Rich B.

I just printed out the April '95 4+3 to ZF article, and the threads by tommelton and nogo on the 700R4 to ZF conversion.

I'd like to know what options are available for the flywheel. If the dual mass flywheel is not used, I know TPiS makes a kit with a 4+3 flywheel and a modified fork pivot. Nogo mentioned a modified Camaro LT1 flywheel (.090" removed), but I don't know if this will work on an L98...

What *are* the single-mass options for a 4+3 to ZF conversion? (Using ZF master/slave cyls)...

Ground-down Camaro flywheel + Camaro ZF pressure plate/friction plate?

4+3 flywheel + 4+3 pressure plate & Camaro friction plate? Is this possible?

I'm not quite ready to do it...But I'd like to know what parts to look for, if the opportunity should arise...

bogus

I think the LT1 flywheel will work with the L98... from what I remember, the cranks are basically the same... so is the short block... sorta.

a Camaro LT1 flywheel ground .090 or so is what is needed.

then... a Corvette clutch of your choice.

For example SPEC lists one clutch for both the Vette and the Camaro.




[Modified by bogus, 9:15 PM 4/10/2002]

Rich B.

Thanks Bogus!

I read in the # 263945 thread that you were going with a "DRM flywheel...Already machined down"...

Did this work out for you? What clutch did you go with?

72tccracer

My car has 4+3 and friends has zf, we use same GM flywheel.

bogus

It fit... the car is still on the lift!!! there were no pressure plate bolts to be had!

The bad part... DRM does not provide the steel flywheel. apparently, they bought a ton of blanks from GM and machined them accordingly. They ran out.

bummer.

I got mine used.




[Modified by bogus, 10:24 PM 4/10/2002]

Rich B.

I just got a Jim Pace GM Performance catalog; they only list three SBC manual flywheels for the 1986-up GM cars:

14088646 12-3/4" OD; 10.4" clutch dia; 153 ring gear teeth "Lightweight nodular iron (16) pounds, for internally balanced 1-piece rear seal crankshaft" $222.67

14088650 12-3/4" OD; 10.4" clutch dia; 153 ring gear teeth "Standard weight production flywheel, for internally balanced 1-piece rear seal crankshaft" $200.05

10105832 14" OD; 11"/11.85" clutch dia; 168 ring gear teeth "Production GM flywheel, for internally balanced 1-piece rear seal crankshaft" $169.65

My Y-Body Parts book shows the 8646 flywheel to be the OEM 4+3 flywheel...So which of the others is the Camaro LT1 flywheel???

If it's the 5832, then it would require a different starter, too...As well as the bigger dia clutch...

scorp508

Is the LT1 flywheel required for the ZF6? I am like 95% positive that the 4+3 flywheel was a factory lightweight. I would be surprised if it weighs 18 pounds. It felt pretty light when I took it out last week.

Rich B.

See post above for 4+3 weight! :D (Great minds think alike!) :crazy:

But I'd rather have the "heavier" 8650 flywheel, all else being equal...I want torque, not high revs...

I'm just wondering if the bigger clutch/flywheel (& starter) is required for the ZF...Pace lists the 1989-93 Corvette L98 and LT1 as using an 11" x 1 1/8"-26 spline...The 4+3 is a 10.4"...

Bogus; what say you??? :jester

bogus

dude... you have enough torque... get a lighter wheel...

here is an item I vaguely remember - a honda civic flywheel weighs about 20lbs. by removing 7lbs from the outer edge of the flywheel has the effect of removing 200lbs from the cars weight!!!

rotating mass is a killer.

the engine will rev up faster and that will make the car feel lighter and faster. it will also start easier! less mass for the starter to spin...

oh, my vette is still on the lift... the hydrolics were original, and until about 6 weeks ago, had the original fluid in it!!!! the aformentioned hydrolics gave up against the new SPEC clutch... oh, well... hopefully, it will be back on the road tomorrow.



[Modified by bogus, 11:19 PM 4/11/2002]

Rich B.

Which flywheel/clutch combo are/will you be using? :confused:

I recall someone saying the single-mass costs ~$169 while the dual-mass was ~$630...That would seem to be that big 11" flywheel that Jim Pace lists...

