Hi, i have a 1986 z51 coupe that has the DN 4+3 trans and im getting ready to swap in a ZF6 speed that i bought that came out of a 1990 corvette. I purchased the trans/bellhousing,all hydraulics,flywheel,clutch,drive shaft ,yoke, clutch pedal ,bascicly everything from the master cylinder back to the drive shaft.?,My car has a crate motor that has a 2 peice rear seal and i was wondering if any of yall could tell me what is the best ''conversion flywheel'' that i should get to make this swap possible,since the duel mass flywheel that i got with the transmission wont work because of my car having a 2 peice rear seal? thanks for your info and any other info that i might need to do this swap sucsessfully.

 

The Dual mass would work just fine. All 1 piece Rear Main seals are the ones that would not interchange with yours. I just did the swap myself, and in an '86~ 2 pc rear main seal. But I went with the single mass flywheel from SPEC. Carolina clutch sold me the kit a while back and since I had it I used it.

It should definately work (unless someone knows better than I), but check the play on the flywheel. The outer and inner pieces should pivot back and forth but certainly not be loose. It should be difficult to pivot, and only about a half an inch at most.

Good Luck.

 

Stock ZF6 DM flywheel only ever came in a 1 pce seal version so flywheel OP has will not fit his 2 pce crank engine
SM his only choice

 

Thanks for replying, that is right, the DM flywheel will only work with a 1 peice rear seal engine.hey cadmaniac, how much did you pay for your kit? And do you have alot of gear noise while the car is idling? What year ZF did you go with?

 

What is acceptable to some is annoying to others
http://forums.corvetteforum.com/1548045072-post4.html
http://forums.corvetteforum.com/1548047692-post10.html

 

is your crate engine internally or externally balanced ? i have a custom flywheel that was mounted on my 406 ci with a zf ,but that engine was internally balanced.

 

I think my engine is internally balanced, not sure, how can I tell?

 

look at the back side of the original flywheel. is it symetrical ? what's wrong with that flywheel ?

 

Theirs nothing wrong with my current flywheel, it's basically brand new. I just installed this crate motor and my cars origional motor was a 1 peice rear seal, so my origional flywheel wouldn't work on my new motor, so I bought a new one. I was told that I couldn't use my 2 peice rear seal flywheel with the ZF 6?

 

that would depend on distance to the back of the block from the clutch surface. by the way,re the earlier comments on dual mass flywheel,besides the difference in crankshaft bolt patterns,i believe the ring gear diameter is different for the starter location. if the flywheel you have is closer to the block,you may be able to have a spacer fabbed.

 

Is their a custom duel mass flywheel that will bolt up to my 2 peice rear seal motor available?

 

no. and i never had any chatter or noise issues with a single mass flywheel.

 

what year zf6 do you have in your car?

 

the car is a 90 vette. trans is the original that came in the car. have now switched to a 4l65e when i swapped to a lq4 engine. the zf wasn't compatible with my coffee drinking habit.

 

so will the flywheel that you have fit a 2 peice rear seal engine,and be used with the zf?

 

that's what it was made for.

 

Stock ZF6 DM flywheel only ever came in a 1 pce seal version so flywheel OP has will not fit his 2 pce crank engine
SM his only choice

Rogj is absolutely correct. I got my "1"s and "2"s (piece rear main seals) mixed up, sorry I could have screwed you all up....I think I'm working too much...My '86 has a 1 piece rear main seal......I'm so embarassed...

 

As other posts have said - the flywheel bolt pattern is significantly different between the Two piece rear main seal cranks and the One piece rear main seal cranks. I believe every single factory application with a ZF tranny also had the One Piece Rear seal, so that is the bolt pattern the Corvette Dual Mass Flywheel will have. If you have a 2 piece rear main seal (which is commonplace in crate engines) - I believe that you can forget about using a DM flywheel.

The dual mass flywheel was one of things Chevrolet did to try to make the Corvettes "more civilized". It's quite heavy (roughly 40 Lb), and it does a superior job in absorbing "chatter" during engagement as compared to the "spring Center" clutch discs. BUT, it's also Very expensive (over $1,000 new - back when they were available from GM), it isn't machinable, and they have been known to fail in ways that left people stranded. You can use a standard flywheel in place of the Dual Mass flywheel as long as the dimensions are right (somewhere there is thread with info about how much you have to machine off a standard Camaro flywheel to make it work as a replacement for the Dual Mass Flywheel - or you can use a aftermarket flywheel designed to replace the DM flywheel) BUT - it will cause the tranny to make a knocking noise in neutral at idle with the clutch engaged (power flowing to the trans). The noise is typically worse as the temp goes up. You'll have to decide for yourself if the knocking noise is tolerable or not, but this may be an easy decision to make as you may not have a choice in the matter.

First - you need to figure out if the motor you installed is internally or externally balanced. Externally balanced motors use a flywheel and/or balancer that is intentionally out of balance - to compensate for the motors being out of balance. Internally balanced motors use both neutral balance flywheels and harmonic balancers. If you know your crate motor part number - check out the GM website, and see what it says. If it doesn't say - check out the part number of the flywheel or flexplate that GM recommends for that motor - that Part Number should lead to a description that says neutral balance or for use on externally balanced motors.

So - bottom line - I think you're going to be looking at a conventional (Non DM) flywheel if your crate motor has the old style 2 piece rear main seal style crank. You need to find out if you need an externally balanced replacement or a neutral balance repalcement.

 

Single mass T56 flywheel from a 93-97 F-Body is 1 pce RMS so he loses that option for his 2 pce RMS engine

 

Thank y'all SO much for all the information. Does anybody on this forumn have a conversion flywheel for sale that I could buy?