Lightened Flywheel Or Not?

[WrenchesInTheGears]

alright guys im halfway through changin the clutch in my r32 gtst,

its pretty standard just the usual fmic, exhuast, vg30 turbo and pof filter.

i bought a second hand flywheel and had it machined so i woudlnt have to bother getting it done with the one in my car i could just swap,

however i just took the box and old clutch out and the flywheel in there is a lightened one, by that i mean it has a hole bunch of large holes drilled into it around the edge,

whats the benefits of a lighterflywheel, should i keep this flywheel (if i did i would go and get it machined of course coz its very glazed)

or should i just chuck the standard one in?

thanks

-Alex

[blind_elk]

The holes are to balance the flywheel (similar to balancing a wheel/tyre by adding wheel weights, on flywheels they subtract weight by drilling holes). It may not necessarily be lighter - you should weigh them both to check.

The advantage, I believe, is a slightly better acceleration - less mass to be made to spin. The downside can be a poor / unstable idle, due to a lack of rotating mass the help keep the engine spinning.

[NZM.031]

i was told by a gtr guru that the best flywheel is the factory one vs a/m lightened one.

get the stock one balanced and lightened (i think it drops from 12kg to 8 or 9kg) as it has a better surface and provides better grip and handles more heat than a lightened billet one.

a lighter flywheel will make the car rev quicker.. which is a good thing on the rb20... but it will affect idle a little bit... not much though.. and it will affect the cars engine braking ability and low down driveabilty as in under 2000rpm.

if youve ridden a motocross bike and a big trail bike.. you'll see the difference. motocross bikes have little to no flywheels. trail bike is happy to lumber along at low revs, and can almost come to a stop before stalling.. motocross bike will stall at the drop of a hat if you arent on the gas, but will rev like mad.

[Birds]

Not a fan of lightened flywheels in turbocharged vehicles. They reduce the drivability even moreso. Better off sticking with the standard part IMO, this is a better modification for N/A vehicles.

Depends how light it is compared to the factory counterpart, but with a lightened flywheel you have the abovementioned symptoms...plus:

- Need to give it more revs to get off the line due to less stable engine RPM, as per less rotating mass / stored kinetic energy (but that's getting into the science of it all!)

- Clutch will wear out faster

- Requires alot more clutch slip for a forgiving/gentle take off

[WrenchesInTheGears]

can u explain how the clutch would wear out faster?

the lighter flywheel was already in the car, and i have had no troubles with the idle or taking off at the lights, no noticable revving up,

ive been getting mixed answers about whether i should keep it or not, i am leaning towards keeping it as it was already in the car so id hate to put the standard one in and find that the car doesnt go as hard as before.

cheers for the answers guys

[Birds]

Well if it was already in the car then how are you going to know the difference between stock and not? You'd just be used to the lightened one with no comparison.

As I said it depends how much lighter the flywheel is...you say there's holes drilled...well that doesn't remove a great deal of weight from the thing (depending on size/number of holes). Have you weighed it yet?

Lightened flywheels wear out the clutch faster because they requires more slip for the gentle starts...and contact of clutch to flywheel is in general a harsher motion.

If you've been driving with it fine then just get it machined and keep it. No point changing something that works fine. As with anything, when you start removing material from it you compromise structural integrity so it will be slightly weaker than a standard flywheel but probably not enough to concern you. Some of the drastically reduced weight flywheels are pretty dangerous (read: come flying through the floorpan). Combine it with re-using high tensile flywheel bolts and you have a recipe for a nice time bomb.

[BASHO]

A lightened flywheel will let you put on revs quicker , so you can spool up boost more quickly , but lowers torque , so you'll find yourself changing gears more often, it actualy can improve braking as you have less inertial mass spinning around to slow down.

Extreme lightness belongs on the track (if anywhere)and is an unnecessary pita on the street ime, a modest lightening can be a nice thing on the street from say 12 to 9/10 kg but you will lose a bit of torque. Its the old no action without reaction thingo.

It realy just depends what characteristics you are happiest with in your ride.

[cobrAA]

Love the infos,

A bunch of friends told me I should get a flywheel for my GTR R32 and after reading thoses infos, I don't think it's worth it. I hate non-gentle start so I don't think the flywheel would be appropriate for me.

[JiN_MaN]

Didnt experience a ruff idle when I had one lightened. It will rev quicker but also dropped revs quicker

[r33cruiser]

Stick with stock. Don't go a lightened flywheel.

I have to putter around in 4th around town. I can't comfortably cruise in 5th until im up to atleast 70km/h. I used to be able to putter along in 5th at 60km/h.

Haven't really noticed if the revs came up faster or whatever.

I have noticed on takeoff that i have to give it more revs than before or it stalls.

Edited February 16, 2010 by r33cruiser