Miata Deceleration Noise

Buzzing/rattling noise during deceleration in gear. Noise is extremely annoying. Car is a 91' currently on stock 5spd trans and diff with 80k miles. Have a 6spd going in over the winter.

[@Jan-ms9tl]

KZbin algorithm...

[@ReXoRofc]

KZbin algorithm strikes again...

[@HonestEngines]

Well it's been 7 years so you probably found out it was your diff right?

[@bt92lude]

Haha yup

[@wisemushroom9996]

Oh is that what that noise is. I Have the same noise on my 91

[@bt92lude]

@@wisemushroom9996 Yeah, noise went away after a did a 4.1 diff swap

[@alex8erg]

@@bt92lude do you still own your miata?

[@bt92lude]

@@alex8erg Unfortunately no

[@canibeatjason]

I have that too is it like a sanding sound?

[@jackbower2679]

Yeah i had this noise on my miata for 3 years after changing the clutch. I recently changed the clutch again, and this time I correctly adjusted the ppf. I don't have the noise anymore :)

[@nielsei]

I researched it, and with allot people it seems to come because of ppf to transmission allignment it needs to be adjusted and than the noise goes away

[@Iamsoundofsoul]

I think its the exhaust plates but I'm really not sure because my making the same noise! I'll get to the bottom of this and let you know

[@bt92lude]

SoundOfSoul Upgrading to a 3.9 torsen solved the problem completely for me. I also did a 1.8 motor swap with a 6speed NB trans, which initially quieted it down, but didn't completely eliminate it. Only thing that made it disappear 100% for me was the torsen swap.

[@BriceTooNice]

what is that above the radio. the 3 holes

[@dylanmonnier3559]

@@BriceTooNice very late but its an rsspeed gauge cluster+radio mount. It's the only one that fits radios well that is produced for na miatas.

[@Jerry1200s]

I’m trying to diagnose this on my 96 Miata. I’m hoping it’s something exhaust related rattling. It goes away when I put the clutch in and the rpms drop down. It seems to only do it when it slows down from 4500 rpm to about 3000 rpm

[@volodymyrhaivoronskyi6530]

I have same thing with mine NB '98:)

[@DeSjeft]

I have the same sound when decelerating. I think it may be the diff that is wearing out. I'm using a torsen diff. Do you still have this problem?

[@bt92lude]

Nope completely gone now but I literally changed everything in the drive train since I made this video. The only thing that got rid of the noise completely was switching to a 3.9 torsen

[@DeSjeft]

btmiata thanks for the quick response! I'm afraid I'll have to go down the same path as you did... I think I'll replace the diff first, I'll let you know if that solves it or not. This kind of information might be useful for other miata owners. Take care :)

[@bt92lude]

No problem DeSjeft! I should also mention that replacing everything in the drive-train was unrelated to me trying to figure this noise out. I built a full turbo set-up on a 1.8 and replaced everything to accommodate for the extra power.... Finding out exactly where the noise was, was just a bonus. Also the reason I know for certain that the noise was in the diff, drive-shaft, or axles is because I had the 1.8, 6speed trans, etc all swapped in and the noise was still there. It only disappeared completely after the diff upgrade.

[@enzoatx2140]

Mine did the same for a while. I changed the flywheel and the sound is much quieter. I believe a part of it comes from the differential, but other than that, I am not sure. I currently have a 1.6 93 NA miata with the Viscous diff & stock 5speed.

[@pass_the_flask]

Did this happen during acceleration too? I have a 90 Eunos Roadster with a similar issue, happens in 4th gear at around 2200rpm, both during acceleration and deceleration. When the rear is lifted on a hoist you can't hear the noise. My noise sounds exactly the same, starting to think I need a new diff.

[@bt92lude]

danrawkz I don't remember experiencing the noise while accelerating. I do know that upgrading to a torsen differential is ultimately what made my noise go away.

[@Nasonix2]

@@bt92lude fyi it happens with torsens as well. It's something most likely needing to be adjusted/rebuilt with the diff Internals. What exactly? I'm not sure yet. But I do plan on finally rebuilding my 4.1 torsen thanks to your help with confirming the diff being the source. I've replaced my driveshaft and didn't really help. It's not the same sound as a bad u joint (CV joint) anyways. It sounds just like a creature snickering or someone bouncing on an old spring mattress. Lol and has a forceful rotation/repetitive nature like gears are involved

[@GuernB2]

I just swapped my 99 from an auto to a 6 speed with a happy meal clutch flywheel kit and I get the same noise. Sounds like a rally car with a dog box on decel. I have a 3.9 diff on the way to replace the stock open 4.3, so hopefully that fixes the issue.

