I love lightweight flywheels. I have been using the ACT "Streetlite" for about 8K miles but would prefer something lighter. I actually bought an ACT "Prolite" about 6 months ago but have yet to install it.

This weekend I pulled the engine and tranny for a rebuild and was surprised to see how much wear was on my ACT HDSS clutch (also about 8K miles on it). I did a little research and found that the HDSS clutch seems to start wearing quickly when you get into the mid-300s. I have not dyno'd but am running BNR stage 2's.

So it looks like a new clutch is in order for when the motor goes back in.

Again, after some research I found that the Exedy Twin Disk ZM022SD sounds like a good choice for my setup. The only reservation I have is that the flywheel it comes with seems a little heavy.

ACT Prolite: ~10lbs
ACT Streetlite: ~11.5lbs
Exedy: 12lbs

Of course, where the weight is located on the flywheel is going to influence its moment of inertia more than how much weight there is in total.

So my question is:

1. Does anybody have first-hand experience between the Exedy flywheel/Twin Disk and either of the ACT flywheels?
2. Is the Exedy flywheel interchangeable? Can I mate my ACT Streetlite with the Exedy Twin Disk, or is the Twin Disk a self-contained package?

 

First off, you can't go wrong with Exedy. Been super happy with their clutches.

I have their Stage 1 on an ACT flywheel (I think it's the pro lite?) and have had ZERO issues - no slipping, easy to drive, and it's been holding up great. I'm making around 350 with 99 twins at 14 psi.

The Stage 1 would be IMHO right on the edge if you start going into the 400 hp range. If you are shooting for 350 you'd be fine all day.

That said, I've never driven the twin disk. I know it is a whole system - you can't mix and match. The flywheel is specifically deigned for the twin disk setup.

On flywheels, you typically want to go with the lightest option. I always say it's about $100 of cool for $300 and a pain in the *** to install. The Exedy multi plate setups also use aluminum pressure plates so I think they save some weight on the total package there. But they get PRICEY fast.

Dale

 

I don't see how anyone would actually notice the difference between an 11lb flywheel and a 12lb.

 

I have the ACT Prolite and ACT SS clutch, works great.
If you look at it as a package with the clutch disk and pressure plate, the difference is marginal between the 2.

 

Yeah that's really what I'm trying to figure out: difference in total package rotational inertia between ACT HDSS + Prolite vs. Exedy Twin Disk.

The ACT clutch disk is 240mm in diameter whereas the Exedy is 200 so no doubt that helps. Dale says the pressure plate(s?) on the Exedy are aluminum so that again helps.

It turns out you can get the ACT SS disk #3000206 by itself is only like $125.... since my pressure plate looks fine and I have this new Profite flywheel already replacing the disk is extremely tempting compared the the insane price of an Exedy Twin Disk.

Here is my old disk from the HDSS with 8K miles on it. The more I look at it the more I think it's not actually all that worn.

 

Yeah that looks like it has a lot of meat on it. What is making you think it's worn?

Get some digital calipers and measure the thickness. Shop manual has new/wear limit specs on clutch disc thickness.

Dale

 

BTW, prolite is 11.8lbs and the counter weight is 4 lbs for a total of ~16lbs.

 

Any disc will probable wear faster with a LWFW, and the lighter you go the faster you can expect it to wear.
But as you apparently noticed yourself, the ACT HDSS holds up fine. Not sure what your research indicated, but I ran that disc about 8 years and maybe 40k miles on a LWFW and it still had life. I’m still using the ACT Pressure plate that’s probably 16 years old with 80k. Only changed the disc b/c the transmission was down for a leaking seal but no slipping or signs of hot spots on anything. Probably 350 hp at the FW.

 

I ended up just buying a new disk ("Street Strip" part #3000206) because:

1. I'm there
2. It is only $125
3. The old one held the BNR power just fine
4. I found its characteristics perfectly pleasant to drive

No reason to spend $$$ on an Exedy.

