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Discussion Starter · #1 ·
So, I have a flywheel that needs to be resurfaced. My normal instructions to the machine shop would be to take off as much material as possible to lighten things up. This can be quite effective on some cars.

However, my Saab flywheel actually isn't all that heavy compared with some other's I've worked on. I was wondering if there is even enought meat on it to bother mentioning the lightening. Does anyone have any experience with having the flywheel lightened? Was it effective?

Just curious. Thanks!
Jamie.
 

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Good and possibly bad.

I had the flywheel lightened on my Alfa.

It made the car rev much faster.

Although the car wasn't torquey, mid range acceleration and response were fantastic.

Problems - maybe related maybe not.

The Alfa's engine went bang about a year later, the tuner told me that a cam timing wheel disintegrated and damaged the crankshaft and cracked the engine block.

After paying out for a new engine and other mods, I sold the car on.

A while later I read somewhere on the net that lightened flywheels can disintegrate and damage the engine and probably should not be done on a street car - coincidence?

Was it really the flywheel that caused damage to the engine and not the cam timing wheel? I don't know.
 

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Funny you should mention this as I have noticed from time to time that the engine braking isnt retarding the car as much as I would have thought/liked. And I have just put it down to the boost remaining in the system until its all dumped. (As you can tell, I need to do some reading up on turbo systems), or a quirk of the EEC programming. Anyway, this little matter of interest (As I dont think its a problem, just a quirk) may be down to the Saabs having a particularly light flywheel.

I am sure somebody will enlighten us - Anybody!
 

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Discussion Starter · #4 ·
Flywheel myths?

Well I don't know much about Saab flywheels, but I do know a bit about flywheels in general. I replaced my ~21lb flywheel in my Miata with a 7lb aluminum racing unit a couple years ago. The main differences is in the quickness of engine speed transitions. Like in redline shifts it's easier and more forgiving when you don't match RPMs to gearbox speed. It's also easier on internal bearings and such, as it doesn't resist the change in speed as much as a heavier unit with more inertia will. The negative effects are that you have to be more careful when taking off from a stand still. It's a lot easier to stall the car out. But once you get used to it, it becomes second nature. Anyway, I'm sure the flywheel had nothing to do with the Alfa's demise ;) - I think the rumor you heard was false.

In regards to engine braking, as I understand it, engine braking is the result of the restriction of the intake system. In a turbo charged engine it would make sense that engine breaking would be less or even nill if there was still some pressure in the intake system after lifting off throttle.

Well, I'll probably not worry about trying to lighten the flywheel - don't thing there is much gain to be had there. Thanks! Jamie.
 
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