How light of a flywheel?

[ebeldesign]

I am going to need to replace the clutch in my AP2 in the next few months (starting to feel some slipping at high rpms) and want to get a lighter flywheel. The issue for me is that I do 90% stop and go driving on my commute and dont want to demolish the drivability. How light is realistic for me to still use day to day, but still enjoy the benefits of a lighter than stock flywheel?

Once again, thanks for all the help and advice. Xviper, I really enjoyed reading your thread about your background, I've wondered about it.

[shamowfski]

I have the ACT flywheel and it's one of the lighter ones I think (around 8 lbs, got it from Xlevel), and I have no issues with it really. It's more likely to continue "bouncing" if it starts, but that's my only real issue with it.

[repiv]

I am going to need to replace the clutch in my AP2 in the next few months (starting to feel some slipping at high rpms) and want to get a lighter flywheel. The issue for me is that I do 90% stop and go driving on my commute and dont want to demolish the drivability. How light is realistic for me to still use day to day, but still enjoy the benefits of a lighter than stock flywheel?

Once again, thanks for all the help and advice. Xviper, I really enjoyed reading your thread about your background, I've wondered about it.

I have the Hardtopguy clutch kit (ACT HD pressure plate, OEM disc, Comptech flywheel, OEM TO bearing). This drops about 5 lbs. off the OEM set-up. I have not found that a lightweight FW affects stop and go driving in any noticeable way. Even the stiffer clutch action is something that you get used to within a couple of days.
What I have discovered is actually a benefit. You know how sometimes when the engine gets hot and it's also really hot outside and you slow down, gas OFF, clutch in, that the engine can dip quite low in rpm to the point where it shutters and almost dies? With the LW FW, this doesn't happen anymore. The ECU can catch the dipping idle very easily and the rpm doesn't have a chance to get that low. And the extra clamping force is a welcome change.
Personally, if I didn't actually need a FW, I'd just machine the one in there and continue to use it.

[ebeldesign]

I have the Hardtopguy clutch kit (ACT HD pressure plate, OEM disc, Comptech flywheel, OEM TO bearing). This drops about 5 lbs. off the OEM set-up. I have not found that a lightweight FW affects stop and go driving in any noticeable way. Even the stiffer clutch action is something that you get used to within a couple of days.
What I have discovered is actually a benefit. You know how sometimes when the engine gets hot and it's also really hot outside and you slow down, gas OFF, clutch in, that the engine can dip quite low in rpm to the point where it shutters and almost dies? With the LW FW, this doesn't happen anymore. The ECU can catch the dipping idle very easily and the rpm doesn't have a chance to get that low. And the extra clamping force is a welcome change.
Personally, if I didn't actually need a FW, I'd just machine the one in there and continue to use it.

I have read that the AP1 flywheel weighs around 13.5 lbs. I also understand that the AP2 flywheel is heavier, and that is what it has always felt like, especially compared to my AP1. Even after removing the CDV, the revs seem to hang when I put in the clutch, and they always have. So, I am assuming that a lighter flywheel will make a more significant differnce in an AP2 than an AP1. Do you happen to know the weight of the AP2 flywheel, or am I working off of an incorrect assumption here? I have also experienced the engine shudder and almost dying quite often. If a lighter flywheel eliminates this, I am in for sure. :thumbup:

[repiv]

I have read that the AP1 flywheel weighs around 13.5 lbs. I also understand that the AP2 flywheel is heavier, and that is what it has always felt like, especially compared to my AP1. Even after removing the CDV, the revs seem to hang when I put in the clutch, and they always have. So, I am assuming that a lighter flywheel will make a more significant differnce in an AP2 than an AP1. Do you happen to know the weight of the AP2 flywheel, or am I working off of an incorrect assumption here? I have also experienced the engine shudder and almost dying quite often. If a lighter flywheel eliminates this, I am in for sure. :thumbup:

My AP1 OEM FW weighed in at 14.0 lbs on a digital scale. Sorry, I don't know what an AP2 FW weighs. I've also "heard" they are a bit heavier but I've never actually seen a figure posted for it.
When your revs "hang", is this during an actual gear change? Or did you make this observation by only pushing in the clutch and letting off the gas and just coasting? Some owners have observed that doing the latter to see if the revs hang. This is kind of an artificial state you put the engine into and the ECU can sometimes get confused for a split second and doesn't react immediately to the situation. If the revs react in such a way so as to not hamper an upshift (ie, it doesn't adversely affect the rev match), then this momentary hang isn't a negative thing.

