924Board.org

Neil924 · Joined: 18 Mar 2003 Posts: 4225 Location: Canada

How long does it take?

How much should it cost?

What safety issues are there to deal with?

Will it shorten the lifespan of the flywheel?

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

I had it done.
It took about an hour, cost me about 15 $ and it needs to be rebalanced after lightening. Since my engine is apart right now, I'm going to balance everything together: crankshaft+pulley+flywheel+pressure plate.

And as for safety? I'm going to install (no, fabricate

) a safety cocoon around the bellhousing (you never know what could happen).
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

AppleBit · Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN

I'll sell ya a lightened flywheel otherwise if you feel uncomfortable with having it lightened safely. Cost me $100 to do it- I'll sell the thing for $75
_________________
Classic British Sports Car Restoration v6 + v8 Engine Conversion Swaps

Porsche 924 Wide Body LS1 Corvette 500 Horsepower Engine

Neil924 · Joined: 18 Mar 2003 Posts: 4225 Location: Canada

Neil924 · Joined: 18 Mar 2003 Posts: 4225 Location: Canada

Does anyone have specs. of how to lighten a fly whell for a 1977 924? Where to "shave" weight, how much and the numbers?

Thanks.

macBdog · Posted: Wed Aug 10, 2005 10:37 am Post subject:

I am also interested in this. Sounds like a good upgrade!
_________________
1979 931 with a 350 chev
1973 911E with EFI

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Here's my lightened 931 flywheel:

_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

Neil it's a great cheap upgrade if you've already got the bell housing off but if you get it done be sure to take it to a high performance engine builder,someone that's done it before.The picture of Raceboy's fly wheel is exactly how you don't want it to be done.All the machinist did to his was to take out a few cuts on a lathe as fast as possible.You'll notice how the cuts he took leave a 90 degree edge ? This is a mechanical term know as a stress riser.A properly done flywheel will have a gentle radius instead of the sharp corners seen above.It should look like someone took an ice cream scoop and scalloped out the sides while spinning on a lathe.I had mine taken down from 17 1/2 lb. to 13 lb.,I really wish it was an easily accesible part or I would show you.My builder charged my $80 Cdn. for the job iirc.
Keep in mind also that if you make it to light and it does explode,ouch.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

The machinist who did mine has done this on a number of cars and many times, no explosions yet. And he didn't take the maximum amount possible, but went the secure way. Plus, the safety-cage will be there anyway.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Neil924 · Joined: 18 Mar 2003 Posts: 4225 Location: Canada

I can'r find anyone in the city that's done them before from a Porsche and no one has said "yes, I can do it". They all say, "yes, I will try but I'm not putting my name behind this!".

I'll keep looking.

My mechanic still has the damn car!

AppleBit · Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

Neil I have a spare that I can have machined then shipped to you if you'd like.I've already Magnafluxed it for cracks,(yes i'm a licensed technician), machining and shipping would be around $110Cdn.Let me know if your interested.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

Neil924 · Joined: 18 Mar 2003 Posts: 4225 Location: Canada

Thanks Apple and Ken, What is the new weight of your flywheels?

I'll keep you both in mind.

Neil

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

My spare is stock right now @17.5 lbs.Like I said I had mine taken down to 13 lbs.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

AppleBit · Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN

I have many stock flywheels and one lightened one that is 15 lbs.

You can lighten them even past 15 lbs- this one was cut off where it counts - the center
_________________
Classic British Sports Car Restoration v6 + v8 Engine Conversion Swaps

Porsche 924 Wide Body LS1 Corvette 500 Horsepower Engine