Vibration at mid 55 mph

My 51 ford 2 door has a 302 with 3 speed trans and at 55 I get a resonating vibration under me. It is not in the steering wheel and u joints seem to be good not slop in driveline.


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wheel balance?
alignment?

 

i had something similar that turned out to be a busted belt in the tire

 

Driveshaft out of balance, bent, misaligned or it still could be a U joint. Check real close around the rubber seals for rust dust. Also check the rear motormount to assure that it isn't bad or broken.

 

joint phasing or balance, .... is it cyclic? like brrrum brrrum noise?

 

I have had a similar problem with my 1950 Ford. After going through every piece on my chassis it turned out that one of my rims was slightly bent and it caused a pulsating vibration around 60.

 

Check your pinion angle too, that can give your driveshaft bad vibes if it's not in the ballpark.

 

Was it ever OK and this just happened, or is this a new build? If a new build, your driveshaft may be too short. Allowing it to orbit around the tailshaft of the trans.

 

Wheel balance is the first thing to check
Rod

 

Check the condition of the transmission mount, too.

 

was just about to say that!^^^

 

I had a new 1966 Chevrolet and had a vibration that I could not figure out. I finally checked the factory steel wheels for roundness. None of the four were round. Put 4 different wheels on and problem was gone.

 

had same problem, wrong u joint up front

 

New build mounts good drive shaft I believe is correct length. I'm goin to go ahead and change u joints just in case. I did find an exhaust hanger broke. Thx fellas


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Good idea. I had this with a 'tight'' U-joint on a OT, and it was a new joint. Check 'em good before re-installing.

 

Try to determine if it is speed or, rpm related. Use a lower gear to achieve the same rpm that you have in high at 55. RPM related vibrations are more likely drive train related.

 

It is speed sensitive when clutch is in the vibe still there. It's not the rpms. I'm also gonna check the wheels for bends and roundness. Also might go ahead and just have drive shaft rebalanced when I swap u joint. Those wheels at just old steels so very well could have some bends in them.


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many good shops can balance the wheel on the car. If you have not looked at this its not a bad idea.

sometimes it can be the rotating assembly that is out of balance and a true wheel on an unbalance assembly can be a bitch to find

 

I had a bad vibration just before 3000 rpm. Turns out my brand new Hayes pressure plate was out of balance. It took a 1" piece of 1/2" round stock to balance it.