24 replies to this topic

[panda]

Hey guys, i was talking to "pro" drag racers and they say that a lighter flywheel would not be that good on drag cars. they say that i doesn't have enough inertia to get you off the line good. Ive always thought that it would make you accelerate better. They said its good for track or autocross so you can exit a turn quicker.

any one seen a difference in time with a light flywheel?

does it really make the launch slower?

this is confusing!!!

[Rampage]

I have heard the same thing, eldo has said to me that he noticed a difference in launching with the lighter flywheel.

I shaved mine down to 12lbs, and I didn't notice a huge difference off the line, but I did notice a considerable improvement in acceleration, and even more so, in engine deceleration/engine braking.

Cheers,
Mark

[Surestick]

Are you going to be competing against him? LOL

[MrDisibility]

don't worry about it. There is a difference felt, and the advantages FAR outweight the disadvantages. I say this from experience. if you are not a dedicated racer with a definate opinion on it (meaning you have actually tried it both ways and found one to be better by .1 sec), you will appriciate a lighter wheel greatly!

[85c-rex]

Is there a method to this madness, or can i just take it to a machine shop and they'll know what to do?

-Alex

[cvcc_wagon]

short history on my car. 83 wagon, used to have a 1.5l and i had to put an accord tranny on it for more reasons than i want to explain but in any case to use the tranny i had to use the heavier accord flywheel and i did notice that it jolted harder on a hard shift from first to second and second to third, i didn't really notice much loss in revving but it's hard to say really because the accord tranny has taller gear ratios. i now have a 1.8l accord motor with the same tranny but a 14.5lb flywheel (originally 18.5lb) and it has more power (obviously) and pretty good off the line pull but 14.5lb isn't that low compared to some out there.

85c-rex: i went to a Lordco machine shop to get mine done, Lordco is an autoparts chain here in BC. any machine shop can do it however an automotive machine shop will be able to balance it properly. mine was not balanced but i haven't noticed anything off about it. one thing to make sure is that they do what you ask, i asked for 12lb when i had mine done, when i brought it to the scale at eldo's shop it was 14.5lb! i decided not to cause a stink about it because of eldo's advice on not going to light so i figure it's a pretty happy median for the street.

[Doodson]

SHAVE IT! You will gain more torque from the engine = faster acceleration . If you really care about the launch in drag racing then just dump the clutch at a higher RPM to get moving

[tencutty]

i now have a 1.8l accord motor with the same tranny but a 14.5lb flywheel (originally 18.5lb) and it has more power (obviously) and pretty good off the line pull but 14.5lb isn't that low compared to some out there.

<{POST_SNAPBACK}>

18.5 lbs??? sheeeesh i wish. I just bought a brand new one from advance auto parts for my 86 si hatch. the mammoth weighs 26 lbs!!!! but brand new at $53 is not too shabby. why spend that much getting it resurfaced when u can buy a new one at that price plus shave the weight off. i tried looking up the 84 hf since i know that one is lighter and they didng have the part number for that, just the 85-87 crx and civic, dx, si , all the same part. since its a daily driver(road rage interriagtor) the lighter flywheel might give it a low idle , near cutting off. so ill just put the mammoth in it and be happy if i was draging it then sure id want the 10 pounder. what is the lightest anyone has had thier car anyways?

[rpr]

The flywheel has nothing to do with a low idle. In fact, it may make it idle slightly higher. And saying that it makes you slower in a drag race is pure crap. Grassroots Motorsports did a comparo between stock and lightened with a Mustang. The ONLY thing they changed was to a lighter flywheel, and in the 1/4 the stock car was consistently slower by at least a car length. I have a Civic/CRX flywheel that is cut down to about 8 pounds, and it rocks. It's for sale too!

[zackspeed]

Paeco Industries

These guys will make you a flywheel and should have them for the 1.5.

I will start off with the fact that its unsafe to cut down a stock flywheel becouse it weakens the metal which can couse it to shatter and if it does its going to send shrapnal thrue the floor into the car. On top of that it changes the distance that the presure plate is from the flywheel and can couse the clutch to wear pre maturly and engagement can be slopy.

As for the idle it could go up or down with a light flywheel becouse it takes so much rotating mass away. This is why you have to youse slightly more rpms to get it going. Inertia is a crazy thing!

Edited by zackspeed, 06 January 2005 - 06:02 PM.

[rpr]

Well, I raced on mine for two years with no problems, and no signs of shrapnel anywhere. I've never even heard of that happening to anyone that wasn't drag racing.

[RexKrazy]

Paeco Industries

These guys will make you a flywheel and should have them for the 1.5.

I will start off with the fact that its unsafe to cut down a stock flywheel becouse it weakens the metal which can couse it to shatter and if it does its going to send shrapnal thrue the floor into the car. On top of that it changes the distance that the presure plate is from the flywheel and can couse the clutch to wear pre maturly and engagement can be slopy.

As for the idle it could go up or down with a light flywheel becouse it takes so much rotating mass away. This is why you have to youse slightly more rpms to get it going. Inertia is a crazy thing!

<{POST_SNAPBACK}>

no, inertia isn't crazy, it's resistance to change. a heavier flywheel has more inertia (more resistance to change). this has NOTHING to do with idle speed. however, more INERTIA will smooth out your idle, and a very light flywheel could cause sparratic idling. cool cams do that too though

edit:
note, torque is a measure of the engines ability to spin all that crap, and removing inertia from the system will effectively give (read: free up) more power.

Edited by RexKrazy, 07 January 2005 - 12:56 AM.

[Doodson]

Paeco Industries

I will start off with the fact that its unsafe to cut down a stock flywheel becouse it weakens the metal which can couse it to shatter and if it does its going to send shrapnal thrue the floor into the car. On top of that it changes the distance that the presure plate is from the flywheel and can couse the clutch to wear pre maturly and engagement can be slopy.

<{POST_SNAPBACK}>

I will start off with the fact that I have never ever seen of or heard of a 1984-87 shaved flywheel to send shrapnal thru the floorboard and I can honestly say I have never seen one come apart.
I know 2 local guys and myself who have raced with no problems on shaved flywheels

and if your shaving the part where it is changing the distance between the pressure plate and the flywheel to cause clutch slippage then you sure aint shaving the rite thing

[Khoal1GenCRX]

dunno why everyone wants to shave the flywheel can't we find an aluminum flywheel to replace stock and still be as sturdy??

[zackspeed]

I have been around racing for 26 years now and I have seen this happen. The reason you have not had one blow up is your not making enough power but I can promise you that if you magnifluxed your flywheel you would find cracks.

Shaving the flywheel will not mess with the clutch but resurfacing it will. I worded that wrong in my other post. Any Honda technision will tell you not to resurface a stock flywheel.

Tom and Doodson,
You may not have had problems with yours but both cars are not driven on a daily bassis which puts a lot more strain on it. As power goes up the more chance there is of it coming apart. If you whant to take that chance then by all means go right ahead.

The metal of the stock flywheel was ment to be that thickness for a reason and this is why light weight units are made of stronger metals. I know quite a few race engineers that have Cart,Trans Am, Imsa GTP,GTO,GTU,and GT Light championships to there credit and they will tell you the same thing. Its just not worth the risk.

I would like to know GT-PILOT's opinion on this.