Pros and cons of lightened flywheel ? Options

[sixaddict]

Have a 3 liter with 46s in 914…..Trying to decide if I want to install a lightened flywheel I have on the shelf. Basically a track car.
Looking for input from anyone who has made that change.
Thanks ,

[Charles Freeborn]

My previous 914 / 4 had a lightened flywheel. I didn't notice spectacular difference in its ability to "spool up quickly" but I'm not an experienced enough driver to notice those levels of nuance. That car was built for a specific class of PCA racing that put it up against very similarly built 914's so every nano second of performance was worth chasing. If you're going to production class or vintage race it, those benefits are harder to justify.
Personally I think that trying to get a 50 plus (in some cases) year old car to behave like a modern "twitchy" car is a fools errand. With the antiquated synchro gearbox there's only so much you can do with modernization. In my book these are vintage cars and should be treated as such, but that's just my .02ç.
I would say look up what Porsche used back in the day for a similar drivetrain and copy that. Trying to out think the Porsche engineers is another fools errand... IHMO, that is.

[stownsen914]

For a track only car, there's not much downside really. Any downsides would be things like
Needing a little finer touch on the clutch to get the car rolling without stalling.
RPM may tend to "hunt" when cruising at lower speeds, like in the pits/paddock.

For a street car, could be a little annoying, but neither is much of an issue for a track car IMO. I've had a light flywheel and clutch in two different 911 powered racecars and have been happy.

[technicalninja]

Dedicated track car I want the very least MOI in the clutch assembly.

Dual disc 5-6" tiny clutch on what looks like a TINY flywheel welded to a flex plate.

Weighs 1/4 what that stock stuff does...

Solid disc, no marcel, no springs in center, bitchy to launch, ceramic or sintered metal pucks, NOT street friendly at ALL!
This set up often rattles like a bitch at idle! Noisy, hard to launch, almost have to spin tires at launch. Bitchy to put on trailer...
The clutch pedal is more like an on/off switch and the initial bite is grabby as hell.

Street cars are the exact opposite in my book.
Heavy flywheel (not stupid heavy), disc with organic faces, marcel, sprung center (if stock has 4 I'd want more).

Smooth, grandma can operate it easily. The heavy set up makes things like AC affect the idle less and, in some cases, the extra weight acts as a damper and helps to isolate the transmission from individual firing pulses.
This can increase transmission input shaft bearing life.

A dual-purpose street-track car would be somewhere in the middle.
Light weight stock size, HD clutch with organic on one side and ceramic on the other
Either marcel or sprung center (big ass springs!).

Now, the above is generic advice...

I don't know what is available for 911 stuff. I would think "skys the limit" and someone has made the dual disc set up already.

If I was building a track focused car and I had either a heavy or a light available, I'd start with the light weight stuff first.

[brant]

our old set up had a window'ed flywheel

the one I've ran for about the last 10 years
(wore out the first one and have already replaced all of the wear components)
is the tilton 5.5 inch, twin disc unit as described above.

[technicalninja]

(IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif)

See, that stuff is available for 911s!

Was it as I described in use?

Those are usually stupid STRONG and last a long time.

Often, they have a very MILD clutch pedal not significantly heavier than stock.

Just difficult to modulate at low speed and at launch.

[sixaddict]

Thanks

[brant]

(IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/agree.gif)

See, that stuff is available for 911s!

Was it as I described in use?

Those are usually stupid STRONG and last a long time.

Often, they have a very MILD clutch pedal not significantly heavier than stock.

Just difficult to modulate at low speed and at launch.

very much like you described...
literally an on/off switch
especially difficult in the pits and low speeds
perfectly fine on the track once rolling

absolutely no way you could drive on/off of a trailer.
I got tired of pushing into the trailer and had to buy a winch due to the clutch

wear and life.
they are pretty sensitive to over heating
the design creates NO slip...
the metal plates warp easily if the driver tries to slip the clutch (to get rolling etc.)

brant

[campbellcj]

I have one in my car now (Sachs lightened flywheel, sport PP & disc) and do not have any issues with drivability at all. Previously around 10 years ago tried a full-race puck disk that was really grabby and chattery, much less pleasant to deal with and seemed unnecessary for my application.

[campbellcj]

Here are the P/N's -

FLW.901.102.026 or 901.102.026.01 Lightweight flywheel (906/911R type)
88.3082.999.741 Sport pressure plate
88.1861.999.783 Sport clutch disc

[sixaddict]

Chris et Al……
Appreciate input.
Posting pics since it looks so much different than what has been posted.
Any idea what this is worth ……based on street useage probably going to sell.
Thanks again

[sixaddict]

According to PO came from John Truman Motorsports

[Charles Freeborn]

Chris et Al……
Appreciate input.
Posting pics since it looks so much different than what has been posted.
Any idea what this is worth ……based on street useage probably going to sell.
Thanks again

Interesting. I have no idea on value, especially not knowing if it also requires matching / dedicated pressure plate, disc, TO brg and starter ring gear... but interesting nonetheless...

[technicalninja]

I've seen a crap ton of multipiece flywheels...

Never seen a RIVETED wear surface.
That's one of the reasons for multipiece, you can replace the wear surface.

Also never seen one without a ring gear on it.

Value ?????

Accurate application from the maker would be only way to know IMO.

[sixaddict]

Thanks

[stownsen914]

Is it an aluminum flywheel? Fidanza makes ones that look like that.

1970 and later 911 flywheels have the separate ring gear, so this looks like one of those.

[sixaddict]

Thanks

[wndsrfr]

Chris et Al……
Appreciate input.
Posting pics since it looks so much different than what has been posted.
Any idea what this is worth ……based on street useage probably going to sell.
Thanks again

Interesting. I have no idea on value, especially not knowing if it also requires matching / dedicated pressure plate, disc, TO brg and starter ring gear... but interesting nonetheless...

Looks like the AASCO unit that I've been running on the 2.7/6 and it's just fine for street or track--has separate ring gear, I use the "sport" Sachs pressure plate. Flywheel retails around $600....

[sixaddict]

Thanks John.
Hope Kermit doing well.
Terry

Chris et Al……
Appreciate input.
Posting pics since it looks so much different than what has been posted.
Any idea what this is worth ……based on street useage probably going to sell.
Thanks again

Interesting. I have no idea on value, especially not knowing if it also requires matching / dedicated pressure plate, disc, TO brg and starter ring gear... but interesting nonetheless...

Looks like the AASCO unit that I've been running on the 2.7/6 and it's just fine for street or track--has separate ring gear, I use the "sport" Sachs pressure plate. Flywheel retails around $600....