Flywheel interchangeability; 964/993/996

[993Speedster]

Ok, so 4lbs of boost is enough to make the stock 964 clutch slip gee... who saw that coming. Anywho, I'm pricing out clutch options and really on the fence on which direction to go (single mass vs dual mass). Leaning towards dual mass so as to have a little bit of inertia stored up for quick take-offs without the need to really rev it (especially with a grabby disc and plate). Car is AWD too, so it won't spin, it'll just bog...


So let's say I go with DMF; It seems "clutch-kit" options are basically anything 964 thru 996(and 997 even I think?) I understand for the replaceable items. My question is, does that relate to the pressure plate and disc only? Or DMF as well? It looks as though the 964 LUK dual mass is $100 more than the 996 LUK DMF and they have different part numbers; but are they interchangeable? I've also heard the 996 DMF is lighter than the 964 DMF but wanting to make sure ring gear and crank trigger pattern is the same.

Option #2; I go single mass GT3 RS flywheel and sprung GT3 disc and sport pressure plate for about the same price as a clutch kit + DMF. I'm not too worried about the gear rattle that supposedly comes as it's loud, turbocharged now, and has stiffer mounts but I'm worried that the car has no harmonic balancer OTHER than the flywheel itself. Is there any longevity draw backs to single mass LWFW or is it all speculation in my head?

[993Speedster]

Another concern of mine is the actual torque handling capabilities of the DMF. I'm very certain the N/A 964 DMF has less torque transmitting ability before failure than a 996 Turbo one? I do intend to launch the car and don't want the DMF to be a failure point. Part of me is saying go full racecar and go single mass now.

Brain is saying "quit being a pussy and learn to work a real clutch"... and now it's saying "I triple dog dare you". I think that pretty much means I'm obligated to at this point right?

[Cobalt]

I am running a 993 engine in one of my 964's with 5 pounds of boost. The clutch I am using is identical to one I found on a 996 cup car. I also have a LWF. I run a LWF in my Stock 964 C2 but needed to chip it to prevent it from stalling as the RPMS will dip down too low upon lift and stall. I don't see why any of the options are an issue although you will need a clutch plate with springs if you go with a single mass flywheel. Something needs to absorb the chatter or you will eventually mess up your tranny.

Not sure where you are located but I have a luk flywheel that was installed on my 90 C4 when I purchased it. The records showed it was installed in the car only 1000 miles before I removed it. If you decide to go that direction and want to save it might be what you need. It also has a sacs pressure plate and clutch disc that were installed and removed at the same time. Although you might consider a stiffer pressure plate and clutch disc compound with more grip.

[993Speedster]

Thanks for the feedback; especially since the vehicle sounds of similar spec. The car does have standalone engine management I should add. I've already been playing with timing-based idle control and also have full control of idle control valve position and fuel mixture. Pretty confident I can overcome the stalling/idle hunt aspect so I'm thinking this might be the route to go.

[Raceboy]

With your VEMS unit you have no problems with idle stalling, it handles single mass flywheel with ease.

[993Speedster]

Originally Posted by Raceboy

With your VEMS unit you have no problems with idle stalling, it handles single mass flywheel with ease.

I ended up going LWF so that's good to hear. I've had the parts in front of me now for almost a week now but once the engine+trans were removed I discovered my car is a total basket case...

I thought the silicone smeared on the outside was trying to fix a leak without cracking the transmission open. Turns out the accident the car was in that caused the body swap cracked/broke the trans case in a few spots...

1.) sheared transmission mount ear
2.) deep crack in planetary gear housing for front output shaft
3.) all repairs/welds porous and smeared with silicone
4.) found ball bearings + a shredded bearing race INSIDE the transmission; had to fish them out with magnets after carefully inspecting all the parts I had removed so far

Turns out nothing I had removed so far was missing bearings or a race so they've been in the trans THE WHOLE TIME!

Went from clutch swap to WTF in a matter of like 5 days.

[Raceboy]

Ugh, that is definitely not a pleasant thing to find out.. Hopefully you get it sorted without further nasty discoveries.

[ian c2]

That sucks .
Hopefully somebody on here can help out .
Matt monson and blackbird immediately spring to mind