Hello all. Here's hoping someone can help me out.
I just started experiencing an overrevving when I shift gears, especially when I try to stomp on it and shift into 4th or 5th. I was thinking about this and it seems more likely it's the clutch starting to slip.
I have a modified '82 RX7-GX that's been coverted over to a '84 GSL-SE 13B 6-street ported mated to a '84 transmission with a Centerforce II clutch. The fuel delivery system is a twin 44mm Mikuni carb along with 2 MSD Digital 6AL. I purchased this car brand new back in fall of 1982. It has treated me extremely well and has a lot of kick.
Age may be a factor in the clutch problems, (I think it's the clutch) since the mods were done about 25 years ago. I pamper this beaut and never drive it in winter or on rainy days.
So if someone can help me out here in Winnipeg that would be very nice.
What other clutch brands are good or appropriate for my setup and who would I trust to do the work? If someone can guide me please, I would be grateful. Thanks again and email me at "apremdas@shaw.ca" please. Thank you so much.

 

I'm using an ACT 6 puck with a sprung hub. Kind of grabby but not too bad. I know two people using Bully clutches.

 

If the clutch has been good to you for 25 years then why not get the same one? Centerforce for the win!

 

DITTO!

apremdas : Damn, boy you got me beat. I've had my Centerforce dual friction clutch for over 18 years...and, knock on wood, still gripping strong. Its been through some hell with drag racing, auto-Xing, and a short NOS phase. The best part is it feels like a stock clutch. Stick with Centerforce - best clutch I've ever owned. I went through many street/strip and race clutches from Mazdatrix/RB and all were misery on the leg if its driven on the street and rarely lasted a year or so before needing replacememt. Went to the Centerforce and never looked back.

Granted my car is no longer a daily driver, but was for a good 8-10 years of that clutches life. If your're not producing over 350hp - it should be your best option.

 

I love my Centerforce Dual Friction very, very much. Easy and pleasant to drive, but still grabs hard. Mine was already well-used when I got it, but it's still holding the power of my blow-through turbo setup like a champ.

And yeah, the RB street/strip clutch discs suck hard. Their pressure plates aren't too bad, though.

 

No experience with the Center Force. I have a ceramic/kevlar stage 3 clutch in the widebody. Pedal pressure is just slightly more than stock but never misses a beat with the dual DCDs, 1/2-bp 1/2-sp 12A with 245-50-15 tires.

 

I have a CF II clutch/pp setup on my 7 with ~15K on it and no issues. I'm putting
out more than the stock HP but nothing major. It works great and has a great
feel to it. I'd stick with it if I were you.

 

Well from all the feedback, and by the way THANKS, it's great to see the so many supportive rotaries, I'm going to stay with CF II clutch. I agree, since it worked so nicely for me over the years you just can't beat reliability and quality. Now the challenge is to find one here in Manitoba Canada. I'll probably end up importing from good ol' USA.
Someone had just told me that it would be a good idea to change out the flywheel also. Does that sound like an expensive addition? The guys doind the job would have to machine the flywheel anyways and that's going to cost me about $80.

Anyone know of a good supplier in North Dakota? I'm only about an hour away and the trip would be worth it.

Thanks all.

 

I had a Centerforce DF unit in my 85 RX7 back in 97, when it still had a stock 12a. I hated it. It didn't grab like I wanted, and it didn't last long. I ended up with a Mazdatrix ss/hd setup when I went 13B....I loved it.

 

i had a c.f. dual F**KTION(friction) and hate is a under statment. it was very inconsistant on when it was gonna grab. and ill NEVER get another. i went with a stocker when the only other unit i could get was a c.f. for my vert.

 

If the flywheel can be resurfaced then just get it resurfaced. Unless you plan to get a lightweight flywheel?

 

Don't always think that a lightened flywheel is better. In low torque cars (for example, the rotary engine), a heavier flywheel creates more rotational inertia in the engine. Once spinning, it will want to continue spinning according to Newton's first law (an object in motion will stay in motion). This is advantageous for low the torque engines. The only time you would want to lighten the flywheel in your rotary would be if you're road racing and having to shift a ton. I say keep the stock flywheel.

 

I've driven Percent's CFDF and I can tell you it does drive really very well. Pedal effort is just about perfect in an '81-'83 chassis (would feel lighter in an '84-'85 due to their longer pedal travel and higher mechanical advantage). It grabs predictably and holds the power of the turbo just fine in top gear at speed. It can also allow second gear chirps on new Sumitomos and a super light steel flywheel of only 8 pounds (made by greddy, aparently, and weighs only a hair more than RB's aluminum at 7.5 pounds). It feels sportier than a stock setup but not difficult to drive at all. I mean that, it's actually easier than a lot of stock vehicles, believe it or not.

