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13LB OR 9LB Flywheel? Differences?

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Old 06-27-05, 12:40 PM
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13LB OR 9LB Flywheel? Differences?

Trying to decide which flywheel to get.

ACT provides a 13lb and a 9lb flywheel.

what differences in driveability will occur between the two?

what differences in performance? shifting i heard is easier with a lighter flywheel.

i was thinking of getting the 13lb flywheel because i wouldnt have to ride the clutch as much to get the car moving... but i guess once its moving who cares =)

i also hear that the lighter the flywheel the car dosent idle as smooth.. true?

anyone driven both?

is it a major difference and has anyone regretted getting too light of a flywheel?

or for that matter regretted not getting the lighter flywheel?

looking for real world experience. ive been reading several posts but havent found a specific description of the changes in driving and the actual weight of their flywheel..

thanks for your help and suggestions.
Old 06-27-05, 01:16 PM
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Originally Posted by Qball
i also hear that the lighter the flywheel the car dosent idle as smooth.. true?
Nope, not true (with the FD that is).

Originally Posted by Qball
is it a major difference and has anyone regretted getting too light of a flywheel?

or for that matter regretted not getting the lighter flywheel?

looking for real world experience. ive been reading several posts but havent found a specific description of the changes in driving and the actual weight of their flywheel..
Check this post:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/flywheel-clutch-306762/
Old 06-27-05, 01:50 PM
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then my question is....is the poor acceleration from a dig that much of a factor to outweigh the benifit of quicker revs to go with a slightly heavier flywheel.

Not for an purely auto-x car, or purely a strip car, but for a street driven and occasionally street raced car.
Old 06-27-05, 01:50 PM
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^ would be good to hear from someone who has driven with both a 13lb and 9lb flywheel

thanks
Old 06-27-05, 01:54 PM
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I've driven both...3lbs in the swing of things isn't night and day.

the lighter you go the faster your revs drop during shifts.

I went with the 13lb, around town it can be a dog under 2k...at autoX launch at 4k, and you are shooting out of the hole and never look back.
Old 06-27-05, 01:56 PM
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Originally Posted by TpCpLaYa
then my question is....is the poor acceleration from a dig that much of a factor to outweigh the benifit of quicker revs to go with a slightly heavier flywheel.

Not for an purely auto-x car, or purely a strip car, but for a street driven and occasionally street raced car.
Nope, it's not a problem on the street. You'll notice the revs fall faster between shifts, but the quicker acceleration makes up for it.

IMO, unless you have a "need" for a lightweight flywheel (tracking or you need to replace your stock one from damage), stick with the stock one.
Old 06-27-05, 02:18 PM
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The lighter flywheel also causes more wear on your clutch, if I'm not mistaken.
Old 06-27-05, 02:22 PM
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Originally Posted by quicksilver_rx7
The lighter flywheel also causes more wear on your clutch, if I'm not mistaken.
Riding the clutch is riding the clutch regarless of the flywheel, and that's what wears out the clutch.
Old 06-27-05, 02:34 PM
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thanx for the imput guyz...been pondering weather or not to do this mod lol. so far sounds like a worth while mod... im still all stock but i think my 5th gear syncro is taking a ****....so i figure while the trannys down any wayz....
Old 06-27-05, 02:50 PM
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Originally Posted by Mahjik
Riding the clutch is riding the clutch regarless of the flywheel, and that's what wears out the clutch.
I agree, but in a street-driven car with a lighter flywheel you're gonna have to rev the engine higher to take off due to the lower weight of the rotating mass. Therfore - premature clutch wear. I don't see the advantage

Last edited by quicksilver_rx7; 06-27-05 at 02:53 PM.
Old 06-27-05, 02:58 PM
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Originally Posted by quicksilver_rx7
I agree, but in a street-driven car with a lighter flywheel you're gonna have to rev the engine higher to take off due to the lower weight of the rotating mass. Therfore - premature clutch wear. I don't see the advantage
It's blown out of proportion. You don't slip the clutch in any more than the stock wheel. You just don't have the same initial power to the wheels as a heavier flywheel would give, thus why people rev it higher. It's not really the revs so much has "slipping" the clutch in that wears on it. The clutch wears mainly due to the friction surface being partially on the surface (i.e. riding the clutch at stop lights or too much slipping of the clutch from a stop). Simply dumping the clutch only causes driveline shock (which tears up other stuff).