[@steveohno]

I've seen multiple people online say it can be because of a lightened flywheel, misaligned ppf, or loose heatshield. Having same problem right now too. Let me know if your new diff fixes it. Update 1: I've adjusted my ppf, have no loose heat shields, and I suspect it may be from the 75w-90 diff fluid I put in. Going to add 80w-140 and go from there. Update 2: The 80w-140 didn't do anything, might have the driveshaft rebuilt and balanced.

[@neonblazesword9339]

@@steveohno update now?

[@steveohno]

@@neonblazesword9339 90% sure my 1.6 VLSD rear end is going bad. I will be replacing it with a 1.8 LSD when I find one. It will require a 1.8 driveshaft and cv axles. (the 1.6 rear ends are known to be junk anyways) I'll update this once the swap is done.

[@Nasonix2]

@@steveohno any updates? I have the same problem but it's louder. Only happens when I snap the throttle shut when engine braking in lower gears like 1st, 2nd. Also happens when I downshift at high RPM from 3rd to 2nd and don't blip the gas high enough. It's on decel, same exact sound. Sounds like there's a lot of force involved with it. Definitely isn't no rattle exhaust or anything. It's driveline/rear end related for sure.... it sounds like a creature is snickering. Sounds like someone bouncing on a creeky bed spring lol but it also has the tone of something severely nearing the end of it's life. I've replaced the driveshaft due to a slightly bad cv joint. Didn't help. It isn't the same sound as bad cv joints anyways

[@steveohno]

@@Nasonix2 I've ordered my 1.8 LSD and I'm currently waiting for it's delivery. As soon as I get it installed I'll let you know. I'm about to put some 80w-250 or redline heavy shockproof in it to see if it'll be quieter...

[@JoLoneyMusic]

Do you have an aftermarket clutch with stock flywheel? My WRX makes the same sound in 3rd and 4th on decel, and I have an Exedy stage 2 and stock flywheel.

[@bt92lude]

ThisIs Duckie At the time I made this video I had an OEM clutch/flywheel. I currently have an upgraded clutch and stock 1.8 flywheel though. I ended up eliminating this noise with a 3.9 torsen swap.

[@bryanzimmerman8737]

btmiata It was the differential ?

[@bt92lude]

Bryan Zimmerman Yes when I swapped to a 3.9 torsen differential, with 1.8 axles and driveshaft the noise completely disappeared and never returned!

[@bryanzimmerman8737]

Thank you so much for the reply. I have replaced the clutch, bearings, flywheel and transmission only to have the noise persist. It has been slowly driving me insane. I will start looking for a Torsen.

[@bt92lude]

Bryan Zimmerman No problem at all! I've replaced every single part of my drive train for my turbo set-up so that was the one single thing that completely eliminated the noise! I'm pretty confident that will remedy the noise for you!

[@Birgantar]

And, did you find out, what's causing it? Have the same here on my 90 Miata.

[@bt92lude]

No but I believe I have it narrowed down the the diff/driveshaft. I now have a turbo 1.8 swapped in with a 6 speed and it's still making the noise.

[@Birgantar]

btmiata They told me it can be low gear box liquids (oil) and an needed ppt allignment...

[@bt92lude]

Birgantar Yeah I swapped the 6 speed in and changed the fluids twice since swapping it. I've tried motorcraft synthetic and amsoil and no change either way. I've also adjusted the ppf a few times. I've basically given up on hunting the noise because it's no longer my daily driver so it only bothers me once in a while. I'll make sure to post back if anything changes when I swap to a torsen diff

[@FC-oh3ho]

+btmiata did you swap the clutch?

[@bt92lude]

+heyhey hey hey I did... I put a Flyin Miata Happy meal in when I swapped the 6speed in there. Just a reminder ( I believe I commented somewhere else) But the noise did in fact disappear 100% after swapping in a 3.9 Torsen and doing the turbo 1.8 setup