[jefspg]

After 70,000 miles, my 9" 9000 style clutch is starting to slip.

Before taking the cheap road of just replacing the clutch, I am looking at upgrading to either a lightened flywheel or an aluminum flywheel.

Is this a pretty good bang for the buck?

$500 for an aluminum flywheel is a good amount of money, but it might be worth it if I can get 5 horsepower in the low RPM range. That's where my car is a dog.

Once the car gets around 2500 rpm, the turbo takes care of the rest.

 

[Matthew]

I drove JohnW's tuned 900T8 whcih has an aluminium flywheel. The car was immensely drivable and very rev-happy. The reduced inertia of the lighter flywheel was immediately noticable.

The correct way to upgrade a clutch is by increasing clamping force by way of an uprated pressure plate. Aggressive friction discs on a stock pressure plate aren't the answer, instead shredding flywheels and reducing drivability. It's also a good idea to keep the clutch/flywheel's mass at the crank's centre.

Most of the above information was discovered after talking to a well known clutch manufacturer (Sachs? Helix? Can't remember! ;oops: ) at the Autosport Show in January.

Small and lightweight aluminium flywheel, very strong pressure plate and essentially OE friction disc is the way to go IMHO

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[Alex]

Most of the above information was discovered after talking to a well known clutch manufacturer (Sachs? Helix? Can't remember! ;oops: ) at the Autosport Show in January.

Actually the info came from Sachs, Helix and AP.

 

[john-w]

Go on Jeff you know you want one...

 

[jefspg]

Go on Jeff you know you want one...

The car is being a money hog this year. My budget for the car has been spent this year. But I don't think the clutch will make it until fall. :roll:

I think this will have to be a secret mod that the wife doesn't know about!

 

[Tomarse]

Go on Jeff you know you want one...

You keep doing this! :nono;

Where can i get one, how much would it cost and would it fit my B engine....

:cheesy:

What sort of pressure plate did you use with it?

 

[nutcase]

You keep doing this! :nono;

Where can i get one, how much would it cost and would it fit my B engine....

:cheesy:

What sort of pressure plate did you use with it?

...and will they do a (small) group discount? :lol:

 

[john-w]

You keep doing this! :nono;

Where can i get one, how much would it cost and would it fit my B engine....

:cheesy:

What sort of pressure plate did you use with it?

I got it shipped from the States, you need to use the 9000 clutch or very late 900 clutch.

If you want a group buy talk to Alex because he's after one & I gave him all the details a little while back.

 

[nutcase]

The thing should fit as the later B engine and all the H engine'd 99's have the same flywheel.

 

[Tomarse]

Alex - You have a PM!

Having lifted my flywheel about tonight, the standard things are mighty heavy, so a lighter one must be an improvement! and any improvement in low down revs has got to be good.

Will a 9000 clutch fit in a 99 alright? There are no real differences between the 99 and the 900 in terms of clutchs and flywheels are there anyway?

 

[Alex]

All who have PM'd me. I will get back to you once I'm home this evening. Off to the pub now :cheesy: :cheesy:

 

[Tomarse]

All who have PM'd me. I will get back to you once I'm home this evening. Off to the pub now :cheesy: :cheesy:

The pub at midday :nono;

Are these PM's actually going to make sense? :lol:

 

[Si_J]

All who have PM'd me. I will get back to you once I'm home this evening. Off to the pub now :cheesy: :cheesy:

Include me please Alex, I'd be interested in a price.

 

[DeLorean]

hey, if we are doing a group buy- get me in on it, I'm interested :cheesy:

 

[Alex]

There seems to be enough interest in this so I will contact Fidanza on Monday and see what the situation is.

The guy that John-W dealt with is no longer a reseller (shame as he was the only one who replied to the first set of emails I sent out to some of the suppliers in the States).

 

[Tomarse]

Thanks!

I also sent a load of emails out to US stockists of the fidanza flywheels yesterday asking about UK shipping. Most of them said they'd do it but to contact them to confirm. I'l let you know if anybody replies.

Edit - 04/06

This place will ship to the UK (costs $50-$75 dollars apparently), however - they dont appear to sell fidanza ones (not that that means much to me personally!) and they arn't the cheapest place either.

