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Discussion Starter · #1 ·
Have the new diaphragm pressure plates overcome the old problem of sticking to the floor at 7K rpms? If yes, what brand do you recommend?

I'm thinking of switching for lighter pedal pressure on my left foot.
 

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Discussion Starter · #2 ·
WOW, 60+ folks thought this was too tough a question to answer. I wonder if I put it in the wrong forum?
 

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Ram Clutch website has a section called "Clutch University". There's a lot of info there and some good advice.

I've had a Centerforce diaphragm clutch that had the weights added between the diaphragm fingers for the very problem that you're talking about. That clutch didn't last very long, I got stuck between gears. I've read that even Centerforce doesn't recommend that clutch for normal use and from the Ram site they talk about the extra mass those weights add, more to accelerate without any positive effect if you're just going to 5 grand.

In general, I don't know the answer to your question and am looking for it myself. Dual disc?
 

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WOW, 60+ folks thought this was too tough a question to answer. I wonder if I put it in the wrong forum?
Hahahahaha. I just have no experience with C3's and M/T's.

On an F-body, the "drill mod" fixes a lot of the sticky pedal issue that's plagued them. It opens up the hydraulic line so the fluid can move faster and not "hang up".

Sorry I'm no help.
 

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On the 'Vette in my avatar I have a Centerforce II. It sees 6 to 7 k regularly for the past 22 years. Never stuck to the floor once. Easy pedal. Only a little firmer than stock. Now C-5's...that's a different story.:smack
 

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Discussion Starter · #7 ·
Thanks for all replies. Yes Fred, I have read 'clutch university' through and through, but it didn't answer my question. So I sent Hays my question and did get a 'tech support ticket number,' but still no reply after 3 business days. Talk about s-l-o-w. But they did say, first come first answered. It must be a long line.

I spoke to Larry at Centerforce. His only recommendation was their LM271675 which is SFI tested to be good up to 9400 rpms. Problem with that one is it is very light weight...the cover is aluminum. With the roadracing M21 trans and 2.20:1 first gear, I need some weight to get it going from a dead stop.

I never had a pedal sticking to the floor problem at 6 grand. Or 6500. Just 7 grand and above. Perhaps a dual-disc setup will be my salvation. The OEM 54 pound MA6 setup (clutch/flywheel combined weight) from '69 302 Camaro's and BB Vette's would be the ticket. However, they became obsolete in the early 70's. And most of the dual discs I see now are geared for oval track racing use.
 

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My experience with the centerforce design is weights that won't stay on center, causing vibration, leading to the centerforce tech admitting that it's somewhat common and I should just cut them off.

Not, "we'll replace that year old plate that's been out 4 times chasing vibration". Not, "something is very wrong there". The answer was to cut off the proprietary weight system that's the focus of their company, because sometimes it causes problems.

What kind of pedal pressure are you willing to live with? Basically will the 70s solution of gorilla pedal, non-diaphragm clutch be driveable for ya?

Most cars with the RPM range and trans ratio you're talking have 3.73 or deeper gears. I've used aluminum flywheels on the street with those ratios and never had a problem getting it moving. Is it possible you're overthinking the need for flywheel/pressure plate mass?

BTW, How much did you pay for the tech advice here? Complaining about lack of response like we're a commercial tech line is poor form my friend.

good luck with your clutch project
 

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Thanks for all replies. Yes Fred, I have read 'clutch university' through and through, but it didn't answer my question. So I sent Hays my question and did get a 'tech support ticket number,' but still no reply after 3 business days. Talk about s-l-o-w. But they did say, first come first answered. It must be a long line.

I spoke to Larry at Centerforce. His only recommendation was their LM271675 which is SFI tested to be good up to 9400 rpms. Problem with that one is it is very light weight...the cover is aluminum. With the roadracing M21 trans and 2.20:1 first gear, I need some weight to get it going from a dead stop.

