Regrets Going With Lightened Flywheel?
 

I have been reading thread after thread on lightened flywheels and I was just curious if anyone has any regrets after having gone with a lighter setup.

I am about to drop my tranny (throwout bearing) and I was contemplating the swap. I am interested in the ACT streetlite flywheel.

I am currently sitting at a little over 360 to the wheels now, but that will increase once I get my streetport done. I do not drag my car (at least not yet:)) and my car is not a daily driver. Has not seen the track either (contemplating it).

Any useful input would be greatly appreciated...

if you are going to drag race, stay away from it. if road racing is what you want to do the lw fw would be better suited for that

Here's my take on lightweight flywheels.

First off, I've only driven FC's with light flywheels. But, everything that applies to an FC should apply to an FD as well, if not moreso.

The big problem with light flywheels are they cost a good amount of money (around $300ish), are a big job to install (pull tranny), and really give you about $50 worth of "cool". You will most likely not notice any difference in power itself with the light flywheel - the only advantage it really has is making the car rev much faster.

People who have installed the heavier steel flywheels felt gypped - it's just not enough of a difference, considering the amount of money spent and the effort involved. Definitely get an aluminum flywheel. I've driven both, and you just don't get the bang for the buck with the steel.

I taught an old girlfriend of mine how to drive stick on my old TII. It had a VERY heavy ACT clutch, a street port, and a light flywheel. She didn't have any trouble after she got generally used to it. If you've driven a stick for more than a month, you will not have any problems driving the car with the aluminum flywheel.

Now, if you do stop and go bumper to bumper traffic uphill both ways every day, I might reconsider. That could get old, as you do have to give it a bit more gas when starting out. Otherwise go for it. This is definitely a mod to consider "while you're in there".

The biggest benefit is for rev-matching and heel/toe downshifting. If you can drive a stick well, you'll really enjoy it. That's where you'll feel the difference - the engine will rev up so easy to revmatch on downshifts. Again, don't expect the car to be way faster or anything.

Again, I have FIRST HAND EXPERIENCE with MANY cars on this one. You'll see a lot of people simply parroting what they read on Mazdatrix's website. This is my experience, and opinions from the RX-7 guys around here.

Dale

the last paragraph of your post reads like a disclaimer. i guess u need one of those these days.

I installed an Exedy 13lb flywheel on my Subaru Impreza (non-turbo, 165hp 165tq). The original flywheel was about 30lbs, so there was a very noticeable difference. I loved it, it didn't take more than a day to get used to the difference. At low RPM's (below 2500), the lightweight flywheel makes you feel like you're driving a car with a smaller engine: you need to give it more gas to get moving. Above 3000 RPM's, the car accelerated noticeably better. Upshifts were faster, because the engine decelerated to the proper speed more quickly. Downshifts were smoother, even when you didn't get the rev-matching exactly right; the engine had less inertia, so it wouldn't upset the balance of the car as much.


From what I've read, the RX-7 has a pretty light flywheel to start with. Dropping 5 lbs from the flywheel isn't going to make the same difference as dropping 20lbs. As Dale mentioned, I wouldn't bother replacing it unless you're already in there. Another thing to consider: a well-designed flywheel will have low inertia in addition to light weight. Look for a flywheel with minimal material on the outer edges, for instance the ACT prolite as opposed to the ACT streetlite.

http://www.rx7.com/store/rx7/fddrivetrain_flywheel.html

^^After reading this page, I'd like to know the weight of the Exedy twin-plate combo.

-s-


edit: don't forget engine mounts while you're in there.

My FD will have a light flywheel but I wont finish the car until the end of the month or so. My old n/a FC had an aluminum flywheel, my friends GSL-SE had an aluminum flywheel on his TII engine and my brother has one in his n/a FC. Ive driven all of these cars alot so my "review" is firehand experience like Dale's. All of these are daily drivers as well but none have a heavy clutch.

I didnt have a problem driving my FC after the flywheel install. It was my daily driver and I didnt think it needed much effort to drive around town. Same thing with my brothers and friends car. They both loved the flywheel and said it was one of the best mods done to the engine. They never complained about it being a pain to drive around town or uphills. All of these were aluminum flywheels using stock-like clutch setups.

I dont have any personal experience with FDs & lightened flywheels but the results should be the same. Im sure I'll love my flywheel once the car is back together.

