Weird vibrations

[blackazz]

Morning gents, I need some info on a buddy's GN.well he had just bought a gn with a blown motor so he does a rebuild all good there. Now that he had the car started an running,I notice a vibration in it an no is not in drive or gear its a vibration well parked at idle. If you give it gas on the de acceleration you really notice it or parked at a red.
Things already checked:
1. Drive shaft/ujoint
2. T/c
3.timing/cam install
4. All lose bolts
5. H/balance
6. New motor mounts
Where else to look? Would timing do this.

 

[blackazz]

Got to looking around lil bit more. So I noticed his exhaust is welded solid to the frame. Would this transfer vibration? Seems like it would need some kinda deflection. T.I.A

 

[5280GN]

Why would someone weld the exhaust to the frame????

 

[blackazz]

That's what I'm saying. it has welds at the rear an nothing after that. Cutting it free now.

 

[5280GN]

Nice. I had to cut off that hooker exhaust to get it out. I beat on it with a hammer for 30min before I grabbed the saw.

 

[robzombie]

Hopefully it's resonance from the exhaust being transferred into the frame and being felt in the car.

I would say that is your problem for sure as you state it's worse on deceleration.

 

[blackazz]

Nice. I had to cut off that hooker exhaust to get it out. I beat on it with a hammer for 30min before I grabbed the saw.

That one was bolted to the frame right.

 

[5280GN]

nah just had those hangers in front of the rear axle.

 

[blackazz]

With silicone on all the nuts.

 

[5280GN]

Haha yup

 

[GNONYX]

If you still have some vibration after fixing the exhaust system, you might want to check the flywheel since that wasn't on your check list.