93FDADR

Hey, i have searched, and cant seem to find info about my question. i have a 93 5spd R1. I recently pulled the stock flywheel off to replace it with an ACT. I ordered the flywheel and the auto counterweight. My main question is, does the new counterweight replace another one? and if so, where is it located. I have the flywheel off, and behind it is what seems to be the rear main seal around the eccentric shaft, and a metal collar type thing bolted to the motor with 6 bolts. is this what i replace, or am i missing something here. thanks

RotaryResurrection

iTrader: (8)

Work on it people...

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

sevensix

iTrader: (1)

learned a lot thanks.

93FDADR

good deal. thanks

Fsunoles06

So is there even going to be a noticable performace gain with an aftermarket flywheel like the ACT Street light, which weighs around 13.9 lbs. then you add about a 3-4 lb counter weight. Thats really only around 3lbs. less than stock. for close to 350.00-400.00 dollars.

Mahjik

iTrader: (1)

Here's a good post to explain it:

https://www.rx7club.com/showpost.php...85&postcount=7

onelife2stories

when i was in japan over the summer i scored a hks gd twin plate for a lower price than msrp buuuut, now i am in florida at school and my current clutch (which i believe is an act of some sort, its yellow, i didnt put it in, whoever had the car before me did) is acting up. i dont know if the hks clutch back at home is from a 93-95 rx7 or one of the later models that i believe would have a different counter weight. would getting it to work on my car be as simple as just switching the counterweight for one from a rx7 the same year range as mine? (i have a 93)

maxcooper

I don't think that explains it very well. ^^

Here's my explanation:

The stock flywheel has a built-in imbalance. Light flywheels are almost always balanced on their own, and you add the Mazda counterweight (a stock part from auto-tranny cars) to provide the necessary imbalance. The imbalance in the flywheel or flywheel+counterweight assembly makes the engine balanced as a whole once it installed. You must use a counterweight that matches (well, complements) the weight of your rotors (see the rotor weights and flywheel pages at Mazdatrix). Also, you need the counterweight to connect the flywheel to the eccentric shaft.

The Mazda counterweight weighs about 4-4.5lbs. It can be hard to find out ahead of time what aftermarket flywheels weigh, since some of the quoted weights include the counterweight and some do not. The Racing Beat aluminum flywheel is listed at 12.5lbs, but that includes the counterweight (the flywheel is ~8.2lbs on it's own). I have to think that flywheels advertised to be 9 or 10 lbs are not including the counterweight. The stock flywheel is about 20 or 21 lbs, and remember that you do not need the counterweight with the stock flywheel.

However, it isn't really the mass or weight of the flywheel assembly that matters from a "how does it feel to drive it" standpoint. It is the rotational inertia, which depends both on how much mass there is, and how far it is from the axis of rotation. The stock flywheel has its mass concentrated around its outer edge, so it has a lot of rotational inertia (and "feels heavy"). Light flywheels tend to have a fairly uniform distribution of mass (i.e. they are about the same thickness from the center to the outer edge), and the Mazda counterweight is relatively small in diameter. So the light flywheel assembly has it's mass closer to the axis of rotation, and it's rotational inertia is relatively low when compared to the stock flywheel. Even if the total mass isn't that different, which it isn't with some of the steel flywheels.

I haven't seen such a beast, but you could even have a flywheel that weighs more than stock but feels lighter (= less rotational inertia), if it had most of its mass at its center.

-Max

neit_jnf

iTrader: (17)

^^well explained

sorry Mahjik but your link is not very good this time, it says that the counter weight does not spin with the flywheel!

InitialFD

do all 3rd gen counterweights weigh the same, stock or aftermarket? ex: 94 rx7 automatic equal the same as an act?

jeff p

nice reply Max!

Jeff

GoodfellaFD3S

iTrader: (213)

ACT uses the stock OEM Mazda automatic counterweight.

M104-AMG

iTrader: (8)

Excellent write-up Max!

If you or anyone can get to the Exploratorium at the San Francisco Palace of Fine Arts, they have a great demonstration of the gyroscopic and inertia effects of mass on the rim of a wheel vs. mass concentrated in the center of the wheel.

You sit in a swivel chair and hold the various spinning wheels and can feel these effects on your arm and against your body.

The link below explains it with the bicycle wheel, but doesn't explain the different wheels they have to experiment with.

The Exploratorium ROCKS!

:-) neil

http://www.exploratorium.edu/snacks/...heel_gyro.html