It also depends on the clutch type used in conjunction with the flywheel.
Old 06-27-05, 02:58 PM
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The reasons to install a lightweight flywheel are increased acceleration in 1st and 2nd gear, less precision required for rev-matching a downshift, less wear on the transmission.

I've not heard of anyone burning through aftermarket clutches because they had to slip the clutch a hair more taking off from a dead start.
Old 06-27-05, 03:16 PM
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I haven't driven the 13lb flywheel, but i have driven stock and compared to a car with the M2 and RB flywheel. The 8-9lb flywheel is nice for performance driving, but does get a little annoying when stuck in stop/go rush hour traffic and when leaving consecutive stop signs in 2nd gear. If I had to do it over again, I might try the 13lb for my mixed use car.
Old 06-27-05, 03:38 PM
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Is 9 lbs the lightest you can get in all national markets (us, jpn, aus, etc.)?
Old 06-27-05, 03:54 PM
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I have a 9lbs Racing Beat wheel matted to my ACT S/S clutch and I love it. I havent driven with a 13lbs flywheel and was PARANOID about the 9lbs version... however the price was right so I just took the chance. The acceleration was VERY noticable compared to the stocker, the revs DO fall quicker but it doesnt make much differance IMO.

As Mahjik said, slipping is slipping, I didnt have to slip too much, no more than I do in my 240sx with the stock setup... normal driving you dont need to worry about getting the revs up anyways so why would you ride it more than usual? If you are racing, chances are you are gonna dump at like 4-5k anywhoo...

~Kris
Old 06-27-05, 04:48 PM
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Originally Posted by tripleseis
Is 9 lbs the lightest you can get in all national markets (us, jpn, aus, etc.)?
No ive seen 8lb or 8.5lb for an FD
Old 06-27-05, 05:05 PM
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My input,

Driving condition: Street only
Flywheel: SR one 8 or 9 and half I don't remember.
My impression: I freaking LOVE it!!!

Yeah, it's can be annoying in traffic. Rev higher when taking off. Can't leave the car in-gear too early when seeing the 'red' from the next traffic light (the car WILL slow down way fast). ETC, but the performance gain is about having the downpipe install IMO. And, you can't have DP installed more than one, right So, no choice. Remember, the gain is not gaining in Power, so it's even more lovely.

POM HB
Old 06-27-05, 05:16 PM
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You could also go in between. I know they have 11lb flywheels as well.
Old 06-27-05, 05:30 PM
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Originally Posted by Quickfini
You could also go in between. I know they have 11lb flywheels as well.
Yep, I got the 11 lb alum flywheel from SR Motorsports going in.
Old 06-27-05, 07:37 PM
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All this talk about flywheels gives me the opportunity to ask, whats the weight of the stock flywheel?
I searched but didnt come up with any #'s for the stock one...sorry if its been covered
Old 06-27-05, 07:38 PM
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about 20-21 lbs.
Old 06-27-05, 07:56 PM
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The auto counterweight needed with an aftermarket flywheel weighs 3-5 pounds. It's nice to know when comparing to stock.
Old 06-27-05, 08:02 PM
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I guess I'm the oddball out, and will say it's a love/hate relationship. I LOVE how easily and fast the revs climb. BUT, I find it's def. harder to get goin off the line at lower rpms, and I HATE getting caught on hills. I mean HATE. I don't like riding my clutch or holding the car on a hill w/ the clutch (duh lol) so every time I get caught on this one specific hill at a specific traffic light (which is often...Murphy's Law I tell ya) I have to engage, drop the clutch again, and re-engage. Twice or three times really quickly. Otherwise, you're gonna have to ride that clutch like a **** (it's a crucial hill). The ACT HD S/S clutch WILL let you know if you ride at all...you'll smell it for a good 5 min. So that's motivation not to ride it too And obviously you gotta have the revs even higher to get going from a dig on any considerable hill... So it's got it's ups and downs. To me, I'd say it's streetable ie you will be ABLE to keep your mind having it on a street car. BUT, I wouldn't say it's daily driver material. Not by a long shot. It'll **** you off REAL quick if you have a lot of stop and go...

FYI, I have the PFS lightened flywheel. Don't even know the weight, since they didn't give me much of an option lol. I think it's 11.5 lbs...
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