This is kind of hard to explain but only on occasion and usually at low rpms in 4th or 5th (just after a shift maybe 2k) under normal conditions my car will make a weird wobbling noise almost like a flat tire sounds and I do feel a slight vibration that matches the sound. When this happens I usually clutch it and coast a second or down shift and the sound goes away completely then when I try to make it happen again I can't get it to do it again. If I were to type out what it sounds like it would look like "wa wa wa wa wa"

The only explanation I can come up with is that at just the right rpm's around 2k, the engine has some sort of weird harmonic shake and I need to check the motor mounts. The engine is cammed so those mounts obviously have been getting more shake from the engine since the install.

Only mods are large cam, valve train, intake, long tubes, and tune.

The tires and alignment are perfect, and the engine sounds and runs flawless.

 

Torque tube or pilot bearing

 

Wouldnt I notice that more often?

 

well it is a vague condition, so it is all a guess. Have you looked at the harmonic balancer for wobble? The reason I suggested the pilot bearing or torque tube is that you explained you could make the condition go away when you pushed in and let out the clutch, which said to me you were able to find a "happy spot". So, the pilot bearing will cause the clutch disc to find an off balance condition when it is pressed against the flywheel/pressure plate. If that bearing is shot, then sometimes the clutch is centered sometimes not. The torque tube "guibos' can do the same thing, throw the clutch off center and give you a vibration. That vibration will have a 1x RPM signature.

So it was your description that drove my suggestion.


Now maybe you are lugging the engine and shifting to higher gears at too low a speed. If you are accelerating, a 2k shift is a little low. Run your shifts at 3k on the street, your engine will like you better, and get rid of the CAGS. Especially with a cam!!!!! My C5 is cammed and it does not like being at anything less than 2k rpm under load. A lugging engine throws out a lot of vibrations as a complaint to the driver.

 

Thanks for the info bud. Well the clutch is on the "to do" list soon so Ill have to check the pilot when I replace it to see if it was the culprit.

 

If you are going as far as a clutch, I would suggest you include looking at the torque tube Guibos and bearings. LT headers put more heat on the TT tunnel, especially in town and that heat may be hard on the rubber guibos.

After that, you are down to the trans as a culprit.

Harmonic balancer OK?

 

Yeah looks to be really smooth and stable. I did replace the stock balancer because the stock one came apart on me right after the cam install.