high speed vibration

[Ric]

I have a 1965 ranchero with 3 speed stick and 170 engine. Both of which have been professionaly rebuilt. When I hit 60 mph I get a real fast type of vibration It also has a new clutch and all in it. I checked the u joints and they were perfect . This feels like it is related to rpm's. Does anyone have any suggestions what it could be
Ric Johnson

[gtaroger]

Does it vibrate in just third gear? Where does it feel like it's coming from? The floor,the steering wheel,the front or the rear of the car? Place you hand on the trans tunnel as you get to the point where it starts to Vibrate. Can you feel it in the trans tunnel.If you push the clutch in ,Does it go away. If you push the clutch in ever so lightly can you feel it in the pedal?Is your drive shaft balanced? Just tring to help you fiure out where the vib is coming from.Also take the drive shaft with your hands and shake it back and forth at thepoint where the yoke goes into the tail of the trans. If you got side to side play where the yoke goes into the trans you might need a new bushing in the tail of the trans. I had this happen to me on my car. Trans guy install wrong yoke to drive shaft . I replaced the yoke and bushing. Fixed my problem.Doubt if it's your problem. Good luck Roger

[Luva65wagon]

Yeah, what the other Roger said...

Reminds me of a story (oh man, here he goes with his stories...). My dad had a 53 Plymouth until his 80's though he stopped driving it in his 60's. He wanted me so bad to take that car home and restore it, but I couldn't. So he ended up selling it for a song to some friend of a friend of his. Only to be upset that this friend intended not to restore it as he thought, but make a hot rod out of it. Anyway, that's not the story I intended to tell. I remember in 1971 (I was 11 at the time) him finally saying enough with this crazy vibration he had in the car. He'd changed everything you could and couldn't figure it out. So he finally concluded it had to be in the motor, so we did a garage rebuild, block still in car (as I recall) and pulled the pistons to find the builder he got the motor from (JC Whitney, believe it or not) had built the motor with half car connecting rods and half truck connecting rods. This flathead 6 was also used in trucks and industrial equipment and had heavier rods for those applications. All car rods and his vibration was finally gone.

Probably unrelated to your issue, but you never know.

[gtaroger]

Finding the problem can be harder than fixing it.I worked in a Ford dealership back in the 70's. We started having problems with rattling coming from new cars.It turned out the Ford had a strike and right before they shut down the plants the workers were pretty mad at Ford for doing some mean crap to the workers.To pay back Fords The workers put washers in the floor pans,exhaust pipes,doors and any other place they could think of.I remember being put in the trunk while another mechanic drove me around the parking lot across from the dealership. It was very rough . Found some rattles that way. Put the cars on hoist and took a rubber hammer and went back and forth hitting the floor pan. Same with the exhaust pipes. Found washers there ,Had to cut the screen out of the end of the pipe if it were in the end closest the the bumper. If on the forward side rear axle we had to cut the pipe and reweld it after removing washer.Be creative . Roger

[BadBird]

I spent a ton of money trying to figure out a vibration. I was told rear end pinion angle. Thought it was tires. After a lot of time and effort I found the drive shaft I had shortened was out of balance. It took three trips to the shop to have them finally get it right. Numerous things it can be. Best of luck. Larry

[gtaroger]

Could be a tire. My friend had a Trans Am that vibrated . It turned out to be a broken belt in a rear tire.

[Ilvmygt]

Do you know what rpm 60mph is? Does it vibrate at that rpm in neutral? If it does not that may eliminate the engine, trans, and clutch.

Is this a new problem or did it show up after some repair was done?

You said you inspected the u joints. Did you inspect the entire drive-line for evidence of missing weights? Maybe a weight fell off.

Will the place you purchased your tires re-balance them?

When was the last time the car was tuned? Could it be missing in a high load condition. Maybe a bad plug or wire.