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terrible rattle from clutch?

Old 02-10-2017, 11:53 PM
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Default terrible rattle from clutch?

I have a terrible rattle that I need help diagnosing. It's in my 97 Miata, 5-speed, GT2554 turbo, methanol injection. I know I should just pull the transmission and take a look but I thought I'd see if anyone might know for sure what's going on. Here's the video of the rattle:


As I mention in the video, I know it's not bad engine mounts or exhaust hitting the bellhousing.

Thanks.
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Old 02-11-2017, 12:52 AM
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Two things come to mind , exhaust hitting somewhere on the rear subframe or less likely a bad u joint. Happy hunting.
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Old 02-11-2017, 07:11 AM
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I would get under that thing and sort out what it is.
It seems the application of torque is either exposing a failing driveline joint, you may have a loose/misadjusted PPF, or may have a rear end loose and floating about as a result of completely failed bushings.
Only one way to find out...Get under the car!
I would not drive it until you get it squared away

It could be clutch related, but clutch related sounds are generally constant.
Could be a lot of things
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Old 02-11-2017, 08:57 PM
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Here's what I discovered under the car.
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Old 02-11-2017, 09:39 PM
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That would do it , alright. Fredb
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Old 02-11-2017, 10:13 PM
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You can make a temporary fix by wrapping 2-3 zip ties (or a hose clamp) around the rubber exhaust hangers to tighten them up. That should help isolate the exhaust.

Even if it's not related to your sound, I'd suggest making sure the PPF is adjusted properly. It's pretty common for people to forget to align it after spending hours under the car working on a clutch. Only takes a couple of minutes.
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Old 02-11-2017, 10:26 PM
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Kind of looked like the exhaust was impacting that point all right.

Also could be you are getting contact because the PPF measurement is set wrong allowing your transmission to sit lower than necessary.....Just a thought.
Just set our NB, but I have seen a different measurement for the NA..not 100% sure on that.
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Old 02-11-2017, 10:34 PM
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Well, I strapped my camera under my car to watch that point while I made it make the noise. Determined that it isn't the exhaust hitting the bellhousing. I'll mount the camera in a couple more spots to try to locate.


Wish I could strap myself under the car like Robert De Niro in Cape Fear.
Too low for that...
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Old 02-11-2017, 11:14 PM
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All the axle and driveshaft joints seem good?
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Old 02-11-2017, 11:31 PM
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They seem ok. I have a different driveshaft I could put on. Also, what happens if the PPF isn't aligned properly? Just more angle on the driveshaft than is good for it? Are noises like this a symptom of bad PPF alignment?
I wonder if I could reproduce the noise if the car was put in gear while on jackstands.
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Old 02-12-2017, 12:45 AM
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I don't know if PPF alignment itself can make that noise...No idea, but I doubt it.
I would be more suspicious of bad PPF alignment will create longer term joint wear issues.

Any vibration or movement through the clutch pedal?
Can you feel it in the shifter?
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Old 02-12-2017, 05:29 PM
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No movement in the clutch pedal. I can feel the clunk in the shifter. Next, I'll mount the camera pointed at the clutch slave cylinder and release fork.
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Old 02-13-2017, 11:27 AM
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I have the same problem with my Miata. It started after I installed a new transmission and a pucked sprung clutch. I had a shop realign my ppf when they did my motor mounts, but it didn't seem to fix anything. My exhaust is pretty stable, so I don't think it's that. It does seem to be coming from behind time though. Hopefully I can add some additional helpful diagnostic information.
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Old 02-13-2017, 12:54 PM
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I have this exact same problem. Mine started after installing a used transmission and a new flywheel/clutch. I tried replacing the driveshaft but that didn't fix anything. I am thinking it's just slop in the driveline somewhere. I found some old threads at miata.net about the same issue and it seems like a lot of people have it, but no solution was found.

When I'm under mine and I rotate the driveshaft by hand there is some slop in the transmission gears that I think might be making the noise.

Last edited by spals; 02-13-2017 at 02:54 PM.
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Old 03-14-2017, 11:34 AM
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Have you been able to record any more videos?
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Old 03-29-2017, 11:11 PM
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Originally Posted by spals View Post
Have you been able to record any more videos?
No. I have given up trying to track this down until I drop the transmission and look inside. However, I have noticed that, when the rattling starts, I can quickly put it in neutral and the rattling immediately stops. That's probably an important clue...
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Old 04-07-2018, 05:40 PM
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It's been over a year and I finally had a reason to drop my transmission. Looked inside the housing and saw that the clutch release pivot ball was broken. The release fork was just wiggling.

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Old 04-07-2018, 09:17 PM
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Props/Pos-Cat for posting a conclusion to a (long lived) troubleshooting thread....
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Old 04-08-2018, 10:57 AM
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Good find man, glad you finally resolved it. Thanks for the bump to share how it ended.

I just saw the thread for the first time today, I had a very similar noise under similar circumstances once. Mine was a result of an idiot not torquing down my flywheel when he reinstalled it. The thing was just clacking around, preparing itself for the right moment to amputate some legs.
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