Vibration, I think I've tried it all, no luck

**1 of 302** · 08-12-2006, 09:37 AM

I have a 96 Formula convertible M6. It has a VERY strong vibration at 145 KPH (about 90 MPH) The car has an aluminum driveshaft (changed years ago under warranty) I had the wheels balanced, no change. Then I checked the trans mount, it's good. Then I installed a Spohn torque arm and confirmed that the pinion angle is within 1 degree of the trans angle. This actually made the vibration feel worse, but I think it's because of the new mounting location and poly bushings. Next I changed the U-joints and had the driveshaft balance checked. Still no change. Finally I switched rims and tires to some old camaro take-offs that I had with Bridgestones on them. Still no change. What else can I do? The car drives well other than this, and the vibration dissapates a bit over 160 KPH (about 100 MPH) but at 145(90) it's VERY pronounced. Any ideas?

**02T/AWS6** · 08-13-2006, 02:51 PM

i have about the same problem on my 02 trans am ws6, i have a nasty vibration at about 75+ and i've changed my tires and rims and balanced a hundred times as well i'm getting my driveshaft balanced in the next couple of days as well, but what i think the real problem, and it might be for u as well is the pinion bearing in the rear-end. does your rear-end make a wining noise at high speeds? mine does and thats why i think its the bearing in the rear-end

**1 of 302** · 08-14-2006, 05:19 AM

Actually yes, I do have a bit of a whine from the diff, but my pinion bearing failed on me about 7 or 8 years ago (when the car was under warranty) and it didn't whine, it growled (LOUDLY!!!) I had always heard that whining was from the mesh of the ring and pinion, not a bearing. Anyway, I actually hope that's it. I don't really care what the problem is, I just want to know what to do next in order to fix the damn thing!!!

**02T/AWS6** · 08-15-2006, 10:57 AM

yeah i know it sucks cuz i'm going through the same problem, i cna't really find what its coming from.... hopeuflly i will and when i do i'll let u know what it was for me

**Hwystar** · 08-16-2006, 06:31 PM

I have a 98 with a moser 12 bolt and a spohn torque arm and I also have a vibration at 90 to 100 mph. I've tried everything to figure it out, readjusted the ta as per every suggested way on this board and others and the only way I' ve found that works is to remove the ta and put it back to stock and the vibration is gone. Try that and see what happens. good luck

**1 of 302** · 08-23-2006, 07:51 AM

Success (well, sort of). I decided that the only thing I haven't tried is the tranny mount. It looked good, no tears or separation, but I bought a new one anyway. Both are factory, but the new one looked MUCH taller than the old one. I think the old one just compressed over the last 10 years. Anyway, with the new mount the vibration is 90% gone! I'm still going to try adjusting the Spohn arm a bit more, and also try swapping back to the stock arm, but I can already live with the car as is, so I'm very happy! Thanks for the help everyone!

**cruz3** · 09-24-2006, 09:34 AM

I had a driveshaft yoke replaced - the one that connects to the tranny. Splines were worn pretty bad. After some research, I believe the tranny mount was worn which allowed the yoke to go bad. That could be the last 10%.

**ninobrn99** · 09-24-2006, 07:06 PM

pinion and yoke or axle bearings

**cruz3** · 10-08-2006, 09:52 AM

Did the tranny mount and the torque arm bushing. Both from Energy Suspension. The tranny mount provides a noticeable increase in vibration - mostly from the engine. My 460LE is always kinda clunky. Maybe I'm spoiled from our other vehicles.

**mysticZ** · 10-13-2006, 03:16 PM

Sorry to get in this late but heres my story. My vibration is RPM related. Changed motor yoke and DS. the only thing I haven't changed is the TC. Right now it is a GM perf 2300 but its the only thing that I know is left. So as soon as I get the extra$$$$ it will be changed. If that don't work than I'll leave it till it breaks something, the problem solved.

**cruz3** · 11-05-2006, 06:52 PM

Just had the driveline balanced and have two brand new u joints. No more vibration, but it is still clunky.

I did notice a significant amount of play in the tranny tailshaft when I had the driveshaft off. Anyone want to bet that this is the clunking noise source? Its better - even with the poly mount, but I don't think all is healthy.

My local Dealer, McCurley Chevrolet, was given two opportunities to fix the situation on my GM Certified used camaro. They replaced the front splined yoke on the driveshaft citing that the splines were worn. I asked them about the tailshaft splines and they said they were fine. Unfortunately, McCurley didn't take the time to check the balance of the driveshaft because it was WAYYYY out of spec.

Anyone have any suggestions?