Front End Vibration

[L36 SS]

So i've noticed this last week that under part throttle the front end vibrates almost like a wheel is out of balance. Suspension parts that have been relpaced include new tie rods, sway bars, struts, trailing arms and LCA's. I heard that it could be the lower motor mount so I replaced that and it took a good amount out. Anyone have any suggestions on what this could be?

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[C.Evans]

TC shudder?

 

[L36 SS]

Could that be? I never thought about that. Converter is original with 74k

 

[C.Evans]

Most definetly. Does it do it mostly when starting from a stop?

 

[PANDA]

Don't listen to Ranger man Neil. Call James

 

[L36 SS]

No trans drives fine, it only happens around 3k or when there is a load on the motor

 

[SaturdaysGS]

Possible axle as it sounds fairly similar to a problem I had.

 

[C.Evans]

Don't listen to Ranger man Neil. Call James

 

[Eagle]

Possible axle as it sounds fairly similar to a problem I had.

Yep, I had similar issues. Axle.

 

[10sec]

That carter smiley gets me every time!!

 

[L36 SS]

Found my problem on club gp, im lowered 1" so i need to shorten the spacer in the end link

 

[phat_ridegt]

just saw your post neil and realized i never texted you back sorry. the vibration wouldnt have just 'appeared' if you needed to mess with the sway bar link. I'd imagine you're due for a couple axles....

 

[1quick]

napa will hook you up with some lifetime units

 

[ProjectGTP]

I had the same problem and it turned out being the bracket that goes from the differential cover to the motor came loose.

 

[Turbocharged400sbc]

the motor mount alleviating at least a portion of the problem is a clue.

2 primary paths for nvh feedback to the driver is through the column and through the floor/seat/chassis

more feedback through the column would tend to be from the steering gear/suspension. feedback through the floor would be related to the engine/trans, mounts, subframe path.

where are you getting most of the feedback through?

you mention part throttle "almost like a wheel out of balance" which is usually high load (low rpm/high gear) so that could point to an ign missfire that your feeling through the chassis (far more likely with urethane mounts) a wheel balance is likely to be felt through the column more-so than the chassis, the missfire would be feelable through both

but is the vibration rpm or mph dependant/related? any work done recently in the last couple months that may have broken a spark plug wire and has finally taken this long to arc enough of the conductor away that you now have a missfire?

 

[L36 SS]

the motor mount alleviating at least a portion of the problem is a clue.

2 primary paths for nvh feedback to the driver is through the column and through the floor/seat/chassis

more feedback through the column would tend to be from the steering gear/suspension. feedback through the floor would be related to the engine/trans, mounts, subframe path.

where are you getting most of the feedback through?

you mention part throttle "almost like a wheel out of balance" which is usually high load (low rpm/high gear) so that could point to an ign missfire that your feeling through the chassis (far more likely with urethane mounts) a wheel balance is likely to be felt through the column more-so than the chassis, the missfire would be feelable through both

but is the vibration rpm or mph dependant/related? any work done recently in the last couple months that may have broken a spark plug wire and has finally taken this long to arc enough of the conductor away that you now have a missfire?

I feel it most through the floor/seat/chassis. I have the urethane upper mounts and just did the lower mount. Recently just replaced lower control arms, gmpp sway bars, and the boxed trailing arms. I feel it most like you said high load, low rpm/high gear and is more rpm related. I haven't touched anything on the motor in months so I don't think i broke a plug wire and have no ses light on for a misfire. The axles are around 2yr old WBS replacements, you think they could be bad?

 

[Turbocharged400sbc]

i would probably check for play in the axles, you may wanna use a block of wood and a floorjack on the LCA out near the lower balljoint/wheel to lift it and keep it closer to ride height then check for play.

but what your describing is quite possibly a bad ign cable as the axles would also be feelable at higher rpm's

 

[Turbocharged400sbc]

feelable? im awesome but dagnabit, im stupid at the same time

 

[L36 SS]

So i ended up taking it to sunrise chevy where my bro works. Tech put it on the lift and got her up to 45mph and there was play in the drivers side axle. Axle came out with the output shaft stuck on which neither me or the tech ever saw. Slid the shaft back in and buttoned it back up and it drives perfect which im happy about. Thanks for everyones input!