ACT clutch engagement noise

[Thisguyuknow]

Also on that thread I shared some direction I can take to possibly alieviate the noise issue. Since I haven't experienced the issue (and most don't) I need more information:

"After seeing how many other stock applications have this issue, the "chewbacca" noise is more common that I ever thought. I have thoughts on possible design changes such as increased marcel as mentioned before, narrower friction material, smaller disc, alternative friction material (all have various tradeoffs of course), but more data is needed first.
I cannot monitor this thread all the time so if you are experiencing the noise issue, please contact me directly either by DM or email at [email protected] so we can gather more detailed information to narrow down the options. I would specifically like to know:
1. Your name and when/where the clutch was purchased?
2. How many miles have been put on the clutch when the noise began?
3. Where does the clutch engage/disengage in the pedal travel?
4. How severe is the noise? Does it occur anytime other than in first and reverse?
5. How difficult is it to avoid the noise when engaging?
6. Gearing and tire size?"

I too am having the noise issue, I dmed you the answers not the listed questions.

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[koldfront_xj]

Late to this thread. Email sent @ACTman

 

[Mr.Turtle]

Did this ever get fixed?

 

[ACTman]

Did this ever get fixed?

Sort of... Let me explain what I found. I only received a handful of people with feedback, and as we were waiting for data and time for testing, clutch sales have soared but the noise complaints stopped. This seemed strange until we did some testing.
On the Jeep JL/JT, we use very little marcel (cushion between the clutch disc linings) to reduce the travel required to operate the clutch, which raises the engagement point and reduces the chance of clutch drag. We found in the past that increasing the marcel reduces the chance of the "Chewbacca" sound. This is a game of thousandths of an inch. When noise complaints started, we tested the cushion leaf used and it had about .008-.009" of cushion (bottom end of our tolerance). We analyzed one of the original test installs (no noise) and we aimed to increase the marcel from .008-009" to .013-014" in hopes that travel would still be good. But what we found is the test vehicle already had .012" of cushion (high end of our tolerance) so the test was unnecessary. Although it did tell us that travel wouldn't be a concern. I then tested the cushion of current production and they had .010-.011" of cushion. That explains why we are getting fewer noise complaints. From those results we "nudged" our tolerance range slightly going forward. I can't guarantee 100% but think the noise will be mostly eliminated. Another approach is to use a different friction material, but that would require a lot of testing and evaluation and the practical options are limited.

 

[Tommy_P]

Just curious if there is judder associated with the noise? I installed the act clutch kit on my 21 sport back at the end of December. I started experiencing judder in reverse only after a few days that i remember. After some time (today) i started noticing judder on clutch engagement in first gear. It's a very noticeable shudder as the clutch starts to engage. If i throttle up the judder isn't noticeable but if i just let out the clutch pedal with no gas the judder happens as soon as the clutch starts to catch. I'm not sure what is causing this issue, but it seems to be getting worse. Looks like I'll be dropping my transmission again... Not really something I'm looking forward to.
I did check all of the mounts and everything seems in tact. All fasteners are tight and in place. If anyone has any insight, please help.

 

[ACTman]

Sorry for the delay. No, the noise is not associated with the judder. Although we expect the ACT clutch to be more aggressive, if the judder is not easy to avoid, this is not normal. There are a few things that could cause this related to the parts or the install. With the tight tolerances we must deal with, there is not much room for error. If we were to inspect and/or test the parts, we could find out why this is occurring for instance:
1. uneven diaphragm fingers - either from install or pressure plate issue. Sometimes this can be corrected by just loosening the clutch bolts on the side where the fingers are lower.
2. pressure plate lifting unevenly. It will show a hot spot, also a pressure plate issue.
3. uneven disc thickness - when the clutch disc has a thick spot.
I would like to at least get you another clutch disc to hopefully help with the noise, but you may need another pressure plate.

 

[Tommy_P]

Sorry for the delay. No, the noise is not associated with the judder. Although we expect the ACT clutch to be more aggressive, if the judder is not easy to avoid, this is not normal. There are a few things that could cause this related to the parts or the install. With the tight tolerances we must deal with, there is not much room for error. If we were to inspect and/or test the parts, we could find out why this is occurring for instance:
1. uneven diaphragm fingers - either from install or pressure plate issue. Sometimes this can be corrected by just loosening the clutch bolts on the side where the fingers are lower.
2. pressure plate lifting unevenly. It will show a hot spot, also a pressure plate issue.
3. uneven disc thickness - when the clutch disc has a thick spot.
I would like to at least get you another clutch disc to hopefully help with the noise, but you may need another pressure plate.

Hey Dirk, I've been trying to get all my info together for you. I've been busy with a honey do list. I'll try to email you tonight with all your requested info. When i installed everything i was sure to check that the fingers were even. Anyway I'll try to get that email to you. I took a video the other day for audio, I'm not sure if I'm hearing the Chewbacca noise or what. I'll let you decide. Thanks,
Tommy

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