I never had a pedal sticking to the floor problem at 6 grand. Or 6500. Just 7 grand and above. Perhaps a dual-disc setup will be my salvation. The OEM 54 pound MA6 setup (clutch/flywheel combined weight) from '69 302 Camaro's and BB Vette's would be the ticket. However, they became obsolete in the early 70's. And most of the dual discs I see now are geared for oval track racing use.
69 chevy,

What engine do you have?

The current clutch I have is a Sachs diaphram-type that I bought from Keisler more than 2 years ago. It is rated for 650 ft-lbs and has a moderate pedal pressure, like a factory diaphragm. I like the feel of it and have been happy with it so far. Regular shifts at 6500 have been no problem. Just got off the phone with the Keisler Service line. They say that this clutch is good for 7000 to 7500 rpm. That satisfies my needs. Don't know if that helps you.

Do you have a Lakewood or similar steel bellhousing?
 

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Discussion Starter · #10 ·
69 chevy,

What engine do you have?

Do you have a Lakewood or similar steel bellhousing?
My engine is the old school way. A '64 283 punched out .090" for something like 297 cubes. I was afraid to go all the way to .125" overbore lest the cylinder walls get too thin. This isn't an all out performance engine anyway, so better to be safe than sorry. I am using the OEM 168 tooth flywheel from the truck I plucked the engine from and a Scheifer Revloc 11" B&B design PP and disc. It takes all the revs I can give it and has been working fine for a very long time. Although there was that spell of rattling somewhere in the clutch area on my way to the Carlisle event this summer. So something's not long for this world.



The problem is it has very stout pedal pressure and somewhere along the years I lost the data sheet that says to throw out the disc when it wears to a certain minimum thickness. I'm not getting any younger and I'm not about to tear into just a clutch disc replacement.

I'd like to kill 3 birds with 1 stone, so to speak. I want a 153 tooth billet steel flywheel, a light pedal pressure 10.4" diaphragm PP and a clutch/flywheel package that comes close to matching the OEM MA6 dual disc clutch weight of 54# that backed the 302's in the 69 Camaro. Of course it also has to be able to shift at 7 grand + and be SFI rated.
The only reason I installed the 11" clutch was the local speed shop had it on the shelf and the owner said he could give me a heluva deal. But now my left leg can't take the high pedal pressure anymore. So it's time for a modern clutch with modern technology. I don't think I'm asking too much.

I spoke with Summit, Jegs and lastly McLeod's tech staff today. Hays has not gotten back to me in 4 days, so screw them. I'll spend my $$$ elsewhere. Luckily there are other choices.

I have come up with McLeod's RST dual organic disc/billet flywheel combo #64003-00-04. Bill at McLeod says that package weighs 47#. So it should have the mass to propel my 3100# car off the line despite its 2.20:1 first gear and 3.70:1 final drive similar to the Camaro. Bill said it's definitely overkill for my situation since I only guess to be making, at most, 400 hp at the crank. But he says it's very street-worthy and should last a very long time. He said even the next owner should have no problems with it.

I know I could probably get away with a less expensive single disc setup, but I've owned this car for almost 39 years, I've been enjoying it for most of my adult life, so nothing is too good for it.

Yes a Lakewood blowproof bell. I never wanted to endure a Don Garlits foot. Like I said, better to be safe than sorry.

Slow & leaky...you're right. I should have just typed 'back to the top.' Forgive me my petulance? :cheers:
 

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My engine is the old school way. A '64 283 punched out .090" for something like 297 cubes. I was afraid to go all the way to .125" overbore lest the cylinder walls get too thin. This isn't an all out performance engine anyway, so better to be safe than sorry. I am using the OEM 168 tooth flywheel from the truck I plucked the engine from and a Scheifer Revloc 11" B&B design PP and disc. It takes all the revs I can give it and has been working fine for a very long time. Although there was that spell of rattling somewhere in the clutch area on my way to the Carlisle event this summer. So something's not long for this world.



The problem is it has very stout pedal pressure and somewhere along the years I lost the data sheet that says to throw out the disc when it wears to a certain minimum thickness. I'm not getting any younger and I'm not about to tear into just a clutch disc replacement.

