G35 Coupe V35 2003 - 07 Discussion about the 1st Generation V35 G35 Coupe

Loud thud, car shake while driving low rpm

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Old 04-17-2018, 12:03 PM
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[VIDEO] Loud thud, car shake while driving low rpm

hey guys, so I’m having this issue and I can’t get a grasp on what it could be. While driving, after the car is warmed up and after some driving, my car gives out a loud thudding from the rear and it’s so loud and violent that the entire car shakes. Only happens while rpm is low and the road has some imperfections. It feels as if something is slipping. The rpms shoot up while thudding and then drop back down. Initially I thought it was the diff so I found a used low mile one at a junkyard and swapped it out as well as swapping all the diff bushings to whiteline. I also changed the endlinks while I was at it. Overall the car is stiffer and the thudding isn’t as violent because of the new bushing but it’s still there. The only other thing I can think of is maybe the tires?


 

Last edited by Genthusiast35; 04-17-2018 at 09:23 PM.
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Old 04-17-2018, 12:10 PM
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rear axle shafts loose?
 
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Old 04-17-2018, 12:11 PM
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I'd get under it and pry around on every single suspension or driveline component to find out what's worn. If it had a bolt or a bushing then it has the potential to fail, also inspect for broken welds. Re-torque everything, including the subframe bolts.

Are you sure you don't have a slipping clutch?
 
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Old 04-17-2018, 12:39 PM
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Originally Posted by SoCal04G35
rear axle shafts loose?
Tightened the axle shafts to spec and applied threadlocker.

Originally Posted by cleric670@gmail
I'd get under it and pry around on every single suspension or driveline component to find out what's worn. If it had a bolt or a bushing then it has the potential to fail, also inspect for broken welds. Re-torque everything, including the subframe bolts.

Are you sure you don't have a slipping clutch?
Everything was tight under there. A lot of rust but nothing looked out of wack. I have an at so clutch is out of the question. Unless my at is slipping.

I just don’t get what could cause such a violent reaction. Makes driving unbearable.

My tires are starting to wear out. Could that have anything to do with it?
 
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Old 04-17-2018, 12:58 PM
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Check your AT fluid level, it could be running low on fluid then you get a sudden burst of torque as line pressure builds up.
 
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Old 04-17-2018, 01:01 PM
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Originally Posted by cleric670@gmail
Check your AT fluid level, it could be running low on fluid then you get a sudden burst of torque as line pressure builds up.
That I haven't checked. I'll def check that.
 
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Old 04-17-2018, 01:26 PM
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Originally Posted by cleric670@gmail
Check your AT fluid level, it could be running low on fluid then you get a sudden burst of torque as line pressure builds up.
Checked atf, levels looked good. This is getting frustrating.
 
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Old 04-17-2018, 01:38 PM
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What happens when you use a service jack to lift up the vehicle? Do you hear any wierd noise coming from the suspension as you raise it? Maybe indicating something is broken or severely worn.

Also if you have a sunroof equipped are you sure the sound isn't coming from the sunroof?
 
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Old 04-17-2018, 01:40 PM
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Also, take out the trunk floor mat and both plastic dividers and check to make sure everything is securely bolted down like the spare tire/jack/HICAS controller, etc
 
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Old 04-17-2018, 01:59 PM
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Originally Posted by cleric670@gmail
What happens when you use a service jack to lift up the vehicle? Do you hear any wierd noise coming from the suspension as you raise it? Maybe indicating something is broken or severely worn.

Also if you have a sunroof equipped are you sure the sound isn't coming from the sunroof?
Originally Posted by cleric670@gmail
Also, take out the trunk floor mat and both plastic dividers and check to make sure everything is securely bolted down like the spare tire/jack/HICAS controller, etc
Nope everything is sound. Even when driving.

It feels as if gears are slipping. It cant be the diff since i swapped it to another one. I dont see how the tranny could be slipping since it doesnt give off erratic downshift or upshift.

And still, somehow the rear just goes nuts and starts thudding and shaking the damn car.
 
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Old 04-17-2018, 02:26 PM
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I'd recommend re checking the rear suspension. Maybe your diff bushing is completely screwed?
 
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Old 04-17-2018, 02:38 PM
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Originally Posted by Urbanengineer
I'd recommend re checking the rear suspension. Maybe your diff bushing is completely screwed?
Well initially i thought it was because of that. So i swapped it and put in whitelines. Now its not AS violent but the judder is still there. Sometimes it gets so bad, that it goes on for 15 seconds. Cant even accelerate to keep up with traffic.
 
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Old 04-17-2018, 05:47 PM
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It sounds like your tranny is about to implode, I'd have it towed somewhere to be looked at. I've been involved in a massive transmission failure in the past and it wasn't a pleasant experience.

I don't know that anything not mechanical could cause the symptoms you are describing and it sounds like you've ruled out the diff. as a potential cause.
 
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Old 04-17-2018, 06:21 PM
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Originally Posted by Blue Dream
It sounds like your tranny is about to implode, I'd have it towed somewhere to be looked at. I've been involved in a massive transmission failure in the past and it wasn't a pleasant experience.

I don't know that anything not mechanical could cause the symptoms you are describing and it sounds like you've ruled out the diff. as a potential cause.
you think so? I dont seen any other sign of a bad tranny. it shifts smoothly.
 
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Old 04-17-2018, 09:24 PM
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Added a video to better help hear it. You can hear it a couple of times in the video.



 


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