A 9lb flywheel is a 9lb flywheel, whether its made of steel or aluminum. Right??

Also $300 is cheap for an FD part :rlaugh:

i like my aluminum flywheel. it is a bit harder to start from stop though like dave says you need to rev up a little higher.

I think he is saying that the steel flywheels are heavier than the aluminum flywheels.

$300 is cheap for an aftermarket part for the FD. :ky: :ky:

if you decide to go for it, I have a brand new ACT street-lite that I don't need. pm me and save some $ :)

Yep, I have the ACT 9.5lb and LOVE IT! Don't be scared. It does take a minor adjustment in driving style to get started, but I would never go back.

I agree with Dale. Their OK. Not exactly worth the $ or trouble unless you are already doing a clutch job and have some extra cash. If you do get one, go with the 9.5 lb aluminum.... I would if I HAD to do it again.

What if I track, autox, drift and drag? (preference in that order) I've been considering the ACT Prolite.

You'll love it at the track and drifting since both of these require lots of rev matching. I dont know much about about drag racing but my friend said he liked his car with a heavier flywheel for drag racing. I personally wouldnt take everything apart just to install the flywheel but I wouldnt think twice about installing one while doing a clutch job or any other time the tranny is apart from the engine.

i have lightweight flywheel...it def makes a difference in the rev...definately....revving in neutral will shoot up to redline before you can blink...it is def a pain though in stop/go traffic, when letting out on the clutch, about half way out, the car feels like a normal stick shift and starts to move foward, then after about half way if your not aware of the lw fw it will buck and stall, it requires extra gas about half way through the clutch

If you're gonna do it, look at the Racing Beat or SR Motorsports ones. They have a replaceable friction disk that can be replaced for ~$80 vs. having to buy a whole new flywheel if something were to happen down the line.

I'm running the SR Motorsports 11 lb aluminum unit. I do like the feel of the car with it and it does make downshifts easier. However, I guess that I will go against the status quo a bit and say, for a pure street-driven car, I would stay with the stock flywheel. This goes double for a car used as a daily driver.

Ive installed both types for myself and customers.

I have never heard a regret from someone who got the ~12lb steel setup unless they ran a solid hub clutch.

I have heard regrets from people who got the ~9lb aluminum setups, *especially*when running an agressive clutch (any kit using an organic disc is not very aggressive).

I personally hate a 9lb setup though it is tolerable. But if you add a 6 puck clutch on top of that it becomes intolerable, to me. I dont like looking like a jackass or a clutch newbie at redlights, and I dont like having to rev to 1800rpm and make the drivetrain shudder to take off smoothly.

My personal favorite combo is the act streetlite with the act SS clutch. This combo will rev faster than stock and launch well, and hold 450rwhp+, yet it is 100% driveable in the city.

Keep in mind I live in hilly Tn and my driveway itself is a big hill that I have to climb to get to the road, so people in texas might have a different opinion.

not all of Texas is flat, just like not all of tenn is imbred ;)

As for the 9lb flywheel and 6puck setup, I will be able to relay firsthand experience of that setup very soon. Didn't want the 6 puck but thats all I could get that wouldn't of taken weeks to get.

I'm running the 9lb flywheel and the ACT 6puck unsprung. It grabs no other but does suck when taking off from a stop on an incline. Its tolerable to me. But when it comes time for a clutch job, I'll try using a sprung 6 puck.

Dale, with all due respect, I disagree w/ you wholeheartedly.

I actually drove my car for several thousand miles in various conditions w/ the stock setup, then I put a lightened flywheel on. The difference was NIGHT AND DAY IMO. Night and day. Not only was the car incredibly quick to rev match, but I felt a LOT more power in 1st and 2nd. My FD was *noticeably* faster after the flywheel. That's my subjective part. As far as objectivity goes, Rynberg posted a report by Max Cooper from a while back w/ testing results from a regular to lightened flywheel.

From back in '03 (https://www.rx7club.com/showthread.p...7&page=2&pp=15)

50hp TO THE WHEELS in 1st, and 16 in 2nd!!! That's 99.99% of the reason why my FD was pulling SO damn hard w/ a dead tired motor w/ 91K original miles, 9 inHg vacuum, and dying stock turbos ;)

~Ramy

PS: I do agree w/ Dave though that for a daily driver, in stop and go traffic, or getting stuck on a bunch of hills (if you actually DON'T want to ride your clutch), it essentially sucks lol.