I was thinking that heavier flywheel would be just the ticket for racing up those Pennsylvania hills on the way to Carlisle... :D


[Modified by Rich B., 6:34 AM 4/12/2002]

Nathan Plemons

There has been a great deal of debate about which flywheel to use with the ZF tranny. The problem is that if you don't use the dual mass flywheel the ZF will rattle like crazy. Also a lightweight flywheel does in fact make the car rev faster, but it makes it lose revs quicker. Inertia works both ways. A lightweight flywheel car will essnentially be harder to drive, easier to stall, etc, etc. Sure it revs fast under no load, but your under load benefit will be minimal with a great deal of downsides.

Somebody posted a thread about that earlier this week, let me see if I can find it.

Nathan Plemons

http://forums.corvetteforum.com/zerothread?id=274924

No Go

Both flywheels are 153 tooth flywheels (Camaro and Corvette).

You won't be able to fit a 168 tooth flywheel in the original bellhousings due to much larger diameter. Adding an even heavier flywheel to the OEM setup is crazy. Your synchros will hate you:)

10125379 is the LT1 production flywheel direct from GM for $168.

I have all my experiences on my Homepage under Current Modifications.

I do believe there is some savings with a lighter flywheel, if for no other reason that you cut nearly 20 pounds of vehicle weight.

Making the car more difficult to drive??? I hardly think so. Matter of fact, I could let someone drive my car who has never driven a Corvette and they would have no problem or complaint...except for the noise:) I'm now used to it and it drives very similar to the original setup. I also drive below 2000 rpm 90% of the time on the street.

Seems like this modification is being blown out of proportion. If you don't mind some noise and want to save some money then the Camaro flywheel is for you otherwise find a dual mass. Like all mods-rarely is there not some downsides...finding the mods with the least detractions is the key :D

So far mine is great with 1000 miles, 4 drag runs, many street runs, and over 100 track miles with no mercy.

:)

Nathan Plemons

I'm sure you can't beat it for the price. But I could never live with the noise.

That aside I was really more referring to the ultra lightweight flywheels, like the aluminum ones. I know the Camaro flywheel is fine, I've driven plenty of those before and they are just as easy to get along with as the Vette one. They are still pretty heavy as far as replacement flywheels go.

Rich B.

Thank you all for the input! :D

When I do this, I will use the 10125379 flywheel, ground down .090".

I *like* the sound of straight-cut gears!... :lol:

Nogo; I read and printed out your page on the conversion; I just wasn't sure if the LT1 and L98 were the same.

This is all good stuff! Makes it much easy converting... :yesnod:

Woohoo!!! :crazy:

bogus

I am still waiting for my Vette to come home... there were no hydrolics to be found in my area... monday... :mad :mad

However, I have run it in the garage on the lift. If there was gonna be more noise, it woulda been heard in said garage - and I did'nt hear it. I was listening for it.

The engine did'nt vibrate at all, either. the wheel seems very well balanced.

Rich B.

...Hydraulics???...You mean the master & slave cylinders & line???...(Are there any other hydraulics???)... :confused:

bogus

thats them... I was spelling phonetically... so sorry.

the new SPEC clutch is too much for the old original 95000 mile slave/master.

the pedal feels like stomping on a rotton tomato.

96LT1

I am seriously thinking about this for my '86. Is there anyway you can email me a copy of that article?

Thanks

pablocruise

I'll add a little more info that I found out FWIW:
My 89 came with the ZF-6speed dual mass set-up.
I'm converting to a single mass set-up for 2 main reasons
CO$T and less rotational mass moving around.
Using a F-body STEEL FW (thanx Vette92 Chris H.) in neutral balance
for my internally balanced L98. The F-body steel FW(w/90 thou removed) weighs 20.27 lbs.
I felt that the Aluminum FW was too light. My engine builder said he even saw one time a center separating from the friction surface on an Al FW.
Using the Valeo pressure plate included in the SPEC kit.
SPEC stage III WILL NOT WORK WITH A DUAL MASS FW. Springs rub crank :eek:
Gotsta use an unsprung clutch disc like a stage IIII for example.
Stage III will work with F-body FW.
Clutch fork MUST be clearanced to clear pressure plate.
I hope to drown out any gear chatter with the Hooker 2149's :lol:
Thanx to forum member MIDNIGHT, VETTE92, and PETE in tech dept. at SPEC for helping with this invaluable info!!!!! also Chris at SpeedDemon MS.