rtbehm

Who has upgraded their stock 964 flywheel and were the benefits of the upgrade worth the cost? What's the recommended flywheel to purchase and why?

I have a 1992 C2 Cab with 20,000 miles which I've upgraded with catbypass, EU chip, replaced secondary muffler etc. Just adding $$ for a little quicker/performance and might be interested in modifying the flywheel. I just dont really know the benefits other then wt and throttle response.

Cheers,
RT Behm

Steve Weiner-Rennsport Systems

RT,

The RS lightweight flywheel & clutch kit would be the appropriate upgrade for your car and it really improves throttle response. One replaces the OEM Dual-Mass 38 lb one with the RS 14 lb unit and all the associated hardware.

This can create some stalling issues unless the engine is in good health with a fresh tune-up and a clean ISV.

rtbehm

Steve, Thanks for the quick reply. What am I looking at as far as expense for the flywheel and what's a ISV?
Regards,

Makmov

It is virtually the same money to do a LWF vs a DMF by time it is all said and done The flywheel is cheaper but you do need some extra stuff to convert it. About $1000.00 + clutch kit.

And an RS LWF works best with a RS DME. When I research this I found about 2/3rds converted. 1/3 never wanted to and went with a stock DMF, of the remaining 2/3rds about half of those wish they hadn't converted because of driveablity and stalling issues. Of the remaining 1/3rd 1/2 of those were very happy, and the other 1/2 basically said if they had to do it over they would have just gone stock.

I guess it depends on what you are planing to use the car for, becuase it will signifiantly change the way it behaves. It is a little more like driving an early 911, which I wouldn't want to do on a regular day to day basis.

ISV is the idle control valve.

964russ

Rs flywheel is the way forward.

Fitted 1 to mine 3 years ago, well better.

crg53

Same here, have had it in the car for 4 years now, very good upgrade.

ISV= Idle Stabilizer Valve. Check out THIS DIY thread.

Steve Weiner-Rennsport Systems

PM sent.

rollingjack

There are now two possibilities for RS LWF:

964.102.239.31, older from 964 and weights 11 lb
and
964.102.239.81, from GT3 RS, which weights 8 lb.

in Adrians book "Porsche 996 the essential companion" is writted, that new ZMS dual mass flywheel fully assembled weights 24lb against older 964 DMF, which was 33 lb.

I weighted just my RS LWF fully assembled (LWF, clutch plate, starter ring, pressure plate and pressure bearing) and got reading 27lb

Maybe is better way to go to 996 ZMF DMF?

Pictures from Cupcar post for two RS LWF:

rollingjack

Not so bad. I weighted now fully assembled (in same condition, as my RS LWF) DMF and it was 42,6 lb.

My RS LWF is then about 1/3 lighter as DMF. It accelerates quicker but has some grinding noise in lower gears.

Overall good upgrade.

D.C.

When it comes time for me to replace my clutch, I will be using the lightweight flywheel kit.
Hopefully I will not run into the stalling issues that everyone talks about.
Steve, Good tip on checking the ICV.

Dave

boxsey911

Mine tends to stall when it's cold. It happens as I come to a stop and press in the clutch. Recently I've found that I can limit that happening by driving the first 10 minutes with the cabin blowers on full and other load like lights and rear screen de-mister. The extra load helps 'catch' the revs so that they don't drop right out. After 10 minutes or so, everything is fine.

The LWF suits me and I can put up with these minor issues because the car is primarily aimed at the track these days. However, I would say that for a 100% street car, sticking with a DMF is the much better option.

Marc Shaw

I have LWF (track car) and have no stalling issues - yes, it does make the car rev much more freely and is a worthy upgrade.

Marc

philchil

+1...no issues on my recent LWF install...Steve W.'s Advice is spot on...

tommyz

I replaced my clutch shortly after buying my car and went with the LWF. Throughout the winter I had no issues at all and loved it. When summer rolled around and I started using the AC the car would stall often until it warned up. It was very annoying and I regretted the choice. Then I found Steve Wong's chip in some other posts (no affiliation). After that upgrade the stalling is all but gone. I might stall once in every 500 miles, and only when the engine is cold.

One other issue is that it seems I have a harder time backing uphill since the change. Maybe this is in my head? I just don't park facing downhill when I can help it.

Overall, I really like the change, even with the minor issues. If I had not been able to fix the stalling, I am certain I would have gone back to OEM.

Off to clean my ISV now... (Thanks for the tip.)

sml

it looks like you believe the myth of the 'spirited drive' system adaptation crap .........
https://rennlist.com/forums/8153039-post16.html
https://rennlist.com/forums/5372271-post15.html

you should try a bosch hammer adaptation. the real thing is great.

mythbusters even did a segment on the myth of the spirited drive system adaptation for a 964 and they confirmed the myth was busted.