Mike Brichta Posted June 28, 2011 Share Posted June 28, 2011 I have lately developed a rather severe vibration which seems to be coming from the rear of the car since I do not feel the vibration in the steering wheel. The car runs great with no issues until I get to around 60 mph then it vibrates so much that the rear view mirror is blurry. Obviously I would like to figure out what is causing the issue but I'm not sure where to start. I have already pulled the driveshaft and rear wheels but have found no problems. I have even switched all 4 wheels and tires but it is still there. In the next few days I will try another driveshaft. The car has a BOP 10-bolt rear and I installed a new 3.55 posi unit a few years ago. I am wondering if the gear lash could now be the issue. Would the vibration indicate the gears are too loose or too tight? Any other suggestion/ideas? Thanks in advance!! Mike Quote Link to comment Share on other sites More sharing options...
Big Jim Posted June 28, 2011 Share Posted June 28, 2011 I was going to suggest wheel balance, Air pressure and possibly flat spots from sitting for a while but you probably already considered that. I had the same issue after getting mine back on the road when I went to Anderson 2 years ago. I don't do a lot of interstate driving so I don't get a chance to notice it I have since completely rebuilt my rearend since then. Quote Link to comment Share on other sites More sharing options...
Mike Brichta Posted June 28, 2011 Author Share Posted June 28, 2011 Hey Jim, Yes one of the first things I tried was switching out all 4 wheels and tires with a known good set. Tonight I will switch out the driveshaft and test drive again. I was considering replacing the rear axel bearings but when they go bad they usually rumble all of the time not just a 60 mph. I will also check the fluid level and maybe pull the rear cover off and look for problems. If all else fails I will have to take the rear to get checked but I know they will want to replace everything and I'm not sure I want to spend $1200 to rebuild a 10-bolt rear. Thanks!! Mike Quote Link to comment Share on other sites More sharing options...
Andreas Posted June 28, 2011 Share Posted June 28, 2011 Just another thought: Have you done any exhaust work recently? Could a piece of exhaust be hitting somewhere? Also, how old are the suspension bushings? Check that all bolts are there (control arms, shocks, etc.) Quote Link to comment Share on other sites More sharing options...
Mike Brichta Posted June 28, 2011 Author Share Posted June 28, 2011 The exhaust is about 4 years old and appears to be nice and tight. All of the bushings are also around 4 years old and since I hardly drive the car they should be good also but I will check to be sure. It sort of has me baffled for now. Everything has been replaced at one time or another and looks good. Anyone have any rear end rebuilding experience? How can I check to see if the posi is shimmed correctly? What happens if it is too loose or too tight? Quote Link to comment Share on other sites More sharing options...
Andreas Posted June 28, 2011 Share Posted June 28, 2011 Once you have the driveshaft removed, see if the yoke on the differential has any in-out movement. If it has, that's a very bad sign... With a bad setup, you will get a lot of noise and vibration and/or excessive wear on the gears... Quote Link to comment Share on other sites More sharing options...
MC-71 Posted June 28, 2011 Share Posted June 28, 2011 Do you feel the vibration at the shifter. Check those rubber isolators on the ends of the tranny crossmember. The crossmember is probably rusted and the rubbers are shot. Over 40 years old. Pick up a Chevelle crossmember. That will bolt to the frame and the problem should go away. I did mine years ago. I believe they repo that crossmember now. Yes, the vibration did come up around 60 MPH. Quote Link to comment Share on other sites More sharing options...
Mike Brichta Posted June 28, 2011 Author Share Posted June 28, 2011 All great suggestion guys!! I will make a list and start checking these things tonight. I think I already converted all of my crossmembers to Chevelle ones years ago but I will check to make sure. I know I already checked to see if the pinion nut was tight and it was. I did not check for front to back play but will check tonight. Keep the ideas coming !! I want to fix this thing. It is driving me crazy and feels really unsafe when driving fast. Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted June 28, 2011 Share Posted June 28, 2011 how about drive line angle? Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted June 29, 2011 Share Posted June 29, 2011 how about drive line angle? I just fixed my vibration because of driveshaft angles Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted June 29, 2011 Share Posted June 29, 2011 Is it possable you could have thrown a weight off the drive shaft especially if it something new . Has any other work been done to the drive line reciently? or suspension? possably rear springs and changed the drive shaft angle. Possably a dent in the drive shaft? bad u joint? could have thrown a weight off a brake drum also. Just a couple thoughts. Quote Link to comment Share on other sites More sharing options...
