Clutch Out, Which Should I Buy?

[cvette98pacecar]

Originally Posted by efnfast

Robert, do you have experience with this? I do.

Steve, if you are talking about the shifter the answer is yes, I have one of each installed in each Callaway.
As for the Ram dual disk,I do not as of yet. All of my past race cars had Powerglide transmissions and currently none of my Corvettes need a clutch so I have not updated to the RAM. Black LPE will be the first to get one. I have talked with several of our members with the big HP big cube cars and they sware by them.

My thought is if you are going to resurface your DMF, recondition your slave cylinder, replace your clutch, throwout bearing and clutch fork. You are at somewhere between $800-$1000. Why not upgrade for an additional $300.

Have you had a bad experience with the DD?

[efnfast]

Robert, I did a Ram single disc, pressure plate, light weight flywheel, and hydraulic throw out recently. I'm not ready to post about it yet.

[cvette98pacecar]

Originally Posted by efnfast

Robert, I did a Ram single disc, pressure plate, light weight flywheel, and hydraulic throw out recently. I'm not ready to post about it yet.

Please let me know how you like it, as well the rattle compared to the fidenza. I am going to do dual disc.

[efnfast]

I'm holding judgment on how I like it. The rattle is horrible, even part way up the rpm range. I have to keep a lot of torque on the tranny to keep it quite. I can't compare to a Fidanza. I have one, but have not had it installed. The Fidanza is what started the whole clutch install.

[cvette98pacecar]

Originally Posted by efnfast

I'm holding judgment on how I like it. The rattle is horrible, even part way up the rpm range. I have to keep a lot of torque on the tranny to keep it quite. I can't compare to a Fidanza. I have one, but have not had it installed. The Fidanza is what started the whole clutch install.

Frank, Had a steel flywheel made by Ram to replace the Aluminum one. I think I am going to go that route to get rid of the rotating noise.

[Bob Eyres]

Originally Posted by BigIke

Bidwell, what was the clutch?

I spoke with Jim at length, I like how my clutch engages and disengages. Looks like i'll be going with a NOS pressure plate and clutch, will reface the flywheel.

Wise move.
I've had a number of different clutches in my car over the last 20 years and 66K mi. with a fair amount of 1/4 mi. runs. The stock units have never failed. But my car is a stock block 350.
The natural impulse is to freshen, or upgrade the clutch if you've got the trans out. But unless the faceplate on the clutch is really beat up, I'd leave the stock pressure plate in. Just pop a fresh disc in there.

I'd like to learn more about the dual-disc setups. Are there more advantages to that than it's ability to handle the extra torque of a stroker motor?

[XfireZ51]

Here's an interesting thread from the ListServ in 2002.

http://maillist.corvettemuseum.com/c...&F=&S=&P=21713

I have a Fidanza on my ZR and have used one for close to 10 years including on my 84 Xfire w the ZF-6 Trans-plant I did. Although I do have the neutral idle rattle, it only becomes noticeable after the car has been run hard. Part of the reason I use the Camaro disk is because it is a "sprung hub". The hub helps absorbs some of the engine pulsing responsible for the ZF gear rattle. This in combination w the use of the heavier weight Castrol trans fluid does a good job dampening the rattle which occurs only at neutral idle. I have never heard my trans rattling under gas whether just cruising or hard acceleration.
Just switched to Amsoil Manual Synchromesh for the trans. In a short drive home from Pete's garage, I honestly didn't notice any difference in shifting. Jury is still out on whether trans rattles more or less than w Castrol.

[A26B]

Originally Posted by Bob Eyres

Wise move.
I'd like to learn more about the dual-disc setups. Are there more advantages to that than it's ability to handle the extra torque of a stroker motor?

I had a long discussion with Jim Janik a couple of days ago. If you are not familiar with Jim J's reputation, he is to the C4 clutch as Bill Boudreau (ZFDoc) is to the ZF6 transmission.

The original clutch is a good clutch. As long as you can maintain it with operative parts, stay with it. That is, unless you have more than roughly 500 RWHP.

