holes about 3/4 of an inch deep at the base of the cast-in counterweight to get it back to zero balance. Photos below.
Heath
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Heath
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