James

Just curious if any of you guys are running a Centerforce DFX clutch? If so how do you like it and how long have been running it? I had a DF in another car and it worked nicely but I was just curious what people have to say about the DFX clutch. Thanks.

gkull

I installed the DFX about three years ago. It works as advertised. I needed a clutch with a very high HP rating. Very light petal. No need for a hydrolic throw out. My big 12 wide slicks never caused it to slip, but i did just have to replace a $800 tom's posi unit that was unrepairable. I'm happy

James

Thanks for the feed back!! Sounds like I might have to try one out.

73BLWN

I planned on asking the same question as you in regards to the DFX. I've been running the DF for several years behind many different combo's. They seem to hold fine up to 620 flywheel hp . My DF slipped at 686 flywheel hp during shifts so I dialed back the boost a bit last season. I'll be running 720 flywheel hp this year.

Hows the driveability? Is there any/much chatter?

gkull

the dfx was rated like 200 or 300 hp over the df. i have the 11 inch clutch with 168 tooth 22 pound billet steel flywheel. Very smooth and easy to drive.

It is actually on it's second motor. My first motor broke the crank shaft. When I inspected everything it was like new.

73BLWN

Thanks for sharing your experience. The dfx sounds perfect for me since it's easy to drive, smooth and will handle 200 -300 over th df. I also needed a flywheel, so you've answered my questions. Theres no cheap way to play. By the time you dfx, flywheel, and scattersheild, your'e at about a grand. Gotta be safe too.



Thanks again

73BLWN

I've been emailing with Roger Warner at Centerforce. He's suggested the 12" DF612909 They use it behind the 720 hp 690 trq ZZ572's. He says they are more street friendly then the DFX. I think I'll be trying one of these out in June. Any thoughts? You still use a standard 11" flywheel.

tshort

I've had one behind my BB and have been happy with it. I've put about 2500 miles on it and so far so good.

gkull

My 22# billet steel fly wheel is just a machined down thinner version that i bought. I considered 15# or so aluminums, but I was concerned with repeated clamping shock eventually cracking them.

It is funny that Centerforce said it was as street friendly. I just changed to 3.55 rear from 4.11 with my tko 600 and have no problem driving around town

73BLWN

I'm sure street friendly is subjective. My 11" DF has a bit of chatter, but I'm running a M21, with 3:36's. I'd bet with 3:73 and or a Keisler set up the drive ability would be improved. My concern now is more with the flywheel weight. 36lbs! Compared to 22 lbs? I'd think that would be noticable. I have no idea what my factory flywheel weighs. I'll have to weigh it when I remove it.

It would seem that a BB with the huge rotating mass would be able to handle a heavy flywheel. My little sb??? Maybe I should be thinking lighter? Any thoughts Gkull?

2500 miles of satisfaction. That's a good testimonial. what type of power are you making?

gkull

Keisler sent me a Sach clutch and pressure plate with my TKO 600 with a blow proof bell housing, engine block saver, and better drive line because I told them that I had a good time Motown 427 7500 rpm intended for road racing motor. I had to have all SFI rated stuff to pass any tech inspection.

I could not find any real info in the clutch and pressure plate. so I just bought the DFX. Within a matter of months I broke the crank shaft in the 427. the block saver plate saved the rear of the block.

I stuffed in my spare mid 500 hp motor to get back to racing while I moved up to a new 434 with even better stuff and 11.8 C/R. No dyno figures, but it should be in the mid 600's. So I stuffed it back in and went racing again.

Road racing is brutal compared to driving or even drag racing. Maybe part throttle in the turns, but wide open unless your on the brakes. I shift lots of times from 3-4-5 5-4-3 on a 4.2 mile track in a 30 minute time period around a 4.2 mile track going from 155 mph down to about 45 mph.

I go through a full set of slicks in two days and a set of front rotors. Then I switch back to my street tires and drive around.

I've probably put on 6-7 thousand miles between the track and the street between the three motors.

I work at a historic race car shop and we have the ability to change things pretty fast. That is why I have a spare motor.

At work I drive and work on these trick multi plate 5-6-7 inch racing clutches. I wanted somthing that runs fine and lasts a long time

73BLWN

Keisler had suggested a Spec 2 for my car when I was given a package bid. Lifes misfortunes put a delay on the purchase. All in good time.

I recall seeing your broken crank picture. So sad.

Oddly, I have a spare 500hp motor too.

I comletely agree on the abuse your motor and transmission/clutch must take at the track. An excellent testimonial to the DFX versatility. I have a friend that instructs and races at Brainerd International Raceway Mn. He drives a 580hp twin turbo Porche. I've been at an event with him riding and driving. Great fun.

You have somewhat of a dream job. I can't complain. I have a great job too. I develope machining and inspection routines to build mechanical heart valves for St. Jude Medical. I inderectly save lives. My best friend and his dad each have one of our valves.

Anyway, obviously the DFX is an excellent clutch set-up and will meet my needs, but I think I may try the 12" DF just to be different.

gkull

12 inch should have a considerable more amount of square inches over a 11 inch.

You have the HP, maybe you should now work on the road racing setup.

I have a friend with a mech valve. He just got it two months ago and he said that the noise bothers him and he can't sleep. I told him when the noise stops it will really bother him!

jussi70

Hello!
I have sbc gen 1 with 168 teeth flywheel. Bell housing is quicktime RM-6039 ( quicktimeinc.com ) and transmission ZF-6 (corvette-94)
I have to buy clutch, but I dont know what is good for my combo...
Engine is ~700hv
How this Centerforce DF612909 ? I read in this topic that 700 hp is ok, but is DF612909 (12") fit in RM-6039? I mean is that bellhouse space for this clutch?
Jussi

gkull

I would get over on the C-4 or c-5 forum and find out what they run with ZF trannys.

As I understand it because of the ZF's straight cut gears you need a dual mass type clutch. The clutch has to absorb the individual cylinder firing impulses because without it the ZF gears chatter.

jussi70

Thanks for advice!
Yes, I know that with ZF´s to use dual mass flywheel, but that zf transmissions noice is not problem for me.
I need to information for assembly. Is it possible to add DF612909 in to RM-6039 bellhousing?

gkull

That Quicktime is a nice bullet proof bell housing. You can use any standard 11 inch 168 tooth flywheel/clutch/pressure plate combo.

jussi70

And 12 inch too? (DF612909 12")

Is this clutch set normal push type (not pull like corvette 90-96)?

gkull

Yes, That is if your flywheels machined face is also bigger than 12 inches

http://www.jegs.com/i/Centerforce/183/DF612909/10002/-1

jussi70

Ok! Thanks a lot gkull!
I have to do order!
Jussi