I read where some people say the heavier FW on the AP2 is what makes for higher torque numbers. This is only part of the equation. A heavier FW holds more inertia and in doing so, can impart more torque to the rest of the drivetrain. However, this works in reverse as well. It takes more effort to turn it and when slowing down, the inertia that's been built up can cause an rpm dip below normal, especially when the Idle Air Control system is having to deal with all kinds of parameters associated with hot operations.

[ebeldesign]

My AP1 OEM FW weighed in at 14.0 lbs on a digital scale. Sorry, I don't know what an AP2 FW weighs. I've also "heard" they are a bit heavier but I've never actually seen a figure posted for it.
When your revs "hang", is this during an actual gear change? Or did you make this observation by only pushing in the clutch and letting off the gas and just coasting? Some owners have observed that doing the latter to see if the revs hang. This is kind of an artificial state you put the engine into and the ECU can sometimes get confused for a split second and doesn't react immediately to the situation. If the revs react in such a way so as to not hamper an upshift (ie, it doesn't adversely affect the rev match), then this momentary hang isn't a negative thing.

I read where some people say the heavier FW on the AP2 is what makes for higher torque numbers. This is only part of the equation. A heavier FW holds more inertia and in doing so, can impart more torque to the rest of the drivetrain. However, this works in reverse as well. It takes more effort to turn it and when slowing down, the inertia that's been built up can cause an rpm dip below normal, especially when the Idle Air Control system is having to deal with all kinds of parameters associated with hot operations.


The rev hanging I am talking about is during shifts. This is one of the major reasons I want to do a lighter flywheel. I've always thought it felt strange, I really prefer the "free wheeling" feel of the AP1 in that respect and expect a lighter flywheel to be even better in this respect. If it doesnt have a severe impact in day to day stop and go driving, it sounds like my next mod.

[repiv]

I have no complaints about my LW FW on any type of driving circumstance.

[raymo19]

The rev hanging I am talking about is during shifts. This is one of the major reasons I want to do a lighter flywheel. I've always thought it felt strange, I really prefer the "free wheeling" feel of the AP1 in that respect and expect a lighter flywheel to be even better in this respect. If it doesnt have a severe impact in day to day stop and go driving, it sounds like my next mod.

What model year is your car? If it's an '06 or later with DBW this may explain what you're experiencing. I have an '06 Civic Si and have felt the same thing.

You let off the throttle and the RPMs don't drop as quickly as you expect, correct?

[Marrk]

'07 here.

I experience the same "hanging RPMs" after letting off the throttle. Thought it was the fly wheel.

Marrk



What model year is your car? If it's an '06 or later with DBW this may explain what you're experiencing. I have an '06 Civic Si and have felt the same thing.

You let off the throttle and the RPMs don't drop as quickly as you expect, correct?

[ebeldesign]

I have no complaints about my LW FW on any type of driving circumstance.

Thanks for the patient explanation, looks like we have a winner.

My car is an '05, so it wouldnt be a DBW issue. But since it sounds like you have the same experience as I have with the revs dropping at a slower than expected rate, mabye is is not a DBW problem in your case either.

[repiv]

The FW may only be part of the equation. Whether or not you have DBW or not, you still have a throttle position sensor. The ECU may still that signal to determine how the injectors and air bypass to the IAC are handled. This "could" cause some delay in bringing the revs down. Absence of clean injectors and a clean TB and intake manifold may contribute to these sorts of conditions.