vibrating at speed, feels like bad u-joint, but
 

When I get around 55 and get accelerator just right where motor is not accelerating or decelerating I get a vibration that seems like a bad u-joint. Had u-joints checked and they seemed to be okay. Mechanic did say that there seemed to be some exaggerted play in drive coming out of rear end. Have noticed that sometimes you can hear a clunk in rearend when placing cr in gear..oh, the car is a 95 Camaro Z-28 with an LT-1 and an automatic transmission..Have had lots of problems with car but still like it a lot..I am thinking it has something to do with the rearend.On a long drive I cant go much over 63 before it starts vibrating more than I like.. would appreciate any help before I decide to take it to a shop.. At least would like to keep from getting reemed too bad if I had some info. of my own.. thanks:bow:

Re: vibrating at speed, feels like bad u-joint, but
 

55 is usually where wheel balance comes into play, and 65 is where it's extremely bad. so...you may have thrown a weight. i did recently, didnt even know it until i was halfway down the interstate and figured it was the driveshaft. slowed down and it stopped. sped up and it started again.

any way, to tell the difference, get the car to vibrate and look into the rear view mirror. if it's a circular vibration on the mirror, it's the driveshaft, and if it's either up and down or left and right, it's the wheels. i forget which is which, but up and down is either a front or rear wheel, and left and right is left or right...it might be the other way around...there's a rule, but i dont know it offhand.

Re: vibrating at speed, feels like bad u-joint, but
 

well, thanks for that reply. I had tires rotated a while back. Maybe something happened during that process. Appreciate your little mirror trick. However, I think I will just take it to the tire shop tomorrow and have tires balanced. Hopefully that might take care of it..fingers crossed..thanks for your help

Re: vibrating at speed, feels like bad u-joint, but
 

had tires balanced.. wasnt the problem.I still think it must have something to do with the rear end slop..when it starts vibrating I can give it some gas and it will stop vibrating.. it clunks sometime when i put it in drive.. I dont think that is right..any other suggestions..

Re: vibrating at speed, feels like bad u-joint, but
 

well, it's going to cost about as much to have someone change the u-joints as it would to get an aluminum one from GM and replace it from there. i would suggest getting an aluminum one from somewhere with decent mileage (under about 40k) and just doing a replacement. even if you go to a mechanic it's not going to be much as the task is only 4 11mm bolts. that's it. if you do decide to go with new u-joints, get the new driveshaft, bring it to the mechanic, have him replace the joints and then you replace the shaft yourself. save you some money and you know the joints were done right.

if you decide that you want to get a new rear, i'd suggest going for a stocker from a manual car with 3.42 gears and getting a programmer to adjust the gearing. it's cheap, a good gear for an auto, and you can upgrade to the LS1 rear brakes all in one. i did it, and i'm happy.

Re: vibrating at speed, feels like bad u-joint, but
 

A clunk when going into gear is a sign of failing U-joints. They are fairly cheap and easy to change. I'd start there. Also take a look to see if your drive shaft is missing any of the balancing plates. There should be atleast on at each end of the shaft.

Re: vibrating at speed, feels like bad u-joint, but
 

Sounds like excessive gear lash. Vibrations from an unbalanced driveshaft would be anytime your 60+ mph, not just when you get the accelerator "just right". You could try flipping your driveshaft over 180 degrees (unbolt the DS from the pinion yoke and rotate the driveshaft 180.

Re: vibrating at speed, feels like bad u-joint, but
 

okay.. thanks for the replys..sounds like a new or used rearend is in the picture..will check driveshaft first. thanks

Re: vibrating at speed, feels like bad u-joint, but
 

You might wanna the check and make sure the rearend is centered on the body. Look between the top of the rear tire on each side and the body where the jounce bumper is. You should see the same distance on both sides. If not, you may need an adj. panhard bar. Worn u-joints will roar lightly all the time....worse when accelerating. Unless they are missing some needle bearings it's difficult to tell if they are bad by a visual inspection on the car.
Doug

Re: vibrating at speed, feels like bad u-joint, but
 

I would say it sounds like your drive shaft is the problem if the vibration is under your counsel, if its in the steering wheel, then its a problem with your wheels being balanced, or you need an alignment.

Re: vibrating at speed, feels like bad u-joint, but
 

thanks for the posts.planning on moving to a new home soon.has a 4 bay garage with hoist among other stuff.. plan on turning a few wrenches soon..