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woodbeecat
06-12-2010, 06:57 AM
Just rebuilt my 69 chevelle power train from the tranny back new fordgline 18 inch wheels new bearings balenced the drive shaft u joints disk brakes all new and now at 70 mph Ive got this harmonic vibration that I cant figure out any one with this same problem have any solutions.

nicks67camaro
06-12-2010, 07:21 AM
would help to know what trans / rear gear / rear suspension / driveshaft shaft diam. / Trans mount / body mounts / who's driveshaft / RPM and Gear vibration happens at.

All these variables can create unwanted harmonics.

Taman
06-12-2010, 07:35 AM
I had a strange vibration but at a certain rpm. New trans, engine and driveshaft. It was the fan clutch.

woodbeecat
06-12-2010, 05:38 PM
the tranny is a turbo 400 with a 3500 stall springs are made by quickensuspension with internal air bags rear end is a 12 bolt posi with 355 gears and mozer axcle bearings the driveshaft is stock and was balanced transmount is new stock body mounts are new stock as for rpm mostley at highway speeds above 4000 rpm under 60 mph its smooth. and the fan clutch is new as well.

Vegas69
06-12-2010, 08:50 PM
Working angles, more specifically driveline angles. You've made some engine and suspension modifications. You need to dial it back in...

nicks67camaro
06-13-2010, 10:23 AM
there is some good info here for checking your angles.

http://www.drivetrain.com/parts_catalog/drivetrain/driveline_angles_and_phasing_problems.html

JEFFTATE
06-14-2010, 07:34 PM
Check your powertrain ( driveline) , driveshaft , and pinion angles..

minendrews68
08-08-2010, 11:56 AM
I had a strange vibration but at a certain rpm. New trans, engine and driveshaft. It was the fan clutch.

I've had this happen as well!!! Although several years ago.

woodbeecat
09-17-2010, 05:53 PM
Thanks for the info checked the u joints first they looked and felt great but just to be on the safe side I changed both the front and back to a high strenght units and it fixed the problem until I get to the 90 to 100 mph speeds and miss harmonic came back now I going to play with the pinion angles to see if this will get rid of it at warp speed the drive train .com web site is a good site for refrence I keep you posted if this works