Vibration at higher speeds
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Senior User
Joined: Sep 2001
Posts: 356
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Vibration at higher speeds
Hey guys
I have a 77 f150 400/C6. Previously it would vribrate at 60+ mph. I took it in and the shop said it was the U-joints and the tailhousing bushing. I pulled the shaft and my mechanic said the u-joints were fine but i replaced tehm anyway cause they were original. Well now I drove it to Cottmans cause they rebuilt the tranny to have them check the bushing. On the way i notice the vibration was gone but i never went over 65 mph. They said it looked good. On the way home i brought it up to 75 and when i let off the gas the vibration was back. If i accelerated back to 70 it was gone. I dont think there was any under 65 either. I do have some slack in the rearend.
Any suggestions as to what this could be? Sorry for the long post but i thought ya'll need all the info.
Thanks
David
I have a 77 f150 400/C6. Previously it would vribrate at 60+ mph. I took it in and the shop said it was the U-joints and the tailhousing bushing. I pulled the shaft and my mechanic said the u-joints were fine but i replaced tehm anyway cause they were original. Well now I drove it to Cottmans cause they rebuilt the tranny to have them check the bushing. On the way i notice the vibration was gone but i never went over 65 mph. They said it looked good. On the way home i brought it up to 75 and when i let off the gas the vibration was back. If i accelerated back to 70 it was gone. I dont think there was any under 65 either. I do have some slack in the rearend.
Any suggestions as to what this could be? Sorry for the long post but i thought ya'll need all the info.
Thanks
David
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Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
It could be from too much play in the rearend. You might want to check the driveshaft balance too, but if it changes with throttle position, then I would say it could be in the rearend. Make sure that the pinion nut is good and tight.
Jimmy
Jimmy