They do get a lot of respect from me for actually answering my email though!

 

[alexis]

They certainly look cool. I'd be interested to know what the group price is and if they aren't to dear I'd be interested also.

Although I'm wondering why they make such an improvement. The site Tomarse mentions say there are tremendous gains to be made, as evidenced by John W's car, with no downside. This just doesn't sound quite right to me. I know exactly why they work better but if there was no downside then why on earth would Saab not have fitted lighter wheels as stock. Saab made so much effort to make a very good engine I'm sure they didn't just forget about the flywheel. A 22plus lb flywheel is about 1% of the total cars mass, so there must be a reason for it.

 

[Matthew]

The reason is that the inertia of the heavy flywheel smooths out the engine's inherent roughness (all four-pot engines would be the same) and improves drivability.

It really does come down to inertia and reducing rotating mass. As enthusiasts interested in performance tuning, our requirements are different which is why we like lightweight flywheels.

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[Tomarse]

I know exactly why they work better but if there was no downside then why on earth would Saab not have fitted lighter wheels as stock. Saab made so much effort to make a very good engine I'm sure they didn't just forget about the flywheel. A 22plus lb flywheel is about 1% of the total cars mass, so there must be a reason for it.

I'm assuming that it is the same as any other 'performance' modification. saab presumably built their engine whilst striking a balance between cost and performance, and bearing things like the fuel consumption in mind.

I'm assuming that ally flywheels cost more to make than normal ones. Which to me is probably one of the main reasons why they dont get fitted to stock engines.
Also, im assuming that if youre actually sitting there designing an engine then there are easier ways to gain power than fitting a different flywheel. We're approaching it from the other direction where we already have the engine and were looking to swap parts to gain some power - we cant (significantly) redesign things!

And when you say about the mass of the flywheel being only 1% of the whole car - when you only consider the moving bits inside the engine, its a much larger percentage of those!

Having just stripped my engine down, i can see why the flywheel can help!. The original one is a very heavy lump of metal - and when you consider that your cylinders are working to turn this weight to actually move the car it seems quite substantial.


One of my mates has a car with an ally flywheel (not a saab). He says that though you do gain revs more quickly, you also loose them faster - so if youre not prepared to be somewhat heavy footed at times a lighter flywheel can decrease the drivability of the car. Since most of us are probably happy with this its not a problem!, but your average driver may not agree.

 

[alexis]

The reason is that the inertia of the heavy flywheel smooths out the engine's inherent roughness (all four-pot engines would be the same) and improves drivability.

I'm assuming that it is the same as any other 'performance' modification. saab presumably built their engine whilst striking a balance between cost and performance, and bearing things like the fuel consumption in mind.

So that website is lying when it says there are no drawbacks from the mod and that Saab fitted an unnecessarily heavy flywheel?

...if youre actually sitting there designing an engine then there are easier ways to gain power than fitting a different flywheel.

On the contrary. It sounds an incredibly easy way to gain power. Far easier than playing around with turbo compressor maps. They wouldn't need an aluminium one, they could just lighten the original steel one.

Don't get me wrong, I'm not trying to knock the idea of them. Indeed I'm all for cool mods which enhance the car. I can understand why car makers don't fit expensive and complex fuel injection systems, kevlar brakes etc., but in the case of a flywheel it is so simple (and cheaper) to put one of optimum size on that I'm thinking there has to be a good reason. When I made my 1% comment I was not saying its only 1%, rather that 1% is an awful lot for no benefit.

It seems to me, as you guys pointed out, the engine will not be as smooth and the decresed 'spin down' time necessitates quicker gear changes to put less wear on the clutch. Also I'm wondering if the heavy flywheel is to limit the forces put on other components. The stress on the timing gear will be far greater in an engine which spins up and down faster for example. Think diesel engine cambelts at the smoke test.

In a race engine yeah, its great and if thats what you guys want your cars for then fine. But I want a car that is good as an all rounder and doesn't need rebuilding every 20,000 miles. I guess I just need a little more convincing before I go out and spend so much money on one.