Flywheel counterweight question
 

Hey lads,

I went to buy a ACT 6 puck sprung clutch and a ACT prolite flywheel today for my 1993 rx-7 and the dealer told me I need to order a counterweight that was a extra $200.

I was just wondering if this is true or not

True..

Yet I have a perfect condition used one for less than 1/2 that shipped

Yep, it's true. Best bet is to track down a used counterweight - they're from the automatic FD's, the flex plate bolts to the counterweight.

Dale

I just bought one for $40 used.

I'll add some useful info to this thread since were swapping out balanced parts for something else!

You can install the auto counter weight just understand that whatever counter weight you put on, your rotating assembly will no longer be in perfect balance unless you find a counter weight that is balanced to your internal rotor weights. You'll notice holes drilled on the factory manual flywheel that your removing. Mazda balances each rotating assembly for three main reasons. 1. To prolong the bearings life. 2. To eliminate any unnecessary stress on the e-shaft and stationary gears. 3. Over smooth operation. Ideally you would want to know the rotor weights inside your engine. Knowing this you can find a used counter weight that is balanced for your particular rotating assembly. If you don't know (most never do) try if all possible to find a counter weight that is off of a "C" weight rotating assembly. That's considered the middle range between A-F which is Mazda's rotor weight range. Reason for this is if you have A-B rotors inside your engine and you put on a used counter weight from another engine that's balanced for E-F rotors, your rotating assembly will be way off balance. This is why a "C" weight counter weight is the best option if you don't know your internal rotor weights. Hope that helps.

Assuming the engine is stock, is there somewhere you can check what rotors you have inside the block without cracking it open?

Good point for those that aren't aware of that kind of stuff. I am having my engine built and so it's all being balanced together. :)

Unfortunately the only way is to open the stock engine. The rotor weights are stamped on the gear sides of each rotor.

hey people,

I am in kinda the same boat. Need to change the clutch so was contemplating weather to go for a lightened flywheel. Seems like its not a good idea to change to a lightened flywheel unless its going to be balanced with your rotors. ( Since i don't know what kinda rotors are in my engine) the only time i would want to get a lightened flywheel is when I do find out which rotors are in my engine and get the whole rotating assembly balanced when i rebuild my engine.

Auto Counter weights ?? how good are they? do they really help balancing the engine?

Hay and this is from left field. I need a heavier flywheel and starter motor. I've almost 100% converted to diesel fuel and need the mass to keep compression going.
I have an act lightened fly with cw. My question is would this counterweight work bolted onto my stock fly? Or should I just get my head examined.

Stock flywheel has the counterweight built in.

In my case, i had my rotors lightened when the engine was rebuilt and had them balanced along with the stock flywheel. Along with the rebuilt, i also went for a single turbo setup. Now i need to change the clutch as it's still an OEM item. What kind of clutch can i buy that handles 480bhp but still retain the stock flywheel ? I only find ACT. Any recommendations please? Thanks!

Might as well stick with ACT. Many members have had very good experiences with them. For your power levels, you might need to go with the zx6-hdg6 setup, or the zx6-xtss. HD pressure plate would need the at least the sprung six puck disk to have the strength required for your power level. The XT pressure plate should be able to hold with the Street Strip disk.

Because you are keeping the stock flywheel, your drivability should stay pretty tame. The drawbacks of each setup:

Zx6-hdg6: (rated to 510 ft/lbs)
The six puck sprung disk may take a little getting used to to avoid chatter, but not having a lightweight flywheel should alleviate this somewhat. But using this disk will allow you to use the heavy duty pressure plate to avoid the heavier pedal feel of the extreme pressure plate.

Zx6-xtss: (rated to 450 ft/lbs)
The extreme pressure plate will require more pedal effort but the street/strip disk will have smoother engagement than the six puck.

I personally have the zx6-hdss (rated to 400 ft/lbs) combination, which is the heavy duty pressure plate and the street/strip disk. However, my power level goals are only around 400 horsepower. I am hoping I don't have to upgrade but time will tell.

Monkman33, many thanks for the info! Really appreciated. Will be going for the ZX6-XTG6 (rated:577 ft/lbs) and MZ028X pressure plate. Will see how it comes ;)

No problem at all.

The part number you first listed (zx6-xtg6) is the (xt) extreme pressure plate with the (g6) six puck sprung clutch disk. You won't need to purchase any other part numbers if you get the kit you listed first.

The way their part numbers break down for clutch kits it like this

Zx6- (rx7 bolt pattern)
XT (pressure plate designator)
G6 (clutch disk designator)

If you are going with the G6 clutch disk, I'd probably recommend the HD pressure plate. Just because I personally like to have the minimum amount of pressure on the clutch fork as possible.

Best of luck with whichever route you go with. I have seen very few issues with ACT setups.

Thanks again Monkman33 !! Are you suggesting that the XT pressure plate may break the clutch fork ?

I'm not saying it will do that. I just don't like to put any more pressure than is needed. However, If I am wrong and I need something stronger, then it gets expensive fast. lol

They sound the correct ones. Low profile 17mm (from memory) heads, black oxide coated, 10mm fine.

Usual rule of thumb for threaded joints is 1 1/2 times the diameter of the fastener for engagement, first 3 threads take something like 90% of the load - or thereabouts anyway.