Metallic clunking noise when car is in motion
 

First of all, I have a '13 BRZ with 85k miles and the only mod so far is the UEL Tomei header with OFT Stage 2+.

So I decided to do some DIY to replace my throwout bearing, clutch fork, fork bushing, throwout bearing clips, fork spring clip, clutch, pressure plate, and flywheel this weekend. Everything is OEM, I got the clutch kit and flywheel from Exedy.

Here is the problem, car starts and idles with no weird noise, but if the car is in motion whether it is in gear or neutral I would hear this metallic clunking noise. The frequency of the noise increases with increasing speed of the car. The noise sounds like is coming from the bottom of the car. I can change gear smoothly, and it definitely feels better except this clunking noise.

FYI, I found a place that rent out a garage with lifts and tools, that's where I replaced everything, but they don't open Monday and Tuesday so I will have to wait, but I am probably going to bring it to a shop to see what's going on with my car.

Have anyone encountered something similar? I can't think of anything that I missed during the clutch install. I have a feeling that my driveshaft could be damaged? But I handled the driveshaft carefully when I removed from the transmission. There was something that I witnessed as I was putting the driveshaft back, I could slide the driveshaft toward the transmission and then it felt like it hit the end of stroke, but when I tried to tie the 4 bolts to the differential there was a gap between them so I had to slide the driveshaft away from transmission to close the gap to the differential.

******** FIXED ********

So it turns out my driveshaft was rubbing the transmission extension housing. The housing got damaged when the transmission was jacked up too high and the shifter linkage bent the circular housing.

https://i.imgur.com/TPer8fp.png
https://i.imgur.com/XbrjP2S.jpg

Now the clunking noise is fixed, I can finally focus on the vibration issue.

The vibration is more apparent when I put into 2nd gear @ around 1.5k RPM, then I put some gas in then I can feel/hear the vibration for maybe a second then it goes away. I marked my driveshaft & differential this time, and I rotated 90 degrees, but the vibration is still there. I will try to rotate it one more time then see if there is any improvement.

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I think I know where I messed up in this installation. I forgot to mark the driveshaft alignment when taking it out from the differential. :brokenheart:

https://i.imgur.com/mA4nj00.png

OK, now whatcha ya gonna do?

I'll dial up @Ultramaroon for you. I'm sure he's messed his up before and figured out how to tell where it was.

:iono:

:D


humfrz

I am still gonna bring it to the mech. Hopefully I didn't damage my driveshaft yoke or differential bearings

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I know you said the noise is coming from underneath the car, but is it in front of, or behind the shifter?

Also, any rattling like that would IMO most likely be dirty transmission fluid or a lack of any fluid at all.

Does it sound like my noise at all?:
https://www.ft86club.com/forums/showthread.php?t=135492

This is random but I was researching transmission issues on Miatas from a post in 2006 and I saw some posts from you lol. I was like this guy is everywhere!

easy to be when you're retired!

:bellyroll:

Oh, I just been around for a while - ;)


humfrz

Not exactly the same noise. I will try to record the noise this weekend. The noise seems to come from in the center of the car
I drained and filled the transmission fluid after I replaced my clutch so I don't think that's the cause

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Highly doubt that is the issue as those of us with one piece drive shafts have rotated them every which way trying to get rid of vibrations.

I agree, I wouldn't think it would make that kind of clunking noise. Anyway, we will soon find out this weekend.
I really wanna put back the driveshaft to the original orientation. I didn't pay attention if there was any mark from the factory. If there is then I am in luck.

So it turns out my driveshaft was rubbing the transmission extension housing. The housing got damaged when the transmission was jacked up too high and the shifter linkage bent the circular housing.

https://i.imgur.com/TPer8fp.png
https://i.imgur.com/XbrjP2S.jpg

Now the clunking noise is fixed, I can finally focus on the vibration issue.

The vibration is more apparent when I put into 2nd gear @ around 1.5k RPM, then I put some gas in then I can feel/hear the vibration for maybe a second then it goes away. I marked my driveshaft & differential this time, and I rotated 90 degrees, but the vibration is still there. I will try to rotate it one more time then see if there is any improvement.

:scared: i'm wondering if the transmission is your entire culprit. if that output shaft was bent/damaged from lifting the transmission too high, that would also cause a driveline vibration.

It's not the output shaft that is bent, it's the circular flange housing that's bent. Driveshaft was carefully removed I highly doubt my output shaft is damaged

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