Hi all...

How do I explain this... here goes...

My CL is currently making phenomenal power. Owned 2 CL's and driven them for a combined 6 years. In its current setup (see sig), the car is as quick as ever. I mean, it shreds 1st gear and 2nd gears with ease on dry pavement. The problem is, I dont think the engine mounts/damper can take the drivetrain flexing when accelerating in 1st, 2nd, or 3rd gear...

In the past, I had horrible engine vibrations which were attributable to a shot front engine mount and possibly shot side engine mounts... I replaced the 3 mounts about 6 months ago prior to headers/pulley/exhaust install (poly filled with construction adhesive, not the liquid fill).... car was fine. It did have a idle vibration caused by the poly fill, but nothing problematic...

Fast forward to today... the cabin feels horribly shaky when I accelerate or apply any throttle when at speed on the highway. The problem is somewhat on/off. Sometime, the shakiness isnt that bad, sometimes its so bad I cannot even attempt a redline shift because the car is shaking so badly. Also, when shifting gears, I can tell the engine is moving quite a bit because when i select the next gear, it has become impossible not to let the cabin feel a little shudder. I can feather the clutch/gas pedal to minimize this, but its gettng worse.

Its not an internal engine issue either as it is eager and willing to spin up to redline.

My question is.... would shot engine dampers contribute to the shakiness as well as the rear engine mount? Would shot 2 tranny mounts cause this as well?

My suspicion is that the dampers are shot and unable to provide any dampening effect. I also suspect that the front mount is shot plus the rear...

Any input is appreciated....

Raj

 

have you ruled out tire/wheel problem?

 

yeah... its too violent to be wheel/tire... also, when coasting, there is no issue at all...

its only when I apply throttle, the car shakes badly... My hunch is that the rear engine mount (never replaced) has fallen apart from time and from the fact that the poly filled front mount caused the rear mount to take on more of the engine movement... i also suspect the dampers are shot....

 

look at the mounts, trans mounts too. just bc u polly fill ur mounts doesnt mean that their gonna last. its how u abuse the car. the dampeners dont make a diff, mine felt like shit when i took it out. i can compress it with my hands. i replaced it with an nrg engine dampener, rear one is still oem.

 

This may be ridiculous, but I read several posts that said their NRG dampers were either disconnected or completely missing. If you haven't already checked, you may be able to fix this for cheap. Good luck!

 

mine was getting loose. so i put some lock tite on it and its all good now.

 

you say it only happens when you gas it?

Axles maybe (cv joints)?

It's gotta be in the drive train if it's getting worse with throttle. but is fine when you coast.