For those curious, the old disk measured about 6.8mm and new 8.2mm. So that's 1.4mm or about 20% wear over ~8K miles. The car made about 300whp most of that time.

But now I'm wondering about the pressure plate. I can't feel any grooves or unevenness with my finger, but it looks sort of "scorched". The flywheel looks similar. Is this reason for concern?

 

edit

 

That picture looks fine. Drive any clutch easy for a few thousand miles and it will look just like that. Totally normal.

I would go over the surfaces with a Scotchbrite pad and then some brake cleaner to make sure they are clean, no crap stuck to them, ready to rock.

Dale

 

Most ACT clutches have historically been 'tuner' clutches rather than well engineered solutions in my opinion. I've used ACTs, and I'll continue to use them on projects that warrant them but I'll always be looking at Exedy twin discs as a first option.

 

I’m curious that you say that.

Specifically, what makes you value the Exedy so much more? Honest question.

 

It's hard to compare a company that just makes performance clutches - maybe a few thousand a year - to a company that is the #1 friction material supplier to Japanese car manufacturers and makes MILLIONS a year. The R&D and quality control are on two different levels.

At the end of the day ACT makes a nice clutch, but I think Exedy's quality is on another level. I've had ACT clutches in the past and have had good luck, but I see what he is saying.

Is it anything you will ever notice? Probably not.

Dale

 

^^Dale hit it on the head. I'm not saying that ACTs are garbage pail, they certainly have their place, though on an FD that runs on the street it's far from my first choice.

 

<Please assume positive intent>

What manufacturing/design/performance specifics make Exedy > ACT?

 

My left foot and dyno I've slipped ACTs that are annoying to drive on my hubs, I haven't on an Exedy that's stock-like. Also even though I try not to be sheeple it's hard for me to believe so many performance OEM cars are all that wrong.

 

Well, there may not be any harm using both your ACT Street/Prolite and I'd assume the Exedy Twin Plate should fit unless it's not a stock diameter?

I'm running the ACT Streetlite and an Exedy Sports Tuff Single organic on the street and it's way better than stock.

As others have mentioned, .5 weight difference between the two options doesn't sound like much. The main considerations though are rotational mass and clutch clamping force.

Do you suffer slippage with your current setup?





Gotta love anything branded as "Tuff" coming with a pink compression plate 😂

 

So what is the latest recommendation for a streetable/wife friendly clutch that can hold 400-500whp?

 

Why would you let your wife drive your FD? Serious question.

 

Hahaha well part of the deal of having more than one is that one is hers. Don't get me wrong. She can drive manual just fine, but she said if I'm going to swap out the auto, it needs to be a nice clutch (as compared to the last one with a 6 puck).

 

A clutch that feels and drives like an oem is the carbonetics. I was impressed when i drove David Hayes 20b back then with a triple disc. I ended up getting a single for mine but it wouldnt last. I have upgraded to the twin clutch. I cant say i felt the same with any ACT or even Os giken or exedy.

 

One of the single best investments I’ve found with a performance pressure plate or any aftermarket performance clutch is a big bore slave. Here is a link for the one I’m running https://www.rhdjapan.com/fujita-engi...nder-fd3s.html You can read the thread about it here https://www.rx7club.com/3rd-generati...ution-1130888/ my pedal feel is equal to or less than stock and modulation is much easier. Most will agree a puck clutch is more aggressive on the engagement than an full disk. I like the act stuff, and the zx6-hdss is a great setup for up to 400 ish ft/lbs level . You could run the act “extreme” pressure plate for more bite but I do not have any first hand experience with that one. For reference I do run the exedy sprung 6 puck twin plate with the big bore slave on my single turbo car. It’s a pleasant drive. I did buy the act kit I mentioned for the twin turbo car and am running the oem flywheel. Zero complaints either.


~GW

 

How long does the shipping typically take from RHDJapan for this?

 

Three weeks if I remember correctly. It does take them a solid week to pack and ship from their facility.


~ GW