Hi All
The clutch has begun to slip in my 84 Corvette (L83 Dough Nash 4+3) so I am in the market for a new clutch kit. I would be happy with genuine GM parts but a quick look on the internet turns a blank. So I'm hoping someone can point me towards a quality clutch kit. I think it's a 26 spline 1 1/8" shaft and possibly a 10.4" clutch plate although some clutch kits state that they are 10.5" (not sure whether or not this makes a difference or is just a rounding error).
Summit have McLeod Street Level Clutch Kits Summit Racing Part Number:MCL-75025which looks ok I think and Zip have this one https://www.zip-corvette.com/71-72-8...plate-kit.html
I'm just looking for a good daily driver type of clutch. The car is not making big HP so a racing clutch is not necessary and I don't want any shuder.
Please let me know your thoughts and recomendations.
Regards Greg

 

I install LUK brand here are stock replacement units and they perform very well. Quality is good. No complaints so far!

You can search/price them and some other brands on sites like www.rockauto.com

 

OK
Thanks for the info confab.
Just had a look at rockauto they are pretty cheep as well.
Regards Greg

 

For some reason there seems to be a lot less info here about clutches for the 4+3 cars. Carolina Clutch has a good reputation among the ZF6 crowd. I see they have a kit for $77 (!) that appears to be the LUK brand, too. Since a 1984 is an old-school (two-piece rear main seal) SBC with a Borg Warner Super T-10, I guess this is as bog-standard a clutch kit as they come.

 

 

Hi All
Just a quick update. I purchased a McLeod MC75125 Street Pro. The reason I purchased this one was primarily that it was available in Australia. I was unable to source a LuK 04-019 locally and I could get a street pro for less than the standard McLeod MC75025. Hopefully this will not be too much clutch for my current engine performance. Anyway I will let you all know how it goes.

 

Let us know what you think about it. That's quite an expensive kit here in the US compared to some others, but distance makes all kinds of difference to price and availability. That disk has an organic material on both sides, so I think it will be a good choice.

 

 

Its after the fact but.... I went with a Centerforce Dual Friction, and couldn't be happier. Originally looked at it for its ability to handle much higher torque than stock. But after I got it, I was blown away by how light the clutch pedal was. Takes half the leg strength that my previous stock clutch took. So much easier to drive in bumper to bumper traffic now. .

 

 

Although 4 years prior this thread is filled with knowledge (much appreciated) that is applicable to me today. - I installed a LUK clutch set, replacing the a perfectly working Mcleod unit for the sole purpose of reducing pedal effort. With "luk" ( no pun intended) If I slowly let the clutch out with the engine idling (900 rpm), I get that dreaded clutch shudder through the drive train. If I pick the RPMs up to 1500 and then let the clutch out/engage, the transition is smooth and not a problem. Installation went perfect, nothing is bent or broken.

I was told that I need to break the clutch in and it will work fine in 500 miles? or Because I have a Comp Cam version of the L79 cam, the problem is a function of low and erratic engine torque at low RPMs which resonates through the drive train, which seems feasible. I think the Mcleod was smooth even at idle, but because I also improved the carburetor transition circuit, things are not the same.

I don't really buy into the "break-in" thing and am dreading pulling the pressure plate out to check for uniform engagement. ( I think both Dan and bj1k would recommend that).
1. could I be wrong about break-in?
2. am I expecting too much to be able to engage the clutch smoothly at idle wit a somewhat radical engine?
Thanks,
Aaron

 

I would definitely drive and break it in first to see if it improves.

I just ripped out my entire setup and went with a RAM conversion with organic disk and steel flywheel.

No shudder/chatter at all so far, highly recommended.

 

This is certainly a possibility, and it's definitely worth a try.

Negative, Ghost Rider! This isn't how these things work.

No. Unless you have a metallic or kevlar disk friction material, that is. If your disk is organic it should work smoothly. I just helped a friend replace the disk in what used to be my 96, which has a 396 with bigly ported heads and a cam with significant overlap. It's a fast car with a lope at idle, and the new organic disk in it is very smooth during engagement. The Centerforce Dual-Friction disk and SPEC Stage 2 kevlar disks before that chattered.

