Found it. Fixed it. DONE!
FOUND IT! FIXED IT! DONE!
Finally nailed it this morning. First thing I want to apologize and/or give props to Jon B, Fast Viper Dan, White Out, Jack B, BW96Snake, and especially to Bruce who got the closest to the solution and Next Phase who I am guessing has the same issue - all guys who posted that it HAS to be a tire issue. Here is where I've been:
1) Felt a slight vibration at 80 mph + or so after powder caoting my brakes calipers and rotors and going to OEM six-spoke wheels with Nitto NT05 tires. Recalled feeling it slightly before doing the work (this feeling would prove to probably prove to be my undoing in diagnosing the issue)
2) Vibration got a bit more pronounced and felt like it was from the drivetrain as it appeared to disappear while coasting and only appear under power. Yanked all three drive shafts to have u-jounts inspected & shafts balanced. All u-joints were fine & only two small weights were added to main shaft and one half-shaft. Inspected tranny and motor mounts and the appeared in great shape with no rubber degradation. Cost = $190 for shaft work + ridiculous amount of hardware so close to $300.
3) As I "tested" after reinstalling the shafts, the vibration became more pronounced, and appeared to clearly be coming from the front of the car. More confusingly it came and went, which lead me to conclude that it was related to heat. Finally, I got a shake so bad I would call it a shimmey instead of a vibration. Inspected the front end for play in tie rods ends and wheels bearings and if there was a blatently out-of-round wheel and found nothing. Called local tech Eddie Martin at Bill Luke Dodge and ran the situation by him (he had been reading this thread!). One thing he asked was if my brake pedal was getting soft during these episodes. When I said no we thought that eliminated a warped brake rotor. When I mentioned I thought it was heat related he agreed with my idea that I might have a wheel bearing issue that was not noticeable in a static inspection. Found out hubs are $285 each new and I would have to wait 4-5 days to get them and pay tax (which would goof me up jumping on the project that weekend) and called Paul Scharf in Wisconsin (800-338-4002) and bought two low mileage hubs for $75 each + $120 overnight shipping. Took the car apart and cleaned it the next morning, ate lunch, then after the UPS truck showed up I put the car back together.
Forty miles of "testing" showed a large improvement, but there was still a pronounced vibration at 85-95 mph. I fixed something with the new wheel bearings, but had not totally fixed the problem. Cost = $270
4) Took the car back to the wheel shop this morning after getting it nice and hot on the 20 mile commute. The idea was to check the wheel balance but I saw the real problem as soon as the first front wheel turned on the balancer. After I had reinstalled the painted brakes, and put on the new wheels and tires (freshly balanced) I went out to test the brakes which involved locking the front tires up for about eight feet of skid mark on the road. I had falt spotted the tires and and even though the spots were very slight at 0.020-0.030", they had thrown the front wheels out of balance. I FINALLY FOUND IT but I truly think that the reason it got very bad was that the out-of-balance was exacerbating a wheel bearing issue, and that this multiple issue situation is why this has been so difficult to pin down (along with the two flat spots going in and out of sync with each other).
Rebalanced all four wheels and tires (and honestly I think my wheel shop was lazy and did not nail it the first time) and left thinking this was the solution. Did my final "testing" on the way home. Managed the traffic so that I could get into the testing speed zone around two large sweeping curves on the freeway. This allowed me to be in the zone while moving the flat spots in comparison to each other due to the smaller arc on the inner wheel on the turn than the outer side (I think that my perception that this was heat related was that I just so happened to get the flat spots in sync later in my test drive which caused a more pronounce vibration and possibly aggravated the wheel bearing issue) so I MUST have had the two flat spots in sync at some time during the longest curve. Cost = $60
NO MORE ISSUE! I finally got it. After 10,000+ miles of Viper seat time, and after going through all the above I can still kind of feel the flat spots, but realistically, balancing around them made them invisible and new tires are not needed. I guess this is why they call it a "hobby car." Total cost = $630 but might have been $60 if I listened to my Viper brothers.
So Bruce called the flat spots even though his came from his car sitting too long, and Next Phase figured out the same solution of rebalancing the wheels even though you just had them balanced (but I bet Next Phase has flat spots that caused his issue). Thanks for playing guys.
