Andrew M

Anybody with any experience (especially cons for road driving) of lightening the flywheel?

Am I right in thinking that Autosportif offer this?

Chris B

I had some weight taken out of my flywheel when I had the clutch replaced last month. I could not begin to explain the benefits as I am no mechanic. However, as yet, I dont think there are any negative effects with regards to this. I did note an improvment in terms of pick up and the bite felt a lot better.
Autosportif supply a 4Kg flywheel with the standard one weighing in considerably heavier.
Chris
98 Type R

clarence

The pros and cons of a lightened flywheel can be found in the tuning guide section of the Gran Turismo manual, at least in the Japanese version.

dice

I am also considering a lightened flywheel. I can let you know the pros and cons based on my research (discussed with people who have done so).

Pros:
1) Engine response is heaps better. You don't have to wait that annoying 1/2 second it takes for the revs to pick up when launching.
2) Gentler on gearbox and clutch. No severe thudding when changing up gears.
3) Better braking when changing down gears. Less of a requirement for heel-toe braking.

Cons:
1) This may be considered a modification which will invalidate warranty and/or insurance.
2) Engine idle is rougher.
3) Easier to stall engine when clutch dumping.
4) Engine revs will drop quick when changing gear (ok maybe you do need to heel-toe).


Hope this helps.

Russell Haley

Dice's pros & cons pretty much sums it up.

All my experience of this comes from 'A' series engine building where the engine was pretty rough anyway, especially with long overlap cams, so the rough idle wasn't too detectable over the rest of the coughing and spluttering.

With the lightened flywheel the engine has less mass to accelerate and the effect is made more noticable in lower gears where the engine "sees" a reduced car mass due to gearing (really a torque multiplication) and so the lightened flywheel is more dominant proportionally.

Only thing to watch for is if the Subaru's flywheel is cast instead of forged (I don't know the answer) as lightening too much makes it weaker and it could disintegrate. I'd imagine you can get forged steel ones from somewhere.

Russ