Body Shakes at 70mph

[Spiller80]

So I bought a 68 Charger about two months ago and when I take it on the highway over 65 the body starts to shake in intervals. It shakes 1 sec then it likely pauses for a second. Like that back and forth any speed over 65mph. Gets worse the faster I go. Is this the driveshaft or something else?

 

[1967coronet]

Start with the basics, check lug nuts, look tires over good for slipped belt, dog nut ect.
Check the rims for missing balance weights and wore out wheel stud holes. Ck, wheel bearings for play.
Check the drive shaft for play at the trans tail bushing and check u joints for wore out loose caps or rusty stuck caps. Ck the drive shaft angle.
Check pinion bearing for play.
Uni lug wheels ? Bent wheel ?

 

[kiwigtx]

Jack the car up at each of the four wheels - in turn / not together.
Check that all four wheels are securely fastened, and not loose against the hubs/brake drums.

I had that happened a long time ago because I used the wrong spacer washers under the lug nuts, and there was a tiny clearance - end result was that it flogged out the lug-holes in the rear wheels. The vibration would come on at speed. It actually ruined the wheels by elongating the holes.

 

[1STMP]

Another culprit could the
harmonic ballancer.
Even road surfaces can
produce a harmonic
effect. Test on a road
with little crown and newer
pavement if possible. This
kinda stuff can be difficult
to pinpoint.

 

[1STMP]

So I bought a 68 Charger about two months ago and when I take it on the highway over 65 the body starts to shake in intervals. It shakes 1 sec then it likely pauses for a second. Like that back and forth any speed over 65mph. Gets worse the faster I go. Is this the driveshaft or something else?

My body shakes (at any
speed), and I'm 69....

 

[kiwigtx]

My body shakes (at any
speed), and I'm 69....

Shaking 69 is a sign of epilepsy....

 

[1STMP]

Shaking 69 is a sign of epilepsy....

I haven't bitten down on any
tounge suppresors as of yet.
Old age sucks. The old
addidge...the mind is willing.
My son is my hands.
I can side with the OP as
I've chased many of these
ghosts.
Laughter is the best
medicine to overcome
any diversity. Appreciate
yours!

 

[Richard Cranium]

 

[1STMP]

Could be my body bushings
are just plain worn out.....
But it's been a long time
since I experienced that
level of turbulance.

 

[chargervert]

Check universal joints, have driveshaft balanced. Also if the torque converter or flywheel is improperly weighted or drilled. Internal balanced engines use neutral balanced converters and flywheels, as well as harmonic balancers. External balances engines use weighted or drilled torque converters,flywheels and harmonic balancers. The wrong combination of these parts will cause vibrations.

 

[Runcharger]

I had a radial T/A decide to separate when it was about 3 years old and cause that. First thing to check.

 

[RemCharger]

There is a date code near the bead, it's the end of a series of numbers/ letters. Like 3214
Is the 32nd week of 2014

 

[haywire 440]

So I bought a 68 Charger about two months ago and when I take it on the highway over 65 the body starts to shake in intervals. It shakes 1 sec then it likely pauses for a second. Like that back and forth any speed over 65mph. Gets worse the faster I go. Is this the driveshaft or something else?

These cars have been around for a long time and who knows the repairs, replacements and mechanics who wrenched on them. I suggest putting on a car lift and inspecting all the frame rails, floors and trunk panels and spot welding to insure they’re in good condition.
Checking tire age, as mentioned above, is also critical.
Keep us updated with your findings.
Happy & safe cruising!

 

[chargervert]

Same thing happened to my 2005 Ram 2500 4x4 diesel. The radial T/A broke the belt, 4 feet of tread peeled off it,and ripped out the fusebox and all the wiring above the left front tire. 3 grand later it's fixed.

 

[Rusty knuckles]

I'd start by checking lug nuts, then u joints. If you don't find it there I'd wager your tires are shot.

 

[Richard Cranium]

Same thing happened to my 2005 Ram 2500 4x4 diesel. The radial T/A broke the belt, 4 feet of tread peeled off it,and ripped out the fusebox and all the wiring above the left front tire. 3 grand later it's fixed.

I remember seeing pictures of the carnage.

 

[Budnicks]

At speed try touching the brakes slightly,
holding the speed it happens at, that can tell you whether
narrowing it down some
it's a brake or wheel component "usually"
could be bent or out of balance driveshaft or dry u-joints or bad
bent axle, bent wheel, warped rotor, dragging rotor/caliper/drum cracked
thrown a weight or 2 even
or your wheel balance
or lug nuts loose or wrong register on the wheels/wobbling etc.

if it's the motor or harmonic balancer/damper
or even a TQ, it will do it at almost all speeds

maybe also a cracked flex-plate
or bad clutch disc if it's a manual
& it could also have a sort of clicking nose too

tires could do it too

 

[Spiller80]

These cars have been around for a long time and who knows the repairs, replacements and mechanics who wrenched on them. I suggest putting on a car lift and inspecting all the frame rails, floors and trunk panels and spot welding to insure they’re in good condition.
Checking tire age, as mentioned above, is also critical.
Keep us updated with your findings.
Happy & safe

At speed try touching the brakes slightly,
holding the speed it happens at, that can tell you whether
narrowing it down some
it's a brake or wheel component "usually"
could be bent or out of balance driveshaft or dry u-joints or bad
bent axle, bent wheel, warped rotor, dragging rotor/caliper/drum cracked
thrown a weight or 2 even
or your wheel balance
or lug nuts loose or wrong register on the wheels/wobbling etc.

if it's the motor or harmonic balancer/damper
or even a TQ, it will do it at almost all speeds

maybe also a cracked flex-plate
or bad clutch disc if it's a manual
& it could also have a sort of clicking nose too

tires could do it too

Thanks for all the ideas for areas to dive into!

 

[luvabbody]

Had a very similar problem years ago with my '72 SSP. Discovered that one of the fan blades had come off! Put a new fan on it and problem gone! Maybe have a look at that.

 

[Spiller80]

Thanks for all the ideas for areas to dive into!

I installed new rear air shocks yesterday and checked all lug nuts. All good with those. Took it out and same problem with the intermittent shaking and vibrating off and on anytime over 65mph.

If I let off the gas or tap the brakes, the rattling goes away, even if I am over 65 mph. So it happens when I am pressing the gas and either holding speed or accelerating.

Does that help narrow it down?

Thanks in advance.