Metallic clunking noise when car is in motion

[humfrz]

Originally Posted by Xx-Ness-xX

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.



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.

That may be a too low of rpm for that engine to pull up from in second gear. I wonder if what you're feeling is just the engine shuddering -


humfrz

[Xx-Ness-xX]

I understand, but I have driven this car for 85k miles, and the way the engine shuddered is definitely not the same comparing to what it used to be. The vibration is obvious enough for someone that has never driven this car before to point out I think.

It somewhat similar to this https://www.ft86club.com/forums/showthread.php?t=126318

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[Xx-Ness-xX]

So I rotated my driveshaft by another 90 degrees yesterday, and test drove the car. The vibration is still there, but I think I have more data on how to reproduce the vibration.
First I think this kind of vibration is categorized as engine load related vibration. In order to get the vibration to occur, I would have to lug the engine a little. E.g. second gear @ 1.5k RPM. The vibration starts around 1.7k to 1.9k RPM if only if the throttle is at least 25% depressed. The vibration is very brief, and once the engine reaches 2k RPM the car is back to normal. The vibration can happen on the 3rd gear as well, let's say I am driving at 2nd gear @ 2.6k RPM, next I shift to 3rd gear, RPM drops to around 1.8k RPM right after that I accel, then you can feel the vibration and loss of power for a brief moment.

There are couple things I am wondering at this point:
1. My driveshaft orientation is probalby still off (Very likely)
2. Is it possible that I damaged my engine mount while taking off the transmission? As a result, the driveshaft operating angles are greater than 3 degrees?
3. Is the transmission mount damaged? Or it was not installed properly. (There are two nuts screwed onto the slotted transmission mount, and I realized that these 2 nuts did not need to be removed when dropping the transmission. Could they be the culprit? Should I tighten these 2 nuts equally before I start torquing them down? Or I can torque down one first then torque the other one?)

[humfrz]

Originally Posted by Xx-Ness-xX

So I rotated my driveshaft by another 90 degrees yesterday, and test drove the car. The vibration is still there, but I think I have more data on how to reproduce the vibration.
First I think this kind of vibration is categorized as engine load related vibration. In order to get the vibration to occur, I would have to lug the engine a little. E.g. second gear @ 1.5k RPM. The vibration starts around 1.7k to 1.9k RPM if only if the throttle is at least 25% depressed. The vibration is very brief, and once the engine reaches 2k RPM the car is back to normal. The vibration can happen on the 3rd gear as well, let's say I am driving at 2nd gear @ 2.6k RPM, next I shift to 3rd gear, RPM drops to around 1.8k RPM right after that I accel, then you can feel the vibration and loss of power for a brief moment.

There are couple things I am wondering at this point:
1. My driveshaft orientation is probalby still off (Very likely)
2. Is it possible that I damaged my engine mount while taking off the transmission? As a result, the driveshaft operating angles are greater than 3 degrees?
3. Is the transmission mount damaged? Or it was not installed properly. (There are two nuts screwed onto the slotted transmission mount, and I realized that these 2 nuts did not need to be removed when dropping the transmission. Could they be the culprit? Should I tighten these 2 nuts equally before I start torquing them down? Or I can torque down one first then torque the other one?)

Usually, if you have more than one bolt holding something down, it's a good idea to tighten them a little at a time until both are tight.

humfrz

[Xx-Ness-xX]

Originally Posted by humfrz

Usually, if you have more than one bolt holding something down, it's a good idea to tighten them a little at a time until both are tight.

humfrz

I will break lose the transmission cradle and wiggle the transmission a bit then tighten the bolts down a little at a time this weekend see if that fixes my vibration issue. Stay tuned

[Xx-Ness-xX]

New update since my last post:
So I have completely rotated the driveshaft 360 degrees (tried all orientations), the vibration is still there.
Next, I broke loose the transmission cradle and tighten the bolts down a little at a time, but unfortunately the vibration is still there. Everything is torque to spec expect 2 out of 4 bolts on the transmission cradle will not tighten all the way to 48 ft-lb. One screw can only be torqued to about 20 ft-lb, and the other one can only be torqued to about 30 ft-lb. I don't think those 2 screws are the root cause of the vibration because they were torqued down to spec the first time I dropped the transmission.

By using process of elimination, that leaves me 2 possibilities:
1. The orientation of my pressure plate is not correct (I did not find out there is a certain oritentation of pressure plate till I put everything back together). Based on the service manual it stated that when replacing the flywheel or the clutch cover with a new one, position the clutch cover so that the angle formed by the imbalance marks (paint marks) on the flywheel and clutch cover becomes 120° or more. (The imbalance marks indicate the direction of residual imbalance.)
2. My engine mount is going bad (this is just my educational guess). What is a good way to check my engine mount is going bad?

Anyway, I am not looking forward to drop my transmission again just to rotate my pressure plate. This vibration issue is more of a nuisance than anything else. If I finally decide to do the valve spring recall, then I would probably have the technician to check my pressure plate orientation and the engine mounts. I sure have learned a lot from doing my first clutch job.

