Technical Good Vibrations - Beach Boys had them but I don't!

I have a slight vibration in the '50 coupe and I thought it might be due to a broken engine mount, I replaced both of them and here was a slight improvement but under acceleration it's still there.

I have had the tires balanced and aligned the front suspension, it seems the next logical thing would be the drive shaft & universal joints.

Is there anything else I need to try? HRP

 

If the universal joints are good I would take the driveshaft out and rotate it 180 degrees. See if the vibration changes at all......

 

Seized u-joint ?
Bad tranny mount ?

When they balanced the tires did they look at them for a shifted belt etc?

Long shot but could you of lost a weight on a drum?

What I do is put my hand at the 12 o’clock position on the steering wheel fingers spread and drive..... do you see you fingers moving?
Or are your balls jiggling?

Better to figure out front or rear vibe, usually a driveline vine will show up through the seat.


Hope it’s sometjing stupid and not expensive or big job!
Good luck

 

Friend had a bad transmission mount, that caused a vibration. Problem was, it was brand new. We figured it was the top and bottom steel parts touching, before the rubber set up between at the factory.(wherever the factory was) Put the old original back in, everything okay.

 

I chased a vibration in my ot Chevelle for the longest time. Did a lot of the same things you did, but it never went away. Turned out to be the rear end. The guy that built it for me set it up wrong and the ring gear was trying to eat it's way out of it! Hope yours turns out to be something simple.

 

4 bar rear? If so check all 8 bolts an sleves

 

No Dana, leaf springs. HRP

 

Is the vibration road speed specific? Or engine rpm specific?

 

Lowering blocks?
Removed leaves ?
Both result in pinion rotation under acceleration. Pinion rotation throws the pinion angle off and you get a vibration under acceleration.
Go pro camera under the car on a drive can catch this. OORR you can chase your tail around

 

I'd look carefully at u-joints first since you say it shows up under acceleration. To my way of thinking that eliminates tire balance. But, remove the driveshaft to check, not on car. Tight/dry joints will cause this but will 'feel' ok with a shake or rotate test. Be sure to check that all cross/cup fitment is good and locks in place.

Next would be a careful look at the tailshaft bushing. Looseness there will cause similar vibration.

 

^^° 31 Vic; Either good diagnosis...
or a misguided maleprop?

 

Run it up to speed, get into the middle of the vibration. Let off gas, does it go away? If not do it again but this time let off gas AND put in neutral does it go away now?

Usually if it goes away letting off gas it's engine related (exhaust, engine miss, mount, etc). Putting in neutral and it goes away usually transmission, drive shaft, joints etc.

Try that and let me know.

 

I will add another possibility it could be a plug wire or the plug itself speaking from a past experience.I have found over the years to never discount any possibility

 

Probably both

 

Balls giggling????.....

 

Nothing to laugh at...

 

Bill, I notice it more under acceleration, the harder I get on it the more severe the vibration. HRP

 

You might be on to something, although I haven't removed any leaves in the spring packs I did remove the lowering blocks.

 

If it is better after new eng mounts ,check exhaust system also.

 

Stock rear? The yoke [companion flange] on the rear chuck maybe bent if it is the Mechanic style; a hard shift and they can tear/bend even with the FH.

 

And since you mentioned it, great in studio footage of Good Vibrations

 

Giggling balls is the exci Tation

 

Maverick rear. HRP

 

Hey blowby! What is the origin of the vibration diagnosis chart you posted. I have never seen anything like that. I would like to see what procedures are outlined for correction as per the codes. Thanks.

 

Crankshaft dampner? Lippy

 

Hey Danny have you tried running the 50 through its rpm range in park ? just to eliminate any engine balance issues IE flexplate and balancer issues? I know you didn't build the combo thats in the car..just saying..

 

What engine/trans?

 

Try putting the rear axle on jack stands and have someone run it through the gears and rpm ranges in the garage while you watch underneath. Might spot something.

 

Before you pull your driveshaft, put an indicator on it and check the runout.

 

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