vibration under load

[Garys1969RR]

My 65 Belvedere has a driveline vibration that occurs only while under load. The more gas pedal you put in, the more it vibrates. Not a severe vibration, but noticeable mainly thru the floor board. I'm thinking possible U Joint? Any ideas?

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Could some loose trans to engine bolt cause this?

 

[69Bee]

U-Joints or a tranny mount.

 

[Supershafts]

joint or related angle issue

 

[Beekeeper]

Sounds like a possible worn Tailshaft bushing

 

[GetX'd]

What about loose motors mounts. Just a thought....

 

[Meep-Meep]

I'm going to rule out loose tail shaft bushing / slip yoke fit. Under load (accel or decel) the yoke tends to stay put and not flop around.

 

[Banzaiii67]

Doubt this is it, but I had a hack of an exhaust job done by the previous owner who had hangers mounted to the back side of the rear seat floor and it vibrated the floor under any decent amount of load.

 

[Garys1969RR]

Thanks for all your suggestions as to a possible cause. Going to check the U Joints, mounts, and tighten all attaching bolts tomorrow.

 

[67 coronet]

if all that looks good,check pinion bearing too.

 

[2059]

pinion angle. possibly due to wear. All stock? Driveline combo? Any changes in engine, driveline components? Leaf spring changes? suspension changes?

 

[Garys1969RR]

Ok I tightened all the engine to tranny bolts yesterday. A few took as much as 3/4 to 1 turn to get them tight! U joints felt good and tight. Could feel no play in them when I grabbed the driveshaft and tried to move it. Rear u joint is tight. Still a slight vibration under heavy load. Guess I will race it wed and see what happens.

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Could a faulty torque converter cause a vibration under heavy load? If you spin the drive train in any gear with the rear wheels in the air, there is no vibration.

 

[sleepar]

Sounds like pinion angle.... under load the rear climbing up the ring gear... cal tracks Or a snubber and a shim are possible fixes...

 

[Herr_Poopschitz]

If trans bolts were loose, verify converter to flex plate as well...

 

[Garys1969RR]

If trans bolts were loose, verify converter to flex plate as well...

Yes those had got loose a few weeks ago. Made a horrible racket when they were hitting the engine block! Lol. Thought it was about to throw a rod. Tightened them and all was fine after that.

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pinion angle. possibly due to wear. All stock? Driveline combo? Any changes in engine, driveline components? Leaf spring changes? suspension changes?

Many changes have been made to this driveline over the cars life span. I am suspecting pinion angle could be a problem. Will look more at that soon.

 

[demonram]

Here is a thought. I had a vibration same as yours. Had the tranny checked(bushing), checked the mounts everything driveline. Turned out to be my clutch on the fan assembly. I don't know what you are running, but it sure surprised me. It was more pronounced while driving, but when I had it in park and revved the engine I could feel it. Maybe this will help. Good luck! Howard

 

[nm9stheham]

So when this vibration is occuring, does it increase in frequency in proportion to car speed, or does it increase in frequency in proportion to engine RPM's? The initial post implies the former since it says 'driveline' vibration and mentions U-joint, but this distinction is important as to location. Being felt through the floorboards more than the seat tends to point towards the front.

With the car on jack stands, did you look at the driveshaft to see if it looked straight while spinning? But that's not much of a test on stands if this is a load related vibration.

 

[Garys1969RR]

Well the extension housing broke in 2 at the track wed nite! Just took it off today. Not sure what caused it to fail, but I have a spare to put on there. Looks like the rear bushing was really worn out.

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Could be another problem caused it to fail. U joints are tight, slightly bent D Shaft maybe?

 

[bigmanjbmopar]

pinion angle??

post pics so we can see

 

[Meep-Meep]

WOW!! Something definitely not right!!! Check everything for straightness and try again. How is the output shaft? Bent? Hard to imagine but at this point better check the not so likely as well. Good luck.

 

[furyus]

I heard when that happens, it takes out the s p r a g in the trans. Better have it gone through.