C-Note

I have done the search and found that opinions vary quite a bit on this subject.

I have a 92 LT1 with a black tag ZF6, I am wondering if anyone here if familiar with what we call NGR (neutral gear rattle) in the Dodge Viper community? It is very common with the Gen 2 Vipers.
I was wondering if the gear rattle picked up by using a aluminum flywheel in a C4 is similar to what I am used to already in my Viper?

Also I have heard varying reports on match balancing the new flywheel to the old DM flywheel, can anyone give me a straight answer for my particular car?

One more thing, Fidanza claimes I can use a OE clutch, I have been reading conflicting reports about this on the board, some say it is fine others say I need a spring hub clutch?????

Thanks in advance for any advise.

Mojave

Yes, a C4 will rattle in neutral with a single mass, especially an aluminum. LT1's are externally balanced at the rear, so get your new one match balanced to your old DM.

I used a Fidanza aluminum with a stock, unsprung clutch with no problems. I would imagine the unsprung is a little more grabby than a sprung disc. Either will work.

C-Note

Thanks Mojave!!

That was the straight type of answer I was looking for.

856SPEED

the black tag will rattle (and so will a blue tag); I know because I have both and ran both with pretty much the same results with the Fidanza, single mass alum. FW. Neutral rattle will be "noticeable", some call it intolerable, however with the clutch engaged it goes away. Mine is even more pronounced with the cam upgrade and high compression motor at low idle. Yes, I would have it balanced to the DM FW

I did not do well with my OEM style Valeo clutch (my original set up); it did not last long (3 yrs.) but I am making a lot of hp and tend to go to the track a couple of times a year. I am now running a RAM clutch set up, so I'll see how this holds up.

rklessdriver

The gear rattle in my 92 will almost drown out a Powerstroke if we are side by side at a light.

Fidanza, Spec Stage 3 (lightweight option), BMW Castrol TWS 10W60.
Will

anesthes

Have you considered a push-style clutch swap? You could then run a sprung hub clutch disc.

-- Joe

C-Note

Thanks for the help guys!!

Mojave

Why do you have to swap to a push style pressure plate to get a sprung disc? You can use an f-body sprung disc with no problems.

anesthes

No kidding? Why didn't they run the sprung hub on the vette and use a single mass flywheel then??

-- Joe

byebyeL98

Probably because even with a sprung hub clutch disc, there would still be a bit of "rattle" at idle with a single mass. The DM was likely the only way to quiet it down completely.

anesthes

I see what he means. I thought he was implying you can run a fbody disc with the DM flywheel. If you run the fbody flywheel + fbody disc, then you need to machine the flywheel (according to the faq).

Centralcoaster is running a 4+3 flywheel, with an unsprung disc and he doesn't seem to have an issue with the rattle but then again it might be a blue tag vs black tag issue.

I have a black tag, and I'm (going to be) running the 4+3 flywheel/clutch setup with a howe hydraulic TOB. I have some concerns about a pull-style pressure plates holding abilities, even if they are false concerns plus the singlemass stuff is way cheaper, and its all new on my shelf from another project I just completed.

-- Joe

Red Tornado

IMO, the ultra-light fidanza is NOT for a daily driver.

it doesn't store energy well (too light), raises major hell at a stop (think hard and ask yourself if you want to be pushing the clutch pedal to the floor every single time you ever come to a stop for the life you have it installed).

i did it, and reversed it. not anywhere near worth the anoyances it unleashed.

rklessdriver

Joe
My Spec Stage 3 has a sprung center hub disk.

Actually the noise worked out pretty good for me when I was trying to talk a loud mouth guy with an LS1 F body into a money race one night at Coastal Plains Dragway. His car was stock with the bottle and my car had only the Spec clutch, Fidanza FW and the bottle.

Once his buddies heard that rattling noise at idle they were like "man listen to that thing the tranny is going to break any second, besides its just a sorry LT1 - you got this man, easy money"

Didn't work out the way they though, considering he had a NOS dry kit set on 75hp to my old Top Gun 150hp fogger kit. Once we dropped the hammer I had over 1/2 a car at the 60ft mark and about 8 cars by the 1/4 mile. Suckers.
Will

Mojave

Using a sprung or unsprung disc doesn't affect the thickness of the flywheel. F-bodies use T-56's, which don't have the neutral gear rattle. So, they use a single mass flywheel and a sprung disc. The thicker flywheel is needed with the T-56.

The ZF6 uses a thicker flywheel no matter what disc you use. The Dual mass was to avoid the gear rattle.

Whatever flywheel you use, it must be ZF6 thickness. But, you can use either a sprung disc or an unsprung disc with any flywheel of the proper thickness.

byebyeL98

Not entirely true. You can use a thinner flywheel with the ZF6 (such as a steel flywheel from a 4+3 car), but then you need a longer pivot ball stud for the fork to keep the geometry the same. With the thinner 4+3 flywheel, you can not use a sprung hub disc, as the springs will interfere with the flywheel bolts.

derekguzz

Unless your racing or have a really loud exhaust I would stay clear. I have one and it is HELL. I am ripping it out and wondering of anyone would want mine. I have about 7,000 miles on it. It's too lud and shakes, I dont think my guy balanced it right.

Mojave

Ak, ok, thanks for the info. I hadn't read anything on the 4+3 stuff.

byebyeL98

anesthes

CentralCoaster said thats not true, that you can re-use the stock pivot stud. I hate to speak for him, but doing a quick search you'll find his exact quotes. He's using a 4+3 flywheel, with a unsprung ZF disc and PP.

I gotta measure my BH to PP fingers tomorrow on my 4+3 housing, than bolt up the ZF bell housing and see how much of a difference there is.
I had forgotten the 4+3 BH is about .100" farther away (closer to block) than the ZF, so assuming the BH is deeper i'll need to add .100 to the back side of the hydraulic TOB..

Good info guys, thanks!

-- Joe

anesthes

So the pocket on the bolting flange is deep enough to clear a sprung Fbody disc?

The FAQ says a T56 flywheel can be used, but needs to be milled .090" so I assumed the T56 flywheel was even deeper than the ZF flywheel, and therefore why it had a sprung hub.

re-reading the faq, now I'm confused. the faq needs to be updated or deleted, because its vague and or missing information, or just plain wrong.

-- Joe