Guest Will Posted January 12, 2002 Share Posted January 12, 2002 The 280 has a persistent driveline vibration problem. As RPM and vehicle speed increase, the shifter vibrates and rattles. I could silence the shifter, but this wouldn't stop the vibration. The vibration is different based on throttle condition: it's worse on lift throttle than applied throttle. The rattle starts about 75-80 mph in O/D, but is somewhat intermittent. Every now and then it's quiet. It also varies in Intensity. I think it has something to do with a dynamic in the differential mounting. Tried hard poly diff mounts once, which helped immensely, but made the interior too buzzy. Component list: 4.3L L99 V8 from '95 Caprice, Saginaw 4spd, B-W R10 O/D, C2 Corvette shifter. Any insight? Quote Link to comment Share on other sites More sharing options...
biohzrd Posted January 13, 2002 Share Posted January 13, 2002 sounds like a drive shaft or half-shaft is out of balance. then again it may be your tires. at any rate something is out of balance or loose. Quote Link to comment Share on other sites More sharing options...
fl327 Posted January 13, 2002 Share Posted January 13, 2002 motor mount? Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted January 14, 2002 Share Posted January 14, 2002 Aside from the obvious balance or worn mount problem, there are several other factors that contribute to your problem. One may be a mis-alignment between the output shaft of the transmission and the input shaft of the differential. A visual of this can be found at: http://www.drivetrain.com/driveline_angle_problem.html Exact alignment is difficult to attain, expecially for the home hobbyist that is concocting hybrid drive trains such as the V8 conversions we are doing. Noise, vibration and harshness (NVH) is an entire field of study in automotive engineering and be assured that automakers spend millions of dollars trying to eliminate NVH during the development of new vehicles. You may be experiencing a harmonic vibration that several components that are capable of producing vibration, (engine, drivetrain, exhaust) are coming together at various rpm to amplify the problem. I know this is not a solution to your problem, but it may provide insight that will help further troubleshooting. Quote Link to comment Share on other sites More sharing options...
Guest Will Posted January 14, 2002 Share Posted January 14, 2002 The vibration problem has survived tire changes, numerous remakings of the driveshaft to be as precise and aligned as we know how to make it--and we definitely know how--and changes in the mounting of the torque cable and rear sway bar. And the link didn't work. We also have poly control arm bushings and softer poly differential mounts, currently. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted January 15, 2002 Share Posted January 15, 2002 The alignment I refer to can only be changed by moving the engine/transmission position or the differential position. Your driveshaft may well be precise, but it is operating in a situation that develops vibration. Even though a driveshaft has u-joints at each end, the velocity of the driveshaft will oscillate if the trans output shaft and the differential pinion are not planar to each other. It is difficult to explain in words. The vibration can sometimes be solved with a constant velocity joint at one end or a double cardan joint. There are ,however, alignment issues with these joints too. Keep trying the link I posted earlier. It works for me. Quote Link to comment Share on other sites More sharing options...
Guest Locutus Posted January 15, 2002 Share Posted January 15, 2002 Basically what he is referring to is the angle of the U-Joints. Pete Paraska has info retaining to this problem and how to correct it on his web page under his Driveline Modifications section. http://members.home.net/pparaska/drivelinemods.htm It is common in this type of swap so it may well be the problem you are having, but there are other factors also to consider. I would first check angles to make sure they are no out of their operation ranges. Mike Quote Link to comment Share on other sites More sharing options...
Guest Will Posted January 15, 2002 Share Posted January 15, 2002 We've tried a CV joint at the rear end of the driveshaft. Didn't help. The link works now. Quote Link to comment Share on other sites More sharing options...
Guest Rick Johnson Posted January 17, 2002 Share Posted January 17, 2002 I thought it was interesting that the vibration is worse when you lift. You should be able to duplicate the decelleration force with a similar amount of acceleration force. If the vibration result is drastically different in decel, I would guess that the coast side of the ring and pinion may be the problem. Thus I might focus some thought to the diff. Plus you said a different diff mount changed the symptoms. What I would do is get someone with an FFT vibration analyzer to instrument your car and determine what the vibration frequency is. The frequency will lead you to the most likely culprit whether it be u-joints or gears. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted January 18, 2002 Share Posted January 18, 2002 Since this is a hybrid, it is almost certain that the problem is the powertrain angles. Since you probably do not want to mess with the angle of the engine/trans, focus on changing the angle of the nose of the diff. Decel vibration usually means the nose of the diff is too low relative to angle of the tranny, so the diff nose needs to raised. However, don't go raising it without knowing the relationship of the 2 angles since sometimes it only takes 1* change to correct it. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted January 19, 2002 Share Posted January 19, 2002 I have a stock 280ZXT with stock drive train and had the same problem. It turned out that a ujoint in the driveshaft get stuck sometimes. Quote Link to comment Share on other sites More sharing options...
Guest Will Posted January 19, 2002 Share Posted January 19, 2002 The driveline angles are correct. They have been measured. The diff is practically new, so wear on it is not an issue. One thing I just thought of: we do have is a poly cushion on top of the diff snout. The original engine vibrated so badly that we couldn't tell a difference between having the cushion and not having it. This L99 is so much smoother that we may be able to tell now. Maybe the cushion is the problem. Quote Link to comment Share on other sites More sharing options...
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