It feels night and day better than an RB HD disc; those things don't last very long, and like to shudder. We've worn out two HD discs in various vehicles, with under 6k miles each. The used CFDF definitely had some miles on it when we put it in, and is still going strong. I'm especially impressed with the performance so far, because so many of you have had so many problems with centerforce products and lots of you prefer the RB HD disc, which has led to early clutch jobs for their owners.

Hey Percent, didn't we swap out two HD discs in a row last year?

 

I would look into OS Giken options as it will probably be the last clutch you will ever have to buy and they can be rebuilt. I currently have a ACT clutch, but it is too grabby for me. The OS Giken units are far more progressive.

I just purchased a new ACT 13.5lb flywheel on ebay for $220 shipped. Granted, my car is used for road racing, but it is a easy way to shave 30lbs off your car.

 

I understand rotational inertia. I wouldnt bother with a lightweight flywheel in my situation. I was merely just telling the OP to get the flywheel resurfaced unless he already had plans to get a different flywheel. But thanks for sharing your info with all of us.

 

Centerforce Dual Friction Clutch = great stuff!

 

Why, yes. Yes, we did. Garbage.

Bollocks. I use my FB as a year-long daily driver in a very hilly area, mostly city and suburban type driving. I've used the stock flywheel, an RB light steel flywheel, and the 8 lb. Greddy flywheel Jeff mentioned, and guess which one I liked best. That's right, the lightest one. Once you're used to a light flywheel, you'll never want to go back. The car actually became easier to drive when I went from the stocker to the RB flywheel. It was certainly faster in the lower gears, and the difference in the subjective feel of the car was night-and-day; the stock flywheel felt sluggish and gross by comparison. As I see it, the only justification for using a stock flywheel in an FB is if you're into drag racing or burnout competitions, neither of which I have any use for.

 

I would vote for the ACT.

My experience with the Centerforce Dual Friction has been:

Behind the 20B, it started slipping after 20 minutes...seriously.

Behind the 390-rwhp 13BT, it forced us to dial the boost down to 14 psi. At 15, the clutch slipped.

In both cases, I replaced the Centerforce with ACT and have had no problems.

 

I'm just talking justifiable physics here.
I agree that driver feel is by far the most important part about creating a performance car. If you have a powerful car that handles well etc etc but feels like **** to drive, it defeats the point. A car that you are comfortable with but is "worse" on paper could end up being faster than the other higher performance vehicle.
I personally have no experience in my FB with a lightened flywheel. Now you've made curious and I want to look into a lighter one...

 

I've gone to the lightened steel flywheel on the RXX-7 in it's earlier life (N/A 2-rotor motor) and on my FB. Major difference. I'm sure you'll like it.

 

Well I'll look into it when I get the time and money for that modification. I've got a list going now...

By the way everyone, sorry for the threadjack. Back to clutches! I'm still using the stock.

 

George, my FB currently has a centerforce pressure plate with an ACT street disc and RB aluminum flywheel. No slipping. That may not be true for long. The plan is to swap to an RB SS pressure plate to hold the increased power when the new engine goes in. It is also to bring the friction point closer down to the floor. It's currently up way too high due to the use of an essentially stock pressure plate (centerforce) with a solid disc. That's how they are.

The RB SS pressure plate is sprung differently in favor of using it with a solid disc. This means it will move the friction point closer to the floor if used with a solid disc and make it feel more normal, if a bit heavier. Or move it to the bottom of clutch pedal travel if used with a stock disc, which can be adjusted up some and still be fine.

 

If it works for you, that's all that counts. Clutch action is very personal, since it's such a part of driving style. If you're combination works for you, then it must be right.

As for clutch travel, the high performance clutch behind the 20B engages about 1 - 1 1/2" off the floor. This means that I have to think about it on the street or I kill the engine at traffic lights when driving on mental autopilot.

In the FB, there's a little over twice the clutch travel.

 

My only complaint about the RB SS p-plate is it's a little stiff for me. Then again, my brother's RX-8 has a stiff pedal as well; I suspect the disc is getting thin (probably the original). It used to give me problems but recently it's been fine. Also recently the centerforce has been feeling weak. So has the pedal in the REPU... It's time to swap to the RB SS in the FB so the centerforce can go in the REPU.