Vibration at over 60

[Kudanut]

Hello. I get a vibration in the floor of my 74 Barracuda when driving at over 60 mph. Driveshaft balance Ball Joints ? 340 automatic trans.


Help !!!! Unsure where to start.....

[dodj]

Put it in neutral at 60mph. then you will know if it is engine or driveline. If the vibe goes away, it's engine. If not, driveline.

[sadil340]

I had a vibration that started after an engine rebuild 35 years ago. I restored the car six years ago and rebuilt or replaced just about everything. The driveline was totally rebuilt. The vibration did not go away. Then one day I was watching "Graveyard Carz" (I always fast forward through the inane dialog to the good parts) where they were finishing a Superbird project. Just as they were about to drop the car from the lift during the final adjustments Worman sees that the engine is sitting crooked in the K-frame and says "that could cause a vibration". I went right down to my garage and put the car up on the lift. Sure as s**t I can see it's crooked.

I loosened all of the engine/trans mounts, jacked the engine around until it all sat straight and then tightened everything up. Vibration gone!

[DocMel]

I had the same prob  Rear end needed rebuilding.   Disconnect driveshaft and wiggle the yoke.  If it wiggles at all, rebuild the dif is the issue

[sadil340]

I had the same prob  Rear end needed rebuilding.   Disconnect driveshaft and wiggle the yoke.  If it wiggles at all, rebuild the dif is the issue

I've also heard the yoke can wear out - most people just throw in U-joints without putting a mic on the yoke.

[ammo]

Had exact same problem a few months back... vibrated at 60mph.   balanced drive shaft, replace bushing/seal in rear of trans... problem gone. 

[Katfish]

First things first, are you sure the tires are all ok? They can become out of round after sitting for a long time.  Swap them around and see if something changes.

[DocMel]

Fellas, I posted about a year ago on this same subject, and this is what I treid till I found the actual prob.  And I rebuilt EVERYTHING that I found along the way, and nothing helped the vibrations:

ALL Tires, balancing and being round
All u joints
front end suspension parts
balanced driveshaft
ALL wheel bearings

Nothing made it better till I checked the yoke

When disconnected from the driveshaft, it would wiggle when worked, and had excessive play when turning by hand 

Come to find out, the rear end was plain worn out. I saw the issues when the pumpkin was pulled:  $1000 later, a complete rebuild of the rear dif and axle, absolutely no vibration

Remember, the rear end is the one thing really no one really pays attention to or wants to deal with if it needs repair, and the average rear end is about 40 years old now

Do check the easy stuff first, but dont avoid looking closely at your dif (not just the yoke) as well: Check your rear end so you dont chase everything around like I did

[Kudanut]

Thanks guys. Now that my driveshaft is out....how do I tell if the rear yoke is worn out and/or rear end has too much play ??   

[Chryco Psycho]

if it moves in any direction other than rotational at all you have a problem

[Kudanut]

Thanks !!! Appreciate the assistance...