[Xx-Ness-xX]

So I decided to do the valve spring recall, and I told the mechanic to check my pressure plate & clutch while he took the engine apart. He did notice that the pressure plate was not torqued down correctly. Also the flywheel and the pressure plate had residual shipping oil on them. Next he told me that my clutch pedal was sitting too high, but I have never made any adjustment to it. The pedal was like that on the first day when I bought the car. Last but not least, he said there was a slight exhaust leak at the flange where the donut gasket is.

Anyway, the vibration did not go away after all the corrections. I talked to the mechanic over the phone, he told me he could not reproduce the issue, and I went about telling him that he would have to be around 1800 RPM @ 3rd gear then give the car a bit of gas, then he told me that it is not good for the engine to be at that low RPM and yada yada. I told him I understand it is not good for the engine to be at that low RPM, but the odd thing is that I have never experienced this vibration for the last 86k miles I have driven this car.

Fast forward to yesterday, I wanna record this vibration issue with my dashcam so I lugged the engine to about 1800 RPM @ 3rd gear then lo and behold I gave it a bit gas then the car started vibrating as expected so no big deal. However, the second time I tried to lug the engine with a bit more gas than before, instead of vibration noise I heard a thud noise accompanied by a shake of the car. I was freaked out by it, but there was no check engine light, and everything else still ran normal. In the beginning I thought maybe I drove over a big rock on the ground, but after checking my dashcam I was able to confirm there was no debris or anything like that on the road.

Here is the footage from the dashcam (sorry for the static noise from the dashcam):
[ame="https://www.youtube.com/watch?v=YMyimzQL-_8"]https://www.youtube.com/watch?v=YMyimzQL-_8[/ame]

The first vibration is @ 7 seconds into the video, and the thud noise is @ 11 second into the video. Does anyone know what that thud noise could be?

Driving to and from work today was fine, no weird engine noise. Hopefully no major harm was done to the engine . I will try to collect some datalog using OFT and report back in couple days.

[mswbrz]

Bro, can you record it again with no talk radio lol ??? I can't hear anything and it sounds like static perhaps that is the vibro though....


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[soundman98]

i think the banging noise is the car backfiring because you're pissing the motor off.

these motors are moody high revvers. trying to lug them like that makes them do odd and angry things. especially if you're modified.

[ActionMaxon]

The video doesn't help very much. A mechanic would never listen to the radio while also listening for a noise. (Unless the noise being listened for was RFI) It's already difficult to diag a noise listening to video, nevermind having to tune out the radio. Re-do video if you want anyone to be able to get a proper listen.


I would not put any more thought into orientation of your driveshaft. Marking driveshafts is standard op for remove and replace, however from time to time I have forgotten to do this over various makes and models and have never had a driveline vibration occur as a result.

As a note: For someone who thinks they have a vibration caused by an out of balance driveshaft which cannot be fixed by re-orienting, try using an adjustable metal band clamp (like you might see on a radiator hose). Install clamp and test drive in the condition of the imbalance. If it gets worse, rotate so screw portion is 180 degrees from initial install. Add clamps, and rotate as needed to eliminate vibration.

Driveline vibrations will not be engine rpm related, they will be speed related and the vibrations will come and go similarly to an unbalanced wheel.

A worn motor mount would not cause a vibration. If anything it will mask a problem.
A new firm motor mount will transmit vibration into the body of the car.

To test for bad motor mount power brake vehicle.
In automatic, foot heavily on brake, transmission in drive, sharply apply and release throttle to load engine. If the engine shifts significantly, you have worn mount. Repeat process in reverse to check the other side.

In manual cars it's not so easy. Best to pry on motor mount with pry bar and check for excessive movement. I have also set parking brake, and hold brake with heel, with toe hold approx. 2K rpm and with other foot sharply engage and disengage clutch. Observe engine for movement. It's not particularly safe and you probably shouldn't do it unless you are confident in your ability to not hurt yourself or others or your car.

Generally, when an issue begins after a repair, you either made a mistake somewhere or you have a bad part. I wouldn't start suspecting things outside of what you had to touch to do the job. That being said, it sounds like this only happens when you lug the engine, which is something you shouldn't be doing because it can lead to internal engine damage as the crank bearings are being abnormally stressed.

If you go back to mechanic, ask him or her to go on test drive with you. You drive. Make the issue happen with mechanic right next to you so you can go "There did you hear that? That's the noise I'm talking about".

When you drive loads of different vehicles every day it can be difficult to recreate unusual driving conditions and hear noises that only occur on Tuesdays when the sun is setting turning left downhill facing North.

If you re-make video I'd be happy to turn volume up and listen, but as it is, I can't focus on the noise.

[disgruntld]

Zombie thread! I'm having this same issue - how did you correct the issue with the extension housing and driveshaft?

[Xx-Ness-xX]

Originally Posted by disgruntld

Zombie thread! I'm having this same issue - how did you correct the issue with the extension housing and driveshaft?

I used a center pin and a hammer to get the extension housing as round as possible so it's not rubbing on the center shaft

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