Mike Brichta Posted June 29, 2011 Author Share Posted June 29, 2011 I looked at the drive shaft again last night and don't see anything missing as far as weights are concerned. U-joints are only a few years old and not many miles. They move freely. I also checked the suspension (already rebuilt) and everything else I could think of to check. So far, nothing conclusive. I wanted to switch out the driveshaft last night but the spare one I have is different because one is for a 12 bolt and one is for a 10 bolt. The U-joints are different sizes. I won't start anything else until I get the driveshaft checked. I will post an update once I get it checked. Mike Quote Link to comment Share on other sites More sharing options...
wallaby Posted July 1, 2011 Share Posted July 1, 2011 Often times you can get an idea of where the problem lies by the frequency of the vibration...maybe resonance is a better word. The wheels and axles rotate rather slowly (but they're heavy) and create a low rumble and shake when they have issues. The driveshaft, u-joints and pinion spin nearly 4 times faster and cause more of a vibration than a shake. It can be difficult to locate such issues. Running the car in gear while in the air can be scary all by itself, but even at idle speeds you should be able to hear a bearing problem with a mechanics stethoscope if you probe around the pinion and axle bearing areas. I had bad carrier bearing a while ago, and they made a grumbling noise but no real vibration to speak of. Another area to check is the front end of the driveshaft; make sure there isn't any up/down movement in the transmission yoke. Quote Link to comment Share on other sites More sharing options...
stangeba Posted July 1, 2011 Share Posted July 1, 2011 In my quest to fix a similar problem, I found a worn axle shaft (where the bearing rides) on a 12 bolt, replaced the bearing with an off set bearing, still there, found a bad U-Joint, only a about 15,000 miles on it, replaced it, still there, found a bad race in a two year old rotor, replaced it mostly gone but not perfect. I'm starting to think it's the STUPID Poly bushings I used when I re-did the ft end. I don't have wheels to try replacing all the tires but they are only 4 years old. Now I just live with it and stay under 72 MPH. Good luck and keep us posted. Bruce Quote Link to comment Share on other sites More sharing options...
Mike Brichta Posted July 4, 2011 Author Share Posted July 4, 2011 I dropped the driveshaft off on Saturday morning but they won't get to check it until sometime this week. I won't be able to pick it up until next Saturday anyway. I remember years ago I was putting a TH400 into a car that previously had a TH350 and took the driveshaft to the same place to have it shortened. The guy called me back and said the driveshaft was bent and could not be balanced. I never had problems with the driveshaft before but they made me a new one and all was ok. Is it possible for these things to just go bad after a long time? Mike Quote Link to comment Share on other sites More sharing options...
Mike Brichta Posted July 11, 2011 Author Share Posted July 11, 2011 Update on the "vibration" issue =============================== I picked up my driveshaft on Saturday morning and the guy told me he tested the driveshaft with the U-joints and front yoke and found the problem to be in the rear U-joint. He said the driveshaft is fine but the rear U-joint spring locks were too narrow. That didn't make any sense to me until I looked at the U-joint and the spring locks. The U-joint was replaced and the joint itself is fine but it has the "inner spring locks" and the locks themselves had lots of play in the slots of the caps. I thought they were all the same thickness but apparently not. He said he didn't have any of the older thicker ones but I was able to find some thicker ones in my "extra parts bin" and that fixed the problem. I'm not sure why the ones on the U-joint were not the correct thickness. Maybe the U-joint came with the wrong ones? Has anyone else experienced this problem? I haven't. Anyway, all is good again. It cost me $45 to find and correct the problem. I will be sure I get the correct thickness spring locks the next time I purchase a new U-joint. Mike Quote Link to comment Share on other sites More sharing options...
stangeba Posted July 12, 2011 Share Posted July 12, 2011 Interesting, thanks for letting us know what the problem was. Glad that fixed it! Mine has outer C clips. When checking mine for a similar vibration I found one of the needles came out and got squished into the end cap. This probably happened when I removed the DS and a U Joint cap fell off dumping all the needles on the floor. Quote Link to comment Share on other sites More sharing options...
Big Jim Posted July 12, 2011 Share Posted July 12, 2011 After I had my rear end rebuilt with all new parts it still has a vibration when I let off of the throttle or easy on the throttle. My mechanic said to drive it for 500 miles and bring it back to him and he will check it out. I bought everything from Randy's Ring and pinion and changed to a limited slip differential and we used high performance gear lube with the posi additive from Chevy Dealer. Quote Link to comment Share on other sites More sharing options...
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