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Message: <blockquote data-quote="ryclef331" data-source="post: 806328" data-attributes="member: 8067">I see you have adjustable control arms. Try this....get the car to the speed it vibes at....Now, you're looking for 3 things....How bad is the vibe AT THAT SPEED when you A) acellerate, B) decel, and C) just cruise. My money is you'll find a difference in all three. With cruise being the middle of the two. If the vibes are WORSE when you accelerate, your PINION ANGLE is too high. If its worse when you slow down...your pinion angle is too low. When you decel, MAKE SURE the clutch is OUT. This loads the rear suspension and makes the rear end react. When you get on it, the pinion wants to move up due to the pinion trying to climb the ring gear. This causes the rear end to attempt to rotate the pinion snout upwards thus changing your pinion angle. Ideally, you want pinion angle to be on the same plane as the crankshaft when you are on the throttle. For MOST applications, depending on the type of bushings used in the control arms, this is 3 degrees down...NOW....that doesn't mean 3 degrees down from "level." It means 3 degrees LESS that what the crankshaft is. The actual angle of thee driveshaft is not an issue. Its the angle of the pinion compared to the crank. How do you get that measurement you ask? Hold on baby birds, I'll feed you....With the car in the air and WITH THE WEIGHT ON THE SUSPENSION (i.e. ramps under the front and jackstands under the axle) and Using an angle finder, place it flat against the face of harmonic balancer....write that angle down. the engine tilts back slightly so lets say you record 5 degrees. Now, measure the angle of the verticle face of the pinon flange (you may wanna unhook the driveshaft and swing it out of the way a bit for this)...lets say you record a -2 degrees....the opposite direction of tilt that the crank was. Your pinion angle would then be 7 degrees. Still with me? To PROPERLY ADJUST THIS, unhook the passenger side upper control arm and let it swing free. Loosen the nuts on the upper driver's side. Now lengthen the driver's side arm while checking the angle off the pinion flange until you get a +2 degree reading. The difference between your crank angle and pinion is 3 degrees....well within your ball park. Loosen the adjustment nuts on the passenger control arm and adjust it to get the bolt to slide in freely while reinstalling it. Doing it this way prevents any sort of binding on the rear suspension that will prevent any erratic handling. If you want to get REAL technical, put someone's a$$ in the driver's seat or something while you do all this. It will simulate the car's "race weight" if you will. EVerything above is FREE. from what you've done and what you've described, THIS is what you issue MOST likely is. There is a distinct difference in a "wheel balance" problem and a driveline vibe. A driveline vibe is much more intense and a higher frequency. Give it a shot before spending money on parts. If you have any confusion on anything i posted, check out <a href="http://www.baselinesuspensions.com" target="_blank">www.baselinesuspensions.com</a> and read their tutorials. GREAT information on getting a rear suspension set up correctly.</blockquote>