I'd like to kill 3 birds with 1 stone, so to speak. I want a 153 tooth billet steel flywheel, a light pedal pressure 10.4" diaphragm PP and a clutch/flywheel package that comes close to matching the OEM MA6 dual disc clutch weight of 54# that backed the 302's in the 69 Camaro. Of course it also has to be able to shift at 7 grand + and be SFI rated.
The only reason I installed the 11" clutch was the local speed shop had it on the shelf and the owner said he could give me a heluva deal. But now my left leg can't take the high pedal pressure anymore. So it's time for a modern clutch with modern technology. I don't think I'm asking too much.

I spoke with Summit, Jegs and lastly McLeod's tech staff today. Hays has not gotten back to me in 4 days, so screw them. I'll spend my $$$ elsewhere. Luckily there are other choices.

I have come up with McLeod's RST dual organic disc/billet flywheel combo #64003-00-04. Bill at McLeod says that package weighs 47#. So it should have the mass to propel my 3100# car off the line despite its 2.20:1 first gear and 3.70:1 final drive similar to the Camaro. Bill said it's definitely overkill for my situation since I only guess to be making, at most, 400 hp at the crank. But he says it's very street-worthy and should last a very long time. He said even the next owner should have no problems with it.

I know I could probably get away with a less expensive single disc setup, but I've owned this car for almost 39 years, I've been enjoying it for most of my adult life, so nothing is too good for it.

Yes a Lakewood blowproof bell. I never wanted to endure a Don Garlits foot. Like I said, better to be safe than sorry.

Slow & leaky...you're right. I should have just typed 'back to the top.' Forgive me my petulance? :cheers:
Interesting engine you have there. Like the mag.

I had a Hayes pressure plate, which had some external riveted washers on it. One came off and rattled around. For an encore, it shot off a second one. It's thrilling to see one of these washers sticking out through the factory bell housing. So I think you'll do ok not getting a call back from Hayes, particuarly with the revs you run. McLeod was on my schedule to call today, until I got the news on the Sach's clutch I already have. I'll find out first hand if it's good for 7000 plus shortly. I may still end up with a twin disc. Lakewood housing going on the car now.

Keep us posted.
 

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Discussion Starter · #12 ·
That Vertex is another thing I had laying around since the mid '70's so I decided to use it. Except I had to turn the base 180 degrees to make the mechanical tach drive turn in the proper direction for the vette's tach. Luckily Pat Mason Racing Ignitions is only a half hour away and he did it while I waited.

I forgot to ask McLeod this question. My engine is balanced. Do I need to have this new clutch/flywheel assembly balanced or is McLeod's factory balance good to go?

If I was picking and choosing individual parts, the answer would be obvious. Send it out to be balanced. But this is a complete assembly and should be balanced as a unit right from McLeod. Opinions?
 

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At 7000 I would consider having a local performance machine shop balance your flywheel and pressure plate assembly. Mcleod is probably going to sell you a couple different boxes off a couple different shelves, that have never been assembled as a unit.

Even if the machine shop says they're perfect you've got peace of mind that you've done everything for bearing longevity and shift smoothness. Any flutter traveling thru the pressure plate housing will translate into it's shift action

Very neat little engine, now the clutch comparisons to DZ 302 are understood. Good luck with the project :cheers:

BTW the condition of the clutch linkage can make gorilla pedal extra bad, factory pivots are usually worn out at this age, and replacement parts seem softer and faster wearing. I haven't seen much discussion of it on the vette forums but chevelle racers looooove spherical rod end clutch linkages. Food for thought........
 

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Discussion Starter · #14 ·
Slow & Leaky,
Your recommendation was spot on. Another long distance call to McLeod's tech Bill confirmed this clutch/flywheel assembly needs to be balanced. No beating around the bush, no if's, and's or but's...get it balanced.

Another thing to add to my to-do list. Now I need to find out if my old machine shop is still in business.
 
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