Clutch Replacement Advice

[4WDlifeform]

My original clutch held up to a 550ish HP build for 30k and occasional 1/4 mile runs. Plus, 40k at stock power. Now, have a new re-build coming, engine just dynoed 600hp at the crank. Stock LS3 block, cam/bolt-ons/tune/internals.

Should I upgrade or shove a new GM clutch back in?

My builder re-ground the flywheel for me, so I'd like to use OEM fly wheel. So, that limits my aftermarket clutch options.

Rock Auto has an Exedy option (higher than OEM rating, single disc organic) that looks appealing. But, it comes with slave cylinder. I did not plan to replace mine. But, should I? I'd rather not deal with bleeding the clutch fluid.

Thanks for any help/advice.

[Fanch1LE]

The clutch choice is wide open for discussion. I'm sure you'll get plenty of input here.

100% replace your slave cylinder! Also get the billet release bearing support for the new slave cylinder. Do yourself a favor and install a remote bleeder line. Bleeding the clutch will be a breeze.

Tick Performance has great pricing right now on their Labor Day sale. Not sure when it ends. I just picked up a Monster clutch, new slave cylinder, etc for a great price, and got a free t shirt.

[CamaroCracka]

IIRC, only replacement aftermarket clutch I thought would do well was from Spec, but I went with the Mantic anyway. You're at the limits of single disc from any mfg, so I would think hard about just going with a double setup.

GM OEM clutches almost always come from Luk, so don't get overly excited about OEM.

I've never used Exedy, but they used to make some high end diesel clutches that apparently worked well.

If you get an extended bleeder line from a mfg like Tick, bleeding the clutch is a much simpler task. It would also be a good time to put in a dedicated fluid reservoir. Those things make maintenance much easier.

Might also want to think about installing a billet bearing support while you're swapping the slave.

[fz4k98]

I'm on summer number 3 on a spec3+ and my car dynod 610 rwhp. Ive had 2 twin disks and really prefer the spec single disk. It drives like stock and handles the power on slicks at the strip.

[4WDlifeform]

Here is the link to the Exedy from Rock Auto. For the way I plan to drive the car, I'm going to give this a try.
https://www.rockauto.com/en/moreinfo...=1993&jsn=1015

This kit comes with the pilot bearing and slave cylinder. And reasonable price. I should be able to use my re-ground OEM fly wheel.

I've already done the clutch reservoir, so adding the remote bleeder from TICK is a great idea. And the billet slave support.

Should I order a shim kit from TICK as well?

Thanks all for your thoughts!

[fz4k98]

The shim kit will help but be prepared to also make a custom shim to get the dimension you want to achieve as the kit does not have a lot of variety to get the correct number. Correct measuring and shimming is critical.

[4WDlifeform]

Wondering if I am getting the shim measurement right here. According to TICK, take measurement A (3.331") minus measurement B (3.255") and I am getting .086". So, I think I need to add a shim to get between .125 and .188. I have a .055 shim which gets me to .141" final. Seems good. Right?

But, thinking about this, when I assemble the engine to the bellhousing, the engine dimension is larger. So, it will compress the slave fully, taking up the 3.255 in my case. But, the engine will need to go on the .086" further, thus pressing the pressure plate in that much. Isnt that bad?? I would have thought that the B measurement should be larger by .125 to .188.

Should I shut my logic brain off, and just follow the instructions!??

EDIT: My B measurement is to the throw out bearing face, not the end of the shaft like I sketched. I'm 99.9% sure I did the measurements correctly.

[CamaroCracka]

According to your numbers there is too little room between the CSC and pressure plate. You don't need any shims. In other words, a shim would be making your 3.255 bigger and your .086 number smaller. I'm not aware of any way to adjust for when the CSC bearing is less than .125 from the pressure plate fingers, although most clutches are self adjusting these days.

Edit, I guess they do have bell housing spacers, but not that thin.

[4WDlifeform]

Thanks for the comment. What do you mean by "self adjusting"?

I just talked with a coworker who ran into this very issue on one of his cars. He had to do the bell housing spacer. He made it himself using the bell housing as a template.

I think I am going to pull the bell housing off, and bolt it to the motor to double check my measurements. If I confirm the .086" interference, I'll be making a 1/4" spacer to get me between the 1/8" to 3/16" clearance. I just hope that doesn't mess up the transmission mount to the chassis?

We also talked that since my engine builder ground down my flywheel, when the clutch was tightened up to the flywheel, it would position the fingers out a bit contributing to the interference problem. Plus, aftermarket clutch.. I guess this is just how it all falls.

[fz4k98]

If it were mine to do, I would not be removing the bellhousing as it is a critical fit for internal bearings and fluid pump. Put your efforts into ensuring correct measuring. When assembled, the slave is compressed most of its travel. The measurement that they want you to achieve ensures the slave is not fully compressed and there is some room for the clutch wear overtime that will reduce the gap.

Too little gap and pressure plate will not fully apply to clutch, too much and the pedal travel will not disengage the clutch.

[Fanch1LE]

Just curious where you got the 0.125 to 0.188 clearance spec. Not saying those numbers are incorrect, just want to confirm that you got that number from Exedy. I'm assuming it was on instructions that came with the clutch?

According to the product description from Exedy, "This kit is a direct OE replacement Performance Clutch Kit and will not require any modifications during installation."

Do you know how much was taken off your flywheel when it was resurfaced? If we're talking just a few thou, which I suspect, then I'd say you're good to go.

Monster recommends 0.080" to 0.100" gap measurement, but I understand that is specific to their product and is likely different for Exedy. I think McLeod calls for 0.18ish.

[4WDlifeform]

Yeah, after researching that the bell housing isn't really removeable, I am going to leave that be..!

Re-checked my measurements again with help, and getting within a few thou of what I got the first time. So, I am quite certain that once I smoosh all this together, the slave will be pressing the clutch fingers .086". Which, as I understand it, is bad.

My builder only took about .008" off the flywheel. Clutch is properly torqued down. I am not sure why I am in this situation, but I believe it is what I have to deal with.

Searching now for a bell housing spacer, maybe 3/16" or 1/4".

I got the .125 to .188 just from general researching what is the acceptable gap on our Camaro. I do not have anything from Exedy providing this measurement. As you said, it is intended to be a direct replacement. Knowing what I know now from taking these measurements, I can't think that just bolting this in and running it is going to be wise.

[Fanch1LE]

Oh crap I didn't notice that the gap was negative. I read through too quickly. Yeah, lol, that's not gonna work.

[CamaroCracka]

Based on your drawing, you will have .086 before the slave is fully compressed. The bearing is supposed to ride on the pressure plate on these and other cars. The CSC just can't be fully compressed or more because your clutch will always be partially engaged. I'm in fz4k98's camp where if it were me, I would run it as is, but it could wear the clutch a little early. I would even go with another clutch before I spaced the bell housing, but I don't like spacers. You should also make sure the CSC is seated properly and nothing is pushing it away from the input shaft a tad.

I'm not exactly sure how self adjusting clutches work, but on my truck clutch there was a tang with a spring on it that moved the pressure plate fingers a slight amount. They don't take up a lot of gap, but will make up a bit of the difference.