Good day. This will be the second time posting this. Not sure what happened to the one l posted last night Anyway here goes again. l went and looked at a 04 Z06 to purchase. From what the current owner tells me the prior owner was building it to track but never did. l think that was a untruth as l saw evidence it was indeed tracked. But that alone doesnt bother me one bit. lt has extended wheel studs all around, racing seat brackets still in it (factory seats are back in it now) and the elephant in the room, a welded in 6 point cage. Now, my concern is the noise/vibration l feel when driving. At like 30 mph l can place in neutral and feel/hear vibration and a hum. lf l whip the wheel back and forth l can feel it transfer side to side. l took the car on the very empty freeway and more than once brought it up to 100 where it felt solid and the noise almost seemed to dissipate or maybe at least couldnt hear due to other things like the eng etc. l could reach back and grab the roll bar and feel it vibrating. The cage is welded directly to the frame. The noise/vibration reminded me of maybe a hub bearing going out, or maybe even a half shaft or worse, the diff. l have owned 6 C5 Z06's and driven countless others that l worked on and have never felt this, even when the cars (l have personally owned 2 that had over 225k on them). This car in question has only 56k on it so l find it hard to believe it can be something that serious even though l have learned through the years, anything is possible. The current owner also has a C6 modified Z06 that l saw. He took the C5 in question to his tuner/mechanic who is also a road racer and expressed the same concern l have, his guy told him its all coming from the roll cage and it is just normal chassis noise vibrations being amplified into the cab via the roll cage and if you were to remove it the noise would all go away. l can get this low mile Z for a very good price, but am a little reluctant to pull the trigger. Any and all thoughts, suggestions, insight into this would be greatly appreciated. Thank you all in advance!

 

I'm curious if you aren't feeling symptoms of two different causes. I replaced my differential mount with an HPI mount, and it certainly amplified harmonics. Does the car have solid motor mounts? Solid TT couplers? Maybe the tires need balanced? It's so hard to guess with these cars as they are SO temperamental with NHV. Just some thoughts and guesses. And if it was built appropriately, some mild track time is probably nothing to worry about at all.....says the guy who searched the country for an all original <50k mile Z06 to modify. I am curious what ya will decide on it!

 

Thank you very much for the quick reply. Those are very good questions and honestly l'm not sure if it has solid/polyurethane mounts as l couldnt put car in air to inspect. But now that you have mentioned it that would make ALOT of sense! And sorry but l'm not to sure what 'NHV' means?

 

Sorry, NHV is used on here for Noise, Harmonics, and Vibrations. The plague of all modified c5's. 😁

 

Ohh ok haha. Did not know that! l actually dont think l have every had a NHV issue with any of my C5's before and l have owned several. Maybe just getting lucky!

 

I agree with CinciZO6 and I would check the
roll bar set up . It may not be welded in and
is a bolt in set up. It maybe the rollbar needs
to be tightened down. You can see how it is
set up from underneath.
Good luck

 

Thank you. lf l have another opportunity to look at it maybe this time l'll take my Landcrusier with a jack and few stands in the back and lift that car in the air and take a good looksie!

 

The frequency will tell you a lot about what your experiencing. (tire rpm vs driveshaft rpm)

 

lt will do it even in neutral at only 30mph so l'm fairly certain its not power driven related either. l guess l could also put rr in the air, start it and slowly give it gas and wait for it and then place
in neutral and look at whats going on in the rear ...

 

Side to side makes me think wheel bearing. Tracking can destroy wheel bearings pretty quickly. Can't say for sure, if its heavily modified the list of things it could be is very long.