Ah, don't be a sissy. I daily drove my FD for 3 years in texas with a light flywheel, not to mention removed a/c, and didn't mind one bit :)

If you are performance oriented, the light flywheel is a no brainer. If you own an FD, you are performance oriented. 'nuff said. [disclaimer: this excludes those who constantly launch their FD]

Haha, we all know you're a masochist, Rich.

Anyone willingly removing the A/C while living in Dallas is a few seals short of a good motor. :D

you can rev match just fine on a stock flywheel.

No one said you can't do it. But doing it w/ a lightened flywheel is a COMPLETELY diff experience.

I remember when I first had the flywheel installed, I had trouble coming off the line, b/c I'd be up to 4K rpm or so immediately overreving, b/c the flywheel was now MUCH lighter than stock!

I'm betting you have never driven an FD with a light flywheel :cylonA:

The stock flywheel if memory serves me correctly is ~23 lbs. So dropping to a 12 lb wheel will make a difference. It also makes a diference where the weight is on the wheel. The closer to the hub the better.

I remember reading 50 hp in first, 25 in second, 12 in third etc.

I say it is defintely worth it. I'm using the Racing Beat 17 lb steel flywheel as a compromise b/t stock and the ultra light flywheels.

Jack

Stocker is a bit over 20lb.

http://www.rotaryresurrection.com/3r...nter_info.html

Also you people talking about 9 and 12lb flywheels are forgetting to add the 4lb counterweight into that, which the stock flywheel has molded in permanently.

http://www.rotaryresurrection.com/3r...vs_aftfly.html

IF the stock FD wheel weighs 20.3lb and you're using a 17lb flywheel plus the 4lb auto ctwt, I fail to see how that is helping matters. :scratch:

I think the 17lb was made for the earlier turbo II motors, some of which came with a HEAVY ASS 27lb flywheel. On that motor, a 17lb flywheel plus 4lb counterweight would make a big difference.

I'm with Ramy on this topic, again

;)

Kevin, are you sure the counterweight is 4 lbs? I have always seen 1 lb thrown around. I installed one the other day, and it didnt feel too heavy.....

10 lb 1-piece chromoly here (JUN). No regrets one bit.

I'm running a 9lb flywheel after my conversion and loving it. Although on hills it does tend to slow you down abit, a tiny bit. Nothing that I can complain about!

All the weights on that page were taken with a digital postage scale. All the counterweights weigh in at 4lb, give or take a few oz.

I put on a RB 9lb Flywheel about 4 years ago and would Never go back, whether for street or road track.

Hmm.... My motor is out right now, so the thought of doing this comes and goes. I have a stock-like(edit: RB street/strip clutch, so I'm told) clutch on there right now w/ ~7k miles on it. I'm not too keen on replacing the clutch until need be, should I do it all at once when I need to?

Keep the clutch, get a lightweight flywheel. I've never had any issues using a new flywheel with a used clutch disc.

:bigeyes: Something's wrong w/ this picture... :scratch:

Its mass is concentrated in the center. It was sold by Racing Beat for the FD, got mine through Rotary Performance in 1998. It's probably the same part they sell for the FC. Looks similar to the 17lb flywheel from Racing Beat that I had on a 1st gen 12A.

It wasn't as drastic as the change from the 1979 30lb flywheel to 17 lb but I still noticed enough difference.

Jack

I sat on this fence for 3 years. I kept stock because I thought "there is no way I am paying that much for something that won't make that much of a difference."

Then I bought an engine with lightened flywheel and sprung 6 puck on it. I had every intention of selling them. But after I rebuilt the engine, and a couple weak attempts of selling them I decided to go ahead and try it out.

And I am extremely happy with the change. I highly recommend it for a weekend street/HPDE car like mine. Daily driver may not like it but if I daily drove mine still I would do it.

The setup I have is much harder to drive than stock/act XT. At first I only got 2 out of 10 shifts right with it. After a couple thousand miles I get 8 out of 10. It makes you drive better I think - I am now rev matching, and heal toeing soo much better because you almost have to.

You can feel a difference big with a lightened flywheel.

When it comes to flywheels. Get the lightest (within reason) you can get your hands on. 9-11 lb is recommended.

I changed to a ACT SS clutch and a ACT streetlight flywheel when i did my clutch this spring. No problems at all with driving in start/stop traffic, but i think it revs faster.