The real problem is the ZR-1 clutch system is 20 years behind the last model produced. NOS, or NOS quality equivalent, replacement components are getting very scarce and expensive when available.

1. Flywheel: ZR-1 Abt $1,350 NOS. Very Rare! Unique & expensive. Can be resurfaced but only by experienced shops.
2. Pressure Plate: Abt $375 NOS. Very Rare! Stock is 3000lb, Shorter L98/LT1 style 2800lb. Can be re-used, resurfaced but requires adjustment to maintain clamp force
3. Release Bearing: Abt $225 NOS. NOS quality is non-existent & expensive. All are aftermarket Chinese mfg of poor quality.
4. Clutch Fork: Abt $225 NOS. NOS is virtually non-existent, Expensive & not likely to be reproduced.
5. Fork Ball Stud: Abt $35 NOS. NOS scarce but around. Could be reproduced but impractical due to lack of other components
6. Slave Cylinder: Abt $200 NOS. Rare. NOS reconditioning $75~100 with core. Aftermarket quality varies greatly

In summary all of the original ZR-1 clutch components are like a chain... only as strong as the weakest link. In this case weak means availability & cost. For the LT5, the uniqueness & limited production is what will ultimately claim extinction of the ZR-1 original clutch. There is not a large enough market to justify tooling & manufacturing of the flywheel and pressure plate for sure. Even if it did, the quality evidenced thusfar by the reproduction of the release bearing, means it's unlikely to be of serviceable quality. Jim J. told me that ALL Valeo parts today are made in China. Metallurgy is the big concern.

In terms of availability, I rank the components as follows. First on the list being the first part to become extinct.

1. Release Bearing: What is available through aftermarket suppliers is junk
2. Pressure Plate: Insofar as ZR-1 original 3000#. Possible to rebuild, not practical due to finger/spring availability & skill to properly recondition.
3. Clutch Fork: Cracked & bent can be repaired, but will eventually wear out.
4. Flywheel: Used will be around, can be reconditioned by experienced shops
5. Fork Ball Stud:
6. Slave Cylinder:
7. Clutch Disc: Common

The above reasons are why I decided to become a distributor for RAM clutches, specifically because of the HRB (Hydraulic Release Bearing). The HRB is the method of choice by auto manufacturers today. Using an HRB requires conversion from the stock style "pull=release" to the more conventional "push-release" clutch.

Even disregarding availability, the economic viability of maintaining the OEM flywheel & clutch is already an issue.

Also gone, unfortunately, is the choice of a dual mass vs single mass flywheel. Increasing the weight of single mass flywheel will lessen the transmission gear rattle caused by engine power pulses, but not as effectively. Increased idle speed and good state of tune will also help.

A few words on installation. Conversion of the ZR-1 from "pull-release" to "push-release" is not quite like a normal clutch job with simple "out with the old & in with the new," nor is it a complex job. It just requires common sense attention to details,a basic understanding of how it works, and decent mechanical skills. For our inventory, I am working on refining RAMS conversion kit and the various mix & match possibilities of flywheels & clutches, which is pretty extensive. My goal is to take RAM's excellent component kits, work with RAM to tweak it a little to become a straightforward, step-by-step, plug & play installation, complete with ZR-1 specific, instruction guide & pictures. It's going to take some time, but we are getting there.

I know this is an extensive subject & I haven't begun to address it all, but it's a start.

[secondchance]

Jerry,

I totally agree with your assessment. Luckily I have one fresh set of OEM replacement release bearing, clutch and pressure plate plus a couple more OEM release bearings.
Once done with what I have, I know I have no option but to give up OEM set up. Thank you for pioneering Ram dual disc set up.

[Paul Workman]

Jerry, I see the RAM clutch listed on your site as a fit for the 89-92 ZR-1s(?). That's good for me, since Ami's and mine are covered. But, curious as to what changed that the clutches wouldn't fit/be appropriate for a 93-95 MY Z?