hi guys i looking for some advice i have a l28 to put in to my 240k should i lighten the flywheel its freshly rebuilt bottom end im going with a mild cam extractors n42 ported head twin su,s .i have been told to lighten flywheel.thanks

Is it a flywheel out of a 2+2 or turbo mobel? Then your using the 240mm clutch. Thats a good strong 780lb (10kn/m) clucth. The coupes used the 225mm 550lb (7.5kn/m) clutch. Both are 10kg standard. Aftermarket aluminium flywheels are around 4kg and not suitable for street use.

If you lighten your own flywheel, don't go under 7.5kg. That way you can still drive in traffic without stalling the engine. It will rev easier (about 25% faster) and idle a little rougher.

My flywheel has 3 sets of 6 holes machined in the outer section. I cant remember the size, but i think they were 15mm in diameter. The flywheel was 7.75kg with ringgear.

The engine reacts much faster and its still drivable. I am glad I did it.

Hope it helps you.

Chas

Instruction I pulled from the net ~ 8 years ago

Hi Blue,

Interesting to know how heavy the flywheel is? I take it the photos are first removing the back section and then complete with holes.

My flywheel has 18 holes against the 21 holes in the photo and ended up about 7.8kg. It started at just a fraction over 10kg.

Cheers cahs

Hey Blue, Thanks for the diagram. I need to do this to my race car's flywheel over winter. Do you have any idea what the weight is of the one in the sketch? I assume that the pics in post #4 do not go with the sketch in post #3, so it would be nice to know how much is removed.

thanks guys. euro dat the to anwser your question my motor is a f54 block with a n42 head out of a nissan patrol so im un sure about the fly wheel il check how many holes and weight but i would think it would be around 10 kgs

A little info on Blues photo's. Its an interesting drawing. Have not seen a Z flywheel lightened like that. They have taken metal off almost every unused surface.

The flywheel with the holes is a Kameari chromoly steel flywheel (based on cs1.0619 steel alloy). Its around 4.3kg and very thin due to the high grade metal used to make it. Even so thin as they are they dont easly get heat spots. Again the metal used distributes the heat better. If your driving on the street its no option.

You can't get a standard flywheel down to this weight because the metal is just not strong enough and the flywheel would fly apart. Flex could also be a problem when engaging the clutch and cause fatigue.

The left photo is a machine shop job, but its not quite as light as the drawing. The drawing looks like it would be another 25 to 35% less weight again.

Chas

i would think it would be around 10 kgs

Nathan,

Both flywheels are standard 10kg. The only differance is the size of the pressure plate and diameter of the clutch disc.

I was just wondering thats all.

Chas

From Smokey Mtn Z Club's Tech Tips:

Flywheel

I was wanting a lighter flywheel for my Z, but I was surprised at

the very high cost ($350+) for the Centerforce 13 lb one. Is there

a flywheel weight in between the stock 24 lb and this 13 lb one

that I can use?

Yes there is! The flywheel from the 7/78 to 6/84 production date

Datsun 810's and Maxima's had a lighter 17.6 lb flywheel, part

number 12310-Y7000. So, these are the one's to locate if you're in

search of the lighter flywheel. The 810/Maxima flywheel can be

identified by the "Y70" cast into the backside of the flywheel.

Most junkyards remove the flywheel from engines and will sell them

separately. Just make sure the clutch disc surface is not worn

excessively. Small groves can be machined out. Check for wear on

the starter gear ring. The ring gear can be replaced, but since

this will cost much more than a good used flywheel, avoid getting

a flywheel that needs the ring gear replaced.

The Maxima/810 flywheel takes the 225mm clutch which was the same

size as the 2-seater Z car clutch.

1999 on zcar.com:

cost me 500yen in japan, and I took my 225mm flywheel down to 7kg. I noticed that the japanese take almost all of the inertia ring off the outside and clean up the entire back of the flywheel. I also bought a car that had the flywheel lightened in the US and it had holes drilled around it and rebalanced. It did not rev like the Japanese unit. I also got the machine shop to drop another 750 grams (about 1.5 lbs) by cutting the outer edge of the flywheel on the backside of the ring gear and cutting it to half it's normal width (cut on the non-engagement side) and on the outermost portion there near the face where the pressure plate mounts. This resulted in a wheel that was about 14 pounds, and accellerated quicker than the american-lightened unit with the holes and balancing. I tried them both in my turbo car...

$50 beats $300 for an 11# aluminum unit. Now that Tilton 9" low inertia unit...