 

I just went through the exact same issue with my 91 Zr1 with a SPEC clutch kit and I was told the exact same thing. The problem never got better. Long story short, I took the transmission out and replaced the Chinese SPEC pressure plate with an original Valeo Pressure plate and my issues completely disappeared. I now have no shudder at all. As said before on this forum, all the pressure plates that can be bought today come from China and it seems to be luck of the draw if you get a bad one or a good one. When I took out the pressure plate, you could see one side completely hot spotted. It was clear that it was not clamping with even amounts of force.

 

While I generally agree with your post, I should note that my Centerforce Dual-Friction disk chattered even though I had a factory OE pressure plate.

 

I agree there are many other factors that cause chatter/shudder. But in my case, my whole car would shudder violently going into 1st and reverse as if the clutch was about to come apart. It was clear that it was not normal and that it would not get better.

 

So it sounds like the probability is high the the Luk clutch set is going back to Summit, and the hunt for a new low effort solution will start.
I did not realize the Luk was from china.

 

How bad is the shudder you are experiencing and how many miles have you put on it? If it's pretty bad like it was in my car, you do risk hotspotting the flywheel by continuing to drive it. That is what happened to mine.
- Scott

 

They are ALL from China. And from the same foundry. The only quality ones are NOS OEM but those are now pretty much unobtanium.

You can procure a new PP via ZFDoc. He attempts to correct and true up the pressure plates to regain even clamping pressure.

If your DMF ends up shot (you are already SMF?), you have options with the stock setup…however

Not to keep harping on this but strongly recommend the RAM setup. The organic disk with steel FW is rated 450-500 hp capable. They also have non organic and aluminum options depending on your needs.

We haven’t even gotten to the issues with TO bearings…

 

If someone's goal is to have minimal pedal pressure from a clutch, The only BEST option in my opinion is getting the Centerforce Dual Friction solution. The complete Kit - that includes both Friction plate and pressure plate togeather as a match set, balanced ready to go.
Centerforce solves the pedal pressure issue by using leverage. (A huge unique benefit over other manufacturers). It has a much easier pedal than stock, without compromising holding performance. Easily holds up to 600hp. And its been as smooth as any clutch that Ive ever used. Its expensive, but worth every penny. Its the only Clutch that I will use on my street / HPDE cars now. With that said, on my Road Race Car, I've burned to shreads a Centerforce Dual Friction clutch. I've recently replaced with the Centerforce Puck style Friction pad, and it seems to holding up better, although a bit clunky at idle. Have about 4 race weekends on it so far. We'll see. With that said, the Mcleod and RAM are nice products and have their place. Maybe they'll hold up better in race, drag or High torque configurations, I dont know. But low pedal pressure isnt their place. The stock Clutch was heavy on the pedal. Thats the primary reason I changed to Centerforce, to get that pleasant to drive light pedal.

Regarding your LUK problem.... If the car is shuttering with just a basic organic pad, only at low IDLE RPM, the Clutch is grabbing to much for that idle speed, or torque is to little for that grab. That can be for many different reasons. The loopy idle CAM suggestion is a possibilty. I know other said its not a problem, but their car may not be tuned the same as yours. Could be an adjustment issue, the pressure plate engaging to far to fast. (throwout bearing or ball stud or master/slave cylinder not properly adjusted. The MCleod may use a different length ball stud, than the stock LUK (depends on setup). It surely would need to be adjusted to a different depth, switching from Mcleod to LUK. Could be an alignment or balance issue. Often people bypass the step to balance the Flywheel with the clutch before installing, or dont properly dial caliper align the bellhousing/trans. (although technically, bellhousing should be good at reinstall, if it was good prior to install). Or could just be a poorly made out-of-tolerance Made-in-China part.

What I do know is that its a pain in the butt to swap out a clutch on a Vette, without a lift. Its worth putting in a good quality clutch from a trusted manufacturer, the first time. Cause you just don't know, until after the car is put back togeather.
I realize the LUK may have been a factory equivellent. But they dont make them like they used to. A lot of people have expressed good results with the RAM brand, and I'd agree its a reliable well made product. But RAM doesnt have a light pedal.