I disagree with the people who state that speed matching is more important with a light flywheel. (lets clarify "speed matching" as a double clutch downshift). The original purpose of a double clutch down shift was to speed up the transmission input shaft to match the linear velocity of the gear teeth on the input shaft to that of the gear teeth on the output shaft, so that the transmission could be shifted into that gear. This is accomplished by shifting the transmission into neutral, engaging the clutch, stomping the throttle to use the engine to speed up the input shaft, disengage the clutch, shift into a lower gear and engage the clutch.

The need for all this was largely obviated by the invention of the syncomesh transmission, which is equipped with "syncronisers" to match up the gear teeth velocities and allow a nice grind-free shift. Still, routine use of a double clutch downshift during aggressive downshifts will greatly increase the life of the syncos.

So today, the primary use of a double clutch downshift is to match the RPM of the flywheel to the RPM of the clutch, so that when the clutch is engaged after the transmission is shifted, it does so nice and smoothly, and the clutch does not have to speed up the flywheel.

And so here is why i disagree with the "its more important to speed match with a light flywheel" statements: If you do not speed match during a downshift, then the faster turning clutch has to speed up the slower turning flywheel (and the engine to which it is attached) to the same speed as the clutch. Now, since it is widely accepted that the lighter flywheel with a lower rotational inertia (Polar Moment of Inertia for you engineers) allows the engine to rev quicker, then the same lower polar moment of inertia of the light flywheel allows the clutch to speed up the engine easier.

Therefore LESS IMPORTANT. Of course it is always more FUN to double clutch downshift.

Mike

^^We're talking about rev matching, no double clutching involved. Depress clutch, blip throttle, let clutch up.

I see no purpose for this "rev matching", as you describe it, other than showing off? Please clarify what the objective is.

Mike

Wear on the clutch maybe? If they are going near same speed on engagement there has to be less wear.

Since the flywheel is so light and I dont shift so "mad quick yo!" on downshifts my engine rpms drop very fast when I let off gas and depress clutch. Blipping the throttle just a bit makes the clutch engagement feel so much better. Maybe its my DIY motor mounts, jimlab diff mounts, or the 6puck clutch but just plopping the clutch out doesnt feel very good.

Besides being able to brake and have throttle control is one of the advanced skills of driving I haven't mastered yet and practice makes perfect!

And as far as showing off goes what would be wrong with that. That may be half of owning an FD...

Back to the topic of the thread though - I have 1 FD friend that has changed to lightened flywheel since they have driven mine.

When braking hard entering a corner, weight is obviously transferred to the front of the car, with less on the rear. The wide spacing between the gears means that unless there is some rev-matching between downshifts, the inertial imbalance between engine and drivetrain will always cause a loss of traction. A loss of traction with unweighted tires entering a corner can be a very bad deal.

This is during very aggressive driving on the track, obviously. On the street, it's pretty much a non-issue.

Maybe I missed something, but wouldn't rev matching, or blipping the throttle on downshift WITHOUT double clutching also tend to be easier on synchros?

Mike Nola, what you speak of sounds like it's right out of a late '70s article about double clutching prior to the advent of synchros. NO ONE double clutches anymore...

As Kento stated, rev matching is ESSENTIAL when you're entering a corner at a higher speed, and are reducing speed, and thus will be downshifting to a more proper gear for maximal corner exit speed. At that point, you want to make sure you DO NOT unsettle the car's balance, or (again like Kento said) you risk losing traction. That can be quite a scary thing.

One thing to add to what Kento said, however, is that I'm sure that the jolt of dropping gears and thus rpms suddenly from downshifting - say when you're braking due to traffic slowing then you're downshifting. If this is done w/o revmatching, there's a substantial jolt when you downshift. I'm sure that causes increased wear on the clutch, tranny, mounts, bushings, etc.

~Ramy

PS: It bewilders me that ppl don't revmatch, but it seems that (from my experience), the vast majority of ppl do NOT do it, let alone know what it is. I guess it's one of those things that you're only exposed to when you track your car? :scratch:

i learned revmatching on accident, i was driving normaly and i was lazy or something, wasnt paying atention to what i was doing and shifted smoothly without using the clutch on an up shift, rpms fell just right. now i do it al the time when im lazy. i didnt use to know that rev matching is what i was doing, i just did it.